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From: Richard Biener <richard.guenther@gmail.com>
To: Alexandre Oliva <oliva@adacore.com>
Cc: gcc-patches@gcc.gnu.org,
	Jeremy Bennett <jeremy.bennett@embecosm.com>,
	 Craig Blackmore <craig.blackmore@embecosm.com>,
	Graham Markall <graham.markall@embecosm.com>,
	 Martin Jambor <mjambor@suse.cz>, Jan Hubicka <hubicka@ucw.cz>,
	Jim Wilson <wilson@tuliptree.org>,
	 Jeff Law <jeffreyalaw@gmail.com>,
	Jakub Jelinek <jakub@redhat.com>
Subject: Re: [PATCH v5] Introduce strub: machine-independent stack scrubbing
Date: Tue, 5 Dec 2023 10:01:27 +0100	[thread overview]
Message-ID: <CAFiYyc12h-oLD31wUjGeHBU35d_BROtrfdTiujh7EAdNic6bDA@mail.gmail.com> (raw)
In-Reply-To: <ormsuswkss.fsf_-_@lxoliva.fsfla.org>

On Sat, Dec 2, 2023 at 6:56 PM Alexandre Oliva <oliva@adacore.com> wrote:
>
> On Nov 30, 2023, Richard Biener <richard.guenther@gmail.com> wrote:
>
> > On Thu, Nov 30, 2023 at 5:13 AM Alexandre Oliva <oliva@adacore.com> wrote:
>
> >> >> Here are changes.html entries for this and for the other newly-added
> >> >> features:
> >>
> >> > LGTM.
> >>
> >> Was that an ok to install, once the relevant pieces are in?
>
> > See below.
>
> FWIW, I meant specifically about the web site changes.html patch in the
> question above.

Ah yes, of course (OK)!

> > In the end I was hoping for general comments on the cgraph usage
> > and for the specifics indeed being able to use IPA mechanisms
> > to perform the stmt re-writing (and re-gimplification) for the value to
> > by-reference replacement.  The core copy_body mechanism
> > might support it by simply registering *new_param as replacement
> > for 'old_param' in the copy_body_data decl_map.
>
> I see.  That's indeed a good direction for evolution, that I'd like us
> to take, and having the base code in with some more manageable way to
> experiment smaller changes will make this transition significantly
> easier IMHO.  But that kind of infrastructure change would also likely
> be stage1 material.

Agreed.

> > Iff the IPA folks (Honza or Martin) don't have any further comments
> > the patch is OK to install by next Monday.
>
> Thanks, here's the consolidated patch that I hope to install by Monday.

Thanks,
Richard.

>
> Introduce strub: machine-independent stack scrubbing
>
> This patch adds the strub attribute for function and variable types,
> command-line options, passes and adjustments to implement it,
> documentation, and tests.
>
> Stack scrubbing is implemented in a machine-independent way: functions
> with strub enabled are modified so that they take an extra stack
> watermark argument, that they update with their stack use, and the
> caller can then zero it out once it regains control, whether by return
> or exception.  There are two ways to go about it: at-calls, that
> modifies the visible interface (signature) of the function, and
> internal, in which the body is moved to a clone, the clone undergoes
> the interface change, and the function becomes a wrapper, preserving
> its original interface, that calls the clone and then clears the stack
> used by it.
>
> Variables can also be annotated with the strub attribute, so that
> functions that read from them get stack scrubbing enabled implicitly,
> whether at-calls, for functions only usable within a translation unit,
> or internal, for functions whose interfaces must not be modified.
>
> There is a strict mode, in which functions that have their stack
> scrubbed can only call other functions with stack-scrubbing
> interfaces, or those explicitly marked as callable from strub
> contexts, so that an entire call chain gets scrubbing, at once or
> piecemeal depending on optimization levels.  In the default mode,
> relaxed, this requirement is not enforced by the compiler.
>
> The implementation adds two IPA passes, one that assigns strub modes
> early on, another that modifies interfaces and adds calls to the
> builtins that jointly implement stack scrubbing.  Another builtin,
> that obtains the stack pointer, is added for use in the implementation
> of the builtins, whether expanded inline or called in libgcc.
>
> There are new command-line options to change operation modes and to
> force the feature disabled; it is enabled by default, but it has no
> effect and is implicitly disabled if the strub attribute is never
> used.  There are also options meant to use for testing the feature,
> enabling different strubbing modes for all (viable) functions.
>
>
> for  gcc/ChangeLog
>
>         * Makefile.in (OBJS): Add ipa-strub.o.
>         (GTFILES): Add ipa-strub.cc.
>         * builtins.def (BUILT_IN_STACK_ADDRESS): New.
>         (BUILT_IN___STRUB_ENTER): New.
>         (BUILT_IN___STRUB_UPDATE): New.
>         (BUILT_IN___STRUB_LEAVE): New.
>         * builtins.cc: Include ipa-strub.h.
>         (STACK_STOPS, STACK_UNSIGNED): Define.
>         (expand_builtin_stack_address): New.
>         (expand_builtin_strub_enter): New.
>         (expand_builtin_strub_update): New.
>         (expand_builtin_strub_leave): New.
>         (expand_builtin): Call them.
>         * common.opt (fstrub=*): New options.
>         * doc/extend.texi (strub): New type attribute.
>         (__builtin_stack_address): New function.
>         (Stack Scrubbing): New section.
>         * doc/invoke.texi (-fstrub=*): New options.
>         (-fdump-ipa-*): New passes.
>         * gengtype-lex.l: Ignore multi-line pp-directives.
>         * ipa-inline.cc: Include ipa-strub.h.
>         (can_inline_edge_p): Test strub_inlinable_to_p.
>         * ipa-split.cc: Include ipa-strub.h.
>         (execute_split_functions): Test strub_splittable_p.
>         * ipa-strub.cc, ipa-strub.h: New.
>         * passes.def: Add strub_mode and strub passes.
>         * tree-cfg.cc (gimple_verify_flow_info): Note on debug stmts.
>         * tree-pass.h (make_pass_ipa_strub_mode): Declare.
>         (make_pass_ipa_strub): Declare.
>         (make_pass_ipa_function_and_variable_visibility): Fix
>         formatting.
>         * tree-ssa-ccp.cc (optimize_stack_restore): Keep restores
>         before strub leave.
>         * multiple_target.cc (pass_target_clone::gate): Test seen_error.
>         * attribs.cc: Include ipa-strub.h.
>         (decl_attributes): Support applying attributes to function
>         type, rather than pointer type, at handler's request.
>         (comp_type_attributes): Combine strub_comptypes and target
>         comp_type results.
>         * doc/tm.texi.in (TARGET_STRUB_USE_DYNAMIC_ARRAY): New.
>         (TARGET_STRUB_MAY_USE_MEMSET): New.
>         * doc/tm.texi: Rebuilt.
>         * cgraph.h (symtab_node::reset): Add preserve_comdat_group
>         param, with a default.
>         * cgraphunit.cc (symtab_node::reset): Use it.
>
> for  gcc/c-family/ChangeLog
>
>         * c-attribs.cc: Include ipa-strub.h.
>         (handle_strub_attribute): New.
>         (c_common_attribute_table): Add strub.
>
> for  gcc/ada/ChangeLog
>
>         * gcc-interface/trans.cc: Include ipa-strub.h.
>         (gigi): Make internal decls for targets of compiler-generated
>         calls strub-callable too.
>         (build_raise_check): Likewise.
>         * gcc-interface/utils.cc: Include ipa-strub.h.
>         (handle_strub_attribute): New.
>         (gnat_internal_attribute_table): Add strub.
>
> for  gcc/testsuite/ChangeLog
>
>         * c-c++-common/strub-O0.c: New.
>         * c-c++-common/strub-O1.c: New.
>         * c-c++-common/strub-O2.c: New.
>         * c-c++-common/strub-O2fni.c: New.
>         * c-c++-common/strub-O3.c: New.
>         * c-c++-common/strub-O3fni.c: New.
>         * c-c++-common/strub-Og.c: New.
>         * c-c++-common/strub-Os.c: New.
>         * c-c++-common/strub-all1.c: New.
>         * c-c++-common/strub-all2.c: New.
>         * c-c++-common/strub-apply1.c: New.
>         * c-c++-common/strub-apply2.c: New.
>         * c-c++-common/strub-apply3.c: New.
>         * c-c++-common/strub-apply4.c: New.
>         * c-c++-common/strub-at-calls1.c: New.
>         * c-c++-common/strub-at-calls2.c: New.
>         * c-c++-common/strub-defer-O1.c: New.
>         * c-c++-common/strub-defer-O2.c: New.
>         * c-c++-common/strub-defer-O3.c: New.
>         * c-c++-common/strub-defer-Os.c: New.
>         * c-c++-common/strub-internal1.c: New.
>         * c-c++-common/strub-internal2.c: New.
>         * c-c++-common/strub-parms1.c: New.
>         * c-c++-common/strub-parms2.c: New.
>         * c-c++-common/strub-parms3.c: New.
>         * c-c++-common/strub-relaxed1.c: New.
>         * c-c++-common/strub-relaxed2.c: New.
>         * c-c++-common/strub-short-O0-exc.c: New.
>         * c-c++-common/strub-short-O0.c: New.
>         * c-c++-common/strub-short-O1.c: New.
>         * c-c++-common/strub-short-O2.c: New.
>         * c-c++-common/strub-short-O3.c: New.
>         * c-c++-common/strub-short-Os.c: New.
>         * c-c++-common/strub-strict1.c: New.
>         * c-c++-common/strub-strict2.c: New.
>         * c-c++-common/strub-tail-O1.c: New.
>         * c-c++-common/strub-tail-O2.c: New.
>         * c-c++-common/torture/strub-callable1.c: New.
>         * c-c++-common/torture/strub-callable2.c: New.
>         * c-c++-common/torture/strub-const1.c: New.
>         * c-c++-common/torture/strub-const2.c: New.
>         * c-c++-common/torture/strub-const3.c: New.
>         * c-c++-common/torture/strub-const4.c: New.
>         * c-c++-common/torture/strub-data1.c: New.
>         * c-c++-common/torture/strub-data2.c: New.
>         * c-c++-common/torture/strub-data3.c: New.
>         * c-c++-common/torture/strub-data4.c: New.
>         * c-c++-common/torture/strub-data5.c: New.
>         * c-c++-common/torture/strub-indcall1.c: New.
>         * c-c++-common/torture/strub-indcall2.c: New.
>         * c-c++-common/torture/strub-indcall3.c: New.
>         * c-c++-common/torture/strub-inlinable1.c: New.
>         * c-c++-common/torture/strub-inlinable2.c: New.
>         * c-c++-common/torture/strub-ptrfn1.c: New.
>         * c-c++-common/torture/strub-ptrfn2.c: New.
>         * c-c++-common/torture/strub-ptrfn3.c: New.
>         * c-c++-common/torture/strub-ptrfn4.c: New.
>         * c-c++-common/torture/strub-pure1.c: New.
>         * c-c++-common/torture/strub-pure2.c: New.
>         * c-c++-common/torture/strub-pure3.c: New.
>         * c-c++-common/torture/strub-pure4.c: New.
>         * c-c++-common/torture/strub-run1.c: New.
>         * c-c++-common/torture/strub-run2.c: New.
>         * c-c++-common/torture/strub-run3.c: New.
>         * c-c++-common/torture/strub-run4.c: New.
>         * c-c++-common/torture/strub-run4c.c: New.
>         * c-c++-common/torture/strub-run4d.c: New.
>         * c-c++-common/torture/strub-run4i.c: New.
>         * g++.dg/strub-run1.C: New.
>         * g++.dg/torture/strub-init1.C: New.
>         * g++.dg/torture/strub-init2.C: New.
>         * g++.dg/torture/strub-init3.C: New.
>         * gnat.dg/strub_attr.adb, gnat.dg/strub_attr.ads: New.
>         * gnat.dg/strub_ind.adb, gnat.dg/strub_ind.ads: New.
>
> for  libgcc/ChangeLog
>
>         * Makefile.in (LIB2ADD): Add strub.c.
>         * libgcc2.h (__strub_enter, __strub_update, __strub_leave):
>         Declare.
>         * strub.c: New.
>         * libgcc-std.ver.in (__strub_enter): Add to GCC_14.0.0.
>         (__strub_update, __strub_leave): Likewise.
> ---
>  gcc/Makefile.in                                    |    2
>  gcc/ada/gcc-interface/trans.cc                     |   18
>  gcc/ada/gcc-interface/utils.cc                     |   73
>  gcc/attribs.cc                                     |   37
>  gcc/builtins.cc                                    |  269 ++
>  gcc/builtins.def                                   |    4
>  gcc/c-family/c-attribs.cc                          |   82
>  gcc/cgraph.h                                       |    2
>  gcc/cgraphunit.cc                                  |    5
>  gcc/common.opt                                     |   29
>  gcc/doc/extend.texi                                |  312 ++
>  gcc/doc/invoke.texi                                |   60
>  gcc/doc/tm.texi                                    |   19
>  gcc/doc/tm.texi.in                                 |   19
>  gcc/gengtype-lex.l                                 |    3
>  gcc/ipa-inline.cc                                  |    6
>  gcc/ipa-split.cc                                   |    7
>  gcc/ipa-strub.cc                                   | 3573 ++++++++++++++++++++
>  gcc/ipa-strub.h                                    |   45
>  gcc/passes.def                                     |    2
>  gcc/testsuite/c-c++-common/strub-O0.c              |   14
>  gcc/testsuite/c-c++-common/strub-O1.c              |   15
>  gcc/testsuite/c-c++-common/strub-O2.c              |   16
>  gcc/testsuite/c-c++-common/strub-O2fni.c           |   15
>  gcc/testsuite/c-c++-common/strub-O3.c              |   12
>  gcc/testsuite/c-c++-common/strub-O3fni.c           |   15
>  gcc/testsuite/c-c++-common/strub-Og.c              |   16
>  gcc/testsuite/c-c++-common/strub-Os.c              |   18
>  gcc/testsuite/c-c++-common/strub-all1.c            |   32
>  gcc/testsuite/c-c++-common/strub-all2.c            |   24
>  gcc/testsuite/c-c++-common/strub-apply1.c          |   15
>  gcc/testsuite/c-c++-common/strub-apply2.c          |   12
>  gcc/testsuite/c-c++-common/strub-apply3.c          |    8
>  gcc/testsuite/c-c++-common/strub-apply4.c          |   21
>  gcc/testsuite/c-c++-common/strub-at-calls1.c       |   30
>  gcc/testsuite/c-c++-common/strub-at-calls2.c       |   23
>  gcc/testsuite/c-c++-common/strub-defer-O1.c        |    7
>  gcc/testsuite/c-c++-common/strub-defer-O2.c        |    8
>  gcc/testsuite/c-c++-common/strub-defer-O3.c        |  110 +
>  gcc/testsuite/c-c++-common/strub-defer-Os.c        |    7
>  gcc/testsuite/c-c++-common/strub-internal1.c       |   31
>  gcc/testsuite/c-c++-common/strub-internal2.c       |   21
>  gcc/testsuite/c-c++-common/strub-parms1.c          |   48
>  gcc/testsuite/c-c++-common/strub-parms2.c          |   36
>  gcc/testsuite/c-c++-common/strub-parms3.c          |   58
>  gcc/testsuite/c-c++-common/strub-relaxed1.c        |   18
>  gcc/testsuite/c-c++-common/strub-relaxed2.c        |   14
>  gcc/testsuite/c-c++-common/strub-short-O0-exc.c    |   10
>  gcc/testsuite/c-c++-common/strub-short-O0.c        |   10
>  gcc/testsuite/c-c++-common/strub-short-O1.c        |   10
>  gcc/testsuite/c-c++-common/strub-short-O2.c        |   10
>  gcc/testsuite/c-c++-common/strub-short-O3.c        |   12
>  gcc/testsuite/c-c++-common/strub-short-Os.c        |   12
>  gcc/testsuite/c-c++-common/strub-strict1.c         |   36
>  gcc/testsuite/c-c++-common/strub-strict2.c         |   25
>  gcc/testsuite/c-c++-common/strub-tail-O1.c         |    8
>  gcc/testsuite/c-c++-common/strub-tail-O2.c         |   14
>  gcc/testsuite/c-c++-common/strub-var1.c            |   24
>  .../c-c++-common/torture/strub-callable1.c         |    9
>  .../c-c++-common/torture/strub-callable2.c         |  264 +
>  gcc/testsuite/c-c++-common/torture/strub-const1.c  |   18
>  gcc/testsuite/c-c++-common/torture/strub-const2.c  |   22
>  gcc/testsuite/c-c++-common/torture/strub-const3.c  |   13
>  gcc/testsuite/c-c++-common/torture/strub-const4.c  |   17
>  gcc/testsuite/c-c++-common/torture/strub-data1.c   |   13
>  gcc/testsuite/c-c++-common/torture/strub-data2.c   |   14
>  gcc/testsuite/c-c++-common/torture/strub-data3.c   |   14
>  gcc/testsuite/c-c++-common/torture/strub-data4.c   |   14
>  gcc/testsuite/c-c++-common/torture/strub-data5.c   |   15
>  .../c-c++-common/torture/strub-indcall1.c          |   14
>  .../c-c++-common/torture/strub-indcall2.c          |   14
>  .../c-c++-common/torture/strub-indcall3.c          |   14
>  .../c-c++-common/torture/strub-inlinable1.c        |   16
>  .../c-c++-common/torture/strub-inlinable2.c        |    7
>  gcc/testsuite/c-c++-common/torture/strub-ptrfn1.c  |   10
>  gcc/testsuite/c-c++-common/torture/strub-ptrfn2.c  |   55
>  gcc/testsuite/c-c++-common/torture/strub-ptrfn3.c  |   50
>  gcc/testsuite/c-c++-common/torture/strub-ptrfn4.c  |   43
>  gcc/testsuite/c-c++-common/torture/strub-pure1.c   |   18
>  gcc/testsuite/c-c++-common/torture/strub-pure2.c   |   22
>  gcc/testsuite/c-c++-common/torture/strub-pure3.c   |   13
>  gcc/testsuite/c-c++-common/torture/strub-pure4.c   |   17
>  gcc/testsuite/c-c++-common/torture/strub-run1.c    |   95 +
>  gcc/testsuite/c-c++-common/torture/strub-run2.c    |   84
>  gcc/testsuite/c-c++-common/torture/strub-run3.c    |   80
>  gcc/testsuite/c-c++-common/torture/strub-run4.c    |  106 +
>  gcc/testsuite/c-c++-common/torture/strub-run4c.c   |    5
>  gcc/testsuite/c-c++-common/torture/strub-run4d.c   |    7
>  gcc/testsuite/c-c++-common/torture/strub-run4i.c   |    5
>  gcc/testsuite/g++.dg/strub-run1.C                  |   19
>  gcc/testsuite/g++.dg/torture/strub-init1.C         |   13
>  gcc/testsuite/g++.dg/torture/strub-init2.C         |   14
>  gcc/testsuite/g++.dg/torture/strub-init3.C         |   13
>  gcc/testsuite/gnat.dg/strub_access.adb             |   21
>  gcc/testsuite/gnat.dg/strub_access1.adb            |   16
>  gcc/testsuite/gnat.dg/strub_attr.adb               |   37
>  gcc/testsuite/gnat.dg/strub_attr.ads               |   12
>  gcc/testsuite/gnat.dg/strub_disp.adb               |   64
>  gcc/testsuite/gnat.dg/strub_disp1.adb              |   79
>  gcc/testsuite/gnat.dg/strub_ind.adb                |   33
>  gcc/testsuite/gnat.dg/strub_ind.ads                |   17
>  gcc/testsuite/gnat.dg/strub_ind1.adb               |   41
>  gcc/testsuite/gnat.dg/strub_ind1.ads               |   17
>  gcc/testsuite/gnat.dg/strub_ind2.adb               |   34
>  gcc/testsuite/gnat.dg/strub_ind2.ads               |   17
>  gcc/testsuite/gnat.dg/strub_intf.adb               |   93 +
>  gcc/testsuite/gnat.dg/strub_intf1.adb              |   86
>  gcc/testsuite/gnat.dg/strub_intf2.adb              |   55
>  gcc/testsuite/gnat.dg/strub_renm.adb               |   21
>  gcc/testsuite/gnat.dg/strub_renm1.adb              |   32
>  gcc/testsuite/gnat.dg/strub_renm2.adb              |   32
>  gcc/testsuite/gnat.dg/strub_var.adb                |   16
>  gcc/testsuite/gnat.dg/strub_var1.adb               |   20
>  gcc/tree-cfg.cc                                    |    1
>  gcc/tree-pass.h                                    |    5
>  gcc/tree-ssa-ccp.cc                                |    4
>  libgcc/Makefile.in                                 |    3
>  libgcc/libgcc-std.ver.in                           |    3
>  libgcc/libgcc2.h                                   |    4
>  libgcc/strub.c                                     |  149 +
>  120 files changed, 7429 insertions(+), 12 deletions(-)
>  create mode 100644 gcc/ipa-strub.cc
>  create mode 100644 gcc/ipa-strub.h
>  create mode 100644 gcc/testsuite/c-c++-common/strub-O0.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-O1.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-O2.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-O2fni.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-O3.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-O3fni.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-Og.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-Os.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-all1.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-all2.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-apply1.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-apply2.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-apply3.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-apply4.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-at-calls1.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-at-calls2.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-defer-O1.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-defer-O2.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-defer-O3.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-defer-Os.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-internal1.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-internal2.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-parms1.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-parms2.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-parms3.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-relaxed1.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-relaxed2.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-short-O0-exc.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-short-O0.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-short-O1.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-short-O2.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-short-O3.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-short-Os.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-strict1.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-strict2.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-tail-O1.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-tail-O2.c
>  create mode 100644 gcc/testsuite/c-c++-common/strub-var1.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-callable1.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-callable2.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-const1.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-const2.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-const3.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-const4.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-data1.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-data2.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-data3.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-data4.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-data5.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-indcall1.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-indcall2.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-indcall3.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-inlinable1.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-inlinable2.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-ptrfn1.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-ptrfn2.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-ptrfn3.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-ptrfn4.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-pure1.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-pure2.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-pure3.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-pure4.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-run1.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-run2.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-run3.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-run4.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-run4c.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-run4d.c
>  create mode 100644 gcc/testsuite/c-c++-common/torture/strub-run4i.c
>  create mode 100644 gcc/testsuite/g++.dg/strub-run1.C
>  create mode 100644 gcc/testsuite/g++.dg/torture/strub-init1.C
>  create mode 100644 gcc/testsuite/g++.dg/torture/strub-init2.C
>  create mode 100644 gcc/testsuite/g++.dg/torture/strub-init3.C
>  create mode 100644 gcc/testsuite/gnat.dg/strub_access.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_access1.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_attr.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_attr.ads
>  create mode 100644 gcc/testsuite/gnat.dg/strub_disp.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_disp1.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_ind.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_ind.ads
>  create mode 100644 gcc/testsuite/gnat.dg/strub_ind1.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_ind1.ads
>  create mode 100644 gcc/testsuite/gnat.dg/strub_ind2.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_ind2.ads
>  create mode 100644 gcc/testsuite/gnat.dg/strub_intf.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_intf1.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_intf2.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_renm.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_renm1.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_renm2.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_var.adb
>  create mode 100644 gcc/testsuite/gnat.dg/strub_var1.adb
>  create mode 100644 libgcc/strub.c
>
> diff --git a/gcc/Makefile.in b/gcc/Makefile.in
> index e154f7c0055f9..68410a86af5a9 100644
> --- a/gcc/Makefile.in
> +++ b/gcc/Makefile.in
> @@ -1557,6 +1557,7 @@ OBJS = \
>         ipa-reference.o \
>         ipa-ref.o \
>         ipa-utils.o \
> +       ipa-strub.o \
>         ipa.o \
>         ira.o \
>         ira-build.o \
> @@ -2879,6 +2880,7 @@ GTFILES = $(CPPLIB_H) $(srcdir)/input.h $(srcdir)/coretypes.h \
>    $(srcdir)/sanopt.cc \
>    $(srcdir)/sancov.cc \
>    $(srcdir)/ipa-devirt.cc \
> +  $(srcdir)/ipa-strub.cc \
>    $(srcdir)/internal-fn.h \
>    $(srcdir)/calls.cc \
>    $(srcdir)/omp-general.h \
> diff --git a/gcc/ada/gcc-interface/trans.cc b/gcc/ada/gcc-interface/trans.cc
> index 9c418beda9643..5e9e92d8b7257 100644
> --- a/gcc/ada/gcc-interface/trans.cc
> +++ b/gcc/ada/gcc-interface/trans.cc
> @@ -69,6 +69,21 @@
>  #include "ada-tree.h"
>  #include "gigi.h"
>
> +/* The following #include is for strub_make_callable.
> +
> +   This function marks a function as safe to call from strub contexts.  We mark
> +   Ada subprograms that may be called implicitly by the compiler, and that won't
> +   leave on the stack caller data passed to them.  This stops implicit calls
> +   introduced in subprograms that have their stack scrubbed from being flagged
> +   as unsafe, even in -fstrub=strict mode.
> +
> +   These subprograms are also marked with the strub(callable) attribute in Ada
> +   sources, but their declarations aren't necessarily imported by GNAT, or made
> +   visible to gigi, in units that end up relying on them.  So when gigi
> +   introduces their declarations on its own, it must also add the attribute, by
> +   calling strub_make_callable.  */
> +#include "ipa-strub.h"
> +
>  /* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
>     for fear of running out of stack space.  If we need more, we use xmalloc
>     instead.  */
> @@ -454,6 +469,7 @@ gigi (Node_Id gnat_root,
>                                                      int64_type, NULL_TREE),
>                            NULL_TREE, is_default, true, true, true, false,
>                            false, NULL, Empty);
> +  strub_make_callable (mulv64_decl);
>
>    if (Enable_128bit_Types)
>      {
> @@ -466,6 +482,7 @@ gigi (Node_Id gnat_root,
>                                                          NULL_TREE),
>                                NULL_TREE, is_default, true, true, true, false,
>                                false, NULL, Empty);
> +      strub_make_callable (mulv128_decl);
>      }
>
>    /* Name of the _Parent field in tagged record types.  */
> @@ -722,6 +739,7 @@ build_raise_check (int check, enum exception_info_kind kind)
>      = create_subprog_decl (get_identifier (Name_Buffer), NULL_TREE, ftype,
>                            NULL_TREE, is_default, true, true, true, false,
>                            false, NULL, Empty);
> +  strub_make_callable (result);
>    set_call_expr_flags (result, ECF_NORETURN | ECF_XTHROW);
>
>    return result;
> diff --git a/gcc/ada/gcc-interface/utils.cc b/gcc/ada/gcc-interface/utils.cc
> index f46454d6545a2..8d1237fdbb3e2 100644
> --- a/gcc/ada/gcc-interface/utils.cc
> +++ b/gcc/ada/gcc-interface/utils.cc
> @@ -39,6 +39,7 @@
>  #include "varasm.h"
>  #include "toplev.h"
>  #include "opts.h"
> +#include "ipa-strub.h"
>  #include "output.h"
>  #include "debug.h"
>  #include "convert.h"
> @@ -6742,9 +6743,77 @@ handle_no_stack_protector_attribute (tree *node, tree name, tree, int,
>     struct attribute_spec.handler.  */
>
>  static tree
> -handle_strub_attribute (tree *, tree, tree, int, bool *no_add_attrs)
> +handle_strub_attribute (tree *node, tree name,
> +                       tree args,
> +                       int ARG_UNUSED (flags), bool *no_add_attrs)
>  {
> -  *no_add_attrs = true;
> +  bool enable = true;
> +
> +  if (args && FUNCTION_POINTER_TYPE_P (*node))
> +    *node = TREE_TYPE (*node);
> +
> +  if (args && FUNC_OR_METHOD_TYPE_P (*node))
> +    {
> +      switch (strub_validate_fn_attr_parm (TREE_VALUE (args)))
> +       {
> +       case 1:
> +       case 2:
> +         enable = true;
> +         break;
> +
> +       case 0:
> +         warning (OPT_Wattributes,
> +                  "%qE attribute ignored because of argument %qE",
> +                  name, TREE_VALUE (args));
> +         *no_add_attrs = true;
> +         enable = false;
> +         break;
> +
> +       case -1:
> +       case -2:
> +         enable = false;
> +         break;
> +
> +       default:
> +         gcc_unreachable ();
> +       }
> +
> +      args = TREE_CHAIN (args);
> +    }
> +
> +  if (args)
> +    {
> +      warning (OPT_Wattributes,
> +              "ignoring attribute %qE because of excess arguments"
> +              " starting at %qE",
> +              name, TREE_VALUE (args));
> +      *no_add_attrs = true;
> +      enable = false;
> +    }
> +
> +  /* Warn about unmet expectations that the strub attribute works like a
> +     qualifier.  ??? Could/should we extend it to the element/field types
> +     here?  */
> +  if (TREE_CODE (*node) == ARRAY_TYPE
> +      || VECTOR_TYPE_P (*node)
> +      || TREE_CODE (*node) == COMPLEX_TYPE)
> +    warning (OPT_Wattributes,
> +            "attribute %qE does not apply to elements"
> +            " of non-scalar type %qT",
> +            name, *node);
> +  else if (RECORD_OR_UNION_TYPE_P (*node))
> +    warning (OPT_Wattributes,
> +            "attribute %qE does not apply to fields"
> +            " of aggregate type %qT",
> +            name, *node);
> +
> +  /* If we see a strub-enabling attribute, and we're at the default setting,
> +     implicitly or explicitly, note that the attribute was seen, so that we can
> +     reduce the compile-time overhead to nearly zero when the strub feature is
> +     not used.  */
> +  if (enable && flag_strub < -2)
> +    flag_strub += 2;
> +
>    return NULL_TREE;
>  }
>
> diff --git a/gcc/attribs.cc b/gcc/attribs.cc
> index eff99002fbb92..dd0408635670f 100644
> --- a/gcc/attribs.cc
> +++ b/gcc/attribs.cc
> @@ -27,6 +27,7 @@ along with GCC; see the file COPYING3.  If not see
>  #include "diagnostic-core.h"
>  #include "attribs.h"
>  #include "fold-const.h"
> +#include "ipa-strub.h"
>  #include "stor-layout.h"
>  #include "langhooks.h"
>  #include "plugin.h"
> @@ -789,8 +790,8 @@ decl_attributes (tree *node, tree attributes, int flags,
>           flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
>         }
>
> -      if (spec->function_type_required && TREE_CODE (*anode) != FUNCTION_TYPE
> -         && TREE_CODE (*anode) != METHOD_TYPE)
> +      if (spec->function_type_required
> +         && !FUNC_OR_METHOD_TYPE_P (*anode))
>         {
>           if (TREE_CODE (*anode) == POINTER_TYPE
>               && FUNC_OR_METHOD_TYPE_P (TREE_TYPE (*anode)))
> @@ -905,7 +906,24 @@ decl_attributes (tree *node, tree attributes, int flags,
>               TYPE_NAME (tt) = *node;
>             }
>
> -         *anode = cur_and_last_decl[0];
> +         if (*anode != cur_and_last_decl[0])
> +           {
> +             /* Even if !spec->function_type_required, allow the attribute
> +                handler to request the attribute to be applied to the function
> +                type, rather than to the function pointer type, by setting
> +                cur_and_last_decl[0] to the function type.  */
> +             if (!fn_ptr_tmp
> +                 && POINTER_TYPE_P (*anode)
> +                 && TREE_TYPE (*anode) == cur_and_last_decl[0]
> +                 && FUNC_OR_METHOD_TYPE_P (TREE_TYPE (*anode)))
> +               {
> +                 fn_ptr_tmp = TREE_TYPE (*anode);
> +                 fn_ptr_quals = TYPE_QUALS (*anode);
> +                 anode = &fn_ptr_tmp;
> +               }
> +             *anode = cur_and_last_decl[0];
> +           }
> +
>           if (ret == error_mark_node)
>             {
>               warning (OPT_Wattributes, "%qE attribute ignored", name);
> @@ -1508,9 +1526,20 @@ comp_type_attributes (const_tree type1, const_tree type2)
>    if ((lookup_attribute ("nocf_check", TYPE_ATTRIBUTES (type1)) != NULL)
>        ^ (lookup_attribute ("nocf_check", TYPE_ATTRIBUTES (type2)) != NULL))
>      return 0;
> +  int strub_ret = strub_comptypes (CONST_CAST_TREE (type1),
> +                                  CONST_CAST_TREE (type2));
> +  if (strub_ret == 0)
> +    return strub_ret;
>    /* As some type combinations - like default calling-convention - might
>       be compatible, we have to call the target hook to get the final result.  */
> -  return targetm.comp_type_attributes (type1, type2);
> +  int target_ret = targetm.comp_type_attributes (type1, type2);
> +  if (target_ret == 0)
> +    return target_ret;
> +  if (strub_ret == 2 || target_ret == 2)
> +    return 2;
> +  if (strub_ret == 1 && target_ret == 1)
> +    return 1;
> +  gcc_unreachable ();
>  }
>
>  /* PREDICATE acts as a function of type:
> diff --git a/gcc/builtins.cc b/gcc/builtins.cc
> index 4fc58a0bda9b8..555d2897938ca 100644
> --- a/gcc/builtins.cc
> +++ b/gcc/builtins.cc
> @@ -71,6 +71,7 @@ along with GCC; see the file COPYING3.  If not see
>  #include "gimple-fold.h"
>  #include "intl.h"
>  #include "file-prefix-map.h" /* remap_macro_filename()  */
> +#include "ipa-strub.h" /* strub_watermark_parm()  */
>  #include "gomp-constants.h"
>  #include "omp-general.h"
>  #include "tree-dfa.h"
> @@ -151,6 +152,7 @@ static rtx expand_builtin_strnlen (tree, rtx, machine_mode);
>  static rtx expand_builtin_alloca (tree);
>  static rtx expand_builtin_unop (machine_mode, tree, rtx, rtx, optab);
>  static rtx expand_builtin_frame_address (tree, tree);
> +static rtx expand_builtin_stack_address ();
>  static tree stabilize_va_list_loc (location_t, tree, int);
>  static rtx expand_builtin_expect (tree, rtx);
>  static rtx expand_builtin_expect_with_probability (tree, rtx);
> @@ -5370,6 +5372,252 @@ expand_builtin_frame_address (tree fndecl, tree exp)
>      }
>  }
>
> +#if ! STACK_GROWS_DOWNWARD
> +# define STACK_TOPS GT
> +#else
> +# define STACK_TOPS LT
> +#endif
> +
> +#ifdef POINTERS_EXTEND_UNSIGNED
> +# define STACK_UNSIGNED POINTERS_EXTEND_UNSIGNED
> +#else
> +# define STACK_UNSIGNED true
> +#endif
> +
> +/* Expand a call to builtin function __builtin_stack_address.  */
> +
> +static rtx
> +expand_builtin_stack_address ()
> +{
> +  return convert_to_mode (ptr_mode, copy_to_reg (stack_pointer_rtx),
> +                         STACK_UNSIGNED);
> +}
> +
> +/* Expand a call to builtin function __builtin_strub_enter.  */
> +
> +static rtx
> +expand_builtin_strub_enter (tree exp)
> +{
> +  if (!validate_arglist (exp, POINTER_TYPE, VOID_TYPE))
> +    return NULL_RTX;
> +
> +  if (optimize < 1 || flag_no_inline)
> +    return NULL_RTX;
> +
> +  rtx stktop = expand_builtin_stack_address ();
> +
> +  tree wmptr = CALL_EXPR_ARG (exp, 0);
> +  tree wmtype = TREE_TYPE (TREE_TYPE (wmptr));
> +  tree wmtree = fold_build2 (MEM_REF, wmtype, wmptr,
> +                            build_int_cst (TREE_TYPE (wmptr), 0));
> +  rtx wmark = expand_expr (wmtree, NULL_RTX, ptr_mode, EXPAND_MEMORY);
> +
> +  emit_move_insn (wmark, stktop);
> +
> +  return const0_rtx;
> +}
> +
> +/* Expand a call to builtin function __builtin_strub_update.  */
> +
> +static rtx
> +expand_builtin_strub_update (tree exp)
> +{
> +  if (!validate_arglist (exp, POINTER_TYPE, VOID_TYPE))
> +    return NULL_RTX;
> +
> +  if (optimize < 2 || flag_no_inline)
> +    return NULL_RTX;
> +
> +  rtx stktop = expand_builtin_stack_address ();
> +
> +#ifdef RED_ZONE_SIZE
> +  /* Here's how the strub enter, update and leave functions deal with red zones.
> +
> +     If it weren't for red zones, update, called from within a strub context,
> +     would bump the watermark to the top of the stack.  Enter and leave, running
> +     in the caller, would use the caller's top of stack address both to
> +     initialize the watermark passed to the callee, and to start strubbing the
> +     stack afterwards.
> +
> +     Ideally, we'd update the watermark so as to cover the used amount of red
> +     zone, and strub starting at the caller's other end of the (presumably
> +     unused) red zone.  Normally, only leaf functions use the red zone, but at
> +     this point we can't tell whether a function is a leaf, nor can we tell how
> +     much of the red zone it uses.  Furthermore, some strub contexts may have
> +     been inlined so that update and leave are called from the same stack frame,
> +     and the strub builtins may all have been inlined, turning a strub function
> +     into a leaf.
> +
> +     So cleaning the range from the caller's stack pointer (one end of the red
> +     zone) to the (potentially inlined) callee's (other end of the) red zone
> +     could scribble over the caller's own red zone.
> +
> +     We avoid this possibility by arranging for callers that are strub contexts
> +     to use their own watermark as the strub starting point.  So, if A calls B,
> +     and B calls C, B will tell A to strub up to the end of B's red zone, and
> +     will strub itself only the part of C's stack frame and red zone that
> +     doesn't overlap with B's.  With that, we don't need to know who's leaf and
> +     who isn't: inlined calls will shrink their strub window to zero, each
> +     remaining call will strub some portion of the stack, and eventually the
> +     strub context will return to a caller that isn't a strub context itself,
> +     that will therefore use its own stack pointer as the strub starting point.
> +     It's not a leaf, because strub contexts can't be inlined into non-strub
> +     contexts, so it doesn't use the red zone, and it will therefore correctly
> +     strub up the callee's stack frame up to the end of the callee's red zone.
> +     Neat!  */
> +  if (true /* (flags_from_decl_or_type (current_function_decl) & ECF_LEAF) */)
> +    {
> +      poly_int64 red_zone_size = RED_ZONE_SIZE;
> +#if STACK_GROWS_DOWNWARD
> +      red_zone_size = -red_zone_size;
> +#endif
> +      stktop = plus_constant (ptr_mode, stktop, red_zone_size);
> +      stktop = force_reg (ptr_mode, stktop);
> +    }
> +#endif
> +
> +  tree wmptr = CALL_EXPR_ARG (exp, 0);
> +  tree wmtype = TREE_TYPE (TREE_TYPE (wmptr));
> +  tree wmtree = fold_build2 (MEM_REF, wmtype, wmptr,
> +                            build_int_cst (TREE_TYPE (wmptr), 0));
> +  rtx wmark = expand_expr (wmtree, NULL_RTX, ptr_mode, EXPAND_MEMORY);
> +
> +  rtx wmarkr = force_reg (ptr_mode, wmark);
> +
> +  rtx_code_label *lab = gen_label_rtx ();
> +  do_compare_rtx_and_jump (stktop, wmarkr, STACK_TOPS, STACK_UNSIGNED,
> +                          ptr_mode, NULL_RTX, lab, NULL,
> +                          profile_probability::very_likely ());
> +  emit_move_insn (wmark, stktop);
> +
> +  /* If this is an inlined strub function, also bump the watermark for the
> +     enclosing function.  This avoids a problem with the following scenario: A
> +     calls B and B calls C, and both B and C get inlined into A.  B allocates
> +     temporary stack space before calling C.  If we don't update A's watermark,
> +     we may use an outdated baseline for the post-C strub_leave, erasing B's
> +     temporary stack allocation.  We only need this if we're fully expanding
> +     strub_leave inline.  */
> +  tree xwmptr = (optimize > 2
> +                ? strub_watermark_parm (current_function_decl)
> +                : wmptr);
> +  if (wmptr != xwmptr)
> +    {
> +      wmptr = xwmptr;
> +      wmtype = TREE_TYPE (TREE_TYPE (wmptr));
> +      wmtree = fold_build2 (MEM_REF, wmtype, wmptr,
> +                           build_int_cst (TREE_TYPE (wmptr), 0));
> +      wmark = expand_expr (wmtree, NULL_RTX, ptr_mode, EXPAND_MEMORY);
> +      wmarkr = force_reg (ptr_mode, wmark);
> +
> +      do_compare_rtx_and_jump (stktop, wmarkr, STACK_TOPS, STACK_UNSIGNED,
> +                              ptr_mode, NULL_RTX, lab, NULL,
> +                              profile_probability::very_likely ());
> +      emit_move_insn (wmark, stktop);
> +    }
> +
> +  emit_label (lab);
> +
> +  return const0_rtx;
> +}
> +
> +
> +/* Expand a call to builtin function __builtin_strub_leave.  */
> +
> +static rtx
> +expand_builtin_strub_leave (tree exp)
> +{
> +  if (!validate_arglist (exp, POINTER_TYPE, VOID_TYPE))
> +    return NULL_RTX;
> +
> +  if (optimize < 2 || optimize_size || flag_no_inline)
> +    return NULL_RTX;
> +
> +  rtx stktop = NULL_RTX;
> +
> +  if (tree wmptr = (optimize
> +                   ? strub_watermark_parm (current_function_decl)
> +                   : NULL_TREE))
> +    {
> +      tree wmtype = TREE_TYPE (TREE_TYPE (wmptr));
> +      tree wmtree = fold_build2 (MEM_REF, wmtype, wmptr,
> +                                build_int_cst (TREE_TYPE (wmptr), 0));
> +      rtx wmark = expand_expr (wmtree, NULL_RTX, ptr_mode, EXPAND_MEMORY);
> +      stktop = force_reg (ptr_mode, wmark);
> +    }
> +
> +  if (!stktop)
> +    stktop = expand_builtin_stack_address ();
> +
> +  tree wmptr = CALL_EXPR_ARG (exp, 0);
> +  tree wmtype = TREE_TYPE (TREE_TYPE (wmptr));
> +  tree wmtree = fold_build2 (MEM_REF, wmtype, wmptr,
> +                            build_int_cst (TREE_TYPE (wmptr), 0));
> +  rtx wmark = expand_expr (wmtree, NULL_RTX, ptr_mode, EXPAND_MEMORY);
> +
> +  rtx wmarkr = force_reg (ptr_mode, wmark);
> +
> +#if ! STACK_GROWS_DOWNWARD
> +  rtx base = stktop;
> +  rtx end = wmarkr;
> +#else
> +  rtx base = wmarkr;
> +  rtx end = stktop;
> +#endif
> +
> +  /* We're going to modify it, so make sure it's not e.g. the stack pointer.  */
> +  base = copy_to_reg (base);
> +
> +  rtx_code_label *done = gen_label_rtx ();
> +  do_compare_rtx_and_jump (base, end, LT, STACK_UNSIGNED,
> +                          ptr_mode, NULL_RTX, done, NULL,
> +                          profile_probability::very_likely ());
> +
> +  if (optimize < 3)
> +    expand_call (exp, NULL_RTX, true);
> +  else
> +    {
> +      /* Ok, now we've determined we want to copy the block, so convert the
> +        addresses to Pmode, as needed to dereference them to access ptr_mode
> +        memory locations, so that we don't have to convert anything within the
> +        loop.  */
> +      base = memory_address (ptr_mode, base);
> +      end = memory_address (ptr_mode, end);
> +
> +      rtx zero = force_operand (const0_rtx, NULL_RTX);
> +      int ulen = GET_MODE_SIZE (ptr_mode);
> +
> +      /* ??? It would be nice to use setmem or similar patterns here,
> +        but they do not necessarily obey the stack growth direction,
> +        which has security implications.  We also have to avoid calls
> +        (memset, bzero or any machine-specific ones), which are
> +        likely unsafe here (see TARGET_STRUB_MAY_USE_MEMSET).  */
> +#if ! STACK_GROWS_DOWNWARD
> +      rtx incr = plus_constant (Pmode, base, ulen);
> +      rtx dstm = gen_rtx_MEM (ptr_mode, base);
> +
> +      rtx_code_label *loop = gen_label_rtx ();
> +      emit_label (loop);
> +      emit_move_insn (dstm, zero);
> +      emit_move_insn (base, force_operand (incr, NULL_RTX));
> +#else
> +      rtx decr = plus_constant (Pmode, end, -ulen);
> +      rtx dstm = gen_rtx_MEM (ptr_mode, end);
> +
> +      rtx_code_label *loop = gen_label_rtx ();
> +      emit_label (loop);
> +      emit_move_insn (end, force_operand (decr, NULL_RTX));
> +      emit_move_insn (dstm, zero);
> +#endif
> +      do_compare_rtx_and_jump (base, end, LT, STACK_UNSIGNED,
> +                              Pmode, NULL_RTX, NULL, loop,
> +                              profile_probability::very_likely ());
> +    }
> +
> +  emit_label (done);
> +
> +  return const0_rtx;
> +}
> +
>  /* Expand EXP, a call to the alloca builtin.  Return NULL_RTX if we
>     failed and the caller should emit a normal call.  */
>
> @@ -7705,6 +7953,27 @@ expand_builtin (tree exp, rtx target, rtx subtarget, machine_mode mode,
>      case BUILT_IN_RETURN_ADDRESS:
>        return expand_builtin_frame_address (fndecl, exp);
>
> +    case BUILT_IN_STACK_ADDRESS:
> +      return expand_builtin_stack_address ();
> +
> +    case BUILT_IN___STRUB_ENTER:
> +      target = expand_builtin_strub_enter (exp);
> +      if (target)
> +       return target;
> +      break;
> +
> +    case BUILT_IN___STRUB_UPDATE:
> +      target = expand_builtin_strub_update (exp);
> +      if (target)
> +       return target;
> +      break;
> +
> +    case BUILT_IN___STRUB_LEAVE:
> +      target = expand_builtin_strub_leave (exp);
> +      if (target)
> +       return target;
> +      break;
> +
>      /* Returns the address of the area where the structure is returned.
>         0 otherwise.  */
>      case BUILT_IN_AGGREGATE_INCOMING_ADDRESS:
> diff --git a/gcc/builtins.def b/gcc/builtins.def
> index 33e6cad8ce14f..f03df32f98013 100644
> --- a/gcc/builtins.def
> +++ b/gcc/builtins.def
> @@ -999,6 +999,10 @@ DEF_EXT_LIB_BUILTIN    (BUILT_IN_FFSLL, "ffsll", BT_FN_INT_LONGLONG, ATTR_CONST_
>  DEF_GCC_BUILTIN        (BUILT_IN_FFSG, "ffsg", BT_FN_INT_VAR, ATTR_CONST_NOTHROW_TYPEGENERIC_LEAF)
>  DEF_EXT_LIB_BUILTIN        (BUILT_IN_FORK, "fork", BT_FN_PID, ATTR_NOTHROW_LIST)
>  DEF_GCC_BUILTIN        (BUILT_IN_FRAME_ADDRESS, "frame_address", BT_FN_PTR_UINT, ATTR_NULL)
> +DEF_GCC_BUILTIN        (BUILT_IN_STACK_ADDRESS, "stack_address", BT_FN_PTR, ATTR_NULL)
> +DEF_BUILTIN_STUB       (BUILT_IN___STRUB_ENTER, "__builtin___strub_enter")
> +DEF_BUILTIN_STUB       (BUILT_IN___STRUB_UPDATE, "__builtin___strub_update")
> +DEF_BUILTIN_STUB       (BUILT_IN___STRUB_LEAVE, "__builtin___strub_leave")
>  /* [trans-mem]: Adjust BUILT_IN_TM_FREE if BUILT_IN_FREE is changed.  */
>  DEF_LIB_BUILTIN        (BUILT_IN_FREE, "free", BT_FN_VOID_PTR, ATTR_NOTHROW_LEAF_LIST)
>  DEF_GCC_BUILTIN        (BUILT_IN_FROB_RETURN_ADDR, "frob_return_addr", BT_FN_PTR_PTR, ATTR_NULL)
> diff --git a/gcc/c-family/c-attribs.cc b/gcc/c-family/c-attribs.cc
> index 45af07453ea3c..acc09e4b27a5b 100644
> --- a/gcc/c-family/c-attribs.cc
> +++ b/gcc/c-family/c-attribs.cc
> @@ -41,6 +41,7 @@ along with GCC; see the file COPYING3.  If not see
>  #include "common/common-target.h"
>  #include "langhooks.h"
>  #include "tree-inline.h"
> +#include "ipa-strub.h"
>  #include "toplev.h"
>  #include "tree-iterator.h"
>  #include "opts.h"
> @@ -69,6 +70,7 @@ static tree handle_asan_odr_indicator_attribute (tree *, tree, tree, int,
>  static tree handle_stack_protect_attribute (tree *, tree, tree, int, bool *);
>  static tree handle_no_stack_protector_function_attribute (tree *, tree,
>                                                         tree, int, bool *);
> +static tree handle_strub_attribute (tree *, tree, tree, int, bool *);
>  static tree handle_noinline_attribute (tree *, tree, tree, int, bool *);
>  static tree handle_noclone_attribute (tree *, tree, tree, int, bool *);
>  static tree handle_nocf_check_attribute (tree *, tree, tree, int, bool *);
> @@ -322,6 +324,8 @@ const struct attribute_spec c_common_gnu_attributes[] =
>    { "no_stack_protector",     0, 0, true, false, false, false,
>                               handle_no_stack_protector_function_attribute,
>                               attr_stack_protect_exclusions },
> +  { "strub",                 0, 1, false, true, false, true,
> +                             handle_strub_attribute, NULL },
>    { "noinline",               0, 0, true,  false, false, false,
>                               handle_noinline_attribute,
>                               attr_noinline_exclusions },
> @@ -1489,6 +1493,84 @@ handle_noipa_attribute (tree *node, tree name, tree, int, bool *no_add_attrs)
>    return NULL_TREE;
>  }
>
> +/* Handle a "strub" attribute; arguments as in
> +   struct attribute_spec.handler.  */
> +
> +static tree
> +handle_strub_attribute (tree *node, tree name,
> +                       tree args,
> +                       int ARG_UNUSED (flags), bool *no_add_attrs)
> +{
> +  bool enable = true;
> +
> +  if (args && FUNCTION_POINTER_TYPE_P (*node))
> +    *node = TREE_TYPE (*node);
> +
> +  if (args && FUNC_OR_METHOD_TYPE_P (*node))
> +    {
> +      switch (strub_validate_fn_attr_parm (TREE_VALUE (args)))
> +       {
> +       case 1:
> +       case 2:
> +         enable = true;
> +         break;
> +
> +       case 0:
> +         warning (OPT_Wattributes,
> +                  "%qE attribute ignored because of argument %qE",
> +                  name, TREE_VALUE (args));
> +         *no_add_attrs = true;
> +         enable = false;
> +         break;
> +
> +       case -1:
> +       case -2:
> +         enable = false;
> +         break;
> +
> +       default:
> +         gcc_unreachable ();
> +       }
> +
> +      args = TREE_CHAIN (args);
> +    }
> +
> +  if (args)
> +    {
> +      warning (OPT_Wattributes,
> +              "ignoring attribute %qE because of excess arguments"
> +              " starting at %qE",
> +              name, TREE_VALUE (args));
> +      *no_add_attrs = true;
> +      enable = false;
> +    }
> +
> +  /* Warn about unmet expectations that the strub attribute works like a
> +     qualifier.  ??? Could/should we extend it to the element/field types
> +     here?  */
> +  if (TREE_CODE (*node) == ARRAY_TYPE
> +      || VECTOR_TYPE_P (*node)
> +      || TREE_CODE (*node) == COMPLEX_TYPE)
> +    warning (OPT_Wattributes,
> +            "attribute %qE does not apply to elements"
> +            " of non-scalar type %qT",
> +            name, *node);
> +  else if (RECORD_OR_UNION_TYPE_P (*node))
> +    warning (OPT_Wattributes,
> +            "attribute %qE does not apply to fields"
> +            " of aggregate type %qT",
> +            name, *node);
> +
> +  /* If we see a strub-enabling attribute, and we're at the default setting,
> +     implicitly or explicitly, note that the attribute was seen, so that we can
> +     reduce the compile-time overhead to nearly zero when the strub feature is
> +     not used.  */
> +  if (enable && flag_strub < -2)
> +    flag_strub += 2;
> +
> +  return NULL_TREE;
> +}
> +
>  /* Handle a "noinline" attribute; arguments as in
>     struct attribute_spec.handler.  */
>
> diff --git a/gcc/cgraph.h b/gcc/cgraph.h
> index cfdd9f693a889..2b32055761688 100644
> --- a/gcc/cgraph.h
> +++ b/gcc/cgraph.h
> @@ -153,7 +153,7 @@ public:
>    void remove (void);
>
>    /* Undo any definition or use of the symbol.  */
> -  void reset (void);
> +  void reset (bool preserve_comdat_group = false);
>
>    /* Dump symtab node to F.  */
>    void dump (FILE *f);
> diff --git a/gcc/cgraphunit.cc b/gcc/cgraphunit.cc
> index bccd2f2abb5a3..9a550a5cce645 100644
> --- a/gcc/cgraphunit.cc
> +++ b/gcc/cgraphunit.cc
> @@ -384,7 +384,7 @@ symbol_table::process_new_functions (void)
>     functions or variables.  */
>
>  void
> -symtab_node::reset (void)
> +symtab_node::reset (bool preserve_comdat_group)
>  {
>    /* Reset our data structures so we can analyze the function again.  */
>    analyzed = false;
> @@ -395,7 +395,8 @@ symtab_node::reset (void)
>    cpp_implicit_alias = false;
>
>    remove_all_references ();
> -  remove_from_same_comdat_group ();
> +  if (!preserve_comdat_group)
> +    remove_from_same_comdat_group ();
>
>    if (cgraph_node *cn = dyn_cast <cgraph_node *> (this))
>      {
> diff --git a/gcc/common.opt b/gcc/common.opt
> index 161a035d736a3..f070aff8cbc1b 100644
> --- a/gcc/common.opt
> +++ b/gcc/common.opt
> @@ -2917,6 +2917,35 @@ fstrict-overflow
>  Common
>  Treat signed overflow as undefined.  Negated as -fwrapv -fwrapv-pointer.
>
> +fstrub=disable
> +Common RejectNegative Var(flag_strub, 0)
> +Disable stack scrub entirely, disregarding strub attributes.
> +
> +fstrub=strict
> +Common RejectNegative Var(flag_strub, -4)
> +Enable stack scrub as per attributes, with strict call checking.
> +
> +; If any strub-enabling attribute is seen when the default or strict
> +; initializer values are in effect, flag_strub is bumped up by 2.  The
> +; scrub mode gate function will then bump these initializer values to
> +; 0 if no strub-enabling attribute is seen.  This minimizes the strub
> +; overhead.
> +fstrub=relaxed
> +Common RejectNegative Var(flag_strub, -3) Init(-3)
> +Restore default strub mode: as per attributes, with relaxed checking.
> +
> +fstrub=all
> +Common RejectNegative Var(flag_strub, 3)
> +Enable stack scrubbing for all viable functions.
> +
> +fstrub=at-calls
> +Common RejectNegative Var(flag_strub, 1)
> +Enable at-calls stack scrubbing for all viable functions.
> +
> +fstrub=internal
> +Common RejectNegative Var(flag_strub, 2)
> +Enable internal stack scrubbing for all viable functions.
> +
>  fsync-libcalls
>  Common Var(flag_sync_libcalls) Init(1)
>  Implement __atomic operations via libcalls to legacy __sync functions.
> diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
> index 9592cfee1d279..e9bc9c4fe84c8 100644
> --- a/gcc/doc/extend.texi
> +++ b/gcc/doc/extend.texi
> @@ -77,6 +77,7 @@ extensions, accepted by GCC in C90 mode and in C++.
>  * Function Names::      Printable strings which are the name of the current
>                          function.
>  * Return Address::      Getting the return or frame address of a function.
> +* Stack Scrubbing::     Stack scrubbing internal interfaces.
>  * Vector Extensions::   Using vector instructions through built-in functions.
>  * Offsetof::            Special syntax for implementing @code{offsetof}.
>  * __sync Builtins::     Legacy built-in functions for atomic memory access.
> @@ -9225,6 +9226,268 @@ pid_t wait (wait_status_ptr_t p)
>  @}
>  @end smallexample
>
> +@cindex @code{strub} type attribute
> +@item strub
> +This attribute defines stack-scrubbing properties of functions and
> +variables, so that functions that access sensitive data can have their
> +stack frames zeroed-out upon returning or propagating exceptions.  This
> +may be enabled explicitly, by selecting certain @code{strub} modes for
> +specific functions, or implicitly, by means of @code{strub} variables.
> +
> +Being a type attribute, it attaches to types, even when specified in
> +function and variable declarations.  When applied to function types, it
> +takes an optional string argument.  When applied to a
> +pointer-to-function type, if the optional argument is given, it gets
> +propagated to the function type.
> +
> +@smallexample
> +/* A strub variable.  */
> +int __attribute__ ((strub)) var;
> +/* A strub variable that happens to be a pointer.  */
> +__attribute__ ((strub)) int *strub_ptr_to_int;
> +/* A pointer type that may point to a strub variable.  */
> +typedef int __attribute__ ((strub)) *ptr_to_strub_int_type;
> +
> +/* A declaration of a strub function.  */
> +extern int __attribute__ ((strub)) foo (void);
> +/* A pointer to that strub function.  */
> +int __attribute__ ((strub ("at-calls"))) (*ptr_to_strub_fn)(void) = foo;
> +@end smallexample
> +
> +A function associated with @code{at-calls} @code{strub} mode
> +(@code{strub("at-calls")}, or just @code{strub}) undergoes interface
> +changes.  Its callers are adjusted to match the changes, and to scrub
> +(overwrite with zeros) the stack space used by the called function after
> +it returns.  The interface change makes the function type incompatible
> +with an unadorned but otherwise equivalent type, so @emph{every}
> +declaration and every type that may be used to call the function must be
> +associated with this strub mode.
> +
> +A function associated with @code{internal} @code{strub} mode
> +(@code{strub("internal")}) retains an unmodified, type-compatible
> +interface, but it may be turned into a wrapper that calls the wrapped
> +body using a custom interface.  The wrapper then scrubs the stack space
> +used by the wrapped body.  Though the wrapped body has its stack space
> +scrubbed, the wrapper does not, so arguments and return values may
> +remain unscrubbed even when such a function is called by another
> +function that enables @code{strub}.  This is why, when compiling with
> +@option{-fstrub=strict}, a @code{strub} context is not allowed to call
> +@code{internal} @code{strub} functions.
> +
> +@smallexample
> +/* A declaration of an internal-strub function.  */
> +extern int __attribute__ ((strub ("internal"))) bar (void);
> +
> +int __attribute__ ((strub))
> +baz (void)
> +@{
> +  /* Ok, foo was declared above as an at-calls strub function.  */
> +  foo ();
> +  /* Not allowed in strict mode, otherwise allowed.  */
> +  bar ();
> +@}
> +@end smallexample
> +
> +An automatically-allocated variable associated with the @code{strub}
> +attribute causes the (immediately) enclosing function to have
> +@code{strub} enabled.
> +
> +A statically-allocated variable associated with the @code{strub}
> +attribute causes functions that @emph{read} it, through its @code{strub}
> +data type, to have @code{strub} enabled.  Reading data by dereferencing
> +a pointer to a @code{strub} data type has the same effect.  Note: The
> +attribute does not carry over from a composite type to the types of its
> +components, so the intended effect may not be obtained with non-scalar
> +types.
> +
> +When selecting a @code{strub}-enabled mode for a function that is not
> +explicitly associated with one, because of @code{strub} variables or
> +data pointers, the function must satisfy @code{internal} mode viability
> +requirements (see below), even when @code{at-calls} mode is also viable
> +and, being more efficient, ends up selected as an optimization.
> +
> +@smallexample
> +/* zapme is implicitly strub-enabled because of strub variables.
> +   Optimization may change its strub mode, but not the requirements.  */
> +static int
> +zapme (int i)
> +@{
> +  /* A local strub variable enables strub.  */
> +  int __attribute__ ((strub)) lvar;
> +  /* Reading strub data through a pointer-to-strub enables strub.  */
> +  lvar = * (ptr_to_strub_int_type) &i;
> +  /* Writing to a global strub variable does not enable strub.  */
> +  var = lvar;
> +  /* Reading from a global strub variable enables strub.  */
> +  return var;
> +@}
> +@end smallexample
> +
> +A @code{strub} context is the body (as opposed to the interface) of a
> +function that has @code{strub} enabled, be it explicitly, by
> +@code{at-calls} or @code{internal} mode, or implicitly, due to
> +@code{strub} variables or command-line options.
> +
> +A function of a type associated with the @code{disabled} @code{strub}
> +mode (@code{strub("disabled")} will not have its own stack space
> +scrubbed.  Such functions @emph{cannot} be called from within
> +@code{strub} contexts.
> +
> +In order to enable a function to be called from within @code{strub}
> +contexts without having its stack space scrubbed, associate it with the
> +@code{callable} @code{strub} mode (@code{strub("callable")}).
> +
> +When a function is not assigned a @code{strub} mode, explicitly or
> +implicitly, the mode defaults to @code{callable}, except when compiling
> +with @option{-fstrub=strict}, that causes @code{strub} mode to default
> +to @code{disabled}.
> +
> +@example
> +extern int __attribute__ ((strub ("callable"))) bac (void);
> +extern int __attribute__ ((strub ("disabled"))) bad (void);
> + /* Implicitly disabled with -fstrub=strict, otherwise callable.  */
> +extern int bah (void);
> +
> +int __attribute__ ((strub))
> +bal (void)
> +@{
> +  /* Not allowed, bad is not strub-callable.  */
> +  bad ();
> +  /* Ok, bac is strub-callable.  */
> +  bac ();
> +  /* Not allowed with -fstrub=strict, otherwise allowed.  */
> +  bah ();
> +@}
> +@end example
> +
> +Function types marked @code{callable} and @code{disabled} are not
> +mutually compatible types, but the underlying interfaces are compatible,
> +so it is safe to convert pointers between them, and to use such pointers
> +or alternate declarations to call them.  Interfaces are also
> +interchangeable between them and @code{internal} (but not
> +@code{at-calls}!), but adding @code{internal} to a pointer type will not
> +cause the pointed-to function to perform stack scrubbing.
> +
> +@example
> +void __attribute__ ((strub))
> +bap (void)
> +@{
> +  /* Assign a callable function to pointer-to-disabled.
> +     Flagged as not quite compatible with -Wpedantic.  */
> +  int __attribute__ ((strub ("disabled"))) (*d_p) (void) = bac;
> +  /* Not allowed: calls disabled type in a strub context.  */
> +  d_p ();
> +
> +  /* Assign a disabled function to pointer-to-callable.
> +     Flagged as not quite compatible with -Wpedantic.  */
> +  int __attribute__ ((strub ("callable"))) (*c_p) (void) = bad;
> +  /* Ok, safe.  */
> +  c_p ();
> +
> +  /* Assign an internal function to pointer-to-callable.
> +     Flagged as not quite compatible with -Wpedantic.  */
> +  c_p = bar;
> +  /* Ok, safe.  */
> +  c_p ();
> +
> +  /* Assign an at-calls function to pointer-to-callable.
> +     Flaggged as incompatible.  */
> +  c_p = bal;
> +  /* The call through an interface-incompatible type will not use the
> +     modified interface expected by the at-calls function, so it is
> +     likely to misbehave at runtime.  */
> +  c_p ();
> +@}
> +@end example
> +
> +@code{Strub} contexts are never inlined into non-@code{strub} contexts.
> +When an @code{internal}-strub function is split up, the wrapper can
> +often be inlined, but the wrapped body @emph{never} is.  A function
> +marked as @code{always_inline}, even if explicitly assigned
> +@code{internal} strub mode, will not undergo wrapping, so its body gets
> +inlined as required.
> +
> +@example
> +inline int __attribute__ ((strub ("at-calls")))
> +inl_atc (void)
> +@{
> +  /* This body may get inlined into strub contexts.  */
> +@}
> +
> +inline int __attribute__ ((strub ("internal")))
> +inl_int (void)
> +@{
> +  /* This body NEVER gets inlined, though its wrapper may.  */
> +@}
> +
> +inline int __attribute__ ((strub ("internal"), always_inline))
> +inl_int_ali (void)
> +@{
> +  /* No internal wrapper, so this body ALWAYS gets inlined,
> +     but it cannot be called from non-strub contexts.  */
> +@}
> +
> +void __attribute__ ((strub ("disabled")))
> +bat (void)
> +@{
> +  /* Not allowed, cannot inline into a non-strub context.  */
> +  inl_int_ali ();
> +@}
> +@end example
> +
> +@cindex strub eligibility and viability
> +Some @option{-fstrub=*} command line options enable @code{strub} modes
> +implicitly where viable.  A @code{strub} mode is only viable for a
> +function if the function is eligible for that mode, and if other
> +conditions, detailed below, are satisfied.  If it's not eligible for a
> +mode, attempts to explicitly associate it with that mode are rejected
> +with an error message.  If it is eligible, that mode may be assigned
> +explicitly through this attribute, but implicit assignment through
> +command-line options may involve additional viability requirements.
> +
> +A function is ineligible for @code{at-calls} @code{strub} mode if a
> +different @code{strub} mode is explicitly requested, if attribute
> +@code{noipa} is present, or if it calls @code{__builtin_apply_args}.
> +@code{At-calls} @code{strub} mode, if not requested through the function
> +type, is only viable for an eligible function if the function is not
> +visible to other translation units, if it doesn't have its address
> +taken, and if it is never called with a function type overrider.
> +
> +@smallexample
> +/* bar is eligible for at-calls strub mode,
> +   but not viable for that mode because it is visible to other units.
> +   It is eligible and viable for internal strub mode.  */
> +void bav () @{@}
> +
> +/* setp is eligible for at-calls strub mode,
> +   but not viable for that mode because its address is taken.
> +   It is eligible and viable for internal strub mode.  */
> +void setp (void) @{ static void (*p)(void); = setp; @}
> +@end smallexample
> +
> +A function is ineligible for @code{internal} @code{strub} mode if a
> +different @code{strub} mode is explicitly requested, or if attribute
> +@code{noipa} is present.  For an @code{always_inline} function, meeting
> +these requirements is enough to make it eligible.  Any function that has
> +attribute @code{noclone}, that uses such extensions as non-local labels,
> +computed gotos, alternate variable argument passing interfaces,
> +@code{__builtin_next_arg}, or @code{__builtin_return_address}, or that
> +takes too many (about 64Ki) arguments is ineligible, unless it is
> +@code{always_inline}.  For @code{internal} @code{strub} mode, all
> +eligible functions are viable.
> +
> +@smallexample
> +/* flop is not eligible, thus not viable, for at-calls strub mode.
> +   Likewise for internal strub mode.  */
> +__attribute__ ((noipa)) void flop (void) @{@}
> +
> +/* flip is eligible and viable for at-calls strub mode.
> +   It would be ineligible for internal strub mode, because of noclone,
> +   if it weren't for always_inline.  With always_inline, noclone is not
> +   an obstacle, so it is also eligible and viable for internal strub mode.  */
> +inline __attribute__ ((noclone, always_inline)) void flip (void) @{@}
> +@end smallexample
> +
>  @cindex @code{unused} type attribute
>  @item unused
>  When attached to a type (including a @code{union} or a @code{struct}),
> @@ -12375,6 +12638,55 @@ option is in effect.  Such calls should only be made in debugging
>  situations.
>  @enddefbuiltin
>
> +@deftypefn {Built-in Function} {void *} __builtin_stack_address ()
> +This function returns the value of the stack pointer register.
> +@end deftypefn
> +
> +@node Stack Scrubbing
> +@section Stack scrubbing internal interfaces
> +
> +Stack scrubbing involves cooperation between a @code{strub} context,
> +i.e., a function whose stack frame is to be zeroed-out, and its callers.
> +The caller initializes a stack watermark, the @code{strub} context
> +updates the watermark according to its stack use, and the caller zeroes
> +it out once it regains control, whether by the callee's returning or by
> +an exception.
> +
> +Each of these steps is performed by a different builtin function call.
> +Calls to these builtins are introduced automatically, in response to
> +@code{strub} attributes and command-line options; they are not expected
> +to be explicitly called by source code.
> +
> +The functions that implement the builtins are available in libgcc but,
> +depending on optimization levels, they are expanded internally, adjusted
> +to account for inlining, and sometimes combined/deferred (e.g. passing
> +the caller-supplied watermark on to callees, refraining from erasing
> +stack areas that the caller will) to enable tail calls and to optimize
> +for code size.
> +
> +@deftypefn {Built-in Function} {void} __builtin___strub_enter (void **@var{wmptr})
> +This function initializes a stack @var{watermark} variable with the
> +current top of the stack.  A call to this builtin function is introduced
> +before entering a @code{strub} context.  It remains as a function call
> +if optimization is not enabled.
> +@end deftypefn
> +
> +@deftypefn {Built-in Function} {void} __builtin___strub_update (void **@var{wmptr})
> +This function updates a stack @var{watermark} variable with the current
> +top of the stack, if it tops the previous watermark.  A call to this
> +builtin function is inserted within @code{strub} contexts, whenever
> +additional stack space may have been used.  It remains as a function
> +call at optimization levels lower than 2.
> +@end deftypefn
> +
> +@deftypefn {Built-in Function} {void} __builtin___strub_leave (void **@var{wmptr})
> +This function overwrites the memory area between the current top of the
> +stack, and the @var{watermark}ed address.  A call to this builtin
> +function is inserted after leaving a @code{strub} context.  It remains
> +as a function call at optimization levels lower than 3, and it is guarded by
> +a condition at level 2.
> +@end deftypefn
> +
>  @node Vector Extensions
>  @section Using Vector Instructions through Built-in Functions
>
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index 2fab4c5d71fd0..04d7ecd4593e1 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -654,6 +654,8 @@ Objective-C and Objective-C++ Dialects}.
>  -fstack-protector-explicit  -fstack-check
>  -fstack-limit-register=@var{reg}  -fstack-limit-symbol=@var{sym}
>  -fno-stack-limit  -fsplit-stack
> +-fstrub=disable  -fstrub=strict  -fstrub=relaxed
> +-fstrub=all  -fstrub=at-calls  -fstrub=internal
>  -fvtable-verify=@r{[}std@r{|}preinit@r{|}none@r{]}
>  -fvtv-counts  -fvtv-debug
>  -finstrument-functions  -finstrument-functions-once
> @@ -17890,6 +17892,56 @@ without @option{-fsplit-stack} always has a large stack.  Support for
>  this is implemented in the gold linker in GNU binutils release 2.21
>  and later.
>
> +@opindex -fstrub=disable
> +@item -fstrub=disable
> +Disable stack scrubbing entirely, ignoring any @code{strub} attributes.
> +See @xref{Common Type Attributes}.
> +
> +@opindex fstrub=strict
> +@item -fstrub=strict
> +Functions default to @code{strub} mode @code{disabled}, and apply
> +@option{strict}ly the restriction that only functions associated with
> +@code{strub}-@code{callable} modes (@code{at-calls}, @code{callable} and
> +@code{always_inline} @code{internal}) are @code{callable} by functions
> +with @code{strub}-enabled modes (@code{at-calls} and @code{internal}).
> +
> +@opindex fstrub=relaxed
> +@item -fstrub=relaxed
> +Restore the default stack scrub (@code{strub}) setting, namely,
> +@code{strub} is only enabled as required by @code{strub} attributes
> +associated with function and data types.  @code{Relaxed} means that
> +strub contexts are only prevented from calling functions explicitly
> +associated with @code{strub} mode @code{disabled}.  This option is only
> +useful to override other @option{-fstrub=*} options that precede it in
> +the command line.
> +
> +@opindex fstrub=at-calls
> +@item -fstrub=at-calls
> +Enable @code{at-calls} @code{strub} mode where viable.  The primary use
> +of this option is for testing.  It exercises the @code{strub} machinery
> +in scenarios strictly local to a translation unit.  This @code{strub}
> +mode modifies function interfaces, so any function that is visible to
> +other translation units, or that has its address taken, will @emph{not}
> +be affected by this option.  Optimization options may also affect
> +viability.  See the @code{strub} attribute documentation for details on
> +viability and eligibility requirements.
> +
> +@opindex fstrub=internal
> +@item -fstrub=internal
> +Enable @code{internal} @code{strub} mode where viable.  The primary use
> +of this option is for testing.  This option is intended to exercise
> +thoroughly parts of the @code{strub} machinery that implement the less
> +efficient, but interface-preserving @code{strub} mode.  Functions that
> +would not be affected by this option are quite uncommon.
> +
> +@opindex fstrub=all
> +@item -fstrub=all
> +Enable some @code{strub} mode where viable.  When both strub modes are
> +viable, @code{at-calls} is preferred.  @option{-fdump-ipa-strubm} adds
> +function attributes that tell which mode was selected for each function.
> +The primary use of this option is for testing, to exercise thoroughly
> +the @code{strub} machinery.
> +
>  @opindex fvtable-verify
>  @item -fvtable-verify=@r{[}std@r{|}preinit@r{|}none@r{]}
>  This option is only available when compiling C++ code.
> @@ -19809,6 +19861,14 @@ and inlining decisions.
>  @item inline
>  Dump after function inlining.
>
> +@item strubm
> +Dump after selecting @code{strub} modes, and recording the selections as
> +function attributes.
> +
> +@item strub
> +Dump @code{strub} transformations: interface changes, function wrapping,
> +and insertion of builtin calls for stack scrubbing and watermarking.
> +
>  @end table
>
>  Additionally, the options @option{-optimized}, @option{-missed},
> diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
> index 7c5d2e523601d..c4b2ee4b8091a 100644
> --- a/gcc/doc/tm.texi
> +++ b/gcc/doc/tm.texi
> @@ -3450,6 +3450,25 @@ in DWARF 2 debug information.  The default is zero.  A different value
>  may reduce the size of debug information on some ports.
>  @end defmac
>
> +@defmac TARGET_STRUB_USE_DYNAMIC_ARRAY
> +If defined to nonzero, @code{__strub_leave} will allocate a dynamic
> +array covering the stack range that needs scrubbing before clearing it.
> +Allocating the array tends to make scrubbing slower, but it enables the
> +scrubbing to be safely implemented with a @code{memset} call, which
> +could make up for the difference.
> +@end defmac
> +
> +@defmac TARGET_STRUB_MAY_USE_MEMSET
> +If defined to nonzero, enable @code{__strub_leave} to be optimized so as
> +to call @code{memset} for stack scrubbing.  This is only enabled by
> +default if @code{TARGET_STRUB_USE_DYNAMIC_ARRAY} is enabled; it's not
> +advisable to enable it otherwise, since @code{memset} would then likely
> +overwrite its own stack frame, but it might work if the target ABI
> +enables @code{memset} to not use the stack at all, not even for
> +arguments or its return address, and its implementation is trivial
> +enough that it doesn't use a stack frame.
> +@end defmac
> +
>  @node Exception Handling
>  @subsection Exception Handling Support
>  @cindex exception handling
> diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
> index c24493add5748..9cbde5f8b740a 100644
> --- a/gcc/doc/tm.texi.in
> +++ b/gcc/doc/tm.texi.in
> @@ -2686,6 +2686,25 @@ in DWARF 2 debug information.  The default is zero.  A different value
>  may reduce the size of debug information on some ports.
>  @end defmac
>
> +@defmac TARGET_STRUB_USE_DYNAMIC_ARRAY
> +If defined to nonzero, @code{__strub_leave} will allocate a dynamic
> +array covering the stack range that needs scrubbing before clearing it.
> +Allocating the array tends to make scrubbing slower, but it enables the
> +scrubbing to be safely implemented with a @code{memset} call, which
> +could make up for the difference.
> +@end defmac
> +
> +@defmac TARGET_STRUB_MAY_USE_MEMSET
> +If defined to nonzero, enable @code{__strub_leave} to be optimized so as
> +to call @code{memset} for stack scrubbing.  This is only enabled by
> +default if @code{TARGET_STRUB_USE_DYNAMIC_ARRAY} is enabled; it's not
> +advisable to enable it otherwise, since @code{memset} would then likely
> +overwrite its own stack frame, but it might work if the target ABI
> +enables @code{memset} to not use the stack at all, not even for
> +arguments or its return address, and its implementation is trivial
> +enough that it doesn't use a stack frame.
> +@end defmac
> +
>  @node Exception Handling
>  @subsection Exception Handling Support
>  @cindex exception handling
> diff --git a/gcc/gengtype-lex.l b/gcc/gengtype-lex.l
> index 34837d9dc9a8f..a7bb44cf2b9ad 100644
> --- a/gcc/gengtype-lex.l
> +++ b/gcc/gengtype-lex.l
> @@ -165,6 +165,9 @@ CXX_KEYWORD inline|public:|private:|protected:|template|operator|friend|static|m
>  [(){},*:<>;=%/|+\!\?\.-]       { return yytext[0]; }
>
>     /* ignore pp-directives */
> +^{HWS}"#"{HWS}[a-z_]+([^\n]*"\\"\n)+[^\n]*\n   {
> +  update_lineno (yytext, yyleng);
> +}
>  ^{HWS}"#"{HWS}[a-z_]+[^\n]*\n   {lexer_line.line++;}
>
>  .                              {
> diff --git a/gcc/ipa-inline.cc b/gcc/ipa-inline.cc
> index dc120e6da5af6..dbc3c7e8fdc88 100644
> --- a/gcc/ipa-inline.cc
> +++ b/gcc/ipa-inline.cc
> @@ -119,6 +119,7 @@ along with GCC; see the file COPYING3.  If not see
>  #include "stringpool.h"
>  #include "attribs.h"
>  #include "asan.h"
> +#include "ipa-strub.h"
>
>  /* Inliner uses greedy algorithm to inline calls in a priority order.
>     Badness is used as the key in a Fibonacci heap which roughly corresponds
> @@ -443,6 +444,11 @@ can_inline_edge_p (struct cgraph_edge *e, bool report,
>        inlinable = false;
>      }
>
> +  if (inlinable && !strub_inlinable_to_p (callee, caller))
> +    {
> +      e->inline_failed = CIF_UNSPECIFIED;
> +      inlinable = false;
> +    }
>    if (!inlinable && report)
>      report_inline_failed_reason (e);
>    return inlinable;
> diff --git a/gcc/ipa-split.cc b/gcc/ipa-split.cc
> index 6730f4f9d0e31..1a7285ff5dcf8 100644
> --- a/gcc/ipa-split.cc
> +++ b/gcc/ipa-split.cc
> @@ -104,6 +104,7 @@ along with GCC; see the file COPYING3.  If not see
>  #include "ipa-fnsummary.h"
>  #include "cfgloop.h"
>  #include "attribs.h"
> +#include "ipa-strub.h"
>
>  /* Per basic block info.  */
>
> @@ -1811,6 +1812,12 @@ execute_split_functions (void)
>                  "section.\n");
>        return 0;
>      }
> +  if (!strub_splittable_p (node))
> +    {
> +      if (dump_file)
> +       fprintf (dump_file, "Not splitting: function is a strub context.\n");
> +      return 0;
> +    }
>
>    /* We enforce splitting after loop headers when profile info is not
>       available.  */
> diff --git a/gcc/ipa-strub.cc b/gcc/ipa-strub.cc
> new file mode 100644
> index 0000000000000..293bec132b885
> --- /dev/null
> +++ b/gcc/ipa-strub.cc
> @@ -0,0 +1,3573 @@
> +/* strub (stack scrubbing) support.
> +   Copyright (C) 2021-2023 Free Software Foundation, Inc.
> +   Contributed by Alexandre Oliva <oliva@adacore.com>.
> +
> +This file is part of GCC.
> +
> +GCC is free software; you can redistribute it and/or modify it under
> +the terms of the GNU General Public License as published by the Free
> +Software Foundation; either version 3, or (at your option) any later
> +version.
> +
> +GCC is distributed in the hope that it will be useful, but WITHOUT ANY
> +WARRANTY; without even the implied warranty of MERCHANTABILITY or
> +FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
> +for more details.
> +
> +You should have received a copy of the GNU General Public License
> +along with GCC; see the file COPYING3.  If not see
> +<http://www.gnu.org/licenses/>.  */
> +
> +#include "config.h"
> +#include "system.h"
> +#include "coretypes.h"
> +#include "backend.h"
> +#include "tree.h"
> +#include "gimple.h"
> +#include "gimplify.h"
> +#include "tree-pass.h"
> +#include "ssa.h"
> +#include "gimple-iterator.h"
> +#include "gimplify-me.h"
> +#include "tree-into-ssa.h"
> +#include "tree-ssa.h"
> +#include "tree-cfg.h"
> +#include "cfghooks.h"
> +#include "cfgloop.h"
> +#include "cfgcleanup.h"
> +#include "tree-eh.h"
> +#include "except.h"
> +#include "builtins.h"
> +#include "attribs.h"
> +#include "tree-inline.h"
> +#include "cgraph.h"
> +#include "alloc-pool.h"
> +#include "symbol-summary.h"
> +#include "ipa-prop.h"
> +#include "ipa-fnsummary.h"
> +#include "gimple-fold.h"
> +#include "fold-const.h"
> +#include "gimple-walk.h"
> +#include "tree-dfa.h"
> +#include "langhooks.h"
> +#include "calls.h"
> +#include "vec.h"
> +#include "stor-layout.h"
> +#include "varasm.h"
> +#include "alias.h"
> +#include "diagnostic.h"
> +#include "intl.h"
> +#include "ipa-strub.h"
> +#include "symtab-thunks.h"
> +#include "attr-fnspec.h"
> +
> +/* This file introduces two passes that, together, implement
> +   machine-independent stack scrubbing, strub for short.  It arranges
> +   for stack frames that have strub enabled to be zeroed-out after
> +   relinquishing control to a caller, whether by returning or by
> +   propagating an exception.  This admittedly unusual design decision
> +   was driven by exception support (one needs a stack frame to be
> +   active to propagate exceptions out of it), and it enabled an
> +   implementation that is entirely machine-independent (no custom
> +   epilogue code is required).
> +
> +   Strub modes can be selected for stack frames by attaching attribute
> +   strub to functions or to variables (to their types, actually).
> +   Different strub modes, with different implementation details, are
> +   available, and they can be selected by an argument to the strub
> +   attribute.  When enabled by strub-enabled variables, whether by
> +   accessing (as in reading from) statically-allocated ones, or by
> +   introducing (as in declaring) automatically-allocated ones, a
> +   suitable mode is selected automatically.
> +
> +   At-calls mode modifies the interface of a function, adding a stack
> +   watermark argument, that callers use to clean up the stack frame of
> +   the called function.  Because of the interface change, it can only
> +   be used when explicitly selected, or when a function is internal to
> +   a translation unit.  Strub-at-calls function types are distinct
> +   from their original types (they're not modified in-place), and they
> +   are not interchangeable with other function types.
> +
> +   Internal mode, in turn, does not modify the type or the interface
> +   of a function.  It is currently implemented by turning the function
> +   into a wrapper, moving the function body to a separate wrapped
> +   function, and scrubbing the wrapped body's stack in the wrapper.
> +   Internal-strub function types are mostly interface-compatible with
> +   other strub modes, namely callable (from strub functions, though
> +   not strub-enabled) and disabled (not callable from strub
> +   functions).
> +
> +   Always_inline functions can be strub functions, but they can only
> +   be called from other strub functions, because strub functions must
> +   never be inlined into non-strub functions.  Internal and at-calls
> +   modes are indistinguishable when it comes to always_inline
> +   functions: they will necessarily be inlined into another strub
> +   function, and will thus be integrated into the caller's stack
> +   frame, whatever the mode.  (Contrast with non-always_inline strub
> +   functions: an at-calls function can be called from other strub
> +   functions, ensuring no discontinuity in stack erasing, whereas an
> +   internal-strub function can only be called from other strub
> +   functions if it happens to be inlined, or if -fstrub=relaxed mode
> +   is in effect (that's the default).  In -fstrub=strict mode,
> +   internal-strub functions are not callable from strub functions,
> +   because the wrapper itself is not strubbed.
> +
> +   The implementation involves two simple-IPA passes.  The earliest
> +   one, strub-mode, assigns strub modes to functions.  It needs to run
> +   before any inlining, so that we can prevent inlining of strub
> +   functions into non-strub functions.  It notes explicit strub mode
> +   requests, enables strub in response to strub variables and testing
> +   options, and flags unsatisfiable requests.
> +
> +   Three possibilities of unsatisfiable requests come to mind: (a)
> +   when a strub mode is explicitly selected, but the function uses
> +   features that make it ineligible for that mode (e.g. at-calls rules
> +   out calling __builtin_apply_args, because of the interface changes,
> +   and internal mode rules out noclone or otherwise non-versionable
> +   functions, non-default varargs, non-local or forced labels, and
> +   functions with far too many arguments); (b) when some strub mode
> +   must be enabled because of a strub variable, but the function is
> +   not eligible or not viable for any mode; and (c) when
> +   -fstrub=strict is enabled, and calls are found in strub functions
> +   to functions that are not callable from strub contexts.
> +   compute_strub_mode implements (a) and (b), and verify_strub
> +   implements (c).
> +
> +   The second IPA pass modifies interfaces of at-calls-strub functions
> +   and types, introduces strub calls in and around them. and splits
> +   internal-strub functions.  It is placed after early inlining, so
> +   that even internal-strub functions get a chance of being inlined
> +   into other strub functions, but before non-early inlining, so that
> +   internal-strub wrapper functions still get a chance of inlining
> +   after splitting.
> +
> +   Wrappers avoid duplicating the copying of large arguments again by
> +   passing them by reference to the wrapped bodies.  This involves
> +   occasional SSA rewriting of address computations, because of the
> +   additional indirection.  Besides these changes, and the
> +   introduction of the stack watermark parameter, wrappers and wrapped
> +   functions cooperate to handle variable argument lists (performing
> +   va_start in the wrapper, passing the list as an argument, and
> +   replacing va_start calls in the wrapped body with va_copy), and
> +   __builtin_apply_args (also called in the wrapper and passed to the
> +   wrapped body as an argument).
> +
> +   Strub bodies (both internal-mode wrapped bodies, and at-calls
> +   functions) always start by adjusting the watermark parameter, by
> +   calling __builtin___strub_update.  The compiler inserts them in the
> +   main strub pass.  Allocations of additional stack space for the
> +   frame (__builtin_alloca) are also followed by watermark updates.
> +   Stack space temporarily allocated to pass arguments to other
> +   functions, released right after the call, is not regarded as part
> +   of the frame.  Around calls to them, i.e., in internal-mode
> +   wrappers and at-calls callers (even calls through pointers), calls
> +   to __builtin___strub_enter and __builtin___strub_leave are
> +   inserted, the latter as a __finally block, so that it runs at
> +   regular and exceptional exit paths.  strub_enter only initializes
> +   the stack watermark, and strub_leave is where the scrubbing takes
> +   place, overwriting with zeros the stack space from the top of the
> +   stack to the watermark.
> +
> +   These calls can be optimized in various cases.  In
> +   pass_ipa_strub::adjust_at_calls_call, for example, we enable
> +   tail-calling and other optimized calls from one strub body to
> +   another by passing on the watermark parameter.  The builtins
> +   themselves may undergo inline substitution during expansion,
> +   dependign on optimization levels.  This involves dealing with stack
> +   red zones (when the builtins are called out-of-line, the red zone
> +   cannot be used) and other ugly details related with inlining strub
> +   bodies into other strub bodies (see expand_builtin_strub_update).
> +   expand_builtin_strub_leave may even perform partial inline
> +   substitution.  */
> +
> +/* Const and pure functions that gain a watermark parameter for strub purposes
> +   are still regarded as such, which may cause the inline expansions of the
> +   __strub builtins to malfunction.  Ideally, attribute "fn spec" would enable
> +   us to inform the backend about requirements and side effects of the call, but
> +   call_fusage building in calls.c:expand_call does not even look at
> +   attr_fnspec, so we resort to asm loads and updates to attain an equivalent
> +   effect.  Once expand_call gains the ability to issue extra memory uses and
> +   clobbers based on pure/const function's fnspec, we can define this to 1.  */
> +#define ATTR_FNSPEC_DECONST_WATERMARK 0
> +
> +enum strub_mode {
> +  /* This mode denotes a regular function, that does not require stack
> +     scrubbing (strubbing).  It may call any other functions, but if
> +     it calls AT_CALLS (or WRAPPED) ones, strubbing logic is
> +     automatically introduced around those calls (the latter, by
> +     inlining INTERNAL wrappers).  */
> +  STRUB_DISABLED = 0,
> +
> +  /* This denotes a function whose signature is (to be) modified to
> +     take an extra parameter, for stack use annotation, and its
> +     callers must initialize and pass that argument, and perform the
> +     strubbing.  Functions that are explicitly marked with attribute
> +     strub must have the mark visible wherever the function is,
> +     including aliases, and overriders and overriding methods.
> +     Functions that are implicitly marked for strubbing, for accessing
> +     variables explicitly marked as such, will only select this
> +     strubbing method if they are internal to a translation unit.  It
> +     can only be inlined into other strubbing functions, i.e.,
> +     STRUB_AT_CALLS or STRUB_WRAPPED.  */
> +  STRUB_AT_CALLS = 1,
> +
> +  /* This denotes a function that is to perform strubbing internally,
> +     without any changes to its interface (the function is turned into
> +     a strubbing wrapper, and its original body is moved to a separate
> +     STRUB_WRAPPED function, with a modified interface).  Functions
> +     may be explicitly marked with attribute strub(2), and the
> +     attribute must be visible at the point of definition.  Functions
> +     that are explicitly marked for strubbing, for accessing variables
> +     explicitly marked as such, may select this strubbing mode if
> +     their interface cannot change, e.g. because its interface is
> +     visible to other translation units, directly, by indirection
> +     (having its address taken), inheritance, etc.  Functions that use
> +     this method must not have the noclone attribute, nor the noipa
> +     one.  Functions marked as always_inline may select this mode, but
> +     they are NOT wrapped, they remain unchanged, and are only inlined
> +     into strubbed contexts.  Once non-always_inline functions are
> +     wrapped, the wrapper becomes STRUB_WRAPPER, and the wrapped becomes
> +     STRUB_WRAPPED.  */
> +  STRUB_INTERNAL = 2,
> +
> +  /* This denotes a function whose stack is not strubbed, but that is
> +     nevertheless explicitly or implicitly marked as callable from strubbing
> +     functions.  Normally, only STRUB_AT_CALLS (and STRUB_INTERNAL ->
> +     STRUB_WRAPPED) functions can be called from strubbing contexts (bodies of
> +     STRUB_AT_CALLS, STRUB_INTERNAL and STRUB_WRAPPED functions), but attribute
> +     strub(3) enables other functions to be (indirectly) called from these
> +     contexts.  Some builtins and internal functions may be implicitly marked as
> +     STRUB_CALLABLE.  */
> +  STRUB_CALLABLE = 3,
> +
> +  /* This denotes the function that took over the body of a
> +     STRUB_INTERNAL function.  At first, it's only called by its
> +     wrapper, but the wrapper may be inlined.  The wrapped function,
> +     in turn, can only be inlined into other functions whose stack
> +     frames are strubbed, i.e., that are STRUB_WRAPPED or
> +     STRUB_AT_CALLS.  */
> +  STRUB_WRAPPED = -1,
> +
> +  /* This denotes the wrapper function that replaced the STRUB_INTERNAL
> +     function.  This mode overrides the STRUB_INTERNAL mode at the time the
> +     internal to-be-wrapped function becomes a wrapper, so that inlining logic
> +     can tell one from the other.  */
> +  STRUB_WRAPPER = -2,
> +
> +  /* This denotes an always_inline function that requires strubbing.  It can
> +     only be called from, and inlined into, other strubbing contexts.  */
> +  STRUB_INLINABLE = -3,
> +
> +  /* This denotes a function that accesses strub variables, so it would call for
> +     internal strubbing (whether or not it's eligible for that), but since
> +     at-calls strubbing is viable, that's selected as an optimization.  This
> +     mode addresses the inconvenience that such functions may have different
> +     modes selected depending on optimization flags, and get a different
> +     callable status depending on that choice: if we assigned them
> +     STRUB_AT_CALLS mode, they would be callable when optimizing, whereas
> +     STRUB_INTERNAL would not be callable.  */
> +  STRUB_AT_CALLS_OPT = -4,
> +
> +};
> +
> +/* Look up a strub attribute in TYPE, and return it.  */
> +
> +static tree
> +get_strub_attr_from_type (tree type)
> +{
> +  return lookup_attribute ("strub", TYPE_ATTRIBUTES (type));
> +}
> +
> +/* Look up a strub attribute in DECL or in its type, and return it.  */
> +
> +static tree
> +get_strub_attr_from_decl (tree decl)
> +{
> +  tree ret = lookup_attribute ("strub", DECL_ATTRIBUTES (decl));
> +  if (ret)
> +    return ret;
> +  return get_strub_attr_from_type (TREE_TYPE (decl));
> +}
> +
> +#define STRUB_ID_COUNT         8
> +#define STRUB_IDENT_COUNT      3
> +#define STRUB_TYPE_COUNT       5
> +
> +#define STRUB_ID_BASE          0
> +#define STRUB_IDENT_BASE       (STRUB_ID_BASE + STRUB_ID_COUNT)
> +#define STRUB_TYPE_BASE                (STRUB_IDENT_BASE + STRUB_IDENT_COUNT)
> +#define STRUB_CACHE_SIZE       (STRUB_TYPE_BASE + STRUB_TYPE_COUNT)
> +
> +/* Keep the strub mode and temp identifiers and types from being GC'd.  */
> +static GTY((deletable)) tree strub_cache[STRUB_CACHE_SIZE];
> +
> +/* Define a function to cache identifier ID, to be used as a strub attribute
> +   parameter for a strub mode named after NAME.  */
> +#define DEF_STRUB_IDS(IDX, NAME, ID)                           \
> +static inline tree get_strub_mode_id_ ## NAME () {             \
> +  int idx = STRUB_ID_BASE + IDX;                               \
> +  tree identifier = strub_cache[idx];                          \
> +  if (!identifier)                                             \
> +    strub_cache[idx] = identifier = get_identifier (ID);       \
> +  return identifier;                                           \
> +}
> +/* Same as DEF_STRUB_IDS, but use the string expansion of NAME as ID.  */
> +#define DEF_STRUB_ID(IDX, NAME)                        \
> +  DEF_STRUB_IDS (IDX, NAME, #NAME)
> +
> +/* Define functions for each of the strub mode identifiers.
> +   Expose dashes rather than underscores.  */
> +DEF_STRUB_ID (0, disabled)
> +DEF_STRUB_IDS (1, at_calls, "at-calls")
> +DEF_STRUB_ID (2, internal)
> +DEF_STRUB_ID (3, callable)
> +DEF_STRUB_ID (4, wrapped)
> +DEF_STRUB_ID (5, wrapper)
> +DEF_STRUB_ID (6, inlinable)
> +DEF_STRUB_IDS (7, at_calls_opt, "at-calls-opt")
> +
> +/* Release the temporary macro names.  */
> +#undef DEF_STRUB_IDS
> +#undef DEF_STRUB_ID
> +
> +/* Return the identifier corresponding to strub MODE.  */
> +
> +static tree
> +get_strub_mode_attr_parm (enum strub_mode mode)
> +{
> +  switch (mode)
> +    {
> +    case STRUB_DISABLED:
> +      return get_strub_mode_id_disabled ();
> +
> +    case STRUB_AT_CALLS:
> +      return get_strub_mode_id_at_calls ();
> +
> +    case STRUB_INTERNAL:
> +      return get_strub_mode_id_internal ();
> +
> +    case STRUB_CALLABLE:
> +      return get_strub_mode_id_callable ();
> +
> +    case STRUB_WRAPPED:
> +      return get_strub_mode_id_wrapped ();
> +
> +    case STRUB_WRAPPER:
> +      return get_strub_mode_id_wrapper ();
> +
> +    case STRUB_INLINABLE:
> +      return get_strub_mode_id_inlinable ();
> +
> +    case STRUB_AT_CALLS_OPT:
> +      return get_strub_mode_id_at_calls_opt ();
> +
> +    default:
> +      gcc_unreachable ();
> +    }
> +}
> +
> +/* Return the parmeters (TREE_VALUE) for a strub attribute of MODE.
> +   We know we use a single parameter, so we bypass the creation of a
> +   tree list.  */
> +
> +static tree
> +get_strub_mode_attr_value (enum strub_mode mode)
> +{
> +  return get_strub_mode_attr_parm (mode);
> +}
> +
> +/* Determine whether ID is a well-formed strub mode-specifying attribute
> +   parameter for a function (type).  Only user-visible modes are accepted, and
> +   ID must be non-NULL.
> +
> +   For unacceptable parms, return 0, otherwise a nonzero value as below.
> +
> +   If the parm enables strub, return positive, otherwise negative.
> +
> +   If the affected type must be a distinct, incompatible type,return an integer
> +   of absolute value 2, otherwise 1.  */
> +
> +int
> +strub_validate_fn_attr_parm (tree id)
> +{
> +  int ret;
> +  const char *s = NULL;
> +  size_t len = 0;
> +
> +  /* do NOT test for NULL.  This is only to be called with non-NULL arguments.
> +     We assume that the strub parameter applies to a function, because only
> +     functions accept an explicit argument.  If we accepted NULL, and we
> +     happened to be called to verify the argument for a variable, our return
> +     values would be wrong.  */
> +  if (TREE_CODE (id) == STRING_CST)
> +    {
> +      s = TREE_STRING_POINTER (id);
> +      len = TREE_STRING_LENGTH (id) - 1;
> +    }
> +  else if (TREE_CODE (id) == IDENTIFIER_NODE)
> +    {
> +      s = IDENTIFIER_POINTER (id);
> +      len = IDENTIFIER_LENGTH (id);
> +    }
> +  else
> +    return 0;
> +
> +  enum strub_mode mode;
> +
> +  if (len != 8)
> +    return 0;
> +
> +  switch (s[0])
> +    {
> +    case 'd':
> +      mode = STRUB_DISABLED;
> +      ret = -1;
> +      break;
> +
> +    case 'a':
> +      mode = STRUB_AT_CALLS;
> +      ret = 2;
> +      break;
> +
> +    case 'i':
> +      mode = STRUB_INTERNAL;
> +      ret = 1;
> +      break;
> +
> +    case 'c':
> +      mode = STRUB_CALLABLE;
> +      ret = -2;
> +      break;
> +
> +    default:
> +      /* Other parms are for internal use only.  */
> +      return 0;
> +    }
> +
> +  tree mode_id = get_strub_mode_attr_parm (mode);
> +
> +  if (TREE_CODE (id) == IDENTIFIER_NODE
> +      ? id != mode_id
> +      : strncmp (s, IDENTIFIER_POINTER (mode_id), len) != 0)
> +    return 0;
> +
> +  return ret;
> +}
> +
> +/* Return the strub mode from STRUB_ATTR.  VAR_P should be TRUE if the attribute
> +   is taken from a variable, rather than from a function, or a type thereof.  */
> +
> +static enum strub_mode
> +get_strub_mode_from_attr (tree strub_attr, bool var_p = false)
> +{
> +  enum strub_mode mode = STRUB_DISABLED;
> +
> +  if (strub_attr)
> +    {
> +      if (!TREE_VALUE (strub_attr))
> +       mode = !var_p ? STRUB_AT_CALLS : STRUB_INTERNAL;
> +      else
> +       {
> +         gcc_checking_assert (!var_p);
> +         tree id = TREE_VALUE (strub_attr);
> +         if (TREE_CODE (id) == TREE_LIST)
> +           id = TREE_VALUE (id);
> +         const char *s = (TREE_CODE (id) == STRING_CST
> +                          ? TREE_STRING_POINTER (id)
> +                          : IDENTIFIER_POINTER (id));
> +         size_t len = (TREE_CODE (id) == STRING_CST
> +                       ? TREE_STRING_LENGTH (id) - 1
> +                       : IDENTIFIER_LENGTH (id));
> +
> +         switch (len)
> +           {
> +           case 7:
> +             switch (s[6])
> +               {
> +               case 'r':
> +                 mode = STRUB_WRAPPER;
> +                 break;
> +
> +               case 'd':
> +                 mode = STRUB_WRAPPED;
> +                 break;
> +
> +               default:
> +                 gcc_unreachable ();
> +               }
> +             break;
> +
> +           case 8:
> +             switch (s[0])
> +               {
> +               case 'd':
> +                 mode = STRUB_DISABLED;
> +                 break;
> +
> +               case 'a':
> +                 mode = STRUB_AT_CALLS;
> +                 break;
> +
> +               case 'i':
> +                 mode = STRUB_INTERNAL;
> +                 break;
> +
> +               case 'c':
> +                 mode = STRUB_CALLABLE;
> +                 break;
> +
> +               default:
> +                 gcc_unreachable ();
> +               }
> +             break;
> +
> +           case 9:
> +             mode = STRUB_INLINABLE;
> +             break;
> +
> +           case 12:
> +             mode = STRUB_AT_CALLS_OPT;
> +             break;
> +
> +           default:
> +             gcc_unreachable ();
> +           }
> +
> +         gcc_checking_assert (TREE_CODE (id) == IDENTIFIER_NODE
> +                              ? id == get_strub_mode_attr_parm (mode)
> +                              : strncmp (IDENTIFIER_POINTER
> +                                         (get_strub_mode_attr_parm (mode)),
> +                                         s, len) == 0);
> +       }
> +    }
> +
> +  return mode;
> +}
> +
> +/* Look up, decode and return the strub mode associated with FNDECL.  */
> +
> +static enum strub_mode
> +get_strub_mode_from_fndecl (tree fndecl)
> +{
> +  return get_strub_mode_from_attr (get_strub_attr_from_decl (fndecl));
> +}
> +
> +/* Look up, decode and return the strub mode associated with NODE.  */
> +
> +static enum strub_mode
> +get_strub_mode (cgraph_node *node)
> +{
> +  return get_strub_mode_from_fndecl (node->decl);
> +}
> +
> +/* Look up, decode and return the strub mode associated with TYPE.  */
> +
> +static enum strub_mode
> +get_strub_mode_from_type (tree type)
> +{
> +  bool var_p = !FUNC_OR_METHOD_TYPE_P (type);
> +  tree attr = get_strub_attr_from_type (type);
> +
> +  if (attr)
> +    return get_strub_mode_from_attr (attr, var_p);
> +
> +  if (flag_strub >= -1 && !var_p)
> +    return STRUB_CALLABLE;
> +
> +  return STRUB_DISABLED;
> +}
> +
> +
> +/* Return TRUE iff NODE calls builtin va_start.  */
> +
> +static bool
> +calls_builtin_va_start_p (cgraph_node *node)
> +{
> +  bool result = false;
> +
> +  for (cgraph_edge *e = node->callees; e; e = e->next_callee)
> +    {
> +      tree cdecl = e->callee->decl;
> +      if (fndecl_built_in_p (cdecl, BUILT_IN_VA_START))
> +       return true;
> +    }
> +
> +  return result;
> +}
> +
> +/* Return TRUE iff NODE calls builtin apply_args, and optionally REPORT it.  */
> +
> +static bool
> +calls_builtin_apply_args_p (cgraph_node *node, bool report = false)
> +{
> +  bool result = false;
> +
> +  for (cgraph_edge *e = node->callees; e; e = e->next_callee)
> +    {
> +      tree cdecl = e->callee->decl;
> +      if (!fndecl_built_in_p (cdecl, BUILT_IN_APPLY_ARGS))
> +       continue;
> +
> +      result = true;
> +
> +      if (!report)
> +       break;
> +
> +      sorry_at (e->call_stmt
> +               ? gimple_location (e->call_stmt)
> +               : DECL_SOURCE_LOCATION (node->decl),
> +               "at-calls %<strub%> does not support call to %qD",
> +               cdecl);
> +    }
> +
> +  return result;
> +}
> +
> +/* Return TRUE iff NODE carries the always_inline attribute.  */
> +
> +static inline bool
> +strub_always_inline_p (cgraph_node *node)
> +{
> +  return lookup_attribute ("always_inline", DECL_ATTRIBUTES (node->decl));
> +}
> +
> +/* Return TRUE iff NODE is potentially eligible for any strub-enabled mode, and
> +   optionally REPORT the reasons for ineligibility.  */
> +
> +static inline bool
> +can_strub_p (cgraph_node *node, bool report = false)
> +{
> +  bool result = true;
> +
> +  if (!report && strub_always_inline_p (node))
> +    return result;
> +
> +  if (lookup_attribute ("noipa", DECL_ATTRIBUTES (node->decl)))
> +    {
> +      result = false;
> +
> +      if (!report)
> +       return result;
> +
> +      sorry_at (DECL_SOURCE_LOCATION (node->decl),
> +               "%qD is not eligible for %<strub%>"
> +               " because of attribute %<noipa%>",
> +               node->decl);
> +    }
> +
> +  /* We can't, and don't want to vectorize the watermark and other
> +     strub-introduced parms.  */
> +  if (lookup_attribute ("simd", DECL_ATTRIBUTES (node->decl)))
> +    {
> +      result = false;
> +
> +      if (!report)
> +       return result;
> +
> +      sorry_at (DECL_SOURCE_LOCATION (node->decl),
> +               "%qD is not eligible for %<strub%>"
> +               " because of attribute %<simd%>",
> +               node->decl);
> +    }
> +
> +  return result;
> +}
> +
> +/* Return TRUE iff NODE is eligible for at-calls strub, and optionally REPORT
> +   the reasons for ineligibility.  Besides general non-eligibility for
> +   strub-enabled modes, at-calls rules out calling builtin apply_args.  */
> +
> +static bool
> +can_strub_at_calls_p (cgraph_node *node, bool report = false)
> +{
> +  bool result = !report || can_strub_p (node, report);
> +
> +  if (!result && !report)
> +    return result;
> +
> +  return !calls_builtin_apply_args_p (node, report);
> +}
> +
> +/* Return TRUE iff the called function (pointer or, if available,
> +   decl) undergoes a significant type conversion for the call.  Strub
> +   mode changes between function types, and other non-useless type
> +   conversions, are regarded as significant.  When the function type
> +   is overridden, the effective strub mode for the call is that of the
> +   call fntype, rather than that of the pointer or of the decl.
> +   Functions called with type overrides cannot undergo type changes;
> +   it's as if their address was taken, so they're considered
> +   non-viable for implicit at-calls strub mode.  */
> +
> +static inline bool
> +strub_call_fntype_override_p (const gcall *gs)
> +{
> +  if (gimple_call_internal_p (gs))
> +    return false;
> +  tree fn_type = TREE_TYPE (TREE_TYPE (gimple_call_fn (gs)));
> +  if (tree decl = gimple_call_fndecl (gs))
> +    fn_type = TREE_TYPE (decl);
> +
> +  /* We do NOT want to take the mode from the decl here.  This
> +     function is used to tell whether we can change the strub mode of
> +     a function, and whether the effective mode for the call is to be
> +     taken from the decl or from an overrider type.  When the strub
> +     mode is explicitly declared, or overridden with a type cast, the
> +     difference will be noticed in function types.  However, if the
> +     strub mode is implicit due to e.g. strub variables or -fstrub=*
> +     command-line flags, we will adjust call types along with function
> +     types.  In either case, the presence of type or strub mode
> +     overriders in calls will prevent a function from having its strub
> +     modes changed in ways that would imply type changes, but taking
> +     strub modes from decls would defeat this, since we set strub
> +     modes and then call this function to tell whether the original
> +     type was overridden to decide whether to adjust the call.  We
> +     need the answer to be about the type, not the decl.  */
> +  enum strub_mode mode = get_strub_mode_from_type (fn_type);
> +  return (get_strub_mode_from_type (gs->u.fntype) != mode
> +         || !useless_type_conversion_p (gs->u.fntype, fn_type));
> +}
> +
> +/* Return TRUE iff NODE is called directly with a type override.  */
> +
> +static bool
> +called_directly_with_type_override_p (cgraph_node *node, void *)
> +{
> +  for (cgraph_edge *e = node->callers; e; e = e->next_caller)
> +    if (e->call_stmt && strub_call_fntype_override_p (e->call_stmt))
> +      return true;
> +
> +  return false;
> +}
> +
> +/* Return TRUE iff NODE or any other nodes aliased to it are called
> +   with type overrides.  We can't safely change the type of such
> +   functions.  */
> +
> +static bool
> +called_with_type_override_p (cgraph_node *node)
> +{
> +  return (node->call_for_symbol_thunks_and_aliases
> +         (called_directly_with_type_override_p, NULL, true, true));
> +}
> +
> +/* Symbolic macro for the max number of arguments that internal strub may add to
> +   a function.  */
> +
> +#define STRUB_INTERNAL_MAX_EXTRA_ARGS 3
> +
> +/* We can't perform internal strubbing if the function body involves certain
> +   features:
> +
> +   - a non-default __builtin_va_start (e.g. x86's __builtin_ms_va_start) is
> +   currently unsupported because we can't discover the corresponding va_copy and
> +   va_end decls in the wrapper, and we don't convey the alternate variable
> +   arguments ABI to the modified wrapped function.  The default
> +   __builtin_va_start is supported by calling va_start/va_end at the wrapper,
> +   that takes variable arguments, passing a pointer to the va_list object to the
> +   wrapped function, that runs va_copy from it where the original function ran
> +   va_start.
> +
> +   __builtin_next_arg is currently unsupported because the wrapped function
> +   won't be a variable argument function.  We could process it in the wrapper,
> +   that remains a variable argument function, and replace calls in the wrapped
> +   body, but we currently don't.
> +
> +   __builtin_return_address is rejected because it's generally used when the
> +   actual caller matters, and introducing a wrapper breaks such uses as those in
> +   the unwinder.  */
> +
> +static bool
> +can_strub_internally_p (cgraph_node *node, bool report = false)
> +{
> +  bool result = !report || can_strub_p (node, report);
> +
> +  if (!result && !report)
> +    return result;
> +
> +  if (!report && strub_always_inline_p (node))
> +    return result;
> +
> +  /* Since we're not changing the function identity proper, just
> +     moving its full implementation, we *could* disable
> +     fun->cannot_be_copied_reason and/or temporarily drop a noclone
> +     attribute, but we'd have to prevent remapping of the labels.  */
> +  if (lookup_attribute ("noclone", DECL_ATTRIBUTES (node->decl)))
> +    {
> +      result = false;
> +
> +      if (!report)
> +       return result;
> +
> +      sorry_at (DECL_SOURCE_LOCATION (node->decl),
> +               "%qD is not eligible for internal %<strub%>"
> +               " because of attribute %<noclone%>",
> +               node->decl);
> +    }
> +
> +  if (node->has_gimple_body_p ())
> +    {
> +      for (cgraph_edge *e = node->callees; e; e = e->next_callee)
> +       {
> +         tree cdecl = e->callee->decl;
> +         if (!((fndecl_built_in_p (cdecl, BUILT_IN_VA_START)
> +                && cdecl != builtin_decl_explicit (BUILT_IN_VA_START))
> +               || fndecl_built_in_p (cdecl, BUILT_IN_NEXT_ARG)
> +               || fndecl_built_in_p (cdecl, BUILT_IN_RETURN_ADDRESS)))
> +           continue;
> +
> +         result = false;
> +
> +         if (!report)
> +           return result;
> +
> +         sorry_at (e->call_stmt
> +                   ? gimple_location (e->call_stmt)
> +                   : DECL_SOURCE_LOCATION (node->decl),
> +                   "%qD is not eligible for internal %<strub%> "
> +                   "because it calls %qD",
> +                   node->decl, cdecl);
> +       }
> +
> +      struct function *fun = DECL_STRUCT_FUNCTION (node->decl);
> +      if (fun->has_nonlocal_label)
> +       {
> +         result = false;
> +
> +         if (!report)
> +           return result;
> +
> +         sorry_at (DECL_SOURCE_LOCATION (node->decl),
> +                   "%qD is not eligible for internal %<strub%> "
> +                   "because it contains a non-local goto target",
> +                   node->decl);
> +       }
> +
> +      if (fun->has_forced_label_in_static)
> +       {
> +         result = false;
> +
> +         if (!report)
> +           return result;
> +
> +         sorry_at (DECL_SOURCE_LOCATION (node->decl),
> +                   "%qD is not eligible for internal %<strub%> "
> +                   "because the address of a local label escapes",
> +                   node->decl);
> +       }
> +
> +      /* Catch any other case that would prevent versioning/cloning
> +        so as to also have it covered above.  */
> +      gcc_checking_assert (!result /* || !node->has_gimple_body_p () */
> +                          || tree_versionable_function_p (node->decl));
> +
> +
> +      /* Label values references are not preserved when copying.  If referenced
> +        in nested functions, as in 920415-1.c and 920721-4.c their decls get
> +        remapped independently.  The exclusion below might be too broad, in
> +        that we might be able to support correctly cases in which the labels
> +        are only used internally in a function, but disconnecting forced labels
> +        from their original declarations is undesirable in general.  */
> +      basic_block bb;
> +      FOR_EACH_BB_FN (bb, DECL_STRUCT_FUNCTION (node->decl))
> +       for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
> +            !gsi_end_p (gsi); gsi_next (&gsi))
> +         {
> +           glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (gsi));
> +           tree target;
> +
> +           if (!label_stmt)
> +             break;
> +
> +           target = gimple_label_label (label_stmt);
> +
> +           if (!FORCED_LABEL (target))
> +             continue;
> +
> +           result = false;
> +
> +           if (!report)
> +             return result;
> +
> +           sorry_at (gimple_location (label_stmt),
> +                     "internal %<strub%> does not support forced labels");
> +         }
> +    }
> +
> +  if (list_length (TYPE_ARG_TYPES (TREE_TYPE (node->decl)))
> +      >= (((HOST_WIDE_INT) 1 << IPA_PARAM_MAX_INDEX_BITS)
> +         - STRUB_INTERNAL_MAX_EXTRA_ARGS))
> +    {
> +      result = false;
> +
> +      if (!report)
> +       return result;
> +
> +      sorry_at (DECL_SOURCE_LOCATION (node->decl),
> +               "%qD has too many arguments for internal %<strub%>",
> +               node->decl);
> +    }
> +
> +  return result;
> +}
> +
> +/* Return TRUE iff NODE has any strub-requiring local variable, or accesses (as
> +   in reading) any variable through a strub-requiring type.  */
> +
> +static bool
> +strub_from_body_p (cgraph_node *node)
> +{
> +  if (!node->has_gimple_body_p ())
> +    return false;
> +
> +  /* If any local variable is marked for strub...  */
> +  unsigned i;
> +  tree var;
> +  FOR_EACH_LOCAL_DECL (DECL_STRUCT_FUNCTION (node->decl),
> +                      i, var)
> +    if (get_strub_mode_from_type (TREE_TYPE (var))
> +       != STRUB_DISABLED)
> +      return true;
> +
> +  /* Now scan the body for loads with strub-requiring types.
> +     ??? Compound types don't propagate the strub requirement to
> +     component types.  */
> +  basic_block bb;
> +  FOR_EACH_BB_FN (bb, DECL_STRUCT_FUNCTION (node->decl))
> +    for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
> +        !gsi_end_p (gsi); gsi_next (&gsi))
> +      {
> +       gimple *stmt = gsi_stmt (gsi);
> +
> +       if (!gimple_assign_load_p (stmt))
> +         continue;
> +
> +       tree rhs = gimple_assign_rhs1 (stmt);
> +       if (get_strub_mode_from_type (TREE_TYPE (rhs))
> +           != STRUB_DISABLED)
> +         return true;
> +      }
> +
> +  return false;
> +}
> +
> +/* Return TRUE iff node is associated with a builtin that should be callable
> +   from strub contexts.  */
> +
> +static inline bool
> +strub_callable_builtin_p (cgraph_node *node)
> +{
> +  if (DECL_BUILT_IN_CLASS (node->decl) != BUILT_IN_NORMAL)
> +    return false;
> +
> +  enum built_in_function fcode = DECL_FUNCTION_CODE (node->decl);
> +
> +  switch (fcode)
> +    {
> +    case BUILT_IN_NONE:
> +      gcc_unreachable ();
> +
> +      /* This temporarily allocates stack for the call, and we can't reasonably
> +        update the watermark for that.  Besides, we don't check the actual call
> +        target, nor its signature, and it seems to be overkill to as much as
> +        try to do so.  */
> +    case BUILT_IN_APPLY:
> +      return false;
> +
> +      /* Conversely, this shouldn't be called from within strub contexts, since
> +        the caller may have had its signature modified.  STRUB_INTERNAL is ok,
> +        the call will remain in the STRUB_WRAPPER, and removed from the
> +        STRUB_WRAPPED clone.  */
> +    case BUILT_IN_APPLY_ARGS:
> +      return false;
> +
> +      /* ??? Make all other builtins callable.  We wish to make any builtin call
> +        the compiler might introduce on its own callable.  Anything that is
> +        predictable enough as to be known not to allow stack data that should
> +        be strubbed to unintentionally escape to non-strub contexts can be
> +        allowed, and pretty much every builtin appears to fit this description.
> +        The exceptions to this rule seem to be rare, and only available as
> +        explicit __builtin calls, so let's keep it simple and allow all of
> +        them...  */
> +    default:
> +      return true;
> +    }
> +}
> +
> +/* Compute the strub mode to be used for NODE.  STRUB_ATTR should be the strub
> +   attribute,found for NODE, if any.  */
> +
> +static enum strub_mode
> +compute_strub_mode (cgraph_node *node, tree strub_attr)
> +{
> +  enum strub_mode req_mode = get_strub_mode_from_attr (strub_attr);
> +
> +  gcc_checking_assert (flag_strub >= -2 && flag_strub <= 3);
> +
> +  /* Symbolic encodings of the -fstrub-* flags.  */
> +  /* Enable strub when explicitly requested through attributes to functions or
> +     variables, reporting errors if the requests cannot be satisfied.  */
> +  const bool strub_flag_auto = flag_strub < 0;
> +  /* strub_flag_auto with strub call verification; without this, functions are
> +     implicitly callable.  */
> +  const bool strub_flag_strict = flag_strub < -1;
> +  /* Disable strub altogether, ignore attributes entirely.  */
> +  const bool strub_flag_disabled = flag_strub == 0;
> +  /* On top of _auto, also enable strub implicitly for functions that can
> +     safely undergo at-calls strubbing.  Internal mode will still be used in
> +     functions that request it explicitly with attribute strub(2), or when the
> +     function body requires strubbing and at-calls strubbing is not viable.  */
> +  const bool strub_flag_at_calls = flag_strub == 1;
> +  /* On top of default, also enable strub implicitly for functions that can
> +     safely undergo internal strubbing.  At-calls mode will still be used in
> +     functions that requiest it explicitly with attribute strub() or strub(1),
> +     or when the function body requires strubbing and internal strubbing is not
> +     viable.  */
> +  const bool strub_flag_internal = flag_strub == 2;
> +  /* On top of default, also enable strub implicitly for functions that can
> +     safely undergo strubbing in either mode.  When both modes are viable,
> +     at-calls is preferred.  */
> +  const bool strub_flag_either = flag_strub == 3;
> +  /* Besides the default behavior, enable strub implicitly for all viable
> +     functions.  */
> +  const bool strub_flag_viable = flag_strub > 0;
> +
> +  /* The consider_* variables should be TRUE if selecting the corresponding
> +     strub modes would be consistent with requests from attributes and command
> +     line flags.  Attributes associated with functions pretty much mandate a
> +     selection, and should report an error if not satisfied; strub_flag_auto
> +     implicitly enables some viable strub mode if that's required by references
> +     to variables marked for strub; strub_flag_viable enables strub if viable
> +     (even when favoring one mode, body-requested strub can still be satisfied
> +     by either mode), and falls back to callable, silently unless variables
> +     require strubbing.  */
> +
> +  const bool consider_at_calls
> +    = (!strub_flag_disabled
> +       && (strub_attr
> +          ? req_mode == STRUB_AT_CALLS
> +          : true));
> +  const bool consider_internal
> +    = (!strub_flag_disabled
> +       && (strub_attr
> +          ? req_mode == STRUB_INTERNAL
> +          : true));
> +
> +  const bool consider_callable
> +    = (!strub_flag_disabled
> +       && (strub_attr
> +          ? req_mode == STRUB_CALLABLE
> +          : (!strub_flag_strict
> +             || strub_callable_builtin_p (node))));
> +
> +  /* This is a shorthand for either strub-enabled mode.  */
> +  const bool consider_strub
> +    = (consider_at_calls || consider_internal);
> +
> +  /* We can cope with always_inline functions even with noipa and noclone,
> +     because we just leave them alone.  */
> +  const bool is_always_inline
> +    = strub_always_inline_p (node);
> +
> +  /* Strubbing in general, and each specific strub mode, may have its own set of
> +     requirements.  We require noipa for strubbing, either because of cloning
> +     required for internal strub, or because of caller enumeration required for
> +     at-calls strub.  We don't consider the at-calls mode eligible if it's not
> +     even considered, it has no further requirements.  Internal mode requires
> +     cloning and the absence of certain features in the body and, like at-calls,
> +     it's not eligible if it's not even under consideration.
> +
> +     ??? Do we need target hooks for further constraints?  E.g., x86's
> +     "interrupt" attribute breaks internal strubbing because the wrapped clone
> +     carries the attribute and thus isn't callable; in this case, we could use a
> +     target hook to adjust the clone instead.  */
> +  const bool strub_eligible
> +    = (consider_strub
> +       && (is_always_inline || can_strub_p (node)));
> +  const bool at_calls_eligible
> +    = (consider_at_calls && strub_eligible
> +       && can_strub_at_calls_p (node));
> +  const bool internal_eligible
> +    = (consider_internal && strub_eligible
> +       && (is_always_inline
> +          || can_strub_internally_p (node)));
> +
> +  /* In addition to the strict eligibility requirements, some additional
> +     constraints are placed on implicit selection of certain modes.  These do
> +     not prevent the selection of a mode if explicitly specified as part of a
> +     function interface (the strub attribute), but they may prevent modes from
> +     being selected by the command line or by function bodies.  The only actual
> +     constraint is on at-calls mode: since we change the function's exposed
> +     signature, we won't do it implicitly if the function can possibly be used
> +     in ways that do not expect the signature change, e.g., if the function is
> +     available to or interposable by other units, if its address is taken,
> +     etc.  */
> +  const bool at_calls_viable
> +    = (at_calls_eligible
> +       && (strub_attr
> +          || (node->has_gimple_body_p ()
> +              && (!node->externally_visible
> +                  || (node->binds_to_current_def_p ()
> +                      && node->can_be_local_p ()))
> +              && node->only_called_directly_p ()
> +              && !called_with_type_override_p (node))));
> +  const bool internal_viable
> +    = (internal_eligible);
> +
> +  /* Shorthand.  */
> +  const bool strub_viable
> +    = (at_calls_viable || internal_viable);
> +
> +  /* We wish to analyze the body, to look for implicit requests for strub, both
> +     to implicitly enable it when the body calls for it, and to report errors if
> +     the body calls for it but neither mode is viable (even if that follows from
> +     non-eligibility because of the explicit specification of some non-strubbing
> +     mode).  We can refrain from scanning the body only in rare circumstances:
> +     when strub is enabled by a function attribute (scanning might be redundant
> +     in telling us to also enable it), and when we are enabling strub implicitly
> +     but there are non-viable modes: we want to know whether strubbing is
> +     required, to fallback to another mode, even if we're only enabling a
> +     certain mode, or, when either mode would do, to report an error if neither
> +     happens to be viable.  */
> +  const bool analyze_body
> +    = (strub_attr
> +       ? !consider_strub
> +       : (strub_flag_auto
> +         || (strub_flag_viable && (!at_calls_viable && !internal_viable))
> +         || (strub_flag_either && !strub_viable)));
> +
> +  /* Cases in which strubbing is enabled or disabled by strub_flag_auto.
> +     Unsatisfiable requests ought to be reported.  */
> +  const bool strub_required
> +    = ((strub_attr && consider_strub)
> +       || (analyze_body && strub_from_body_p (node)));
> +
> +  /* Besides the required cases, we want to abide by the requests to enabling on
> +     an if-viable basis.  */
> +  const bool strub_enable
> +    = (strub_required
> +       || (strub_flag_at_calls && at_calls_viable)
> +       || (strub_flag_internal && internal_viable)
> +       || (strub_flag_either && strub_viable));
> +
> +  /* And now we're finally ready to select a mode that abides by the viability
> +     and eligibility constraints, and that satisfies the strubbing requirements
> +     and requests, subject to the constraints.  If both modes are viable and
> +     strub is to be enabled, pick STRUB_AT_CALLS unless STRUB_INTERNAL was named
> +     as preferred.  */
> +  const enum strub_mode mode
> +    = ((strub_enable && is_always_inline)
> +       ? (strub_required ? STRUB_INLINABLE : STRUB_CALLABLE)
> +       : (strub_enable && internal_viable
> +         && (strub_flag_internal || !at_calls_viable))
> +       ? STRUB_INTERNAL
> +       : (strub_enable && at_calls_viable)
> +       ? (strub_required && !strub_attr
> +         ? STRUB_AT_CALLS_OPT
> +         : STRUB_AT_CALLS)
> +       : consider_callable
> +       ? STRUB_CALLABLE
> +       : STRUB_DISABLED);
> +
> +  switch (mode)
> +    {
> +    case STRUB_CALLABLE:
> +      if (is_always_inline)
> +       break;
> +      /* Fall through.  */
> +
> +    case STRUB_DISABLED:
> +      if (strub_enable && !strub_attr)
> +       {
> +         gcc_checking_assert (analyze_body);
> +         error_at (DECL_SOURCE_LOCATION (node->decl),
> +                   "%qD requires %<strub%>,"
> +                   " but no viable %<strub%> mode was found",
> +                   node->decl);
> +         break;
> +       }
> +      /* Fall through.  */
> +
> +    case STRUB_AT_CALLS:
> +    case STRUB_INTERNAL:
> +    case STRUB_INLINABLE:
> +      /* Differences from an mode requested through a function attribute are
> +        reported in set_strub_mode_to.  */
> +      break;
> +
> +    case STRUB_AT_CALLS_OPT:
> +      /* Functions that select this mode do so because of references to strub
> +        variables.  Even if we choose at-calls as an optimization, the
> +        requirements for internal strub must still be satisfied.  Optimization
> +        options may render implicit at-calls strub not viable (-O0 sets
> +        force_output for static non-inline functions), and it would not be good
> +        if changing optimization options turned a well-formed into an
> +        ill-formed one.  */
> +      if (!internal_viable)
> +       can_strub_internally_p (node, true);
> +      break;
> +
> +    case STRUB_WRAPPED:
> +    case STRUB_WRAPPER:
> +    default:
> +      gcc_unreachable ();
> +    }
> +
> +  return mode;
> +}
> +
> +/* Set FNDT's strub mode to MODE; FNDT may be a function decl or
> +   function type.  If OVERRIDE, do not check whether a mode is already
> +   set.  */
> +
> +static void
> +strub_set_fndt_mode_to (tree fndt, enum strub_mode mode, bool override)
> +{
> +  gcc_checking_assert (override
> +                      || !(DECL_P (fndt)
> +                           ? get_strub_attr_from_decl (fndt)
> +                           : get_strub_attr_from_type (fndt)));
> +
> +  tree attr = tree_cons (get_identifier ("strub"),
> +                        get_strub_mode_attr_value (mode),
> +                        NULL_TREE);
> +  tree *attrp = NULL;
> +  if (DECL_P (fndt))
> +    {
> +      gcc_checking_assert (FUNC_OR_METHOD_TYPE_P (TREE_TYPE (fndt)));
> +      attrp = &DECL_ATTRIBUTES (fndt);
> +    }
> +  else if (FUNC_OR_METHOD_TYPE_P (fndt))
> +    attrp = &TYPE_ATTRIBUTES (fndt);
> +  else
> +    gcc_unreachable ();
> +
> +  TREE_CHAIN (attr) = *attrp;
> +  *attrp = attr;
> +}
> +
> +/* Set FNDT's strub mode to callable.
> +   FNDT may be a function decl or a function type.  */
> +
> +void
> +strub_make_callable (tree fndt)
> +{
> +  strub_set_fndt_mode_to (fndt, STRUB_CALLABLE, false);
> +}
> +
> +/* Set NODE to strub MODE.  Report incompatibilities between MODE and the mode
> +   requested through explicit attributes, and cases of non-eligibility.  */
> +
> +static void
> +set_strub_mode_to (cgraph_node *node, enum strub_mode mode)
> +{
> +  tree attr = get_strub_attr_from_decl (node->decl);
> +  enum strub_mode req_mode = get_strub_mode_from_attr (attr);
> +
> +  if (attr)
> +    {
> +      /* Check for and report incompatible mode changes.  */
> +      if (mode != req_mode
> +         && !(req_mode == STRUB_INTERNAL
> +              && (mode == STRUB_WRAPPED
> +                  || mode == STRUB_WRAPPER))
> +         && !((req_mode == STRUB_INTERNAL
> +               || req_mode == STRUB_AT_CALLS
> +               || req_mode == STRUB_CALLABLE)
> +              && mode == STRUB_INLINABLE))
> +       {
> +         error_at (DECL_SOURCE_LOCATION (node->decl),
> +                   "%<strub%> mode %qE selected for %qD, when %qE was requested",
> +                   get_strub_mode_attr_parm (mode),
> +                   node->decl,
> +                   get_strub_mode_attr_parm (req_mode));
> +         if (node->alias)
> +           {
> +             cgraph_node *target = node->ultimate_alias_target ();
> +             if (target != node)
> +               error_at (DECL_SOURCE_LOCATION (target->decl),
> +                         "the incompatible selection was determined"
> +                         " by ultimate alias target %qD",
> +                         target->decl);
> +           }
> +
> +         /* Report any incompatibilities with explicitly-requested strub.  */
> +         switch (req_mode)
> +           {
> +           case STRUB_AT_CALLS:
> +             can_strub_at_calls_p (node, true);
> +             break;
> +
> +           case STRUB_INTERNAL:
> +             can_strub_internally_p (node, true);
> +             break;
> +
> +           default:
> +             break;
> +           }
> +       }
> +
> +      /* Drop any incompatible strub attributes leading the decl attribute
> +        chain.  Return if we find one with the mode we need.  */
> +      for (;;)
> +       {
> +         if (mode == req_mode)
> +           return;
> +
> +         if (DECL_ATTRIBUTES (node->decl) != attr)
> +           break;
> +
> +         DECL_ATTRIBUTES (node->decl) = TREE_CHAIN (attr);
> +         attr = get_strub_attr_from_decl (node->decl);
> +         if (!attr)
> +           break;
> +
> +         req_mode = get_strub_mode_from_attr (attr);
> +       }
> +    }
> +  else if (mode == req_mode)
> +    return;
> +
> +  strub_set_fndt_mode_to (node->decl, mode, attr);
> +}
> +
> +/* Compute and set NODE's strub mode.  */
> +
> +static void
> +set_strub_mode (cgraph_node *node)
> +{
> +  tree attr = get_strub_attr_from_decl (node->decl);
> +
> +  if (attr)
> +    switch (get_strub_mode_from_attr (attr))
> +      {
> +       /* These can't have been requested through user attributes, so we must
> +          have already gone through them.  */
> +      case STRUB_WRAPPER:
> +      case STRUB_WRAPPED:
> +      case STRUB_INLINABLE:
> +      case STRUB_AT_CALLS_OPT:
> +       return;
> +
> +      case STRUB_DISABLED:
> +      case STRUB_AT_CALLS:
> +      case STRUB_INTERNAL:
> +      case STRUB_CALLABLE:
> +       break;
> +
> +      default:
> +       gcc_unreachable ();
> +      }
> +
> +  cgraph_node *xnode = node;
> +  if (node->alias)
> +    xnode = node->ultimate_alias_target ();
> +  /* Weakrefs may remain unresolved (the above will return node) if
> +     their targets are not defined, so make sure we compute a strub
> +     mode for them, instead of defaulting to STRUB_DISABLED and
> +     rendering them uncallable.  */
> +  enum strub_mode mode = (xnode != node && !xnode->alias
> +                         ? get_strub_mode (xnode)
> +                         : compute_strub_mode (node, attr));
> +
> +  set_strub_mode_to (node, mode);
> +}
> +
> +
> +/* Non-strub functions shouldn't be called from within strub contexts,
> +   except through callable ones.  Always inline strub functions can
> +   only be called from strub functions.  */
> +
> +static bool
> +strub_callable_from_p (strub_mode caller_mode, strub_mode callee_mode)
> +{
> +  switch (caller_mode)
> +    {
> +    case STRUB_WRAPPED:
> +    case STRUB_AT_CALLS_OPT:
> +    case STRUB_AT_CALLS:
> +    case STRUB_INTERNAL:
> +    case STRUB_INLINABLE:
> +      break;
> +
> +    case STRUB_WRAPPER:
> +    case STRUB_DISABLED:
> +    case STRUB_CALLABLE:
> +      return callee_mode != STRUB_INLINABLE;
> +
> +    default:
> +      gcc_unreachable ();
> +    }
> +
> +  switch (callee_mode)
> +    {
> +    case STRUB_WRAPPED:
> +    case STRUB_AT_CALLS:
> +    case STRUB_INLINABLE:
> +      break;
> +
> +    case STRUB_AT_CALLS_OPT:
> +    case STRUB_INTERNAL:
> +    case STRUB_WRAPPER:
> +      return (flag_strub >= -1);
> +
> +    case STRUB_DISABLED:
> +      return false;
> +
> +    case STRUB_CALLABLE:
> +      break;
> +
> +    default:
> +      gcc_unreachable ();
> +    }
> +
> +  return true;
> +}
> +
> +/* Return TRUE iff CALLEE can be inlined into CALLER.  We wish to avoid inlining
> +   WRAPPED functions back into their WRAPPERs.  More generally, we wish to avoid
> +   inlining strubbed functions into non-strubbed ones.  CALLER doesn't have to
> +   be an immediate caller of CALLEE: the immediate caller may have already been
> +   cloned for inlining, and then CALLER may be further up the original call
> +   chain.  ???  It would be nice if our own caller would retry inlining callee
> +   if caller gets inlined.  */
> +
> +bool
> +strub_inlinable_to_p (cgraph_node *callee, cgraph_node *caller)
> +{
> +  strub_mode callee_mode = get_strub_mode (callee);
> +
> +  switch (callee_mode)
> +    {
> +    case STRUB_WRAPPED:
> +    case STRUB_AT_CALLS:
> +    case STRUB_INTERNAL:
> +    case STRUB_INLINABLE:
> +    case STRUB_AT_CALLS_OPT:
> +      break;
> +
> +    case STRUB_WRAPPER:
> +    case STRUB_DISABLED:
> +    case STRUB_CALLABLE:
> +      /* When we consider inlining, we've already verified callability, so we
> +        can even inline callable and then disabled into a strub context.  That
> +        will get strubbed along with the context, so it's hopefully not a
> +        problem.  */
> +      return true;
> +
> +    default:
> +      gcc_unreachable ();
> +    }
> +
> +  strub_mode caller_mode = get_strub_mode (caller);
> +
> +  switch (caller_mode)
> +    {
> +    case STRUB_WRAPPED:
> +    case STRUB_AT_CALLS:
> +    case STRUB_INTERNAL:
> +    case STRUB_INLINABLE:
> +    case STRUB_AT_CALLS_OPT:
> +      return true;
> +
> +    case STRUB_WRAPPER:
> +    case STRUB_DISABLED:
> +    case STRUB_CALLABLE:
> +      break;
> +
> +    default:
> +      gcc_unreachable ();
> +    }
> +
> +  return false;
> +}
> +
> +/* Check that types T1 and T2 are strub-compatible.  Return 1 if the strub modes
> +   are the same, 2 if they are interchangeable, and 0 otherwise.  */
> +
> +int
> +strub_comptypes (tree t1, tree t2)
> +{
> +  if (TREE_CODE (t1) != TREE_CODE (t2))
> +    return 0;
> +
> +  enum strub_mode m1 = get_strub_mode_from_type (t1);
> +  enum strub_mode m2 = get_strub_mode_from_type (t2);
> +
> +  if (m1 == m2)
> +    return 1;
> +
> +  /* We're dealing with types, so only strub modes that can be selected by
> +     attributes in the front end matter.  If either mode is at-calls (for
> +     functions) or internal (for variables), the conversion is not
> +     compatible.  */
> +  bool var_p = !FUNC_OR_METHOD_TYPE_P (t1);
> +  enum strub_mode mr = var_p ? STRUB_INTERNAL : STRUB_AT_CALLS;
> +  if (m1 == mr || m2 == mr)
> +    return 0;
> +
> +  return 2;
> +}
> +
> +/* Return the effective strub mode used for CALL, and set *TYPEP to
> +   the effective type used for the call.  The effective type and mode
> +   are those of the callee, unless the call involves a typecast.  */
> +
> +static enum strub_mode
> +effective_strub_mode_for_call (gcall *call, tree *typep)
> +{
> +  tree type;
> +  enum strub_mode mode;
> +
> +  if (strub_call_fntype_override_p (call))
> +    {
> +      type = gimple_call_fntype (call);
> +      mode = get_strub_mode_from_type (type);
> +    }
> +  else
> +    {
> +      type = TREE_TYPE (TREE_TYPE (gimple_call_fn (call)));
> +      tree decl = gimple_call_fndecl (call);
> +      if (decl)
> +       mode = get_strub_mode_from_fndecl (decl);
> +      else
> +       mode = get_strub_mode_from_type (type);
> +    }
> +
> +  if (typep)
> +    *typep = type;
> +
> +  return mode;
> +}
> +
> +/* Create a distinct copy of the type of NODE's function, and change
> +   the fntype of all calls to it with the same main type to the new
> +   type.  */
> +
> +static void
> +distinctify_node_type (cgraph_node *node)
> +{
> +  tree old_type = TREE_TYPE (node->decl);
> +  tree new_type = build_distinct_type_copy (old_type);
> +  tree new_ptr_type = NULL_TREE;
> +
> +  /* Remap any calls to node->decl that use old_type, or a variant
> +     thereof, to new_type as well.  We don't look for aliases, their
> +     declarations will have their types changed independently, and
> +     we'll adjust their fntypes then.  */
> +  for (cgraph_edge *e = node->callers; e; e = e->next_caller)
> +    {
> +      if (!e->call_stmt)
> +       continue;
> +      tree fnaddr = gimple_call_fn (e->call_stmt);
> +      gcc_checking_assert (TREE_CODE (fnaddr) == ADDR_EXPR
> +                          && TREE_OPERAND (fnaddr, 0) == node->decl);
> +      if (strub_call_fntype_override_p (e->call_stmt))
> +       continue;
> +      if (!new_ptr_type)
> +       new_ptr_type = build_pointer_type (new_type);
> +      TREE_TYPE (fnaddr) = new_ptr_type;
> +      gimple_call_set_fntype (e->call_stmt, new_type);
> +    }
> +
> +  TREE_TYPE (node->decl) = new_type;
> +}
> +
> +/* Return TRUE iff TYPE and any variants have the same strub mode.  */
> +
> +static bool
> +same_strub_mode_in_variants_p (tree type)
> +{
> +  enum strub_mode mode = get_strub_mode_from_type (type);
> +
> +  for (tree other = TYPE_MAIN_VARIANT (type);
> +       other != NULL_TREE; other = TYPE_NEXT_VARIANT (other))
> +    if (type != other && mode != get_strub_mode_from_type (other))
> +      return false;
> +
> +  /* Check that the canonical type, if set, either is in the same
> +     variant chain, or has the same strub mode as type.  Also check
> +     the variants of the canonical type.  */
> +  if (TYPE_CANONICAL (type)
> +      && (TYPE_MAIN_VARIANT (TYPE_CANONICAL (type))
> +         != TYPE_MAIN_VARIANT (type)))
> +    {
> +      if (mode != get_strub_mode_from_type (TYPE_CANONICAL (type)))
> +       return false;
> +      else
> +       return same_strub_mode_in_variants_p (TYPE_CANONICAL (type));
> +    }
> +
> +  return true;
> +}
> +
> +/* Check that strub functions don't call non-strub functions, and that
> +   always_inline strub functions are only called by strub
> +   functions.  */
> +
> +static void
> +verify_strub ()
> +{
> +  cgraph_node *node;
> +
> +  /* It's expected that check strub-wise pointer type compatibility of variables
> +     and of functions is already taken care of by front-ends, on account of the
> +     attribute's being marked as affecting type identity and of the creation of
> +     distinct types.  */
> +
> +  /* Check that call targets in strub contexts have strub-callable types.  */
> +
> +  FOR_EACH_FUNCTION_WITH_GIMPLE_BODY (node)
> +  {
> +    enum strub_mode caller_mode = get_strub_mode (node);
> +
> +    for (cgraph_edge *e = node->indirect_calls; e; e = e->next_callee)
> +      {
> +       gcc_checking_assert (e->indirect_unknown_callee);
> +
> +       if (!e->call_stmt)
> +         continue;
> +
> +       enum strub_mode callee_mode
> +         = effective_strub_mode_for_call (e->call_stmt, NULL);
> +
> +       if (!strub_callable_from_p (caller_mode, callee_mode))
> +         error_at (gimple_location (e->call_stmt),
> +                   "indirect non-%<strub%> call in %<strub%> context %qD",
> +                   node->decl);
> +      }
> +
> +    for (cgraph_edge *e = node->callees; e; e = e->next_callee)
> +      {
> +       gcc_checking_assert (!e->indirect_unknown_callee);
> +
> +       if (!e->call_stmt)
> +         continue;
> +
> +       tree callee_fntype;
> +       enum strub_mode callee_mode
> +         = effective_strub_mode_for_call (e->call_stmt, &callee_fntype);
> +
> +       if (!strub_callable_from_p (caller_mode, callee_mode))
> +         {
> +           if (callee_mode == STRUB_INLINABLE)
> +             error_at (gimple_location (e->call_stmt),
> +                       "calling %<always_inline%> %<strub%> %qD"
> +                       " in non-%<strub%> context %qD",
> +                       e->callee->decl, node->decl);
> +           else if (fndecl_built_in_p (e->callee->decl, BUILT_IN_APPLY_ARGS)
> +                    && caller_mode == STRUB_INTERNAL)
> +             /* This is ok, it will be kept in the STRUB_WRAPPER, and removed
> +                from the STRUB_WRAPPED's strub context.  */
> +             continue;
> +           else if (!strub_call_fntype_override_p (e->call_stmt))
> +             error_at (gimple_location (e->call_stmt),
> +                       "calling non-%<strub%> %qD in %<strub%> context %qD",
> +                       e->callee->decl, node->decl);
> +           else
> +             error_at (gimple_location (e->call_stmt),
> +                       "calling %qD using non-%<strub%> type %qT"
> +                       " in %<strub%> context %qD",
> +                       e->callee->decl, callee_fntype, node->decl);
> +         }
> +      }
> +  }
> +}
> +
> +namespace {
> +
> +/* Define a pass to compute strub modes.  */
> +const pass_data pass_data_ipa_strub_mode = {
> +  SIMPLE_IPA_PASS,
> +  "strubm",
> +  OPTGROUP_NONE,
> +  TV_NONE,
> +  PROP_cfg, // properties_required
> +  0,       // properties_provided
> +  0,       // properties_destroyed
> +  0,       // properties_start
> +  0,       // properties_finish
> +};
> +
> +class pass_ipa_strub_mode : public simple_ipa_opt_pass
> +{
> +public:
> +  pass_ipa_strub_mode (gcc::context *ctxt)
> +    : simple_ipa_opt_pass (pass_data_ipa_strub_mode, ctxt)
> +  {}
> +  opt_pass *clone () { return new pass_ipa_strub_mode (m_ctxt); }
> +  virtual bool gate (function *) {
> +    /* In relaxed (-3) and strict (-4) settings, that only enable strub at a
> +       function or variable attribute's request, the attribute handler changes
> +       flag_strub to -1 or -2, respectively, if any strub-enabling occurence of
> +       the attribute is found.  Therefore, if it remains at -3 or -4, nothing
> +       that would enable strub was found, so we can disable it and avoid the
> +       overhead.  */
> +    if (flag_strub < -2)
> +      flag_strub = 0;
> +    return flag_strub;
> +  }
> +  virtual unsigned int execute (function *);
> +};
> +
> +/* Define a pass to introduce strub transformations.  */
> +const pass_data pass_data_ipa_strub = {
> +  SIMPLE_IPA_PASS,
> +  "strub",
> +  OPTGROUP_NONE,
> +  TV_NONE,
> +  PROP_cfg | PROP_ssa, // properties_required
> +  0,       // properties_provided
> +  0,       // properties_destroyed
> +  0,       // properties_start
> +  TODO_update_ssa
> +  | TODO_cleanup_cfg
> +  | TODO_rebuild_cgraph_edges
> +  | TODO_verify_il, // properties_finish
> +};
> +
> +class pass_ipa_strub : public simple_ipa_opt_pass
> +{
> +public:
> +  pass_ipa_strub (gcc::context *ctxt)
> +    : simple_ipa_opt_pass (pass_data_ipa_strub, ctxt)
> +  {}
> +  opt_pass *clone () { return new pass_ipa_strub (m_ctxt); }
> +  virtual bool gate (function *) { return flag_strub && !seen_error (); }
> +  virtual unsigned int execute (function *);
> +
> +  /* Define on demand and cache some types we use often.  */
> +#define DEF_TYPE(IDX, NAME, INIT)              \
> +  static inline tree get_ ## NAME () {         \
> +    int idx = STRUB_TYPE_BASE + IDX;           \
> +    static tree type = strub_cache[idx];       \
> +    if (!type)                                 \
> +      strub_cache[idx] = type = (INIT);                \
> +    return type;                               \
> +  }
> +
> +  /* Use a distinct ptr_type_node to denote the watermark, so that we can
> +     recognize it in arg lists and avoid modifying types twice.  */
> +  DEF_TYPE (0, wmt, build_variant_type_copy (ptr_type_node))
> +
> +  DEF_TYPE (1, pwmt, build_reference_type (get_wmt ()))
> +
> +  DEF_TYPE (2, qpwmt,
> +           build_qualified_type (get_pwmt (),
> +                                 TYPE_QUAL_RESTRICT
> +                                 /* | TYPE_QUAL_CONST */))
> +
> +  DEF_TYPE (3, qptr,
> +           build_qualified_type (ptr_type_node,
> +                                 TYPE_QUAL_RESTRICT
> +                                 | TYPE_QUAL_CONST))
> +
> +  DEF_TYPE (4, qpvalst,
> +           build_qualified_type (build_reference_type
> +                                 (va_list_type_node),
> +                                 TYPE_QUAL_RESTRICT
> +                                 /* | TYPE_QUAL_CONST */))
> +
> +#undef DEF_TYPE
> +
> +  /* Define non-strub builtins on demand.  */
> +#define DEF_NM_BUILTIN(NAME, CODE, FNTYPELIST)                 \
> +  static tree get_ ## NAME () {                                        \
> +    tree decl = builtin_decl_explicit (CODE);                  \
> +    if (!decl)                                                 \
> +      {                                                                \
> +       tree type = build_function_type_list FNTYPELIST;        \
> +       decl = add_builtin_function                             \
> +         ("__builtin_" #NAME,                                  \
> +          type, CODE, BUILT_IN_NORMAL,                         \
> +          NULL, NULL);                                         \
> +       TREE_NOTHROW (decl) = true;                             \
> +       set_builtin_decl ((CODE), decl, true);                  \
> +      }                                                                \
> +    return decl;                                               \
> +  }
> +
> +  DEF_NM_BUILTIN (stack_address,
> +                 BUILT_IN_STACK_ADDRESS,
> +                 (ptr_type_node, NULL))
> +
> +#undef DEF_NM_BUILTIN
> +
> +  /* Define strub builtins on demand.  */
> +#define DEF_SS_BUILTIN(NAME, FNSPEC, CODE, FNTYPELIST)         \
> +  static tree get_ ## NAME () {                                        \
> +    tree decl = builtin_decl_explicit (CODE);                  \
> +    if (!decl)                                                 \
> +      {                                                                \
> +       tree type = build_function_type_list FNTYPELIST;        \
> +       tree attrs = NULL;                                      \
> +       if (FNSPEC)                                             \
> +         attrs = tree_cons (get_identifier ("fn spec"),        \
> +                            build_tree_list                    \
> +                            (NULL_TREE,                        \
> +                             build_string (strlen (FNSPEC),    \
> +                                           (FNSPEC))),         \
> +                            attrs);                            \
> +       decl = add_builtin_function_ext_scope                   \
> +         ("__builtin___strub_" #NAME,                          \
> +          type, CODE, BUILT_IN_NORMAL,                         \
> +          "__strub_" #NAME, attrs);                            \
> +       TREE_NOTHROW (decl) = true;                             \
> +       set_builtin_decl ((CODE), decl, true);                  \
> +      }                                                                \
> +    return decl;                                               \
> +  }
> +
> +  DEF_SS_BUILTIN (enter, ". Ot",
> +                 BUILT_IN___STRUB_ENTER,
> +                 (void_type_node, get_qpwmt (), NULL))
> +  DEF_SS_BUILTIN (update, ". Wt",
> +                 BUILT_IN___STRUB_UPDATE,
> +                 (void_type_node, get_qpwmt (), NULL))
> +  DEF_SS_BUILTIN (leave, ". w ",
> +                 BUILT_IN___STRUB_LEAVE,
> +                 (void_type_node, get_qpwmt (), NULL))
> +
> +#undef DEF_SS_BUILTIN
> +
> +    /* Define strub identifiers on demand.  */
> +#define DEF_IDENT(IDX, NAME)                                           \
> +  static inline tree get_ ## NAME () {                                 \
> +    int idx = STRUB_IDENT_BASE + IDX;                                  \
> +    tree identifier = strub_cache[idx];                                        \
> +    if (!identifier)                                                   \
> +      strub_cache[idx] = identifier = get_identifier (".strub." #NAME);        \
> +    return identifier;                                                 \
> +  }
> +
> +  DEF_IDENT (0, watermark_ptr)
> +  DEF_IDENT (1, va_list_ptr)
> +  DEF_IDENT (2, apply_args)
> +
> +#undef DEF_IDENT
> +
> +  static inline int adjust_at_calls_type (tree);
> +  static inline void adjust_at_calls_call (cgraph_edge *, int, tree);
> +  static inline void adjust_at_calls_calls (cgraph_node *);
> +
> +  /* Add to SEQ a call to the strub watermark update builtin, taking NODE's
> +     location if given.  Optionally add the corresponding edge from NODE, with
> +     execution frequency COUNT.  Return the modified SEQ.  */
> +
> +  static inline gimple_seq
> +  call_update_watermark (tree wmptr, cgraph_node *node, profile_count count,
> +                        gimple_seq seq = NULL)
> +    {
> +      tree uwm = get_update ();
> +      gcall *update = gimple_build_call (uwm, 1, wmptr);
> +      if (node)
> +       gimple_set_location (update, DECL_SOURCE_LOCATION (node->decl));
> +      gimple_seq_add_stmt (&seq, update);
> +      if (node)
> +       node->create_edge (cgraph_node::get_create (uwm), update, count, false);
> +      return seq;
> +    }
> +
> +};
> +
> +} // anon namespace
> +
> +/* Gather with this type a collection of parameters that we're turning into
> +   explicit references.  */
> +
> +typedef hash_set<tree> indirect_parms_t;
> +
> +/* Dereference OP's incoming turned-into-reference parm if it's an
> +   INDIRECT_PARMS or an ADDR_EXPR thereof.  Set *REC and return according to
> +   gimple-walking expectations.  */
> +
> +static tree
> +maybe_make_indirect (indirect_parms_t &indirect_parms, tree op, int *rec)
> +{
> +  if (DECL_P (op))
> +    {
> +      *rec = 0;
> +      if (indirect_parms.contains (op))
> +       {
> +         tree ret = gimple_fold_indirect_ref (op);
> +         if (!ret)
> +           ret = build2 (MEM_REF,
> +                         TREE_TYPE (TREE_TYPE (op)),
> +                         op,
> +                         build_int_cst (TREE_TYPE (op), 0));
> +         return ret;
> +       }
> +    }
> +  else if (TREE_CODE (op) == ADDR_EXPR
> +          && DECL_P (TREE_OPERAND (op, 0)))
> +    {
> +      *rec = 0;
> +      if (indirect_parms.contains (TREE_OPERAND (op, 0)))
> +       {
> +         op = TREE_OPERAND (op, 0);
> +         return op;
> +       }
> +    }
> +
> +  return NULL_TREE;
> +}
> +
> +/* A gimple-walking function that adds dereferencing to indirect parms.  */
> +
> +static tree
> +walk_make_indirect (tree *op, int *rec, void *arg)
> +{
> +  walk_stmt_info *wi = (walk_stmt_info *)arg;
> +  indirect_parms_t &indirect_parms = *(indirect_parms_t *)wi->info;
> +
> +  if (!*op || TYPE_P (*op))
> +    {
> +      *rec = 0;
> +      return NULL_TREE;
> +    }
> +
> +  if (tree repl = maybe_make_indirect (indirect_parms, *op, rec))
> +    {
> +      *op = repl;
> +      wi->changed = true;
> +    }
> +
> +  return NULL_TREE;
> +}
> +
> +/* A gimple-walking function that turns any non-gimple-val ADDR_EXPRs into a
> +   separate SSA.  Though addresses of e.g. parameters, and of members thereof,
> +   are gimple vals, turning parameters into references, with an extra layer of
> +   indirection and thus explicit dereferencing, need to be regimplified.  */
> +
> +static tree
> +walk_regimplify_addr_expr (tree *op, int *rec, void *arg)
> +{
> +  walk_stmt_info *wi = (walk_stmt_info *)arg;
> +  gimple_stmt_iterator &gsi = *(gimple_stmt_iterator *)wi->info;
> +
> +  *rec = 0;
> +
> +  if (!*op || TREE_CODE (*op) != ADDR_EXPR)
> +    return NULL_TREE;
> +
> +  if (!is_gimple_val (*op))
> +    {
> +      tree ret = force_gimple_operand_gsi (&gsi, *op, true,
> +                                          NULL_TREE, true, GSI_SAME_STMT);
> +      gcc_assert (ret != *op);
> +      *op = ret;
> +      wi->changed = true;
> +    }
> +
> +  return NULL_TREE;
> +}
> +
> +/* Turn STMT's PHI arg defs into separate SSA defs if they've become
> +   non-gimple_val.  Return TRUE if any edge insertions need to be committed.  */
> +
> +static bool
> +walk_regimplify_phi (gphi *stmt)
> +{
> +  bool needs_commit = false;
> +
> +  for (unsigned i = 0, n = gimple_phi_num_args (stmt); i < n; i++)
> +    {
> +      tree op = gimple_phi_arg_def (stmt, i);
> +      if ((TREE_CODE (op) == ADDR_EXPR
> +          && !is_gimple_val (op))
> +         /* ??? A PARM_DECL that was addressable in the original function and
> +            had its address in PHI nodes, but that became a reference in the
> +            wrapped clone would NOT be updated by update_ssa in PHI nodes.
> +            Alas, if we were to create a default def for it now, update_ssa
> +            would complain that the symbol that needed rewriting already has
> +            SSA names associated with it.  OTOH, leaving the PARM_DECL alone,
> +            it eventually causes errors because it remains unchanged in PHI
> +            nodes, but it gets rewritten as expected if it appears in other
> +            stmts.  So we cheat a little here, and force the PARM_DECL out of
> +            the PHI node and into an assignment.  It's a little expensive,
> +            because we insert it at the edge, which introduces a basic block
> +            that's entirely unnecessary, but it works, and the block will be
> +            removed as the default def gets propagated back into the PHI node,
> +            so the final optimized code looks just as expected.  */
> +         || (TREE_CODE (op) == PARM_DECL
> +             && !TREE_ADDRESSABLE (op)))
> +       {
> +         tree temp = make_ssa_name (TREE_TYPE (op), stmt);
> +         if (TREE_CODE (op) == PARM_DECL)
> +           SET_SSA_NAME_VAR_OR_IDENTIFIER (temp, DECL_NAME (op));
> +         SET_PHI_ARG_DEF (stmt, i, temp);
> +
> +         gimple *assign = gimple_build_assign (temp, op);
> +         if (gimple_phi_arg_has_location (stmt, i))
> +           gimple_set_location (assign, gimple_phi_arg_location (stmt, i));
> +         gsi_insert_on_edge (gimple_phi_arg_edge (stmt, i), assign);
> +         needs_commit = true;
> +       }
> +    }
> +
> +  return needs_commit;
> +}
> +
> +/* Create a reference type to use for PARM when turning it into a reference.
> +   NONALIASED causes the reference type to gain its own separate alias set, so
> +   that accessing the indirectly-passed parm won'will not add aliasing
> +   noise.  */
> +
> +static tree
> +build_ref_type_for (tree parm, bool nonaliased = true)
> +{
> +  gcc_checking_assert (TREE_CODE (parm) == PARM_DECL);
> +
> +  tree ref_type = build_reference_type (TREE_TYPE (parm));
> +
> +  if (!nonaliased)
> +    return ref_type;
> +
> +  /* Each PARM turned indirect still points to the distinct memory area at the
> +     wrapper, and the reference in unchanging, so we might qualify it, but...
> +     const is not really important, since we're only using default defs for the
> +     reference parm anyway, and not introducing any defs, and restrict seems to
> +     cause trouble.  E.g., libgnat/s-concat3.adb:str_concat_3 has memmoves that,
> +     if it's wrapped, the memmoves are deleted in dse1.  Using a distinct alias
> +     set seems to not run afoul of this problem, and it hopefully enables the
> +     compiler to tell the pointers do point to objects that are not otherwise
> +     aliased.  */
> +  tree qref_type = build_variant_type_copy (ref_type);
> +
> +  TYPE_ALIAS_SET (qref_type) = new_alias_set ();
> +  record_alias_subset (TYPE_ALIAS_SET (qref_type), get_alias_set (ref_type));
> +
> +  return qref_type;
> +}
> +
> +/* Add cgraph edges from current_function_decl to callees in SEQ with frequency
> +   COUNT, assuming all calls in SEQ are direct.  */
> +
> +static void
> +add_call_edges_for_seq (gimple_seq seq, profile_count count)
> +{
> +  cgraph_node *node = cgraph_node::get_create (current_function_decl);
> +
> +  for (gimple_stmt_iterator gsi = gsi_start (seq);
> +       !gsi_end_p (gsi); gsi_next (&gsi))
> +    {
> +      gimple *stmt = gsi_stmt (gsi);
> +
> +      gcall *call = dyn_cast <gcall *> (stmt);
> +      if (!call)
> +       continue;
> +
> +      tree callee = gimple_call_fndecl (call);
> +      gcc_checking_assert (callee);
> +      node->create_edge (cgraph_node::get_create (callee), call, count, false);
> +    }
> +}
> +
> +/* Insert SEQ after the call at GSI, as if the call was in a try block with SEQ
> +   as finally, i.e., SEQ will run after the call whether it returns or
> +   propagates an exception.  This handles block splitting, EH edge and block
> +   creation, noreturn and nothrow optimizations, and even throwing calls without
> +   preexisting local handlers.  */
> +
> +static void
> +gsi_insert_finally_seq_after_call (gimple_stmt_iterator gsi, gimple_seq seq)
> +{
> +  if (!seq)
> +    return;
> +
> +  gimple *stmt = gsi_stmt (gsi);
> +
> +  if (gimple_has_location (stmt))
> +    annotate_all_with_location (seq, gimple_location (stmt));
> +
> +  gcall *call = dyn_cast <gcall *> (stmt);
> +  bool noreturn_p = call && gimple_call_noreturn_p (call);
> +  int eh_lp = lookup_stmt_eh_lp (stmt);
> +  bool must_not_throw_p = eh_lp < 0;
> +  bool nothrow_p = (must_not_throw_p
> +                   || (call && gimple_call_nothrow_p (call))
> +                   || (eh_lp <= 0
> +                       && (TREE_NOTHROW (cfun->decl)
> +                           || !flag_exceptions)));
> +
> +  if (noreturn_p && nothrow_p)
> +    return;
> +
> +  /* Don't expect an EH edge if we're not to throw, or if we're not in an EH
> +     region yet.  */
> +  bool no_eh_edge_p = (nothrow_p || !eh_lp);
> +  bool must_end_bb = stmt_ends_bb_p (stmt);
> +
> +  edge eft = NULL, eeh = NULL;
> +  if (must_end_bb && !(noreturn_p && no_eh_edge_p))
> +    {
> +      gcc_checking_assert (gsi_one_before_end_p (gsi));
> +
> +      edge e;
> +      edge_iterator ei;
> +      FOR_EACH_EDGE (e, ei, gsi_bb (gsi)->succs)
> +       {
> +         if ((e->flags & EDGE_EH))
> +           {
> +             gcc_checking_assert (!eeh);
> +             eeh = e;
> +#if !CHECKING_P
> +             if (eft || noreturn_p)
> +               break;
> +#endif
> +           }
> +         if ((e->flags & EDGE_FALLTHRU))
> +           {
> +             gcc_checking_assert (!eft);
> +             eft = e;
> +#if !CHECKING_P
> +             if (eeh || no_eh_edge_p)
> +               break;
> +#endif
> +           }
> +       }
> +
> +      gcc_checking_assert (!(eft && (eft->flags & EDGE_FALLTHRU))
> +                          == noreturn_p);
> +      gcc_checking_assert (!(eeh && (eeh->flags & EDGE_EH))
> +                          == no_eh_edge_p);
> +      gcc_checking_assert (eft != eeh);
> +    }
> +
> +  if (!noreturn_p)
> +    {
> +      gimple_seq nseq = nothrow_p ? seq : gimple_seq_copy (seq);
> +
> +      if (must_end_bb)
> +       {
> +         gcc_checking_assert (gsi_one_before_end_p (gsi));
> +         add_call_edges_for_seq (nseq, eft->count ());
> +         gsi_insert_seq_on_edge_immediate (eft, nseq);
> +       }
> +      else
> +       {
> +         add_call_edges_for_seq (nseq, gsi_bb (gsi)->count);
> +         gsi_insert_seq_after (&gsi, nseq, GSI_SAME_STMT);
> +       }
> +    }
> +
> +  if (nothrow_p)
> +    return;
> +
> +  if (eh_lp)
> +    {
> +      add_call_edges_for_seq (seq, eeh->count ());
> +      gsi_insert_seq_on_edge_immediate (eeh, seq);
> +      return;
> +    }
> +
> +  /* A throwing call may appear within a basic block in a function that doesn't
> +     have any EH regions.  We're going to add a cleanup if so, therefore the
> +     block will have to be split.  */
> +  basic_block bb = gsi_bb (gsi);
> +  if (!gsi_one_before_end_p (gsi))
> +    split_block (bb, stmt);
> +
> +  /* Create a new block for the EH cleanup.  */
> +  basic_block bb_eh_cleanup = create_empty_bb (bb);
> +  if (dom_info_available_p (CDI_DOMINATORS))
> +    set_immediate_dominator (CDI_DOMINATORS, bb_eh_cleanup, bb);
> +  if (current_loops)
> +    add_bb_to_loop (bb_eh_cleanup, current_loops->tree_root);
> +
> +  /* Make the new block an EH cleanup for the call.  */
> +  eh_region new_r = gen_eh_region_cleanup (NULL);
> +  eh_landing_pad lp = gen_eh_landing_pad (new_r);
> +  tree label = gimple_block_label (bb_eh_cleanup);
> +  lp->post_landing_pad = label;
> +  EH_LANDING_PAD_NR (label) = lp->index;
> +  add_stmt_to_eh_lp (stmt, lp->index);
> +
> +  /* Add the cleanup code to the EH cleanup block.  */
> +  gsi = gsi_after_labels (bb_eh_cleanup);
> +  gsi_insert_seq_before (&gsi, seq, GSI_SAME_STMT);
> +
> +  /* And then propagate the exception further.  */
> +  gresx *resx = gimple_build_resx (new_r->index);
> +  if (gimple_has_location (stmt))
> +    gimple_set_location (resx, gimple_location (stmt));
> +  gsi_insert_before (&gsi, resx, GSI_SAME_STMT);
> +
> +  /* Finally, wire the EH cleanup block into the CFG.  */
> +  edge neeh = make_eh_edge (stmt);
> +  neeh->probability = profile_probability::never ();
> +  gcc_checking_assert (neeh->dest == bb_eh_cleanup);
> +  gcc_checking_assert (!neeh->dest->count.initialized_p ());
> +  neeh->dest->count = neeh->count ();
> +  add_call_edges_for_seq (seq, neeh->dest->count);
> +}
> +
> +/* Copy the attribute list at *ATTRS, minus any NAME attributes, leaving
> +   shareable trailing nodes alone.  */
> +
> +static inline void
> +remove_named_attribute_unsharing (const char *name, tree *attrs)
> +{
> +  while (tree found = lookup_attribute (name, *attrs))
> +    {
> +      /* Copy nodes up to the next NAME attribute.  */
> +      while (*attrs != found)
> +       {
> +         *attrs = tree_cons (TREE_PURPOSE (*attrs),
> +                             TREE_VALUE (*attrs),
> +                             TREE_CHAIN (*attrs));
> +         attrs = &TREE_CHAIN (*attrs);
> +       }
> +      /* Then drop it.  */
> +      gcc_checking_assert (*attrs == found);
> +      *attrs = TREE_CHAIN (*attrs);
> +    }
> +}
> +
> +/* Record the order of the last cgraph entry whose mode we've already set, so
> +   that we can perform mode setting incrementally without duplication.  */
> +static int last_cgraph_order;
> +
> +/* Set strub modes for functions introduced since the last call.  */
> +
> +static void
> +ipa_strub_set_mode_for_new_functions ()
> +{
> +  if (symtab->order == last_cgraph_order)
> +    return;
> +
> +  cgraph_node *node;
> +
> +  /* Go through the functions twice, once over non-aliases, and then over
> +     aliases, so that aliases can reuse the mode computation of their ultimate
> +     targets.  */
> +  for (int aliases = 0; aliases <= 1; aliases++)
> +    FOR_EACH_FUNCTION (node)
> +    {
> +      if (!node->alias != !aliases)
> +       continue;
> +
> +      /*  Already done.  */
> +      if (node->order < last_cgraph_order)
> +       continue;
> +
> +      set_strub_mode (node);
> +    }
> +
> +  last_cgraph_order = symtab->order;
> +}
> +
> +/* Return FALSE if NODE is a strub context, and TRUE otherwise.  */
> +
> +bool
> +strub_splittable_p (cgraph_node *node)
> +{
> +  switch (get_strub_mode (node))
> +    {
> +    case STRUB_WRAPPED:
> +    case STRUB_AT_CALLS:
> +    case STRUB_AT_CALLS_OPT:
> +    case STRUB_INLINABLE:
> +    case STRUB_INTERNAL:
> +    case STRUB_WRAPPER:
> +      return false;
> +
> +    case STRUB_CALLABLE:
> +    case STRUB_DISABLED:
> +      break;
> +
> +    default:
> +      gcc_unreachable ();
> +    }
> +
> +  return true;
> +}
> +
> +/* Return the PARM_DECL of the incoming watermark pointer, if there is one.  */
> +
> +tree
> +strub_watermark_parm (tree fndecl)
> +{
> +  switch (get_strub_mode_from_fndecl (fndecl))
> +    {
> +    case STRUB_WRAPPED:
> +    case STRUB_AT_CALLS:
> +    case STRUB_AT_CALLS_OPT:
> +      break;
> +
> +    case STRUB_INTERNAL:
> +    case STRUB_WRAPPER:
> +    case STRUB_CALLABLE:
> +    case STRUB_DISABLED:
> +    case STRUB_INLINABLE:
> +      return NULL_TREE;
> +
> +    default:
> +      gcc_unreachable ();
> +    }
> +
> +  for (tree parm = DECL_ARGUMENTS (fndecl); parm; parm = DECL_CHAIN (parm))
> +    /* The type (variant) compare finds the parameter even in a just-created
> +       clone, before we set its name, but the type-based compare doesn't work
> +       during builtin expansion within the lto compiler, because we'll have
> +       created a separate variant in that run.  */
> +    if (TREE_TYPE (parm) == pass_ipa_strub::get_qpwmt ()
> +       || DECL_NAME (parm) == pass_ipa_strub::get_watermark_ptr ())
> +      return parm;
> +
> +  gcc_unreachable ();
> +}
> +
> +/* Adjust a STRUB_AT_CALLS function TYPE, adding a watermark pointer if it
> +   hasn't been added yet.  Return the named argument count.  */
> +
> +int
> +pass_ipa_strub::adjust_at_calls_type (tree type)
> +{
> +  int named_args = 0;
> +
> +  gcc_checking_assert (same_strub_mode_in_variants_p (type));
> +
> +  if (!TYPE_ARG_TYPES (type))
> +    return named_args;
> +
> +  tree *tlist = &TYPE_ARG_TYPES (type);
> +  tree qpwmptrt = get_qpwmt ();
> +  while (*tlist && TREE_VALUE (*tlist) != void_type_node)
> +    {
> +      /* The type has already been adjusted.  */
> +      if (TREE_VALUE (*tlist) == qpwmptrt)
> +       return named_args;
> +      named_args++;
> +      *tlist = tree_cons (TREE_PURPOSE (*tlist),
> +                         TREE_VALUE (*tlist),
> +                         TREE_CHAIN (*tlist));
> +      tlist = &TREE_CHAIN (*tlist);
> +    }
> +
> +  /* Add the new argument after all named arguments, so as to not mess with
> +     attributes that reference parameters.  */
> +  *tlist = tree_cons (NULL_TREE, get_qpwmt (), *tlist);
> +
> +#if ATTR_FNSPEC_DECONST_WATERMARK
> +  if (!type_already_adjusted)
> +    {
> +      int flags = flags_from_decl_or_type (type);
> +      tree fnspec = lookup_attribute ("fn spec", type);
> +
> +      if ((flags & (ECF_CONST | ECF_PURE | ECF_NOVOPS)) || fnspec)
> +       {
> +         size_t xargs = 1;
> +         size_t curlen = 0, tgtlen = 2 + 2 * (named_args + xargs);
> +         auto_vec<char> nspecv (tgtlen);
> +         char *nspec = &nspecv[0]; /* It will *not* be NUL-terminated!  */
> +         if (fnspec)
> +           {
> +             tree fnspecstr = TREE_VALUE (TREE_VALUE (fnspec));
> +             curlen = TREE_STRING_LENGTH (fnspecstr);
> +             memcpy (nspec, TREE_STRING_POINTER (fnspecstr), curlen);
> +           }
> +         if (!curlen)
> +           {
> +             nspec[curlen++] = '.';
> +             nspec[curlen++] = ((flags & ECF_CONST)
> +                                ? 'c'
> +                                : (flags & ECF_PURE)
> +                                ? 'p'
> +                                : ' ');
> +           }
> +         while (curlen < tgtlen - 2 * xargs)
> +           {
> +             nspec[curlen++] = '.';
> +             nspec[curlen++] = ' ';
> +           }
> +         nspec[curlen++] = 'W';
> +         nspec[curlen++] = 't';
> +
> +         /* The type has already been copied, if needed, before adding
> +            parameters.  */
> +         TYPE_ATTRIBUTES (type)
> +           = tree_cons (get_identifier ("fn spec"),
> +                        build_tree_list (NULL_TREE,
> +                                         build_string (tgtlen, nspec)),
> +                        TYPE_ATTRIBUTES (type));
> +       }
> +    }
> +#endif
> +
> +  return named_args;
> +}
> +
> +/* Adjust a call to an at-calls call target.  Create a watermark local variable
> +   if needed, initialize it before, pass it to the callee according to the
> +   modified at-calls interface, and release the callee's stack space after the
> +   call, if not deferred.  If the call is const or pure, arrange for the
> +   watermark to not be assumed unused or unchanged.  */
> +
> +void
> +pass_ipa_strub::adjust_at_calls_call (cgraph_edge *e, int named_args,
> +                                     tree callee_fntype)
> +{
> +  gcc_checking_assert (e->call_stmt);
> +  gcall *ocall = e->call_stmt;
> +  gimple_stmt_iterator gsi = gsi_for_stmt (ocall);
> +
> +  /* Make sure we haven't modified this call yet.  */
> +  gcc_checking_assert (!(int (gimple_call_num_args (ocall)) > named_args
> +                        && (TREE_TYPE (gimple_call_arg (ocall, named_args))
> +                            == get_pwmt ())));
> +
> +  /* If we're already within a strub context, pass on the incoming watermark
> +     pointer, and omit the enter and leave calls around the modified call, as an
> +     optimization, or as a means to satisfy a tail-call requirement.  */
> +  tree swmp = ((optimize_size || optimize > 2
> +               || gimple_call_must_tail_p (ocall)
> +               || (optimize == 2 && gimple_call_tail_p (ocall)))
> +              ? strub_watermark_parm (e->caller->decl)
> +              : NULL_TREE);
> +  bool omit_own_watermark = swmp;
> +  tree swm = NULL_TREE;
> +  if (!omit_own_watermark)
> +    {
> +      swm = create_tmp_var (get_wmt (), ".strub.watermark");
> +      TREE_ADDRESSABLE (swm) = true;
> +      swmp = build1 (ADDR_EXPR, get_pwmt (), swm);
> +
> +      /* Initialize the watermark before the call.  */
> +      tree enter = get_enter ();
> +      gcall *stptr = gimple_build_call (enter, 1,
> +                                       unshare_expr (swmp));
> +      if (gimple_has_location (ocall))
> +       gimple_set_location (stptr, gimple_location (ocall));
> +      gsi_insert_before (&gsi, stptr, GSI_SAME_STMT);
> +      e->caller->create_edge (cgraph_node::get_create (enter),
> +                             stptr, gsi_bb (gsi)->count, false);
> +    }
> +
> +
> +  /* Replace the call with one that passes the swmp argument first.  */
> +  gcall *wrcall;
> +  { gcall *stmt = ocall;
> +    // Mostly copied from gimple_call_copy_skip_args.
> +    int i = 0;
> +    int nargs = gimple_call_num_args (stmt);
> +    auto_vec<tree> vargs (MAX (nargs, named_args) + 1);
> +    gcall *new_stmt;
> +
> +    /* pr71109.c calls a prototypeless function, then defines it with
> +       additional arguments.  It's ill-formed, but after it's inlined,
> +       it somehow works out.  */
> +    for (; i < named_args && i < nargs; i++)
> +      vargs.quick_push (gimple_call_arg (stmt, i));
> +    for (; i < named_args; i++)
> +      vargs.quick_push (null_pointer_node);
> +
> +    vargs.quick_push (unshare_expr (swmp));
> +
> +    for (; i < nargs; i++)
> +      vargs.quick_push (gimple_call_arg (stmt, i));
> +
> +    if (gimple_call_internal_p (stmt))
> +      gcc_unreachable ();
> +    else
> +      new_stmt = gimple_build_call_vec (gimple_call_fn (stmt), vargs);
> +    gimple_call_set_fntype (new_stmt, callee_fntype);
> +
> +    if (gimple_call_lhs (stmt))
> +      gimple_call_set_lhs (new_stmt, gimple_call_lhs (stmt));
> +
> +    gimple_move_vops (new_stmt, stmt);
> +
> +    if (gimple_has_location (stmt))
> +      gimple_set_location (new_stmt, gimple_location (stmt));
> +    gimple_call_copy_flags (new_stmt, stmt);
> +    gimple_call_set_chain (new_stmt, gimple_call_chain (stmt));
> +
> +    gimple_set_modified (new_stmt, true);
> +
> +    wrcall = new_stmt;
> +  }
> +
> +  update_stmt (wrcall);
> +  gsi_replace (&gsi, wrcall, true);
> +  cgraph_edge::set_call_stmt (e, wrcall, false);
> +
> +  /* Insert the strub code after the call.  */
> +  gimple_seq seq = NULL;
> +
> +#if !ATTR_FNSPEC_DECONST_WATERMARK
> +  /* If the call will be assumed to not modify or even read the
> +     watermark, make it read and modified ourselves.  */
> +  if ((gimple_call_flags (wrcall)
> +       & (ECF_CONST | ECF_PURE | ECF_NOVOPS)))
> +    {
> +      if (!swm)
> +       swm = build2 (MEM_REF,
> +                     TREE_TYPE (TREE_TYPE (swmp)),
> +                     swmp,
> +                     build_int_cst (TREE_TYPE (swmp), 0));
> +
> +      vec<tree, va_gc> *inputs = NULL;
> +      vec<tree, va_gc> *outputs = NULL;
> +      vec_safe_push (outputs,
> +                    build_tree_list
> +                    (build_tree_list
> +                     (NULL_TREE, build_string (2, "=m")),
> +                     unshare_expr (swm)));
> +      vec_safe_push (inputs,
> +                    build_tree_list
> +                    (build_tree_list
> +                     (NULL_TREE, build_string (1, "m")),
> +                     unshare_expr (swm)));
> +      gasm *forcemod = gimple_build_asm_vec ("", inputs, outputs,
> +                                            NULL, NULL);
> +      gimple_seq_add_stmt (&seq, forcemod);
> +
> +      /* If the call will be assumed to not even read the watermark,
> +        make sure it is already in memory before the call.  */
> +      if ((gimple_call_flags (wrcall) & ECF_CONST))
> +       {
> +         vec<tree, va_gc> *inputs = NULL;
> +         vec_safe_push (inputs,
> +                        build_tree_list
> +                        (build_tree_list
> +                         (NULL_TREE, build_string (1, "m")),
> +                         unshare_expr (swm)));
> +         gasm *force_store = gimple_build_asm_vec ("", inputs, NULL,
> +                                                   NULL, NULL);
> +         if (gimple_has_location (wrcall))
> +           gimple_set_location (force_store, gimple_location (wrcall));
> +         gsi_insert_before (&gsi, force_store, GSI_SAME_STMT);
> +       }
> +    }
> +#endif
> +
> +  if (!omit_own_watermark)
> +    {
> +      gcall *sleave = gimple_build_call (get_leave (), 1,
> +                                        unshare_expr (swmp));
> +      gimple_seq_add_stmt (&seq, sleave);
> +
> +      gassign *clobber = gimple_build_assign (swm,
> +                                             build_clobber
> +                                             (TREE_TYPE (swm)));
> +      gimple_seq_add_stmt (&seq, clobber);
> +    }
> +
> +  gsi_insert_finally_seq_after_call (gsi, seq);
> +}
> +
> +/* Adjust all at-calls calls in NODE. */
> +
> +void
> +pass_ipa_strub::adjust_at_calls_calls (cgraph_node *node)
> +{
> +  /* Adjust unknown-callee indirect calls with STRUB_AT_CALLS types within
> +     onode.  */
> +  if (node->indirect_calls)
> +    {
> +      push_cfun (DECL_STRUCT_FUNCTION (node->decl));
> +      for (cgraph_edge *e = node->indirect_calls; e; e = e->next_callee)
> +       {
> +         gcc_checking_assert (e->indirect_unknown_callee);
> +
> +         if (!e->call_stmt)
> +           continue;
> +
> +         tree callee_fntype;
> +         enum strub_mode callee_mode
> +           = effective_strub_mode_for_call (e->call_stmt, &callee_fntype);
> +
> +         if (callee_mode != STRUB_AT_CALLS
> +             && callee_mode != STRUB_AT_CALLS_OPT)
> +           continue;
> +
> +         int named_args = adjust_at_calls_type (callee_fntype);
> +
> +         adjust_at_calls_call (e, named_args, callee_fntype);
> +       }
> +      pop_cfun ();
> +    }
> +
> +  if (node->callees)
> +    {
> +      push_cfun (DECL_STRUCT_FUNCTION (node->decl));
> +      for (cgraph_edge *e = node->callees; e; e = e->next_callee)
> +       {
> +         gcc_checking_assert (!e->indirect_unknown_callee);
> +
> +         if (!e->call_stmt)
> +           continue;
> +
> +         tree callee_fntype;
> +         enum strub_mode callee_mode
> +           = effective_strub_mode_for_call (e->call_stmt, &callee_fntype);
> +
> +         if (callee_mode != STRUB_AT_CALLS
> +             && callee_mode != STRUB_AT_CALLS_OPT)
> +           continue;
> +
> +         int named_args = adjust_at_calls_type (callee_fntype);
> +
> +         adjust_at_calls_call (e, named_args, callee_fntype);
> +       }
> +      pop_cfun ();
> +    }
> +}
> +
> +/* The strubm (strub mode) pass computes a strub mode for each function in the
> +   call graph, and checks, before any inlining, that strub callability
> +   requirements in effect are satisfied.  */
> +
> +unsigned int
> +pass_ipa_strub_mode::execute (function *)
> +{
> +  last_cgraph_order = 0;
> +  ipa_strub_set_mode_for_new_functions ();
> +
> +  /* Verify before any inlining or other transformations.  */
> +  verify_strub ();
> +
> +  return 0;
> +}
> +
> +/* Create a strub mode pass.  */
> +
> +simple_ipa_opt_pass *
> +make_pass_ipa_strub_mode (gcc::context *ctxt)
> +{
> +  return new pass_ipa_strub_mode (ctxt);
> +}
> +
> +/* The strub pass proper adjusts types, signatures, and at-calls calls, and
> +   splits internal-strub functions.  */
> +
> +unsigned int
> +pass_ipa_strub::execute (function *)
> +{
> +  cgraph_node *onode;
> +
> +  ipa_strub_set_mode_for_new_functions ();
> +
> +  /* First, adjust the signature of at-calls functions.  We adjust types of
> +     at-calls functions first, so that we don't modify types in place unless
> +     strub is explicitly requested.  */
> +  FOR_EACH_FUNCTION (onode)
> +  {
> +    enum strub_mode mode = get_strub_mode (onode);
> +
> +    if (mode == STRUB_AT_CALLS
> +       || mode == STRUB_AT_CALLS_OPT)
> +      {
> +       /* Create a type variant if strubbing was not explicitly requested in
> +          the function type.  */
> +       if (get_strub_mode_from_type (TREE_TYPE (onode->decl)) != mode)
> +         distinctify_node_type (onode);
> +
> +       int named_args = adjust_at_calls_type (TREE_TYPE (onode->decl));
> +
> +       /* An external function explicitly declared with strub won't have a
> +          body.  Even with implicit at-calls strub, a function may have had its
> +          body removed after we selected the mode, and then we have nothing
> +          further to do.  */
> +       if (!onode->has_gimple_body_p ())
> +         continue;
> +
> +       tree *pargs = &DECL_ARGUMENTS (onode->decl);
> +
> +       /* A noninterposable_alias reuses the same parm decl chain, don't add
> +          the parm twice.  */
> +       bool aliased_parms = (onode->alias && *pargs
> +                             && DECL_CONTEXT (*pargs) != onode->decl);
> +
> +       if (aliased_parms)
> +         continue;
> +
> +       for (int i = 0; i < named_args; i++)
> +         pargs = &DECL_CHAIN (*pargs);
> +
> +       tree wmptr = build_decl (DECL_SOURCE_LOCATION (onode->decl),
> +                                PARM_DECL,
> +                                get_watermark_ptr (),
> +                                get_qpwmt ());
> +       DECL_ARTIFICIAL (wmptr) = 1;
> +       DECL_ARG_TYPE (wmptr) = get_qpwmt ();
> +       DECL_CONTEXT (wmptr) = onode->decl;
> +       TREE_USED (wmptr) = 1;
> +       DECL_CHAIN (wmptr) = *pargs;
> +       *pargs = wmptr;
> +
> +       if (onode->alias)
> +         continue;
> +
> +       cgraph_node *nnode = onode;
> +       push_cfun (DECL_STRUCT_FUNCTION (nnode->decl));
> +
> +       {
> +         edge e = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun));
> +         gimple_seq seq = call_update_watermark (wmptr, nnode, e->src->count);
> +         gsi_insert_seq_on_edge_immediate (e, seq);
> +       }
> +
> +       if (DECL_STRUCT_FUNCTION (nnode->decl)->calls_alloca)
> +         {
> +           basic_block bb;
> +           FOR_EACH_BB_FN (bb, cfun)
> +             for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
> +                  !gsi_end_p (gsi); gsi_next (&gsi))
> +               {
> +                 gimple *stmt = gsi_stmt (gsi);
> +
> +                 gcall *call = dyn_cast <gcall *> (stmt);
> +
> +                 if (!call)
> +                   continue;
> +
> +                 if (gimple_alloca_call_p (call))
> +                   {
> +                     /* Capture stack growth.  */
> +                     gimple_seq seq = call_update_watermark (wmptr, NULL,
> +                                                             gsi_bb (gsi)
> +                                                             ->count);
> +                     gsi_insert_finally_seq_after_call (gsi, seq);
> +                   }
> +               }
> +         }
> +
> +       pop_cfun ();
> +      }
> +  }
> +
> +  FOR_EACH_FUNCTION (onode)
> +  {
> +    if (!onode->has_gimple_body_p ())
> +      continue;
> +
> +    enum strub_mode mode = get_strub_mode (onode);
> +
> +    if (mode != STRUB_INTERNAL)
> +      {
> +       adjust_at_calls_calls (onode);
> +       continue;
> +      }
> +
> +    bool is_stdarg = calls_builtin_va_start_p (onode);;
> +    bool apply_args = calls_builtin_apply_args_p (onode);
> +
> +    vec<ipa_adjusted_param, va_gc> *nparms = NULL;
> +    unsigned j = 0;
> +    {
> +      // The following loop copied from ipa-split.c:split_function.
> +      for (tree parm = DECL_ARGUMENTS (onode->decl);
> +          parm; parm = DECL_CHAIN (parm), j++)
> +       {
> +         ipa_adjusted_param adj = {};
> +         adj.op = IPA_PARAM_OP_COPY;
> +         adj.base_index = j;
> +         adj.prev_clone_index = j;
> +         vec_safe_push (nparms, adj);
> +       }
> +
> +      if (apply_args)
> +       {
> +         ipa_adjusted_param aaadj = {};
> +         aaadj.op = IPA_PARAM_OP_NEW;
> +         aaadj.type = get_qptr ();
> +         vec_safe_push (nparms, aaadj);
> +       }
> +
> +      if (is_stdarg)
> +       {
> +         ipa_adjusted_param vladj = {};
> +         vladj.op = IPA_PARAM_OP_NEW;
> +         vladj.type = get_qpvalst ();
> +         vec_safe_push (nparms, vladj);
> +       }
> +
> +      ipa_adjusted_param wmadj = {};
> +      wmadj.op = IPA_PARAM_OP_NEW;
> +      wmadj.type = get_qpwmt ();
> +      vec_safe_push (nparms, wmadj);
> +    }
> +    ipa_param_adjustments adj (nparms, -1, false);
> +
> +    cgraph_node *nnode = onode->create_version_clone_with_body
> +      (auto_vec<cgraph_edge *> (0),
> +       NULL, &adj, NULL, NULL, "strub", NULL);
> +
> +    if (!nnode)
> +      {
> +       error_at (DECL_SOURCE_LOCATION (onode->decl),
> +                 "failed to split %qD for %<strub%>",
> +                 onode->decl);
> +       continue;
> +      }
> +
> +    onode->split_part = true;
> +    if (onode->calls_comdat_local)
> +      nnode->add_to_same_comdat_group (onode);
> +
> +    set_strub_mode_to (onode, STRUB_WRAPPER);
> +    set_strub_mode_to (nnode, STRUB_WRAPPED);
> +
> +    adjust_at_calls_calls (nnode);
> +
> +    /* Decide which of the wrapped function's parms we want to turn into
> +       references to the argument passed to the wrapper.  In general, we want to
> +       copy small arguments, and avoid copying large ones.  Variable-sized array
> +       lengths given by other arguments, as in 20020210-1.c, would lead to
> +       problems if passed by value, after resetting the original function and
> +       dropping the length computation; passing them by reference works.
> +       DECL_BY_REFERENCE is *not* a substitute for this: it involves copying
> +       anyway, but performed at the caller.  */
> +    indirect_parms_t indirect_nparms (3, false);
> +    unsigned adjust_ftype = 0;
> +    unsigned named_args = 0;
> +    for (tree parm = DECL_ARGUMENTS (onode->decl),
> +          nparm = DECL_ARGUMENTS (nnode->decl),
> +          nparmt = TYPE_ARG_TYPES (TREE_TYPE (nnode->decl));
> +        parm;
> +        named_args++,
> +          parm = DECL_CHAIN (parm),
> +          nparm = DECL_CHAIN (nparm),
> +          nparmt = nparmt ? TREE_CHAIN (nparmt) : NULL_TREE)
> +      if (!(0 /* DECL_BY_REFERENCE (narg) */
> +           || is_gimple_reg_type (TREE_TYPE (nparm))
> +           || VECTOR_TYPE_P (TREE_TYPE (nparm))
> +           || TREE_CODE (TREE_TYPE (nparm)) == COMPLEX_TYPE
> +           || (tree_fits_uhwi_p (TYPE_SIZE_UNIT (TREE_TYPE (nparm)))
> +               && (tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (nparm)))
> +                   <= 4 * UNITS_PER_WORD))))
> +       {
> +         indirect_nparms.add (nparm);
> +
> +         /* ??? Is there any case in which it is not safe to suggest the parms
> +            turned indirect don't alias anything else?  They are distinct,
> +            unaliased memory in the wrapper, and the wrapped can't possibly
> +            take pointers into them because none of the pointers passed to the
> +            wrapper can alias other incoming parameters passed by value, even
> +            if with transparent reference, and the wrapper doesn't take any
> +            extra parms that could point into wrapper's parms.  So we can
> +            probably drop the TREE_ADDRESSABLE and keep the TRUE.  */
> +         tree ref_type = build_ref_type_for (nparm,
> +                                             true
> +                                             || !TREE_ADDRESSABLE (parm));
> +
> +         DECL_ARG_TYPE (nparm) = TREE_TYPE (nparm) = ref_type;
> +         relayout_decl (nparm);
> +         TREE_ADDRESSABLE (nparm) = 0;
> +         DECL_BY_REFERENCE (nparm) = 0;
> +         DECL_NOT_GIMPLE_REG_P (nparm) = 0;
> +         /* ??? This avoids mismatches in debug info bind stmts in
> +            e.g. a-chahan .  */
> +         DECL_ABSTRACT_ORIGIN (nparm) = NULL;
> +
> +         if (nparmt)
> +           adjust_ftype++;
> +       }
> +
> +    /* Also adjust the wrapped function type, if needed.  */
> +    if (adjust_ftype)
> +      {
> +       tree nftype = TREE_TYPE (nnode->decl);
> +
> +       /* We always add at least one argument at the end of the signature, when
> +          cloning the function, so we don't expect to need to duplicate the
> +          type here.  */
> +       gcc_checking_assert (TYPE_ARG_TYPES (nftype)
> +                            != TYPE_ARG_TYPES (TREE_TYPE (onode->decl)));
> +
> +       /* Check that fnspec still works for the modified function signature,
> +          and drop it otherwise.  */
> +       bool drop_fnspec = false;
> +       tree fnspec = lookup_attribute ("fn spec", TYPE_ATTRIBUTES (nftype));
> +       attr_fnspec spec = fnspec ? attr_fnspec (fnspec) : attr_fnspec ("");
> +
> +       unsigned retcopy;
> +       if (!(fnspec && spec.returns_arg (&retcopy)))
> +         retcopy = (unsigned) -1;
> +
> +       unsigned i = 0;
> +       for (tree nparm = DECL_ARGUMENTS (nnode->decl),
> +              nparmt = TYPE_ARG_TYPES (nftype);
> +            adjust_ftype > 0;
> +            i++, nparm = DECL_CHAIN (nparm), nparmt = TREE_CHAIN (nparmt))
> +         if (indirect_nparms.contains (nparm))
> +           {
> +             TREE_VALUE (nparmt) = TREE_TYPE (nparm);
> +             adjust_ftype--;
> +
> +             if (fnspec && !drop_fnspec)
> +               {
> +                 if (i == retcopy)
> +                   drop_fnspec = true;
> +                 else if (spec.arg_specified_p (i))
> +                   {
> +                     /* Properties that apply to pointers only must not be
> +                        present, because we don't make pointers further
> +                        indirect.  */
> +                     gcc_checking_assert
> +                       (!spec.arg_max_access_size_given_by_arg_p (i, NULL));
> +                     gcc_checking_assert (!spec.arg_copied_to_arg_p (i, NULL));
> +
> +                     /* Any claim of direct access only is invalidated by
> +                        adding an indirection level.  */
> +                     if (spec.arg_direct_p (i))
> +                       drop_fnspec = true;
> +
> +                     /* If there's a claim the argument is not read from, the
> +                        added indirection invalidates it: if the argument is
> +                        used at all, then the pointer will necessarily be
> +                        read.  */
> +                     if (!spec.arg_maybe_read_p (i)
> +                         && spec.arg_used_p (i))
> +                       drop_fnspec = true;
> +                   }
> +               }
> +           }
> +
> +       /* ??? Maybe we could adjust it instead.  */
> +       if (drop_fnspec)
> +         remove_named_attribute_unsharing ("fn spec",
> +                                           &TYPE_ATTRIBUTES (nftype));
> +
> +       TREE_TYPE (nnode->decl) = nftype;
> +      }
> +
> +#if ATTR_FNSPEC_DECONST_WATERMARK
> +    {
> +      int flags = flags_from_decl_or_type (nnode->decl);
> +      tree fnspec = lookup_attribute ("fn spec", TREE_TYPE (nnode->decl));
> +
> +      if ((flags & (ECF_CONST | ECF_PURE | ECF_NOVOPS)) || fnspec)
> +       {
> +         size_t xargs = 1 + int (is_stdarg) + int (apply_args);
> +         size_t curlen = 0, tgtlen = 2 + 2 * (named_args + xargs);
> +         auto_vec<char> nspecv (tgtlen);
> +         char *nspec = &nspecv[0]; /* It will *not* be NUL-terminated!  */
> +         bool no_writes_p = true;
> +         if (fnspec)
> +           {
> +             tree fnspecstr = TREE_VALUE (TREE_VALUE (fnspec));
> +             curlen = TREE_STRING_LENGTH (fnspecstr);
> +             memcpy (nspec, TREE_STRING_POINTER (fnspecstr), curlen);
> +             if (!(flags & (ECF_CONST | ECF_PURE | ECF_NOVOPS))
> +                 && curlen >= 2
> +                 && nspec[1] != 'c' && nspec[1] != 'C'
> +                 && nspec[1] != 'p' && nspec[1] != 'P')
> +               no_writes_p = false;
> +           }
> +         if (!curlen)
> +           {
> +             nspec[curlen++] = '.';
> +             nspec[curlen++] = ((flags & ECF_CONST)
> +                                ? 'c'
> +                                : (flags & ECF_PURE)
> +                                ? 'p'
> +                                : ' ');
> +           }
> +         while (curlen < tgtlen - 2 * xargs)
> +           {
> +             nspec[curlen++] = '.';
> +             nspec[curlen++] = ' ';
> +           }
> +
> +         /* These extra args are unlikely to be present in const or pure
> +            functions.  It's conceivable that a function that takes variable
> +            arguments, or that passes its arguments on to another function,
> +            could be const or pure, but it would not modify the arguments, and,
> +            being pure or const, it couldn't possibly modify or even access
> +            memory referenced by them.  But it can read from these internal
> +            data structures created by the wrapper, and from any
> +            argument-passing memory referenced by them, so we denote the
> +            possibility of reading from multiple levels of indirection, but
> +            only of reading because const/pure.  */
> +         if (apply_args)
> +           {
> +             nspec[curlen++] = 'r';
> +             nspec[curlen++] = ' ';
> +           }
> +         if (is_stdarg)
> +           {
> +             nspec[curlen++] = (no_writes_p ? 'r' : '.');
> +             nspec[curlen++] = (no_writes_p ? 't' : ' ');
> +           }
> +
> +         nspec[curlen++] = 'W';
> +         nspec[curlen++] = 't';
> +
> +         /* The type has already been copied before adding parameters.  */
> +         gcc_checking_assert (TYPE_ARG_TYPES (TREE_TYPE (nnode->decl))
> +                              != TYPE_ARG_TYPES (TREE_TYPE (onode->decl)));
> +         TYPE_ATTRIBUTES (TREE_TYPE (nnode->decl))
> +           = tree_cons (get_identifier ("fn spec"),
> +                        build_tree_list (NULL_TREE,
> +                                         build_string (tgtlen, nspec)),
> +                        TYPE_ATTRIBUTES (TREE_TYPE (nnode->decl)));
> +       }
> +    }
> +#endif
> +
> +    {
> +      tree decl = onode->decl;
> +      cgraph_node *target = nnode;
> +
> +      { // copied from create_wrapper
> +
> +       /* Preserve DECL_RESULT so we get right by reference flag.  */
> +       tree decl_result = DECL_RESULT (decl);
> +
> +       /* Remove the function's body but keep arguments to be reused
> +          for thunk.  */
> +       onode->release_body (true);
> +       onode->reset (/* unlike create_wrapper: preserve_comdat_group = */true);
> +
> +       DECL_UNINLINABLE (decl) = false;
> +       DECL_RESULT (decl) = decl_result;
> +       DECL_INITIAL (decl) = NULL;
> +       allocate_struct_function (decl, false);
> +       set_cfun (NULL);
> +
> +       /* Turn alias into thunk and expand it into GIMPLE representation.  */
> +       onode->definition = true;
> +
> +       thunk_info::get_create (onode);
> +       onode->thunk = true;
> +       onode->create_edge (target, NULL, onode->count);
> +       onode->callees->can_throw_external = !TREE_NOTHROW (target->decl);
> +
> +       tree arguments = DECL_ARGUMENTS (decl);
> +
> +       while (arguments)
> +         {
> +           TREE_ADDRESSABLE (arguments) = false;
> +           arguments = TREE_CHAIN (arguments);
> +         }
> +
> +       {
> +         tree alias = onode->callees->callee->decl;
> +         tree thunk_fndecl = decl;
> +         tree a;
> +
> +         int nxargs = 1 + is_stdarg + apply_args;
> +
> +         { // Simplified from expand_thunk.
> +           tree restype;
> +           basic_block bb, then_bb, else_bb, return_bb;
> +           gimple_stmt_iterator bsi;
> +           int nargs = 0;
> +           tree arg;
> +           int i;
> +           tree resdecl;
> +           tree restmp = NULL;
> +
> +           gcall *call;
> +           greturn *ret;
> +           bool alias_is_noreturn = TREE_THIS_VOLATILE (alias);
> +
> +           a = DECL_ARGUMENTS (thunk_fndecl);
> +
> +           current_function_decl = thunk_fndecl;
> +
> +           /* Ensure thunks are emitted in their correct sections.  */
> +           resolve_unique_section (thunk_fndecl, 0,
> +                                   flag_function_sections);
> +
> +           bitmap_obstack_initialize (NULL);
> +
> +           /* Build the return declaration for the function.  */
> +           restype = TREE_TYPE (TREE_TYPE (thunk_fndecl));
> +           if (DECL_RESULT (thunk_fndecl) == NULL_TREE)
> +             {
> +               resdecl = build_decl (input_location, RESULT_DECL, 0, restype);
> +               DECL_ARTIFICIAL (resdecl) = 1;
> +               DECL_IGNORED_P (resdecl) = 1;
> +               DECL_CONTEXT (resdecl) = thunk_fndecl;
> +               DECL_RESULT (thunk_fndecl) = resdecl;
> +             }
> +           else
> +             resdecl = DECL_RESULT (thunk_fndecl);
> +
> +           profile_count cfg_count = onode->count;
> +           if (!cfg_count.initialized_p ())
> +             cfg_count = profile_count::from_gcov_type (BB_FREQ_MAX).guessed_local ();
> +
> +           bb = then_bb = else_bb = return_bb
> +             = init_lowered_empty_function (thunk_fndecl, true, cfg_count);
> +
> +           bsi = gsi_start_bb (bb);
> +
> +           /* Build call to the function being thunked.  */
> +           if (!VOID_TYPE_P (restype)
> +               && (!alias_is_noreturn
> +                   || TREE_ADDRESSABLE (restype)
> +                   || TREE_CODE (TYPE_SIZE_UNIT (restype)) != INTEGER_CST))
> +             {
> +               if (DECL_BY_REFERENCE (resdecl))
> +                 {
> +                   restmp = gimple_fold_indirect_ref (resdecl);
> +                   if (!restmp)
> +                     restmp = build2 (MEM_REF,
> +                                      TREE_TYPE (TREE_TYPE (resdecl)),
> +                                      resdecl,
> +                                      build_int_cst (TREE_TYPE (resdecl), 0));
> +                 }
> +               else if (!is_gimple_reg_type (restype))
> +                 {
> +                   if (aggregate_value_p (resdecl, TREE_TYPE (thunk_fndecl)))
> +                     {
> +                       restmp = resdecl;
> +
> +                       if (VAR_P (restmp))
> +                         {
> +                           add_local_decl (cfun, restmp);
> +                           BLOCK_VARS (DECL_INITIAL (current_function_decl))
> +                             = restmp;
> +                         }
> +                     }
> +                   else
> +                     restmp = create_tmp_var (restype, "retval");
> +                 }
> +               else
> +                 restmp = create_tmp_reg (restype, "retval");
> +             }
> +
> +           for (arg = a; arg; arg = DECL_CHAIN (arg))
> +             nargs++;
> +           auto_vec<tree> vargs (nargs + nxargs);
> +           i = 0;
> +           arg = a;
> +
> +           if (nargs)
> +             for (tree nparm = DECL_ARGUMENTS (nnode->decl);
> +                  i < nargs;
> +                  i++, arg = DECL_CHAIN (arg), nparm = DECL_CHAIN (nparm))
> +               {
> +                 tree save_arg = arg;
> +                 tree tmp = arg;
> +
> +                 /* Arrange to pass indirectly the parms, if we decided to do
> +                    so, and revert its type in the wrapper.  */
> +                 if (indirect_nparms.contains (nparm))
> +                   {
> +                     tree ref_type = TREE_TYPE (nparm);
> +                     TREE_ADDRESSABLE (arg) = true;
> +                     tree addr = build1 (ADDR_EXPR, ref_type, arg);
> +                     tmp = arg = addr;
> +                   }
> +                 else
> +                   DECL_NOT_GIMPLE_REG_P (arg) = 0;
> +
> +                 /* Convert the argument back to the type used by the calling
> +                    conventions, e.g. a non-prototyped float type is passed as
> +                    double, as in 930603-1.c, and needs to be converted back to
> +                    double to be passed on unchanged to the wrapped
> +                    function.  */
> +                 if (TREE_TYPE (nparm) != DECL_ARG_TYPE (nparm))
> +                   arg = fold_convert (DECL_ARG_TYPE (nparm), arg);
> +
> +                 if (!is_gimple_val (arg))
> +                   {
> +                     tmp = create_tmp_reg (TYPE_MAIN_VARIANT
> +                                           (TREE_TYPE (arg)), "arg");
> +                     gimple *stmt = gimple_build_assign (tmp, arg);
> +                     gsi_insert_after (&bsi, stmt, GSI_NEW_STMT);
> +                   }
> +                 vargs.quick_push (tmp);
> +                 arg = save_arg;
> +               }
> +           /* These strub arguments are adjusted later.  */
> +           if (apply_args)
> +             vargs.quick_push (null_pointer_node);
> +           if (is_stdarg)
> +             vargs.quick_push (null_pointer_node);
> +           vargs.quick_push (null_pointer_node);
> +           call = gimple_build_call_vec (build_fold_addr_expr_loc (0, alias),
> +                                         vargs);
> +           onode->callees->call_stmt = call;
> +           // gimple_call_set_from_thunk (call, true);
> +           if (DECL_STATIC_CHAIN (alias))
> +             {
> +               tree p = DECL_STRUCT_FUNCTION (alias)->static_chain_decl;
> +               tree type = TREE_TYPE (p);
> +               tree decl = build_decl (DECL_SOURCE_LOCATION (thunk_fndecl),
> +                                       PARM_DECL, create_tmp_var_name ("CHAIN"),
> +                                       type);
> +               DECL_ARTIFICIAL (decl) = 1;
> +               DECL_IGNORED_P (decl) = 1;
> +               TREE_USED (decl) = 1;
> +               DECL_CONTEXT (decl) = thunk_fndecl;
> +               DECL_ARG_TYPE (decl) = type;
> +               TREE_READONLY (decl) = 1;
> +
> +               struct function *sf = DECL_STRUCT_FUNCTION (thunk_fndecl);
> +               sf->static_chain_decl = decl;
> +
> +               gimple_call_set_chain (call, decl);
> +             }
> +
> +           /* Return slot optimization is always possible and in fact required to
> +              return values with DECL_BY_REFERENCE.  */
> +           if (aggregate_value_p (resdecl, TREE_TYPE (thunk_fndecl))
> +               && (!is_gimple_reg_type (TREE_TYPE (resdecl))
> +                   || DECL_BY_REFERENCE (resdecl)))
> +             gimple_call_set_return_slot_opt (call, true);
> +
> +           if (restmp)
> +             {
> +               gimple_call_set_lhs (call, restmp);
> +               gcc_assert (useless_type_conversion_p (TREE_TYPE (restmp),
> +                                                      TREE_TYPE (TREE_TYPE (alias))));
> +             }
> +           gsi_insert_after (&bsi, call, GSI_NEW_STMT);
> +           if (!alias_is_noreturn)
> +             {
> +               /* Build return value.  */
> +               if (!DECL_BY_REFERENCE (resdecl))
> +                 ret = gimple_build_return (restmp);
> +               else
> +                 ret = gimple_build_return (resdecl);
> +
> +               gsi_insert_after (&bsi, ret, GSI_NEW_STMT);
> +             }
> +           else
> +             {
> +               remove_edge (single_succ_edge (bb));
> +             }
> +
> +           cfun->gimple_df->in_ssa_p = true;
> +           update_max_bb_count ();
> +           profile_status_for_fn (cfun)
> +             = cfg_count.initialized_p () && cfg_count.ipa_p ()
> +             ? PROFILE_READ : PROFILE_GUESSED;
> +           /* FIXME: C++ FE should stop setting TREE_ASM_WRITTEN on thunks.  */
> +           // TREE_ASM_WRITTEN (thunk_fndecl) = false;
> +           delete_unreachable_blocks ();
> +           update_ssa (TODO_update_ssa);
> +           checking_verify_flow_info ();
> +           free_dominance_info (CDI_DOMINATORS);
> +
> +           /* Since we want to emit the thunk, we explicitly mark its name as
> +              referenced.  */
> +           onode->thunk = false;
> +           onode->lowered = true;
> +           bitmap_obstack_release (NULL);
> +         }
> +         current_function_decl = NULL;
> +         set_cfun (NULL);
> +       }
> +
> +       thunk_info::remove (onode);
> +
> +       // some more of create_wrapper at the end of the next block.
> +      }
> +    }
> +
> +    {
> +      tree aaval = NULL_TREE;
> +      tree vaptr = NULL_TREE;
> +      tree wmptr = NULL_TREE;
> +      for (tree arg = DECL_ARGUMENTS (nnode->decl); arg; arg = DECL_CHAIN (arg))
> +       {
> +         aaval = vaptr;
> +         vaptr = wmptr;
> +         wmptr = arg;
> +       }
> +
> +      if (!apply_args)
> +       aaval = NULL_TREE;
> +      /* The trailing args are [apply_args], [va_list_ptr], and
> +        watermark.  If we don't have a va_list_ptr, the penultimate
> +        argument is apply_args.
> +       */
> +      else if (!is_stdarg)
> +       aaval = vaptr;
> +
> +      if (!is_stdarg)
> +       vaptr = NULL_TREE;
> +
> +      DECL_NAME (wmptr) = get_watermark_ptr ();
> +      DECL_ARTIFICIAL (wmptr) = 1;
> +      DECL_IGNORED_P (wmptr) = 1;
> +      TREE_USED (wmptr) = 1;
> +
> +      if (is_stdarg)
> +       {
> +         DECL_NAME (vaptr) = get_va_list_ptr ();
> +         DECL_ARTIFICIAL (vaptr) = 1;
> +         DECL_IGNORED_P (vaptr) = 1;
> +         TREE_USED (vaptr) = 1;
> +       }
> +
> +      if (apply_args)
> +       {
> +         DECL_NAME (aaval) = get_apply_args ();
> +         DECL_ARTIFICIAL (aaval) = 1;
> +         DECL_IGNORED_P (aaval) = 1;
> +         TREE_USED (aaval) = 1;
> +       }
> +
> +      push_cfun (DECL_STRUCT_FUNCTION (nnode->decl));
> +
> +      {
> +       edge e = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun));
> +       gimple_seq seq = call_update_watermark (wmptr, nnode, e->src->count);
> +       gsi_insert_seq_on_edge_immediate (e, seq);
> +      }
> +
> +      bool any_indirect = !indirect_nparms.is_empty ();
> +
> +      if (any_indirect)
> +       {
> +         basic_block bb;
> +         bool needs_commit = false;
> +         FOR_EACH_BB_FN (bb, cfun)
> +           {
> +             for (gphi_iterator gsi = gsi_start_nonvirtual_phis (bb);
> +                  !gsi_end_p (gsi);
> +                  gsi_next_nonvirtual_phi (&gsi))
> +               {
> +                 gphi *stmt = gsi.phi ();
> +
> +                 walk_stmt_info wi = {};
> +                 wi.info = &indirect_nparms;
> +                 walk_gimple_op (stmt, walk_make_indirect, &wi);
> +                 if (wi.changed && !is_gimple_debug (gsi_stmt (gsi)))
> +                   if (walk_regimplify_phi (stmt))
> +                     needs_commit = true;
> +               }
> +
> +             for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
> +                  !gsi_end_p (gsi); gsi_next (&gsi))
> +               {
> +                 gimple *stmt = gsi_stmt (gsi);
> +
> +                 walk_stmt_info wi = {};
> +                 wi.info = &indirect_nparms;
> +                 walk_gimple_op (stmt, walk_make_indirect, &wi);
> +                 if (wi.changed)
> +                   {
> +                     if (!is_gimple_debug (stmt))
> +                       {
> +                         wi.info = &gsi;
> +                         walk_gimple_op (stmt, walk_regimplify_addr_expr,
> +                                         &wi);
> +                       }
> +                     update_stmt (stmt);
> +                   }
> +               }
> +           }
> +         if (needs_commit)
> +           gsi_commit_edge_inserts ();
> +       }
> +
> +      if (DECL_STRUCT_FUNCTION (nnode->decl)->calls_alloca
> +         || is_stdarg || apply_args)
> +       for (cgraph_edge *e = nnode->callees, *enext; e; e = enext)
> +         {
> +           if (!e->call_stmt)
> +             continue;
> +
> +           gcall *call = e->call_stmt;
> +           gimple_stmt_iterator gsi = gsi_for_stmt (call);
> +           tree fndecl = e->callee->decl;
> +
> +           enext = e->next_callee;
> +
> +           if (gimple_alloca_call_p (call))
> +             {
> +               gimple_seq seq = call_update_watermark (wmptr, NULL,
> +                                                       gsi_bb (gsi)->count);
> +               gsi_insert_finally_seq_after_call (gsi, seq);
> +             }
> +           else if (fndecl && is_stdarg
> +                    && fndecl_built_in_p (fndecl, BUILT_IN_VA_START))
> +             {
> +               /* Using a non-default stdarg ABI makes the function ineligible
> +                  for internal strub.  */
> +               gcc_checking_assert (builtin_decl_explicit (BUILT_IN_VA_START)
> +                                    == fndecl);
> +               tree bvacopy = builtin_decl_explicit (BUILT_IN_VA_COPY);
> +               gimple_call_set_fndecl (call, bvacopy);
> +               tree arg = vaptr;
> +               /* The va_copy source must be dereferenced, unless it's an array
> +                  type, that would have decayed to a pointer.  */
> +               if (TREE_CODE (TREE_TYPE (TREE_TYPE (vaptr))) != ARRAY_TYPE)
> +                 {
> +                   arg = gimple_fold_indirect_ref (vaptr);
> +                   if (!arg)
> +                     arg = build2 (MEM_REF,
> +                                   TREE_TYPE (TREE_TYPE (vaptr)),
> +                                   vaptr,
> +                                   build_int_cst (TREE_TYPE (vaptr), 0));
> +                   if (!is_gimple_val (arg))
> +                     arg = force_gimple_operand_gsi (&gsi, arg, true,
> +                                                     NULL_TREE, true, GSI_SAME_STMT);
> +                 }
> +               gimple_call_set_arg (call, 1, arg);
> +               update_stmt (call);
> +               e->redirect_callee (cgraph_node::get_create (bvacopy));
> +             }
> +           else if (fndecl && apply_args
> +                    && fndecl_built_in_p (fndecl, BUILT_IN_APPLY_ARGS))
> +             {
> +               tree lhs = gimple_call_lhs (call);
> +               gimple *assign = (lhs
> +                                 ? gimple_build_assign (lhs, aaval)
> +                                 : gimple_build_nop ());
> +               gsi_replace (&gsi, assign, true);
> +               cgraph_edge::remove (e);
> +             }
> +         }
> +
> +      { // a little more copied from create_wrapper
> +
> +       /* Inline summary set-up.  */
> +       nnode->analyze ();
> +       // inline_analyze_function (nnode);
> +      }
> +
> +      pop_cfun ();
> +    }
> +
> +    {
> +      push_cfun (DECL_STRUCT_FUNCTION (onode->decl));
> +      gimple_stmt_iterator gsi
> +       = gsi_after_labels (single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
> +
> +      gcall *wrcall;
> +      while (!(wrcall = dyn_cast <gcall *> (gsi_stmt (gsi))))
> +       gsi_next (&gsi);
> +
> +      tree swm = create_tmp_var (get_wmt (), ".strub.watermark");
> +      TREE_ADDRESSABLE (swm) = true;
> +      tree swmp = build1 (ADDR_EXPR, get_pwmt (), swm);
> +
> +      tree enter = get_enter ();
> +      gcall *stptr = gimple_build_call (enter, 1, unshare_expr (swmp));
> +      gimple_set_location (stptr, gimple_location (wrcall));
> +      gsi_insert_before (&gsi, stptr, GSI_SAME_STMT);
> +      onode->create_edge (cgraph_node::get_create (enter),
> +                         stptr, gsi_bb (gsi)->count, false);
> +
> +      int nargs = gimple_call_num_args (wrcall);
> +
> +      gimple_seq seq = NULL;
> +
> +      if (apply_args)
> +       {
> +         tree aalst = create_tmp_var (ptr_type_node, ".strub.apply_args");
> +         tree bappargs = builtin_decl_explicit (BUILT_IN_APPLY_ARGS);
> +         gcall *appargs = gimple_build_call (bappargs, 0);
> +         gimple_call_set_lhs (appargs, aalst);
> +         gimple_set_location (appargs, gimple_location (wrcall));
> +         gsi_insert_before (&gsi, appargs, GSI_SAME_STMT);
> +         gimple_call_set_arg (wrcall, nargs - 2 - is_stdarg, aalst);
> +         onode->create_edge (cgraph_node::get_create (bappargs),
> +                             appargs, gsi_bb (gsi)->count, false);
> +       }
> +
> +      if (is_stdarg)
> +       {
> +         tree valst = create_tmp_var (va_list_type_node, ".strub.va_list");
> +         TREE_ADDRESSABLE (valst) = true;
> +         tree vaptr = build1 (ADDR_EXPR,
> +                              build_pointer_type (va_list_type_node),
> +                              valst);
> +         gimple_call_set_arg (wrcall, nargs - 2, unshare_expr (vaptr));
> +
> +         tree bvastart = builtin_decl_explicit (BUILT_IN_VA_START);
> +         gcall *vastart = gimple_build_call (bvastart, 2,
> +                                             unshare_expr (vaptr),
> +                                             integer_zero_node);
> +         gimple_set_location (vastart, gimple_location (wrcall));
> +         gsi_insert_before (&gsi, vastart, GSI_SAME_STMT);
> +         onode->create_edge (cgraph_node::get_create (bvastart),
> +                             vastart, gsi_bb (gsi)->count, false);
> +
> +         tree bvaend = builtin_decl_explicit (BUILT_IN_VA_END);
> +         gcall *vaend = gimple_build_call (bvaend, 1, unshare_expr (vaptr));
> +         gimple_set_location (vaend, gimple_location (wrcall));
> +         gimple_seq_add_stmt (&seq, vaend);
> +       }
> +
> +      gimple_call_set_arg (wrcall, nargs - 1, unshare_expr (swmp));
> +      // gimple_call_set_tail (wrcall, false);
> +      update_stmt (wrcall);
> +
> +      {
> +#if !ATTR_FNSPEC_DECONST_WATERMARK
> +       /* If the call will be assumed to not modify or even read the
> +          watermark, make it read and modified ourselves.  */
> +       if ((gimple_call_flags (wrcall)
> +            & (ECF_CONST | ECF_PURE | ECF_NOVOPS)))
> +         {
> +           vec<tree, va_gc> *inputs = NULL;
> +           vec<tree, va_gc> *outputs = NULL;
> +           vec_safe_push (outputs,
> +                          build_tree_list
> +                          (build_tree_list
> +                           (NULL_TREE, build_string (2, "=m")),
> +                           swm));
> +           vec_safe_push (inputs,
> +                          build_tree_list
> +                          (build_tree_list
> +                           (NULL_TREE, build_string (1, "m")),
> +                           swm));
> +           gasm *forcemod = gimple_build_asm_vec ("", inputs, outputs,
> +                                                  NULL, NULL);
> +           gimple_seq_add_stmt (&seq, forcemod);
> +
> +           /* If the call will be assumed to not even read the watermark,
> +              make sure it is already in memory before the call.  */
> +           if ((gimple_call_flags (wrcall) & ECF_CONST))
> +             {
> +               vec<tree, va_gc> *inputs = NULL;
> +               vec_safe_push (inputs,
> +                              build_tree_list
> +                              (build_tree_list
> +                               (NULL_TREE, build_string (1, "m")),
> +                               swm));
> +               gasm *force_store = gimple_build_asm_vec ("", inputs, NULL,
> +                                                         NULL, NULL);
> +               gimple_set_location (force_store, gimple_location (wrcall));
> +               gsi_insert_before (&gsi, force_store, GSI_SAME_STMT);
> +             }
> +         }
> +#endif
> +
> +       gcall *sleave = gimple_build_call (get_leave (), 1,
> +                                          unshare_expr (swmp));
> +       gimple_seq_add_stmt (&seq, sleave);
> +
> +       gassign *clobber = gimple_build_assign (swm,
> +                                               build_clobber
> +                                               (TREE_TYPE (swm)));
> +       gimple_seq_add_stmt (&seq, clobber);
> +      }
> +
> +      gsi_insert_finally_seq_after_call (gsi, seq);
> +
> +      /* For nnode, we don't rebuild edges because we wish to retain
> +        any redirections copied to it from earlier passes, so we add
> +        call graph edges explicitly there, but for onode, we create a
> +        fresh function, so we may as well just issue the calls and
> +        then rebuild all cgraph edges.  */
> +      // cgraph_edge::rebuild_edges ();
> +      onode->analyze ();
> +      // inline_analyze_function (onode);
> +
> +      pop_cfun ();
> +    }
> +  }
> +
> +  return 0;
> +}
> +
> +simple_ipa_opt_pass *
> +make_pass_ipa_strub (gcc::context *ctxt)
> +{
> +  return new pass_ipa_strub (ctxt);
> +}
> +
> +#include "gt-ipa-strub.h"
> diff --git a/gcc/ipa-strub.h b/gcc/ipa-strub.h
> new file mode 100644
> index 0000000000000..f367a4a0ef827
> --- /dev/null
> +++ b/gcc/ipa-strub.h
> @@ -0,0 +1,45 @@
> +/* strub (stack scrubbing) infrastructure.
> +   Copyright (C) 2021-2023 Free Software Foundation, Inc.
> +   Contributed by Alexandre Oliva <oliva@adacore.com>.
> +
> +This file is part of GCC.
> +
> +GCC is free software; you can redistribute it and/or modify it under
> +the terms of the GNU General Public License as published by the Free
> +Software Foundation; either version 3, or (at your option) any later
> +version.
> +
> +GCC is distributed in the hope that it will be useful, but WITHOUT ANY
> +WARRANTY; without even the implied warranty of MERCHANTABILITY or
> +FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
> +for more details.
> +
> +You should have received a copy of the GNU General Public License
> +along with GCC; see the file COPYING3.  If not see
> +<http://www.gnu.org/licenses/>.  */
> +
> +/* Return TRUE if CALLEE can be inlined into CALLER, as far as stack scrubbing
> +   constraints are concerned.  CALLEE doesn't have to be called directly by
> +   CALLER, but the returned value says nothing about intervening functions.  */
> +extern bool strub_inlinable_to_p (cgraph_node *callee, cgraph_node *caller);
> +
> +/* Return FALSE if NODE is a strub context, and TRUE otherwise.  */
> +extern bool strub_splittable_p (cgraph_node *node);
> +
> +/* Locate and return the watermark_ptr parameter for FNDECL.  If FNDECL is not a
> +   strub context, return NULL.  */
> +extern tree strub_watermark_parm (tree fndecl);
> +
> +/* Make a function type or declaration callable.  */
> +extern void strub_make_callable (tree fndecl);
> +
> +/* Return zero iff ID is NOT an acceptable parameter for a user-supplied strub
> +   attribute for a function.  Otherwise, return >0 if it enables strub, <0 if it
> +   does not.  Return +/-1 if the attribute-modified type is compatible with the
> +   type without the attribute, or +/-2 if it is not compatible.  */
> +extern int strub_validate_fn_attr_parm (tree id);
> +
> +/* Like comptypes, return 0 if t1 and t2 are not compatible, 1 if they are
> +   compatible, and 2 if they are nearly compatible.  Same strub mode is
> +   compatible, interface-compatible strub modes are nearly compatible.  */
> +extern int strub_comptypes (tree t1, tree t2);
> diff --git a/gcc/passes.def b/gcc/passes.def
> index 1e1950bdb39cb..d515e77be0399 100644
> --- a/gcc/passes.def
> +++ b/gcc/passes.def
> @@ -52,6 +52,7 @@ along with GCC; see the file COPYING3.  If not see
>    INSERT_PASSES_AFTER (all_small_ipa_passes)
>    NEXT_PASS (pass_ipa_free_lang_data);
>    NEXT_PASS (pass_ipa_function_and_variable_visibility);
> +  NEXT_PASS (pass_ipa_strub_mode);
>    NEXT_PASS (pass_build_ssa_passes);
>    PUSH_INSERT_PASSES_WITHIN (pass_build_ssa_passes)
>        NEXT_PASS (pass_fixup_cfg);
> @@ -115,6 +116,7 @@ along with GCC; see the file COPYING3.  If not see
>    POP_INSERT_PASSES ()
>
>    NEXT_PASS (pass_ipa_remove_symbols);
> +  NEXT_PASS (pass_ipa_strub);
>    NEXT_PASS (pass_ipa_oacc);
>    PUSH_INSERT_PASSES_WITHIN (pass_ipa_oacc)
>        NEXT_PASS (pass_ipa_pta);
> diff --git a/gcc/testsuite/c-c++-common/strub-O0.c b/gcc/testsuite/c-c++-common/strub-O0.c
> new file mode 100644
> index 0000000000000..c7a79a6ea0d8a
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-O0.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O0 -fstrub=strict -fdump-rtl-expand" } */
> +
> +/* At -O0, none of the strub builtins are expanded inline.  */
> +
> +int __attribute__ ((__strub__)) var;
> +
> +int f() {
> +  return var;
> +}
> +
> +/* { dg-final { scan-rtl-dump "strub_enter" "expand" } } */
> +/* { dg-final { scan-rtl-dump "strub_update" "expand" } } */
> +/* { dg-final { scan-rtl-dump "strub_leave" "expand" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-O1.c b/gcc/testsuite/c-c++-common/strub-O1.c
> new file mode 100644
> index 0000000000000..96285c975d98e
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-O1.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fstrub=strict -fdump-rtl-expand" } */
> +
> +/* At -O1, without -fno-inline, we fully expand enter, but neither update nor
> +   leave.  */
> +
> +int __attribute__ ((__strub__)) var;
> +
> +int f() {
> +  return var;
> +}
> +
> +/* { dg-final { scan-rtl-dump-not "strub_enter" "expand" } } */
> +/* { dg-final { scan-rtl-dump "strub_update" "expand" } } */
> +/* { dg-final { scan-rtl-dump "strub_leave" "expand" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-O2.c b/gcc/testsuite/c-c++-common/strub-O2.c
> new file mode 100644
> index 0000000000000..8edc0d8aa1321
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-O2.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fstrub=strict -fdump-rtl-expand" } */
> +
> +/* At -O2, without -fno-inline, we fully expand enter and update, and add a test
> +   around the leave call.  */
> +
> +int __attribute__ ((__strub__)) var;
> +
> +int f() {
> +  return var;
> +}
> +
> +/* { dg-final { scan-rtl-dump-not "strub_enter" "expand" } } */
> +/* { dg-final { scan-rtl-dump-not "strub_update" "expand" } } */
> +/* { dg-final { scan-rtl-dump "strub_leave" "expand" } } */
> +/* { dg-final { scan-rtl-dump "\[(\]call\[^\n\]*strub_leave.*\n\[(\]code_label" "expand" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-O2fni.c b/gcc/testsuite/c-c++-common/strub-O2fni.c
> new file mode 100644
> index 0000000000000..c6d900cf3c45b
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-O2fni.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fstrub=strict -fdump-rtl-expand -fno-inline" } */
> +
> +/* With -fno-inline, none of the strub builtins are inlined.  */
> +
> +int __attribute__ ((__strub__)) var;
> +
> +int f() {
> +  return var;
> +}
> +
> +/* { dg-final { scan-rtl-dump "strub_enter" "expand" } } */
> +/* { dg-final { scan-rtl-dump "strub_update" "expand" } } */
> +/* { dg-final { scan-rtl-dump "strub_leave" "expand" } } */
> +/* { dg-final { scan-rtl-dump-not "\[(\]call\[^\n\]*strub_leave.*\n\[(\]code_label" "expand" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-O3.c b/gcc/testsuite/c-c++-common/strub-O3.c
> new file mode 100644
> index 0000000000000..33ee465e51cb6
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-O3.c
> @@ -0,0 +1,12 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -fstrub=strict -fdump-rtl-expand" } */
> +
> +int __attribute__ ((__strub__)) var;
> +
> +int f() {
> +  return var;
> +}
> +
> +/* { dg-final { scan-rtl-dump-not "strub_enter" "expand" } } */
> +/* { dg-final { scan-rtl-dump-not "strub_update" "expand" } } */
> +/* { dg-final { scan-rtl-dump-not "strub_leave" "expand" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-O3fni.c b/gcc/testsuite/c-c++-common/strub-O3fni.c
> new file mode 100644
> index 0000000000000..2936f82079e18
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-O3fni.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -fstrub=strict -fdump-rtl-expand -fno-inline" } */
> +
> +/* With -fno-inline, none of the strub builtins are inlined.  */
> +
> +int __attribute__ ((__strub__)) var;
> +
> +int f() {
> +  return var;
> +}
> +
> +/* { dg-final { scan-rtl-dump "strub_enter" "expand" } } */
> +/* { dg-final { scan-rtl-dump "strub_update" "expand" } } */
> +/* { dg-final { scan-rtl-dump "strub_leave" "expand" } } */
> +/* { dg-final { scan-rtl-dump-not "\[(\]call\[^\n\]*strub_leave.*\n\[(\]code_label" "expand" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-Og.c b/gcc/testsuite/c-c++-common/strub-Og.c
> new file mode 100644
> index 0000000000000..479746e57d87e
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-Og.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-Og -fstrub=strict -fdump-rtl-expand" } */
> +
> +/* At -Og, without -fno-inline, we fully expand enter, but neither update nor
> +   leave.  */
> +
> +int __attribute__ ((__strub__)) var;
> +
> +int f() {
> +  return var;
> +}
> +
> +/* { dg-final { scan-rtl-dump-not "strub_enter" "expand" } } */
> +/* { dg-final { scan-rtl-dump "strub_update" "expand" } } */
> +/* { dg-final { scan-rtl-dump "strub_leave" "expand" } } */
> +/* { dg-final { scan-rtl-dump-not "\[(\]call\[^\n\]*strub_leave.*\n\[(\]code_label" "expand" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-Os.c b/gcc/testsuite/c-c++-common/strub-Os.c
> new file mode 100644
> index 0000000000000..2241d4ea07f27
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-Os.c
> @@ -0,0 +1,18 @@
> +/* { dg-do compile } */
> +/* { dg-options "-Os -fstrub=strict -fdump-rtl-expand" } */
> +
> +/* At -Os, without -fno-inline, we fully expand enter, and also update.  The
> +   expanded update might be larger than a call proper, but argument saving and
> +   restoring required by the call will most often make it larger.  The leave
> +   call is left untouched.  */
> +
> +int __attribute__ ((__strub__)) var;
> +
> +int f() {
> +  return var;
> +}
> +
> +/* { dg-final { scan-rtl-dump-not "strub_enter" "expand" } } */
> +/* { dg-final { scan-rtl-dump-not "strub_update" "expand" } } */
> +/* { dg-final { scan-rtl-dump "strub_leave" "expand" } } */
> +/* { dg-final { scan-rtl-dump-not "\[(\]call\[^\n\]*strub_leave.*\n\[(\]code_label" "expand" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-all1.c b/gcc/testsuite/c-c++-common/strub-all1.c
> new file mode 100644
> index 0000000000000..a322bcc5da606
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-all1.c
> @@ -0,0 +1,32 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=all -fdump-ipa-strubm -fdump-ipa-strub" } */
> +
> +/* h becomes STRUB_CALLABLE, rather than STRUB_INLINABLE, because of the
> +   strub-enabling -fstrub flag, and gets inlined before pass_ipa_strub.  */
> +static inline void
> +__attribute__ ((__always_inline__))
> +h() {
> +}
> +
> +/* g becomes STRUB_AT_CALLS, because of the flag.  */
> +static inline void
> +g() {
> +  h();
> +}
> +
> +/* f becomes STRUB_INTERNAL because of the flag, and gets split into
> +   STRUB_WRAPPER and STRUB_WRAPPED.  */
> +void
> +f() {
> +  g();
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 3 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]callable\[)\]" 1 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]at-calls\[)\]" 1 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]internal\[)\]" 1 "strubm" } } */
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 3 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]at-calls\[)\]" 1 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]wrapped\[)\]" 1 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]wrapper\[)\]" 1 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-all2.c b/gcc/testsuite/c-c++-common/strub-all2.c
> new file mode 100644
> index 0000000000000..db60026d0e080
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-all2.c
> @@ -0,0 +1,24 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=all -fdump-ipa-strubm -fdump-ipa-strub" } */
> +
> +/* g becomes STRUB_INTERNAL, because of the flag.  Without inline, force_output
> +   is set for static non-inline functions when not optimizing, and that keeps
> +   only_called_directly_p from returning true, which makes STRUB_AT_CALLS
> +   non-viable.  */
> +static void
> +g() {
> +}
> +
> +/* f becomes STRUB_INTERNAL because of the flag, and gets split into
> +   STRUB_WRAPPER and STRUB_WRAPPED.  */
> +void
> +f() {
> +  g();
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 2 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]internal\[)\]" 2 "strubm" } } */
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 4 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]wrapped\[)\]" 2 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]wrapper\[)\]" 2 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-apply1.c b/gcc/testsuite/c-c++-common/strub-apply1.c
> new file mode 100644
> index 0000000000000..2f462adc1efe0
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-apply1.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict" } */
> +
> +void __attribute__ ((__strub__ ("callable")))
> +apply_function (void *args)
> +{
> +  __builtin_apply (0, args, 0);
> +}
> +
> +void __attribute__ ((__strub__ ("internal")))
> +apply_args (int i, int j, double d)
> +{
> +  void *args = __builtin_apply_args ();
> +  apply_function (args);
> +}
> diff --git a/gcc/testsuite/c-c++-common/strub-apply2.c b/gcc/testsuite/c-c++-common/strub-apply2.c
> new file mode 100644
> index 0000000000000..a5d7551f5da5c
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-apply2.c
> @@ -0,0 +1,12 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict" } */
> +
> +extern void __attribute__ ((__strub__))
> +apply_function (void *args);
> +
> +void __attribute__ ((__strub__))
> +apply_args (int i, int j, double d) /* { dg-error "selected" } */
> +{
> +  void *args = __builtin_apply_args (); /* { dg-message "does not support" } */
> +  apply_function (args);
> +}
> diff --git a/gcc/testsuite/c-c++-common/strub-apply3.c b/gcc/testsuite/c-c++-common/strub-apply3.c
> new file mode 100644
> index 0000000000000..64422a0d1e880
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-apply3.c
> @@ -0,0 +1,8 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict" } */
> +
> +void __attribute__ ((__strub__))
> +apply_function (void *args)
> +{
> +  __builtin_apply (0, args, 0); /* { dg-error "in .strub. context" } */
> +}
> diff --git a/gcc/testsuite/c-c++-common/strub-apply4.c b/gcc/testsuite/c-c++-common/strub-apply4.c
> new file mode 100644
> index 0000000000000..15ffaa031b899
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-apply4.c
> @@ -0,0 +1,21 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fstrub=strict -fdump-ipa-strubm" } */
> +
> +/* Check that implicit enabling of strub mode selects internal strub when the
> +   function uses __builtin_apply_args, that prevents the optimization to
> +   at-calls mode.  */
> +
> +int __attribute__ ((__strub__)) var;
> +
> +static inline void
> +apply_args (int i, int j, double d)
> +{
> +  var++;
> +  __builtin_apply_args ();
> +}
> +
> +void f() {
> +  apply_args (1, 2, 3);
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]internal\[)\]" 1 "strubm" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-at-calls1.c b/gcc/testsuite/c-c++-common/strub-at-calls1.c
> new file mode 100644
> index 0000000000000..b70843b4215a4
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-at-calls1.c
> @@ -0,0 +1,30 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=at-calls -fdump-ipa-strubm -fdump-ipa-strub" } */
> +
> +/* h becomes STRUB_CALLABLE, rather than STRUB_INLINABLE, because of the
> +   strub-enabling -fstrub flag, and gets inlined before pass_ipa_strub.  */
> +static inline void
> +__attribute__ ((__always_inline__))
> +h() {
> +}
> +
> +/* g becomes STRUB_AT_CALLS, because of the flag.  */
> +static inline void
> +g() {
> +  h();
> +}
> +
> +/* f does NOT become STRUB_AT_CALLS because it is visible; it becomes
> +   STRUB_CALLABLE.  */
> +void
> +f() {
> +  g();
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 3 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]at-calls\[)\]" 1 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]callable\[)\]" 2 "strubm" } } */
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 2 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]at-calls\[)\]" 1 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]callable\[)\]" 1 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-at-calls2.c b/gcc/testsuite/c-c++-common/strub-at-calls2.c
> new file mode 100644
> index 0000000000000..97a3988a6b922
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-at-calls2.c
> @@ -0,0 +1,23 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=at-calls -fdump-ipa-strubm -fdump-ipa-strub" } */
> +
> +/* g does NOT become STRUB_AT_CALLS because it's not viable.  Without inline,
> +   force_output is set for static non-inline functions when not optimizing, and
> +   that keeps only_called_directly_p from returning true, which makes
> +   STRUB_AT_CALLS non-viable.  It becomes STRUB_CALLABLE instead.  */
> +static void
> +g() {
> +}
> +
> +/* f does NOT become STRUB_AT_CALLS because it is visible; it becomes
> +   STRUB_CALLABLE.  */
> +void
> +f() {
> +  g();
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 2 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]callable\[)\]" 2 "strubm" } } */
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 2 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]callable\[)\]" 2 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-defer-O1.c b/gcc/testsuite/c-c++-common/strub-defer-O1.c
> new file mode 100644
> index 0000000000000..3d73431b3dcd3
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-defer-O1.c
> @@ -0,0 +1,7 @@
> +/* { dg-do run } */
> +/* { dg-options "-fstrub=strict -O1" } */
> +
> +/* Check that a strub function called by another strub function does NOT defer
> +   the strubbing to its caller at -O1.  */
> +
> +#include "strub-defer-O2.c"
> diff --git a/gcc/testsuite/c-c++-common/strub-defer-O2.c b/gcc/testsuite/c-c++-common/strub-defer-O2.c
> new file mode 100644
> index 0000000000000..fddf3c745e7e6
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-defer-O2.c
> @@ -0,0 +1,8 @@
> +/* { dg-do run } */
> +/* { dg-options "-fstrub=strict -O2" } */
> +
> +/* Check that a strub function called by another strub function does NOT defer
> +   the strubbing to its caller at -O2.  */
> +
> +#define EXPECT_DEFERRAL !
> +#include "strub-defer-O3.c"
> diff --git a/gcc/testsuite/c-c++-common/strub-defer-O3.c b/gcc/testsuite/c-c++-common/strub-defer-O3.c
> new file mode 100644
> index 0000000000000..7ebc65b58dd72
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-defer-O3.c
> @@ -0,0 +1,110 @@
> +/* { dg-do run } */
> +/* { dg-options "-fstrub=strict -O3" } */
> +
> +/* Check that a strub function called by another strub function defers the
> +   strubbing to its caller at -O3.  */
> +
> +#ifndef EXPECT_DEFERRAL
> +/* Other strub-defer*.c tests override this macro.  */
> +# define EXPECT_DEFERRAL
> +#endif
> +
> +const char test_string[] = "\x55\xde\xad\xbe\xef\xc0\x1d\xca\xfe\x55\xaa";
> +
> +/* Pad before and after the string on the stack, so that it's not overwritten by
> +   regular stack use.  */
> +#define PAD 7
> +
> +static inline __attribute__ ((__always_inline__, __strub__ ("callable")))
> +char *
> +leak_string (void)
> +{
> +  /* We use this variable to avoid any stack red zone.  Stack scrubbing covers
> +     it, but __builtin_stack_address, that we take as a reference, doesn't, so
> +     if e.g. callable() were to store the string in the red zone, we wouldn't
> +     find it because it would be outside the range we searched.  */
> +  typedef void __attribute__ ((__strub__ ("callable"))) callable_t (char *);
> +  callable_t *f = 0;
> +
> +  char s[2 * PAD + 1][sizeof (test_string)];
> +  __builtin_strcpy (s[PAD], test_string);
> +  asm ("" : "+m" (s), "+r" (f));
> +
> +  if (__builtin_expect (!f, 1))
> +    return (char*)__builtin_stack_address ();
> +
> +  f (s[PAD]);
> +  return 0;
> +}
> +
> +static inline __attribute__ ((__always_inline__, __strub__ ("callable")))
> +int
> +look_for_string (char *e)
> +{
> +  char *p = (char*)__builtin_stack_address ();
> +
> +  if (p == e)
> +    __builtin_abort ();
> +
> +  if (p > e)
> +    {
> +      char *q = p;
> +      p = e;
> +      e = q;
> +    }
> +
> +  for (char *re = e - sizeof (test_string); p < re; p++)
> +    for (int i = 0; p[i] == test_string[i]; i++)
> +      if (i == sizeof (test_string) - 1)
> +       return i;
> +
> +  return 0;
> +}
> +
> +static __attribute__ ((__strub__ ("at-calls"), __noinline__, __noclone__))
> +char *
> +at_calls ()
> +{
> +  return leak_string ();
> +}
> +
> +static __attribute__ ((__strub__ ("at-calls")))
> +char *
> +deferred_at_calls ()
> +{
> +  char *ret;
> +  int i = 1;
> +  /* Since these test check stack contents above the top of the stack, an
> +     unexpected asynchronous signal or interrupt might overwrite the bits we
> +     expect to find and cause spurious fails.  Tolerate one such overall
> +     spurious fail by retrying.  */
> +  while (EXPECT_DEFERRAL !look_for_string ((ret = at_calls ())))
> +    if (!i--) __builtin_abort ();
> +  return ret;
> +}
> +
> +static __attribute__ ((__strub__ ("internal")))
> +char *
> +deferred_internal ()
> +{
> +  int i = 1;
> +  char *ret;
> +  while (EXPECT_DEFERRAL !look_for_string ((ret = at_calls ())))
> +    if (!i--) __builtin_abort ();
> +  return ret;
> +}
> +
> +int main ()
> +{
> +  int i = 1;
> +  /* These calls should not be subject to spurious fails: whether or not some
> +     asynchronous event overwrites the scrubbed stack space, the string won't
> +     remain there.  Unless the asynchronous event happens to write the string
> +     where we look for it, but what are the odds?  Anyway, it doesn't hurt to
> +     retry, even if just for symmetry.  */
> +  while (look_for_string (deferred_at_calls ()))
> +    if (!i--) __builtin_abort ();
> +  while (look_for_string (deferred_internal ()))
> +    if (!i--) __builtin_abort ();
> +  __builtin_exit (0);
> +}
> diff --git a/gcc/testsuite/c-c++-common/strub-defer-Os.c b/gcc/testsuite/c-c++-common/strub-defer-Os.c
> new file mode 100644
> index 0000000000000..fbaf85fe0fafe
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-defer-Os.c
> @@ -0,0 +1,7 @@
> +/* { dg-do run } */
> +/* { dg-options "-fstrub=strict -Os" } */
> +
> +/* Check that a strub function called by another strub function defers the
> +   strubbing to its caller at -Os.  */
> +
> +#include "strub-defer-O3.c"
> diff --git a/gcc/testsuite/c-c++-common/strub-internal1.c b/gcc/testsuite/c-c++-common/strub-internal1.c
> new file mode 100644
> index 0000000000000..e9d7b7b9ee0a8
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-internal1.c
> @@ -0,0 +1,31 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=internal -fdump-ipa-strubm -fdump-ipa-strub" } */
> +
> +/* h becomes STRUB_CALLABLE, rather than STRUB_INLINABLE, because of the
> +   strub-enabling -fstrub flag, and gets inlined before pass_ipa_strub.  */
> +static inline void
> +__attribute__ ((__always_inline__))
> +h() {
> +}
> +
> +/* g becomes STRUB_INTERNAL because of the flag, and gets split into
> +   STRUB_WRAPPER and STRUB_WRAPPED.  */
> +static inline void
> +g() {
> +  h();
> +}
> +
> +/* f becomes STRUB_INTERNAL because of the flag, and gets split into
> +   STRUB_WRAPPER and STRUB_WRAPPED.  */
> +void
> +f() {
> +  g();
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 3 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]callable\[)\]" 1 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]internal\[)\]" 2 "strubm" } } */
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 4 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]wrapped\[)\]" 2 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]wrapper\[)\]" 2 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-internal2.c b/gcc/testsuite/c-c++-common/strub-internal2.c
> new file mode 100644
> index 0000000000000..8b8e15a51c71c
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-internal2.c
> @@ -0,0 +1,21 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=internal -fdump-ipa-strubm -fdump-ipa-strub" } */
> +
> +/* g becomes STRUB_INTERNAL, because of the flag.  */
> +static void
> +g() {
> +}
> +
> +/* f becomes STRUB_INTERNAL because of the flag, and gets split into
> +   STRUB_WRAPPER and STRUB_WRAPPED.  */
> +void
> +f() {
> +  g();
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 2 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]internal\[)\]" 2 "strubm" } } */
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 4 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]wrapped\[)\]" 2 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]wrapper\[)\]" 2 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-parms1.c b/gcc/testsuite/c-c++-common/strub-parms1.c
> new file mode 100644
> index 0000000000000..0a4a7539d3489
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-parms1.c
> @@ -0,0 +1,48 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +#include <stdarg.h>
> +
> +void __attribute__ ((__strub__ ("internal")))
> +small_args (int i, long long l, void *p, void **q, double d, char c)
> +{
> +}
> +
> +/* { dg-final { scan-ipa-dump "\n(void )?\[^ \]*small_args\[^ \]*.strub.\[0-9\]* \[(\]int i, long long int l, void \\* p, void \\* \\* q, double d, char c, void \\* &\[^&,\]*.strub.watermark_ptr\[)\]" "strub" } } */
> +/* { dg-final { scan-ipa-dump " \[^ \]*small_args\[^ \]*.strub.\[0-9\]* \[(\]\[^&\]*&.strub.watermark.\[0-9\]*\[)\]" "strub" } } */
> +
> +
> +struct large_arg {
> +  int x[128];
> +};
> +
> +void __attribute__ ((__strub__ ("internal")))
> +large_byref_arg (struct large_arg la)
> +{
> +}
> +
> +/* { dg-final { scan-ipa-dump "\n(void )?\[^ \]*large_byref_arg\[^ \]*.strub.\[0-9\]* \[(\]struct large_arg & la, void \\* &\[^&,\]*.strub.watermark_ptr\[)\]" "strub" } } */
> +/* { dg-final { scan-ipa-dump " \[^ \]*large_byref_arg\[^ \]*.strub.\[0-9\]* \[(\]&\[^&\]*&.strub.watermark.\[0-9\]*\[)\]" "strub" } } */
> +
> +void __attribute__ ((__strub__ ("internal")))
> +std_arg (int i, ...)
> +{
> +  va_list vl;
> +  va_start (vl, i);
> +  va_end (vl);
> +}
> +
> +/* { dg-final { scan-ipa-dump "\n(void )?\[^ \]*std_arg\[^ \]*.strub.\[0-9\]* \[(\]int i, \[^&,\]* &\[^&,\]*.strub.va_list_ptr, void \\* &\[^&,\]*.strub.watermark_ptr\[)\]" "strub" } } */
> +/* { dg-final { scan-ipa-dump " \[^ \]*std_arg\[^ \]*.strub.\[0-9\]* \[(\]\[^&\]*&.strub.va_list.\[0-9\]*, &.strub.watermark.\[0-9\]*\[)\]" "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "va_start \\(" 1 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "va_copy \\(" 1 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "va_end \\(" 2 "strub" } } */
> +
> +void __attribute__ ((__strub__ ("internal")))
> +apply_args (int i, int j, double d)
> +{
> +  __builtin_apply_args ();
> +}
> +
> +/* { dg-final { scan-ipa-dump "\n(void )?\[^ \]*apply_args\[^ \]*.strub.\[0-9\]* \[(\]int i, int j, double d, void \\*\[^&,\]*.strub.apply_args, void \\* &\[^&,\]*.strub.watermark_ptr\[)\]" "strub" } } */
> +/* { dg-final { scan-ipa-dump " \[^ \]*apply_args\[^ \]*.strub.\[0-9\]* \[(\]\[^&\]*.strub.apply_args.\[0-9\]*_\[0-9\]*, &.strub.watermark.\[0-9\]*\[)\]" "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-parms2.c b/gcc/testsuite/c-c++-common/strub-parms2.c
> new file mode 100644
> index 0000000000000..147171d96d5a1
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-parms2.c
> @@ -0,0 +1,36 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +#include <stdarg.h>
> +
> +void __attribute__ ((__strub__ ("at-calls")))
> +small_args (int i, long long l, void *p, void **q, double d, char c)
> +{
> +}
> +
> +/* { dg-final { scan-ipa-dump "\n(void )?\[^ \]*small_args\[^ \]* \[(\]int i, long long int l, void \\* p, void \\* \\* q, double d, char c, void \\* &\[^&,\]*.strub.watermark_ptr\[)\]" "strub" } } */
> +
> +
> +struct large_arg {
> +  int x[128];
> +};
> +
> +void __attribute__ ((__strub__ ("at-calls")))
> +large_byref_arg (struct large_arg la)
> +{
> +}
> +
> +/* { dg-final { scan-ipa-dump "\n(void )?\[^ \]*large_byref_arg\[^ \]* \[(\]struct large_arg la, void \\* &\[^&,\]*.strub.watermark_ptr\[)\]" "strub" } } */
> +
> +void __attribute__ ((__strub__ ("at-calls")))
> +std_arg (int i, ...)
> +{
> +  va_list vl;
> +  va_start (vl, i);
> +  va_end (vl);
> +}
> +
> +/* { dg-final { scan-ipa-dump "\n(void )?\[^ \]*std_arg\[^ \]* \[(\]int i, void \\* &\[^&,\]*.strub.watermark_ptr\[, .]*\[)\]" "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "va_start \\(" 1 "strub" } } */
> +/* { dg-final { scan-ipa-dump-not "va_copy \\(" "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "va_end \\(" 1 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-parms3.c b/gcc/testsuite/c-c++-common/strub-parms3.c
> new file mode 100644
> index 0000000000000..4e92682895a43
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-parms3.c
> @@ -0,0 +1,58 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* Check that uses of a strub variable implicitly enables internal strub for
> +   publicly-visible functions, and causes the same transformations to their
> +   signatures as those in strub-parms1.c.  */
> +
> +#include <stdarg.h>
> +
> +int __attribute__ ((__strub__)) var;
> +
> +void
> +small_args (int i, long long l, void *p, void **q, double d, char c)
> +{
> +  var++;
> +}
> +
> +/* { dg-final { scan-ipa-dump "\n(void )?\[^ \]*small_args\[^ \]*.strub.\[0-9\]* \[(\]int i, long long int l, void \\* p, void \\* \\* q, double d, char c, void \\* &\[^&,\]*.strub.watermark_ptr\[)\]" "strub" } } */
> +/* { dg-final { scan-ipa-dump " \[^ \]*small_args\[^ \]*.strub.\[0-9\]* \[(\]\[^&\]*&.strub.watermark.\[0-9\]*\[)\]" "strub" } } */
> +
> +
> +struct large_arg {
> +  int x[128];
> +};
> +
> +void
> +large_byref_arg (struct large_arg la)
> +{
> +  var++;
> +}
> +
> +/* { dg-final { scan-ipa-dump "\n(void )?\[^ \]*large_byref_arg\[^ \]*.strub.\[0-9\]* \[(\]struct large_arg & la, void \\* &\[^&,\]*.strub.watermark_ptr\[)\]" "strub" } } */
> +/* { dg-final { scan-ipa-dump " \[^ \]*large_byref_arg\[^ \]*.strub.\[0-9\]* \[(\]&\[^&\]*&.strub.watermark.\[0-9\]*\[)\]" "strub" } } */
> +
> +void
> +std_arg (int i, ...)
> +{
> +  va_list vl;
> +  va_start (vl, i);
> +  var++;
> +  va_end (vl);
> +}
> +
> +/* { dg-final { scan-ipa-dump "\n(void )?\[^ \]*std_arg\[^ \]*.strub.\[0-9\]* \[(\]int i, \[^&,\]* &\[^&,\]*.strub.va_list_ptr, void \\* &\[^&,\]*.strub.watermark_ptr\[)\]" "strub" } } */
> +/* { dg-final { scan-ipa-dump " \[^ \]*std_arg\[^ \]*.strub.\[0-9\]* \[(\]\[^&\]*&.strub.va_list.\[0-9\]*, &.strub.watermark.\[0-9\]*\[)\]" "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "va_start \\(" 1 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "va_copy \\(" 1 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "va_end \\(" 2 "strub" } } */
> +
> +void
> +apply_args (int i, int j, double d)
> +{
> +  var++;
> +  __builtin_apply_args ();
> +}
> +
> +/* { dg-final { scan-ipa-dump "\n(void )?\[^ \]*apply_args\[^ \]*.strub.\[0-9\]* \[(\]int i, int j, double d, void \\*\[^&,\]*.strub.apply_args, void \\* &\[^&,\]*.strub.watermark_ptr\[)\]" "strub" } } */
> +/* { dg-final { scan-ipa-dump " \[^ \]*apply_args\[^ \]*.strub.\[0-9\]* \[(\]\[^&\]*.strub.apply_args.\[0-9\]*_\[0-9\]*, &.strub.watermark.\[0-9\]*\[)\]" "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-relaxed1.c b/gcc/testsuite/c-c++-common/strub-relaxed1.c
> new file mode 100644
> index 0000000000000..e2f9d8aebca58
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-relaxed1.c
> @@ -0,0 +1,18 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=relaxed -fdump-ipa-strubm -fdump-ipa-strub" } */
> +
> +/* The difference between relaxed and strict in this case is that we accept the
> +   call from one internal-strub function to another.  Without the error,
> +   inlining takes place.  */
> +
> +#include "strub-strict1.c"
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 3 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]inlinable\[)\]" 1 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]at-calls-opt\[)\]" 1 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]internal\[)\]" 1 "strubm" } } */
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 3 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]at-calls-opt\[)\]" 1 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]wrapped\[)\]" 1 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]wrapper\[)\]" 1 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-relaxed2.c b/gcc/testsuite/c-c++-common/strub-relaxed2.c
> new file mode 100644
> index 0000000000000..98474435d2e59
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-relaxed2.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=relaxed -fdump-ipa-strubm -fdump-ipa-strub" } */
> +
> +/* The difference between relaxed and strict in this case is that we accept the
> +   call from one internal-strub function to another.  */
> +
> +#include "strub-strict2.c"
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 2 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]internal\[)\]" 2 "strubm" } } */
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 4 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]wrapped\[)\]" 2 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]wrapper\[)\]" 2 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-short-O0-exc.c b/gcc/testsuite/c-c++-common/strub-short-O0-exc.c
> new file mode 100644
> index 0000000000000..1de15342595e4
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-short-O0-exc.c
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O0 -fstrub=strict -fexceptions -fdump-ipa-strub" } */
> +
> +/* Check that the expected strub calls are issued.  */
> +
> +#include "torture/strub-callable1.c"
> +
> +/* { dg-final { scan-ipa-dump-times "strub_enter" 45 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_update" 4 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_leave" 89 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-short-O0.c b/gcc/testsuite/c-c++-common/strub-short-O0.c
> new file mode 100644
> index 0000000000000..f9209c819004b
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-short-O0.c
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O0 -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
> +
> +/* Check that the expected strub calls are issued.  */
> +
> +#include "torture/strub-callable1.c"
> +
> +/* { dg-final { scan-ipa-dump-times "strub_enter" 45 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_update" 4 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_leave" 45 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-short-O1.c b/gcc/testsuite/c-c++-common/strub-short-O1.c
> new file mode 100644
> index 0000000000000..bed1dcfb54a45
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-short-O1.c
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
> +
> +/* Check that the expected strub calls are issued.  */
> +
> +#include "torture/strub-callable1.c"
> +
> +/* { dg-final { scan-ipa-dump-times "strub_enter" 45 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_update" 4 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_leave" 45 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-short-O2.c b/gcc/testsuite/c-c++-common/strub-short-O2.c
> new file mode 100644
> index 0000000000000..6bf0071f52b93
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-short-O2.c
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
> +
> +/* Check that the expected strub calls are issued.  */
> +
> +#include "torture/strub-callable1.c"
> +
> +/* { dg-final { scan-ipa-dump-times "strub_enter" 45 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_update" 4 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_leave" 45 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-short-O3.c b/gcc/testsuite/c-c++-common/strub-short-O3.c
> new file mode 100644
> index 0000000000000..4732f515bf70c
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-short-O3.c
> @@ -0,0 +1,12 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
> +
> +/* Check that the expected strub calls are issued.  At -O3 and -Os, we omit
> +   enter and leave calls within strub contexts, passing on the enclosing
> +   watermark.  */
> +
> +#include "torture/strub-callable1.c"
> +
> +/* { dg-final { scan-ipa-dump-times "strub_enter" 15 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_update" 4 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_leave" 15 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-short-Os.c b/gcc/testsuite/c-c++-common/strub-short-Os.c
> new file mode 100644
> index 0000000000000..8d6424c479a3a
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-short-Os.c
> @@ -0,0 +1,12 @@
> +/* { dg-do compile } */
> +/* { dg-options "-Os -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
> +
> +/* Check that the expected strub calls are issued.  At -O3 and -Os, we omit
> +   enter and leave calls within strub contexts, passing on the enclosing
> +   watermark.  */
> +
> +#include "torture/strub-callable1.c"
> +
> +/* { dg-final { scan-ipa-dump-times "strub_enter" 15 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_update" 4 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_leave" 15 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-strict1.c b/gcc/testsuite/c-c++-common/strub-strict1.c
> new file mode 100644
> index 0000000000000..368522442066e
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-strict1.c
> @@ -0,0 +1,36 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strubm" } */
> +
> +static int __attribute__ ((__strub__)) var;
> +
> +/* h becomes STRUB_INLINABLE, because of the use of the strub variable,
> +   and the always_inline flag.  It would get inlined before pass_ipa_strub, if
> +   it weren't for the error.  */
> +static inline void
> +__attribute__ ((__always_inline__))
> +h() {
> +  var++;
> +}
> +
> +/* g becomes STRUB_AT_CALLS_OPT, because of the use of the strub variable, and
> +   the viability of at-calls strubbing.  Though internally a strub context, its
> +   interface is not strub-enabled, so it's not callable from within strub
> +   contexts.  */
> +static inline void
> +g() {
> +  var--;
> +  h();
> +}
> +
> +/* f becomes STRUB_INTERNAL because of the use of the strub variable, and gets
> +   split into STRUB_WRAPPER and STRUB_WRAPPED.  */
> +void
> +f() {
> +  var++;
> +  g();  /* { dg-error "calling non-.strub." } */
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 3 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]inlinable\[)\]" 1 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]at-calls-opt\[)\]" 1 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]internal\[)\]" 1 "strubm" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-strict2.c b/gcc/testsuite/c-c++-common/strub-strict2.c
> new file mode 100644
> index 0000000000000..b4f2888321821
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-strict2.c
> @@ -0,0 +1,25 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strubm" } */
> +
> +static int __attribute__ ((__strub__)) var;
> +
> +/* g becomes STRUB_INTERNAL because of the use of the strub variable, and gets
> +   split into STRUB_WRAPPER and STRUB_WRAPPED.  It's not STRUB_AT_CALLS_OPT
> +   because force_output is set for static non-inline functions when not
> +   optimizing, and that keeps only_called_directly_p from returning true, which
> +   makes STRUB_AT_CALLS[_OPT] non-viable.  */
> +static void
> +g() {
> +  var--;
> +}
> +
> +/* f becomes STRUB_INTERNAL because of the use of the strub variable, and gets
> +   split into STRUB_WRAPPER and STRUB_WRAPPED.  */
> +void
> +f() {
> +  var++;
> +  g();  /* { dg-error "calling non-.strub." } */
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]" 2 "strubm" } } */
> +/* { dg-final { scan-ipa-dump-times "strub \[(\]internal\[)\]" 2 "strubm" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-tail-O1.c b/gcc/testsuite/c-c++-common/strub-tail-O1.c
> new file mode 100644
> index 0000000000000..e48e0610e079b
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-tail-O1.c
> @@ -0,0 +1,8 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
> +
> +#include "strub-tail-O2.c"
> +
> +/* { dg-final { scan-ipa-dump-times "strub_enter" 2 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_update" 2 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_leave" 2 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-tail-O2.c b/gcc/testsuite/c-c++-common/strub-tail-O2.c
> new file mode 100644
> index 0000000000000..87cda7ab21b16
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-tail-O2.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
> +
> +/* Check that the expected strub calls are issued.
> +   Tail calls are short-circuited at -O2+.  */
> +
> +int __attribute__ ((__strub__))
> +g (int i, int j) {
> +  return g (i, j);
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "strub_enter" 0 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_update" 2 "strub" } } */
> +/* { dg-final { scan-ipa-dump-times "strub_leave" 0 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/strub-var1.c b/gcc/testsuite/c-c++-common/strub-var1.c
> new file mode 100644
> index 0000000000000..eb6250fd39c90
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/strub-var1.c
> @@ -0,0 +1,24 @@
> +/* { dg-do compile } */
> +
> +int __attribute__ ((strub)) x;
> +float __attribute__ ((strub)) f;
> +double __attribute__ ((strub)) d;
> +
> +/* The attribute applies to the type of the declaration, i.e., to the pointer
> +   variable p, not to the pointed-to integer.  */
> +int __attribute__ ((strub)) *
> +p = &x; /* { dg-message "incompatible|invalid conversion" } */
> +
> +typedef int __attribute__ ((strub)) strub_int;
> +strub_int *q = &x; /* Now this is compatible.  */
> +
> +int __attribute__ ((strub))
> +a[2]; /* { dg-warning "does not apply to elements" } */
> +
> +int __attribute__ ((vector_size (4 * sizeof (int))))
> +    __attribute__ ((strub))
> +v; /* { dg-warning "does not apply to elements" } */
> +
> +struct s {
> +  int i, j;
> +} __attribute__ ((strub)) w; /* { dg-warning "does not apply to fields" } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-callable1.c b/gcc/testsuite/c-c++-common/torture/strub-callable1.c
> new file mode 100644
> index 0000000000000..b5e45ab0525ad
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-callable1.c
> @@ -0,0 +1,9 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict" } */
> +
> +/* Check that strub and non-strub functions can be called from non-strub
> +   contexts, and that strub and callable functions can be called from strub
> +   contexts.  */
> +
> +#define OMIT_IMPERMISSIBLE_CALLS 1
> +#include "strub-callable2.c"
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-callable2.c b/gcc/testsuite/c-c++-common/torture/strub-callable2.c
> new file mode 100644
> index 0000000000000..96aa7fe4b07f7
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-callable2.c
> @@ -0,0 +1,264 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict" } */
> +
> +/* Check that impermissible (cross-strub-context) calls are reported.  */
> +
> +extern int __attribute__ ((__strub__ ("callable"))) xcallable (void);
> +extern int __attribute__ ((__strub__ ("internal"))) xinternal (void);
> +extern int __attribute__ ((__strub__ ("at-calls"))) xat_calls (void);
> +extern int __attribute__ ((__strub__ ("disabled"))) xdisabled (void);
> +
> +int __attribute__ ((__strub__ ("callable"))) callable (void);
> +int __attribute__ ((__strub__ ("internal"))) internal (void);
> +int __attribute__ ((__strub__ ("at-calls"))) at_calls (void);
> +int __attribute__ ((__strub__ ("disabled"))) disabled (void);
> +
> +int __attribute__ ((__strub__)) var;
> +int var_user (void);
> +
> +static inline int __attribute__ ((__always_inline__, __strub__ ("callable")))
> +icallable (void);
> +static inline int __attribute__ ((__always_inline__, __strub__ ("internal")))
> +iinternal (void);
> +static inline int __attribute__ ((__always_inline__, __strub__ ("at-calls")))
> +iat_calls (void);
> +static inline int __attribute__ ((__always_inline__, __strub__ ("disabled")))
> +idisabled (void);
> +static inline int __attribute__ ((__always_inline__))
> +ivar_user (void);
> +
> +static inline int __attribute__ ((__always_inline__, __strub__ ("callable")))
> +i_callable (void) { return 0; }
> +static inline int __attribute__ ((__always_inline__, __strub__ ("internal")))
> +i_internal (void) { return var; }
> +static inline int __attribute__ ((__always_inline__, __strub__ ("at-calls")))
> +i_at_calls (void) { return var; }
> +static inline int __attribute__ ((__always_inline__, __strub__ ("disabled")))
> +i_disabled (void) { return 0; }
> +static inline int __attribute__ ((__always_inline__))
> +i_var_user (void) { return var; }
> +
> +#define CALLS_GOOD_FOR_STRUB_CONTEXT(ISEP)     \
> +  do {                                         \
> +    ret += i ## ISEP ## at_calls ();           \
> +    ret += i ## ISEP ## internal ();           \
> +    ret += i ## ISEP ## var_user ();           \
> +  } while (0)
> +
> +#define CALLS_GOOD_FOR_NONSTRUB_CONTEXT(ISEP)  \
> +  do {                                         \
> +    ret += internal ();                                \
> +    ret += disabled ();                                \
> +    ret += var_user ();                                \
> +                                               \
> +    ret += i ## ISEP ## disabled ();           \
> +                                               \
> +    ret += xinternal ();                       \
> +    ret += xdisabled ();                       \
> +  } while (0)
> +
> +#define CALLS_GOOD_FOR_EITHER_CONTEXT(ISEP)    \
> +  do {                                         \
> +    ret += i ## ISEP ## callable ();           \
> +                                               \
> +    ret += callable ();                                \
> +    ret += at_calls ();                                \
> +                                               \
> +    ret += xat_calls ();                       \
> +    ret += xcallable ();                       \
> +  } while (0)
> +
> +/* Not a strub context, so it can call anything.
> +   Explicitly declared as callable even from within strub contexts.  */
> +int __attribute__ ((__strub__ ("callable")))
> +callable (void) {
> +  int ret = 0;
> +
> +  /* CALLS_GOOD_FOR_STRUB_CONTEXT(); */
> +#if !OMIT_IMPERMISSIBLE_CALLS
> +    ret += iat_calls (); /* { dg-error "in non-.strub. context" } */
> +    ret += iinternal (); /* { dg-error "in non-.strub. context" } */
> +    ret += ivar_user (); /* { dg-error "in non-.strub. context" } */
> +#endif
> +  CALLS_GOOD_FOR_EITHER_CONTEXT();
> +  CALLS_GOOD_FOR_NONSTRUB_CONTEXT();
> +
> +  return ret;
> +}
> +
> +/* Internal strubbing means the body is a strub context, so it can only call
> +   strub functions, and it's not itself callable from strub functions.  */
> +int __attribute__ ((__strub__ ("internal")))
> +internal (void) {
> +  int ret = var;
> +
> +  CALLS_GOOD_FOR_STRUB_CONTEXT();
> +  CALLS_GOOD_FOR_EITHER_CONTEXT();
> +  /* CALLS_GOOD_FOR_NONSTRUB_CONTEXT(); */
> +#if !OMIT_IMPERMISSIBLE_CALLS
> +    ret += internal (); /* { dg-error "in .strub. context" } */
> +    ret += disabled (); /* { dg-error "in .strub. context" } */
> +    ret += var_user (); /* { dg-error "in .strub. context" } */
> +
> +    ret += idisabled (); /* { dg-error "in .strub. context" } */
> +
> +    ret += xinternal (); /* { dg-error "in .strub. context" } */
> +    ret += xdisabled (); /* { dg-error "in .strub. context" } */
> +#endif
> +
> +  return ret;
> +}
> +
> +int __attribute__ ((__strub__ ("at-calls")))
> +at_calls (void) {
> +  int ret = var;
> +
> +  CALLS_GOOD_FOR_STRUB_CONTEXT();
> +  CALLS_GOOD_FOR_EITHER_CONTEXT();
> +  /* CALLS_GOOD_FOR_NONSTRUB_CONTEXT(); */
> +#if !OMIT_IMPERMISSIBLE_CALLS
> +    ret += internal (); /* { dg-error "in .strub. context" } */
> +    ret += disabled (); /* { dg-error "in .strub. context" } */
> +    ret += var_user (); /* { dg-error "in .strub. context" } */
> +
> +    ret += idisabled (); /* { dg-error "in .strub. context" } */
> +
> +    ret += xinternal (); /* { dg-error "in .strub. context" } */
> +    ret += xdisabled (); /* { dg-error "in .strub. context" } */
> +#endif
> +
> +  return ret;
> +}
> +
> +int __attribute__ ((__strub__ ("disabled")))
> +disabled () {
> +  int ret = 0;
> +
> +  /* CALLS_GOOD_FOR_STRUB_CONTEXT(); */
> +#if !OMIT_IMPERMISSIBLE_CALLS
> +    ret += iat_calls (); /* { dg-error "in non-.strub. context" } */
> +    ret += iinternal (); /* { dg-error "in non-.strub. context" } */
> +    ret += ivar_user (); /* { dg-error "in non-.strub. context" } */
> +#endif
> +  CALLS_GOOD_FOR_EITHER_CONTEXT();
> +  CALLS_GOOD_FOR_NONSTRUB_CONTEXT();
> +
> +  return ret;
> +}
> +
> +int
> +var_user (void) {
> +  int ret = var;
> +
> +  CALLS_GOOD_FOR_STRUB_CONTEXT();
> +  CALLS_GOOD_FOR_EITHER_CONTEXT();
> +  /* CALLS_GOOD_FOR_NONSTRUB_CONTEXT(); */
> +#if !OMIT_IMPERMISSIBLE_CALLS
> +    ret += internal (); /* { dg-error "in .strub. context" } */
> +    ret += disabled (); /* { dg-error "in .strub. context" } */
> +    ret += var_user (); /* { dg-error "in .strub. context" } */
> +
> +    ret += idisabled (); /* { dg-error "in .strub. context" } */
> +
> +    ret += xinternal (); /* { dg-error "in .strub. context" } */
> +    ret += xdisabled (); /* { dg-error "in .strub. context" } */
> +#endif
> +
> +  return ret;
> +}
> +
> +int
> +icallable (void)
> +{
> +  int ret = 0;
> +
> +  /* CALLS_GOOD_FOR_STRUB_CONTEXT(_); */
> +#if !OMIT_IMPERMISSIBLE_CALLS
> +    ret += i_at_calls (); /* { dg-error "in non-.strub. context" } */
> +    ret += i_internal (); /* { dg-error "in non-.strub. context" } */
> +    ret += i_var_user (); /* { dg-error "in non-.strub. context" } */
> +#endif
> +  CALLS_GOOD_FOR_EITHER_CONTEXT(_);
> +  CALLS_GOOD_FOR_NONSTRUB_CONTEXT(_);
> +
> +  return ret;
> +}
> +
> +int
> +iinternal (void) {
> +  int ret = var;
> +
> +  CALLS_GOOD_FOR_STRUB_CONTEXT(_);
> +  CALLS_GOOD_FOR_EITHER_CONTEXT(_);
> +  /* CALLS_GOOD_FOR_NONSTRUB_CONTEXT(_); */
> +#if !OMIT_IMPERMISSIBLE_CALLS
> +    ret += internal (); /* { dg-error "in .strub. context" } */
> +    ret += disabled (); /* { dg-error "in .strub. context" } */
> +    ret += var_user (); /* { dg-error "in .strub. context" } */
> +
> +    ret += i_disabled (); /* { dg-error "in .strub. context" } */
> +
> +    ret += xinternal (); /* { dg-error "in .strub. context" } */
> +    ret += xdisabled (); /* { dg-error "in .strub. context" } */
> +#endif
> +
> +  return ret;
> +}
> +
> +int __attribute__ ((__always_inline__, __strub__ ("at-calls")))
> +iat_calls (void) {
> +  int ret = var;
> +
> +  CALLS_GOOD_FOR_STRUB_CONTEXT(_);
> +  CALLS_GOOD_FOR_EITHER_CONTEXT(_);
> +  /* CALLS_GOOD_FOR_NONSTRUB_CONTEXT(_); */
> +#if !OMIT_IMPERMISSIBLE_CALLS
> +    ret += internal (); /* { dg-error "in .strub. context" } */
> +    ret += disabled (); /* { dg-error "in .strub. context" } */
> +    ret += var_user (); /* { dg-error "in .strub. context" } */
> +
> +    ret += i_disabled (); /* { dg-error "in .strub. context" } */
> +
> +    ret += xinternal (); /* { dg-error "in .strub. context" } */
> +    ret += xdisabled (); /* { dg-error "in .strub. context" } */
> +#endif
> +
> +  return ret;
> +}
> +
> +int
> +idisabled () {
> +  int ret = 0;
> +
> +  /* CALLS_GOOD_FOR_STRUB_CONTEXT(_); */
> +#if !OMIT_IMPERMISSIBLE_CALLS
> +    ret += i_at_calls (); /* { dg-error "in non-.strub. context" } */
> +    ret += i_internal (); /* { dg-error "in non-.strub. context" } */
> +    ret += i_var_user (); /* { dg-error "in non-.strub. context" } */
> +#endif
> +  CALLS_GOOD_FOR_EITHER_CONTEXT(_);
> +  CALLS_GOOD_FOR_NONSTRUB_CONTEXT(_);
> +
> +  return ret;
> +}
> +
> +int
> +ivar_user (void) {
> +  int ret = var;
> +
> +  CALLS_GOOD_FOR_STRUB_CONTEXT(_);
> +  CALLS_GOOD_FOR_EITHER_CONTEXT(_);
> +  /* CALLS_GOOD_FOR_NONSTRUB_CONTEXT(_); */
> +#if !OMIT_IMPERMISSIBLE_CALLS
> +    ret += internal (); /* { dg-error "in .strub. context" } */
> +    ret += disabled (); /* { dg-error "in .strub. context" } */
> +    ret += var_user (); /* { dg-error "in .strub. context" } */
> +
> +    ret += i_disabled (); /* { dg-error "in .strub. context" } */
> +
> +    ret += xinternal (); /* { dg-error "in .strub. context" } */
> +    ret += xdisabled (); /* { dg-error "in .strub. context" } */
> +#endif
> +
> +  return ret;
> +}
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-const1.c b/gcc/testsuite/c-c++-common/torture/strub-const1.c
> new file mode 100644
> index 0000000000000..2857195706ed6
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-const1.c
> @@ -0,0 +1,18 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* Check that, along with a strub const function call, we issue an asm statement
> +   to make sure the watermark passed to it is held in memory before the call,
> +   and another to make sure it is not assumed to be unchanged.  */
> +
> +int __attribute__ ((__strub__, __const__))
> +f() {
> +  return 0;
> +}
> +
> +int
> +g() {
> +  return f();
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "__asm__" 2 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-const2.c b/gcc/testsuite/c-c++-common/torture/strub-const2.c
> new file mode 100644
> index 0000000000000..98a92bc9eac2b
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-const2.c
> @@ -0,0 +1,22 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* Check that, along with a strub implicitly-const function call, we issue an
> +   asm statement to make sure the watermark passed to it is held in memory
> +   before the call, and another to make sure it is not assumed to be
> +   unchanged.  */
> +
> +int __attribute__ ((__strub__))
> +#if ! __OPTIMIZE__
> +__attribute__ ((__const__))
> +#endif
> +f() {
> +  return 0;
> +}
> +
> +int
> +g() {
> +  return f();
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "__asm__" 2 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-const3.c b/gcc/testsuite/c-c++-common/torture/strub-const3.c
> new file mode 100644
> index 0000000000000..5511a6e1e71d3
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-const3.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* Check that, along with a strub const wrapping call, we issue an asm statement
> +   to make sure the watermark passed to it is held in memory before the call,
> +   and another to make sure it is not assumed to be unchanged.  */
> +
> +int __attribute__ ((__strub__ ("internal"), __const__))
> +f() {
> +  return 0;
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "__asm__" 2 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-const4.c b/gcc/testsuite/c-c++-common/torture/strub-const4.c
> new file mode 100644
> index 0000000000000..47ee927964dff
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-const4.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* Check that, along with a strub implicitly-const wrapping call, we issue an
> +   asm statement to make sure the watermark passed to it is held in memory
> +   before the call, and another to make sure it is not assumed to be
> +   unchanged.  */
> +
> +int __attribute__ ((__strub__ ("internal")))
> +#if ! __OPTIMIZE__
> +__attribute__ ((__const__))
> +#endif
> +f() {
> +  return 0;
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "__asm__" 2 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-data1.c b/gcc/testsuite/c-c++-common/torture/strub-data1.c
> new file mode 100644
> index 0000000000000..7c27a2a1a6dca
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-data1.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* The pointed-to data enables strubbing if accessed.  */
> +int __attribute__ ((__strub__)) var;
> +
> +int f() {
> +  return var;
> +}
> +
> +/* { dg-final { scan-ipa-dump "strub_enter" "strub" } } */
> +/* { dg-final { scan-ipa-dump "strub_leave" "strub" } } */
> +/* { dg-final { scan-ipa-dump "strub_update" "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-data2.c b/gcc/testsuite/c-c++-common/torture/strub-data2.c
> new file mode 100644
> index 0000000000000..e66d903780afd
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-data2.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* The pointer itself is a strub variable, enabling internal strubbing when
> +   its value is used.  */
> +int __attribute__ ((__strub__)) *ptr;
> +
> +int *f() {
> +  return ptr;
> +}
> +
> +/* { dg-final { scan-ipa-dump "strub_enter" "strub" } } */
> +/* { dg-final { scan-ipa-dump "strub_leave" "strub" } } */
> +/* { dg-final { scan-ipa-dump "strub_update" "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-data3.c b/gcc/testsuite/c-c++-common/torture/strub-data3.c
> new file mode 100644
> index 0000000000000..5e08e0e58c658
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-data3.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* The pointer itself is a strub variable, that would enable internal strubbing
> +   if its value was used.  Here, it's only overwritten, so no strub.  */
> +int __attribute__ ((__strub__)) var;
> +
> +void f() {
> +  var = 0;
> +}
> +
> +/* { dg-final { scan-ipa-dump-not "strub_enter" "strub" } } */
> +/* { dg-final { scan-ipa-dump-not "strub_leave" "strub" } } */
> +/* { dg-final { scan-ipa-dump-not "strub_update" "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-data4.c b/gcc/testsuite/c-c++-common/torture/strub-data4.c
> new file mode 100644
> index 0000000000000..a818e7a38bb5f
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-data4.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* The pointer itself is a strub variable, that would enable internal strubbing
> +   if its value was used.  Here, it's only overwritten, so no strub.  */
> +int __attribute__ ((__strub__)) *ptr;
> +
> +void f() {
> +  ptr = 0;
> +}
> +
> +/* { dg-final { scan-ipa-dump-not "strub_enter" "strub" } } */
> +/* { dg-final { scan-ipa-dump-not "strub_leave" "strub" } } */
> +/* { dg-final { scan-ipa-dump-not "strub_update" "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-data5.c b/gcc/testsuite/c-c++-common/torture/strub-data5.c
> new file mode 100644
> index 0000000000000..ddb0b5c0543b0
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-data5.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict" } */
> +
> +/* It would be desirable to issue at least warnings for these.  */
> +
> +typedef int __attribute__ ((__strub__)) strub_int;
> +strub_int *ptr;
> +
> +int *f () {
> +  return ptr; /* { dg-message "incompatible|invalid conversion" } */
> +}
> +
> +strub_int *g () {
> +  return f (); /* { dg-message "incompatible|invalid conversion" } */
> +}
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-indcall1.c b/gcc/testsuite/c-c++-common/torture/strub-indcall1.c
> new file mode 100644
> index 0000000000000..c165f312f16de
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-indcall1.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +typedef void __attribute__ ((__strub__)) fntype ();
> +fntype (*ptr);
> +
> +void f() {
> +  ptr ();
> +}
> +
> +/* { dg-final { scan-ipa-dump "strub_enter" "strub" } } */
> +/* { dg-final { scan-ipa-dump "(&\.strub\.watermark\.\[0-9\]\+)" "strub" } } */
> +/* { dg-final { scan-ipa-dump "strub_leave" "strub" } } */
> +/* { dg-final { scan-ipa-dump-not "strub_update" "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-indcall2.c b/gcc/testsuite/c-c++-common/torture/strub-indcall2.c
> new file mode 100644
> index 0000000000000..69fcff8d3763d
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-indcall2.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +typedef void __attribute__ ((__strub__)) fntype (int, int);
> +fntype (*ptr);
> +
> +void f() {
> +  ptr (0, 0);
> +}
> +
> +/* { dg-final { scan-ipa-dump "strub_enter" "strub" } } */
> +/* { dg-final { scan-ipa-dump "(0, 0, &\.strub\.watermark\.\[0-9\]\+)" "strub" } } */
> +/* { dg-final { scan-ipa-dump "strub_leave" "strub" } } */
> +/* { dg-final { scan-ipa-dump-not "strub_update" "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-indcall3.c b/gcc/testsuite/c-c++-common/torture/strub-indcall3.c
> new file mode 100644
> index 0000000000000..ff006224909bd
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-indcall3.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +typedef void __attribute__ ((__strub__)) fntype (int, int, ...);
> +fntype (*ptr);
> +
> +void f() {
> +  ptr (0, 0, 1, 1);
> +}
> +
> +/* { dg-final { scan-ipa-dump "strub_enter" "strub" } } */
> +/* { dg-final { scan-ipa-dump "(0, 0, &\.strub\.watermark\.\[0-9\]\+, 1, 1)" "strub" } } */
> +/* { dg-final { scan-ipa-dump "strub_leave" "strub" } } */
> +/* { dg-final { scan-ipa-dump-not "strub_update" "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-inlinable1.c b/gcc/testsuite/c-c++-common/torture/strub-inlinable1.c
> new file mode 100644
> index 0000000000000..614b02228ba29
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-inlinable1.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=relaxed" } */
> +
> +inline void __attribute__ ((strub ("internal"), always_inline))
> +inl_int_ali (void)
> +{
> +  /* No internal wrapper, so this body ALWAYS gets inlined,
> +     but it cannot be called from non-strub contexts.  */
> +}
> +
> +void
> +bat (void)
> +{
> +  /* Not allowed, not a strub context.  */
> +  inl_int_ali (); /* { dg-error "context" } */
> +}
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-inlinable2.c b/gcc/testsuite/c-c++-common/torture/strub-inlinable2.c
> new file mode 100644
> index 0000000000000..f9a6b4a16faf8
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-inlinable2.c
> @@ -0,0 +1,7 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=all" } */
> +
> +#include "strub-inlinable1.c"
> +
> +/* With -fstrub=all, the caller becomes a strub context, so the strub-inlinable
> +   callee is not rejected.  */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-ptrfn1.c b/gcc/testsuite/c-c++-common/torture/strub-ptrfn1.c
> new file mode 100644
> index 0000000000000..b4a7f3992bbaa
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-ptrfn1.c
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict" } */
> +
> +typedef void ft (void);
> +typedef void ft2 (int, int);
> +extern ft __attribute__ ((__strub__)) fnac;
> +
> +ft * f (void) {
> +  return fnac; /* { dg-message "incompatible|invalid conversion" } */
> +}
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-ptrfn2.c b/gcc/testsuite/c-c++-common/torture/strub-ptrfn2.c
> new file mode 100644
> index 0000000000000..d9d2c0caec42d
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-ptrfn2.c
> @@ -0,0 +1,55 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=relaxed -Wpedantic" } */
> +
> +/* C++ does not warn about the partial incompatibilities.
> +
> +   The d_p () calls are actually rejected, even in C++, but they are XFAILed
> +   here because we don't get far enough in the compilation as to observe them,
> +   because the incompatibilities are errors without -fpermissive.
> +   strub-ptrfn3.c uses -fpermissive to check those.
> + */
> +
> +extern int __attribute__ ((strub ("callable"))) bac (void);
> +extern int __attribute__ ((strub ("disabled"))) bad (void);
> +extern int __attribute__ ((strub ("internal"))) bar (void);
> +extern int __attribute__ ((strub ("at-calls"))) bal (void);
> +
> +void __attribute__ ((strub))
> +bap (void)
> +{
> +  int __attribute__ ((strub ("disabled"))) (*d_p) (void) = bad;
> +  int __attribute__ ((strub ("callable"))) (*c_p) (void) = bac;
> +  int __attribute__ ((strub ("at-calls"))) (*a_p) (void) = bal;
> +
> +  d_p = bac; /* { dg-warning "not quite compatible" "" { xfail c++ } } */
> +  c_p = bad; /* { dg-warning "not quite compatible" "" { xfail c++ } } */
> +  c_p = bar; /* { dg-warning "not quite compatible" "" { xfail c++ } } */
> +  c_p = bal; /* { dg-message "incompatible|invalid conversion" } */
> +  a_p = bac; /* { dg-message "incompatible|invalid conversion" } */
> +
> +  d_p (); /* { dg-error "indirect non-.strub. call in .strub. context" "" { xfail c++ } } */
> +  c_p ();
> +  a_p ();
> +}
> +
> +void __attribute__ ((strub))
> +baP (void)
> +{
> +  typedef int __attribute__ ((strub ("disabled"))) d_fn_t (void);
> +  typedef int __attribute__ ((strub ("callable"))) c_fn_t (void);
> +  typedef int __attribute__ ((strub ("at-calls"))) a_fn_t (void);
> +
> +  d_fn_t *d_p = bad;
> +  c_fn_t *c_p = bac;
> +  a_fn_t *a_p = bal;
> +
> +  d_p = bac; /* { dg-warning "not quite compatible" "" { xfail c++ } } */
> +  c_p = bad; /* { dg-warning "not quite compatible" "" { xfail c++ } } */
> +  c_p = bar; /* { dg-warning "not quite compatible" "" { xfail c++ } } */
> +  c_p = bal; /* { dg-message "incompatible|invalid conversion" } */
> +  a_p = bac; /* { dg-message "incompatible|invalid conversion" } */
> +
> +  d_p (); /* { dg-error "indirect non-.strub. call in .strub. context" "" { xfail c++ } } */
> +  c_p ();
> +  a_p ();
> +}
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-ptrfn3.c b/gcc/testsuite/c-c++-common/torture/strub-ptrfn3.c
> new file mode 100644
> index 0000000000000..e1f179e160e5c
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-ptrfn3.c
> @@ -0,0 +1,50 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=relaxed -Wpedantic -fpermissive" } */
> +/* { dg-prune-output "command-line option .-fpermissive." } */
> +
> +/* See strub-ptrfn2.c.  */
> +
> +extern int __attribute__ ((strub ("callable"))) bac (void);
> +extern int __attribute__ ((strub ("disabled"))) bad (void);
> +extern int __attribute__ ((strub ("internal"))) bar (void);
> +extern int __attribute__ ((strub ("at-calls"))) bal (void);
> +
> +void __attribute__ ((strub))
> +bap (void)
> +{
> +  int __attribute__ ((strub ("disabled"))) (*d_p) (void) = bad;
> +  int __attribute__ ((strub ("callable"))) (*c_p) (void) = bac;
> +  int __attribute__ ((strub ("at-calls"))) (*a_p) (void) = bal;
> +
> +  d_p = bac; /* { dg-warning "not quite compatible" "" { xfail c++ } } */
> +  c_p = bad; /* { dg-warning "not quite compatible" "" { xfail c++ } } */
> +  c_p = bar; /* { dg-warning "not quite compatible" "" { xfail c++ } } */
> +  c_p = bal; /* { dg-message "incompatible|invalid conversion" } */
> +  a_p = bac; /* { dg-message "incompatible|invalid conversion" } */
> +
> +  d_p (); /* { dg-error "indirect non-.strub. call in .strub. context" } */
> +  c_p ();
> +  a_p ();
> +}
> +
> +void __attribute__ ((strub))
> +baP (void)
> +{
> +  typedef int __attribute__ ((strub ("disabled"))) d_fn_t (void);
> +  typedef int __attribute__ ((strub ("callable"))) c_fn_t (void);
> +  typedef int __attribute__ ((strub ("at-calls"))) a_fn_t (void);
> +
> +  d_fn_t *d_p = bad;
> +  c_fn_t *c_p = bac;
> +  a_fn_t *a_p = bal;
> +
> +  d_p = bac; /* { dg-warning "not quite compatible" "" { xfail c++ } } */
> +  c_p = bad; /* { dg-warning "not quite compatible" "" { xfail c++ } } */
> +  c_p = bar; /* { dg-warning "not quite compatible" "" { xfail c++ } } */
> +  c_p = bal; /* { dg-message "incompatible|invalid conversion" } */
> +  a_p = bac; /* { dg-message "incompatible|invalid conversion" } */
> +
> +  d_p (); /* { dg-error "indirect non-.strub. call in .strub. context" } */
> +  c_p ();
> +  a_p ();
> +}
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-ptrfn4.c b/gcc/testsuite/c-c++-common/torture/strub-ptrfn4.c
> new file mode 100644
> index 0000000000000..70b558afad040
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-ptrfn4.c
> @@ -0,0 +1,43 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=relaxed" } */
> +
> +/* This is strub-ptrfn2.c without -Wpedantic.
> +
> +   Even C doesn't report the (not-quite-)compatible conversions without it.  */
> +
> +extern int __attribute__ ((strub ("callable"))) bac (void);
> +extern int __attribute__ ((strub ("disabled"))) bad (void);
> +extern int __attribute__ ((strub ("internal"))) bar (void);
> +extern int __attribute__ ((strub ("at-calls"))) bal (void);
> +
> +void __attribute__ ((strub))
> +bap (void)
> +{
> +  int __attribute__ ((strub ("disabled"))) (*d_p) (void) = bad;
> +  int __attribute__ ((strub ("callable"))) (*c_p) (void) = bac;
> +  int __attribute__ ((strub ("at-calls"))) (*a_p) (void) = bal;
> +
> +  d_p = bac;
> +  c_p = bad;
> +  c_p = bar;
> +  c_p = bal; /* { dg-message "incompatible|invalid conversion" } */
> +  a_p = bac; /* { dg-message "incompatible|invalid conversion" } */
> +}
> +
> +void __attribute__ ((strub))
> +baP (void)
> +{
> +  typedef int __attribute__ ((strub ("disabled"))) d_fn_t (void);
> +  typedef int __attribute__ ((strub ("callable"))) c_fn_t (void);
> +  typedef int __attribute__ ((strub ("at-calls"))) a_fn_t (void);
> +
> +  d_fn_t *d_p = bad;
> +  c_fn_t *c_p = bac;
> +  a_fn_t *a_p = bal;
> +
> +  d_p = bac;
> +  c_p = bad;
> +  c_p = bar;
> +  c_p = bal; /* { dg-message "incompatible|invalid conversion" } */
> +  a_p = bac; /* { dg-message "incompatible|invalid conversion" } */
> +}
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-pure1.c b/gcc/testsuite/c-c++-common/torture/strub-pure1.c
> new file mode 100644
> index 0000000000000..a262a086837b2
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-pure1.c
> @@ -0,0 +1,18 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* Check that, along with a strub pure function call, we issue an asm statement
> +   to make sure the watermark passed to it is not assumed to be unchanged.  */
> +
> +int __attribute__ ((__strub__, __pure__))
> +f() {
> +  static int i; /* Stop it from being detected as const.  */
> +  return i;
> +}
> +
> +int
> +g() {
> +  return f();
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "__asm__" 1 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-pure2.c b/gcc/testsuite/c-c++-common/torture/strub-pure2.c
> new file mode 100644
> index 0000000000000..4c4bd50c209a0
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-pure2.c
> @@ -0,0 +1,22 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* Check that, along with a strub implicitly-pure function call, we issue an asm
> +   statement to make sure the watermark passed to it is not assumed to be
> +   unchanged.  */
> +
> +int __attribute__ ((__strub__))
> +#if ! __OPTIMIZE__ /* At -O0, implicit pure detection doesn't run.  */
> +__attribute__ ((__pure__))
> +#endif
> +f() {
> +  static int i; /* Stop it from being detected as const.  */
> +  return i;
> +}
> +
> +int
> +g() {
> +  return f();
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "__asm__" 1 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-pure3.c b/gcc/testsuite/c-c++-common/torture/strub-pure3.c
> new file mode 100644
> index 0000000000000..ce195c6b1f1b6
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-pure3.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* Check that, along with a strub pure wrapping call, we issue an asm statement
> +   to make sure the watermark passed to it is not assumed to be unchanged.  */
> +
> +int __attribute__ ((__strub__ ("internal"), __pure__))
> +f() {
> +  static int i; /* Stop it from being detected as const.  */
> +  return i;
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "__asm__" 1 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-pure4.c b/gcc/testsuite/c-c++-common/torture/strub-pure4.c
> new file mode 100644
> index 0000000000000..75cd54ccb5b5d
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-pure4.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +/* Check that, along with a strub implicitly-pure wrapping call, we issue an asm
> +   statement to make sure the watermark passed to it is not assumed to be
> +   unchanged.  */
> +
> +int __attribute__ ((__strub__ ("internal")))
> +#if ! __OPTIMIZE__ /* At -O0, implicit pure detection doesn't run.  */
> +__attribute__ ((__pure__))
> +#endif
> +f() {
> +  static int i; /* Stop it from being detected as const.  */
> +  return i;
> +}
> +
> +/* { dg-final { scan-ipa-dump-times "__asm__" 1 "strub" } } */
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-run1.c b/gcc/testsuite/c-c++-common/torture/strub-run1.c
> new file mode 100644
> index 0000000000000..7458b3fb54da5
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-run1.c
> @@ -0,0 +1,95 @@
> +/* { dg-do run } */
> +/* { dg-options "-fstrub=strict" } */
> +
> +/* Check that a non-strub function leaves a string behind in the stack, and that
> +   equivalent strub functions don't.  Avoid the use of red zones by avoiding
> +   leaf functions.  */
> +
> +const char test_string[] = "\x55\xde\xad\xbe\xef\xc0\x1d\xca\xfe\x55\xaa";
> +
> +/* Pad before and after the string on the stack, so that it's not overwritten by
> +   regular stack use.  */
> +#define PAD 7
> +
> +static inline __attribute__ ((__always_inline__, __strub__ ("callable")))
> +char *
> +leak_string (void)
> +{
> +  /* We use this variable to avoid any stack red zone.  Stack scrubbing covers
> +     it, but __builtin_stack_address, that we take as a reference, doesn't, so
> +     if e.g. callable() were to store the string in the red zone, we wouldn't
> +     find it because it would be outside the range we searched.  */
> +  typedef void __attribute__ ((__strub__ ("callable"))) callable_t (char *);
> +  callable_t *f = 0;
> +
> +  char s[2 * PAD + 1][sizeof (test_string)];
> +  __builtin_strcpy (s[PAD], test_string);
> +  asm ("" : "+m" (s), "+r" (f));
> +
> +  if (__builtin_expect (!f, 1))
> +    return (char *) __builtin_stack_address ();
> +
> +  f (s[PAD]);
> +  return 0;
> +}
> +
> +static inline __attribute__ ((__always_inline__))
> +int
> +look_for_string (char *e)
> +{
> +  char *p = (char *) __builtin_stack_address ();
> +
> +  if (p == e)
> +    __builtin_abort ();
> +
> +  if (p > e)
> +    {
> +      char *q = p;
> +      p = e;
> +      e = q;
> +    }
> +
> +  for (char *re = e - sizeof (test_string); p < re; p++)
> +    for (int i = 0; p[i] == test_string[i]; i++)
> +      if (i == sizeof (test_string) - 1)
> +       return i;
> +
> +  return 0;
> +}
> +
> +static __attribute__ ((__noinline__, __noclone__))
> +char *
> +callable ()
> +{
> +  return leak_string ();
> +}
> +
> +static __attribute__ ((__strub__ ("at-calls")))
> +char *
> +at_calls ()
> +{
> +  return leak_string ();
> +}
> +
> +static __attribute__ ((__strub__ ("internal")))
> +char *
> +internal ()
> +{
> +  return leak_string ();
> +}
> +
> +int main ()
> +{
> +  /* Since these test check stack contents above the top of the stack, an
> +     unexpected asynchronous signal or interrupt might overwrite the bits we
> +     expect to find and cause spurious fails.  Tolerate one such overall
> +     spurious fail by retrying.  */
> +  int i = 1;
> +  while (!look_for_string (callable ()))
> +    if (!i--) __builtin_abort ();
> +  while (look_for_string (at_calls ()))
> +    if (!i--) __builtin_abort ();
> +  while (look_for_string (internal ()))
> +    if (!i--) __builtin_abort ();
> +  __builtin_exit (0);
> +}
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-run2.c b/gcc/testsuite/c-c++-common/torture/strub-run2.c
> new file mode 100644
> index 0000000000000..5d60a7775f4bb
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-run2.c
> @@ -0,0 +1,84 @@
> +/* { dg-do run } */
> +/* { dg-options "-fstrub=strict" } */
> +
> +/* Check that a non-strub function leaves a string behind in the stack, and that
> +   equivalent strub functions don't.  Allow red zones to be used.  */
> +
> +const char test_string[] = "\x55\xde\xad\xbe\xef\xc0\x1d\xca\xfe\x55\xaa";
> +
> +/* Pad before and after the string on the stack, so that it's not overwritten by
> +   regular stack use.  */
> +#define PAD 7
> +
> +static inline __attribute__ ((__always_inline__, __strub__ ("callable")))
> +char *
> +leak_string (void)
> +{
> +  int len = sizeof (test_string);
> +  asm ("" : "+rm" (len));
> +  char s[2 * PAD + 1][len];
> +  __builtin_strcpy (s[PAD], test_string);
> +  asm ("" : "+m" (s));
> +  return (char *) __builtin_stack_address ();
> +}
> +
> +static inline __attribute__ ((__always_inline__))
> +int
> +look_for_string (char *e)
> +{
> +  char *p = (char *) __builtin_stack_address ();
> +
> +  if (p == e)
> +    __builtin_abort ();
> +
> +  if (p > e)
> +    {
> +      char *q = p;
> +      p = e;
> +      e = q;
> +    }
> +
> +  for (char *re = e - sizeof (test_string); p < re; p++)
> +    for (int i = 0; p[i] == test_string[i]; i++)
> +      if (i == sizeof (test_string) - 1)
> +       return i;
> +
> +  return 0;
> +}
> +
> +static __attribute__ ((__noinline__, __noclone__))
> +char *
> +callable ()
> +{
> +  return leak_string ();
> +}
> +
> +static __attribute__ ((__strub__ ("at-calls")))
> +char *
> +at_calls ()
> +{
> +  return leak_string ();
> +}
> +
> +static __attribute__ ((__strub__ ("internal")))
> +char *
> +internal ()
> +{
> +  return leak_string ();
> +}
> +
> +int main ()
> +{
> +  /* Since these test check stack contents above the top of the stack, an
> +     unexpected asynchronous signal or interrupt might overwrite the bits we
> +     expect to find and cause spurious fails.  Tolerate one such overall
> +     spurious fail by retrying.  */
> +  int i = 1;
> +  while (!look_for_string (callable ()))
> +    if (!i--) __builtin_abort ();
> +  while (look_for_string (at_calls ()))
> +    if (!i--) __builtin_abort ();
> +  while (look_for_string (internal ()))
> +    if (!i--) __builtin_abort ();
> +  __builtin_exit (0);
> +}
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-run3.c b/gcc/testsuite/c-c++-common/torture/strub-run3.c
> new file mode 100644
> index 0000000000000..c2ad710858e87
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-run3.c
> @@ -0,0 +1,80 @@
> +/* { dg-do run } */
> +/* { dg-options "-fstrub=strict" } */
> +/* { dg-require-effective-target alloca } */
> +
> +/* Check that a non-strub function leaves a string behind in the stack, and that
> +   equivalent strub functions don't.  */
> +
> +const char test_string[] = "\x55\xde\xad\xbe\xef\xc0\x1d\xca\xfe\x55\xaa";
> +
> +static inline __attribute__ ((__always_inline__, __strub__ ("callable")))
> +char *
> +leak_string (void)
> +{
> +  int len = sizeof (test_string);
> +  char *s = (char *) __builtin_alloca (len);
> +  __builtin_strcpy (s, test_string);
> +  asm ("" : "+m" (s));
> +  return (char *) __builtin_stack_address ();
> +}
> +
> +static inline __attribute__ ((__always_inline__))
> +int
> +look_for_string (char *e)
> +{
> +  char *p = (char *) __builtin_stack_address ();
> +
> +  if (p == e)
> +    __builtin_abort ();
> +
> +  if (p > e)
> +    {
> +      char *q = p;
> +      p = e;
> +      e = q;
> +    }
> +
> +  for (char *re = e - sizeof (test_string); p < re; p++)
> +    for (int i = 0; p[i] == test_string[i]; i++)
> +      if (i == sizeof (test_string) - 1)
> +       return i;
> +
> +  return 0;
> +}
> +
> +static __attribute__ ((__noinline__, __noclone__))
> +char *
> +callable ()
> +{
> +  return leak_string ();
> +}
> +
> +static __attribute__ ((__strub__ ("at-calls")))
> +char *
> +at_calls ()
> +{
> +  return leak_string ();
> +}
> +
> +static __attribute__ ((__strub__ ("internal")))
> +char *
> +internal ()
> +{
> +  return leak_string ();
> +}
> +
> +int main ()
> +{
> +  /* Since these test check stack contents above the top of the stack, an
> +     unexpected asynchronous signal or interrupt might overwrite the bits we
> +     expect to find and cause spurious fails.  Tolerate one such overall
> +     spurious fail by retrying.  */
> +  int i = 1;
> +  while (!look_for_string (callable ()))
> +    if (!i--) __builtin_abort ();
> +  while (look_for_string (at_calls ()))
> +    if (!i--) __builtin_abort ();
> +  while (look_for_string (internal ()))
> +    if (!i--) __builtin_abort ();
> +  __builtin_exit (0);
> +}
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-run4.c b/gcc/testsuite/c-c++-common/torture/strub-run4.c
> new file mode 100644
> index 0000000000000..3b36b8e5d68ef
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-run4.c
> @@ -0,0 +1,106 @@
> +/* { dg-do run } */
> +/* { dg-options "-fstrub=all" } */
> +/* { dg-require-effective-target alloca } */
> +
> +/* Check that multi-level, multi-inlined functions still get cleaned up as
> +   expected, without overwriting temporary stack allocations while they should
> +   still be available.  */
> +
> +#ifndef ATTR_STRUB_AT_CALLS
> +# define ATTR_STRUB_AT_CALLS /* Defined in strub-run4d.c.  */
> +#endif
> +
> +const char test_string[] = "\x55\xde\xad\xbe\xef\xc0\x1d\xca\xfe\x55\xaa";
> +
> +static inline __attribute__ ((__always_inline__))
> +char *
> +leak_string (void)
> +{
> +  int __attribute__ ((__strub__)) len = 512;
> +  asm ("" : "+r" (len));
> +  char s[len];
> +  __builtin_strcpy (s, test_string);
> +  __builtin_strcpy (s + len - sizeof (test_string), test_string);
> +  asm ("" : "+m" (s));
> +  return (char *) __builtin_stack_address ();
> +}
> +
> +static inline __attribute__ ((__always_inline__))
> +int
> +look_for_string (char *e)
> +{
> +  char *p = (char *) __builtin_stack_address ();
> +
> +  if (p == e)
> +    __builtin_abort ();
> +
> +  if (p > e)
> +    {
> +      char *q = p;
> +      p = e;
> +      e = q;
> +    }
> +
> +  for (char *re = e - sizeof (test_string); p < re; p++)
> +    for (int i = 0; p[i] == test_string[i]; i++)
> +      if (i == sizeof (test_string) - 1)
> +       return i;
> +
> +  return 0;
> +}
> +
> +static inline ATTR_STRUB_AT_CALLS
> +char *
> +innermost ()
> +{
> +  int __attribute__ ((__strub__)) len = 512;
> +  asm ("" : "+r" (len));
> +  char s[len];
> +  __builtin_strcpy (s, test_string);
> +  __builtin_strcpy (s + len - sizeof (test_string), test_string);
> +  asm ("" : "+m" (s));
> +  char *ret = leak_string ();
> +  if (__builtin_strcmp (s, test_string) != 0)
> +    __builtin_abort ();
> +  if (__builtin_strcmp (s + len - sizeof (test_string), test_string) != 0)
> +    __builtin_abort ();
> +  return ret;
> +}
> +
> +static inline ATTR_STRUB_AT_CALLS
> +char *
> +intermediate ()
> +{
> +  int __attribute__ ((__strub__)) len = 512;
> +  asm ("" : "+r" (len));
> +  char s[len];
> +  __builtin_strcpy (s, test_string);
> +  __builtin_strcpy (s + len - sizeof (test_string), test_string);
> +  asm ("" : "+m" (s));
> +  char *ret = innermost ();
> +  if (__builtin_strcmp (s, test_string) != 0)
> +    __builtin_abort ();
> +  if (__builtin_strcmp (s + len - sizeof (test_string), test_string) != 0)
> +    __builtin_abort ();
> +  return ret;
> +}
> +
> +static inline __attribute__ ((__strub__ ("internal")))
> +char *
> +internal ()
> +{
> +  return intermediate ();
> +}
> +
> +int __attribute__ ((__strub__ ("disabled")))
> +main ()
> +{
> +  /* Since these test check stack contents above the top of the stack, an
> +     unexpected asynchronous signal or interrupt might overwrite the bits we
> +     expect to find and cause spurious fails.  Tolerate one such overall
> +     spurious fail by retrying.  */
> +  int i = 1;
> +  while (look_for_string (internal ()))
> +    if (!i--) __builtin_abort ();
> +  __builtin_exit (0);
> +}
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-run4c.c b/gcc/testsuite/c-c++-common/torture/strub-run4c.c
> new file mode 100644
> index 0000000000000..57f9baf758ded
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-run4c.c
> @@ -0,0 +1,5 @@
> +/* { dg-do run } */
> +/* { dg-options "-fstrub=at-calls" } */
> +/* { dg-require-effective-target alloca } */
> +
> +#include "strub-run4.c"
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-run4d.c b/gcc/testsuite/c-c++-common/torture/strub-run4d.c
> new file mode 100644
> index 0000000000000..08de3f1c3b17c
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-run4d.c
> @@ -0,0 +1,7 @@
> +/* { dg-do run } */
> +/* { dg-options "-fstrub=strict" } */
> +/* { dg-require-effective-target alloca } */
> +
> +#define ATTR_STRUB_AT_CALLS __attribute__ ((__strub__ ("at-calls")))
> +
> +#include "strub-run4.c"
> diff --git a/gcc/testsuite/c-c++-common/torture/strub-run4i.c b/gcc/testsuite/c-c++-common/torture/strub-run4i.c
> new file mode 100644
> index 0000000000000..459f6886c5499
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/torture/strub-run4i.c
> @@ -0,0 +1,5 @@
> +/* { dg-do run } */
> +/* { dg-options "-fstrub=internal" } */
> +/* { dg-require-effective-target alloca } */
> +
> +#include "strub-run4.c"
> diff --git a/gcc/testsuite/g++.dg/strub-run1.C b/gcc/testsuite/g++.dg/strub-run1.C
> new file mode 100644
> index 0000000000000..0d367fb83d09d
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/strub-run1.C
> @@ -0,0 +1,19 @@
> +// { dg-do run }
> +// { dg-options "-fstrub=internal" }
> +
> +// Check that we don't get extra copies.
> +
> +struct T {
> +  T &self;
> +  void check () const { if (&self != this) __builtin_abort (); }
> +  T() : self (*this) { check (); }
> +  T(const T& ck) : self (*this) { ck.check (); check (); }
> +  ~T() { check (); }
> +};
> +
> +T foo (T q) { q.check (); return T(); }
> +T bar (T p) { p.check (); return foo (p); }
> +
> +int main () {
> +  bar (T()).check ();
> +}
> diff --git a/gcc/testsuite/g++.dg/torture/strub-init1.C b/gcc/testsuite/g++.dg/torture/strub-init1.C
> new file mode 100644
> index 0000000000000..c226ab10ff651
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/torture/strub-init1.C
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +extern int __attribute__((__strub__)) initializer ();
> +
> +int f() {
> +  static int x = initializer ();
> +  return x;
> +}
> +
> +/* { dg-final { scan-ipa-dump "strub_enter" "strub" } } */
> +/* { dg-final { scan-ipa-dump "strub_leave" "strub" } } */
> +/* { dg-final { scan-ipa-dump-not "strub_update" "strub" } } */
> diff --git a/gcc/testsuite/g++.dg/torture/strub-init2.C b/gcc/testsuite/g++.dg/torture/strub-init2.C
> new file mode 100644
> index 0000000000000..a7911f1fa7212
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/torture/strub-init2.C
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +extern int __attribute__((__strub__)) initializer ();
> +
> +static int x = initializer ();
> +
> +int f() {
> +  return x;
> +}
> +
> +/* { dg-final { scan-ipa-dump "strub_enter" "strub" } } */
> +/* { dg-final { scan-ipa-dump "strub_leave" "strub" } } */
> +/* { dg-final { scan-ipa-dump-not "strub_update" "strub" } } */
> diff --git a/gcc/testsuite/g++.dg/torture/strub-init3.C b/gcc/testsuite/g++.dg/torture/strub-init3.C
> new file mode 100644
> index 0000000000000..6ebebcd01e8ea
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/torture/strub-init3.C
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
> +
> +extern int __attribute__((__strub__)) initializer ();
> +
> +int f() {
> +  int x = initializer ();
> +  return x;
> +}
> +
> +/* { dg-final { scan-ipa-dump "strub_enter" "strub" } } */
> +/* { dg-final { scan-ipa-dump "strub_leave" "strub" } } */
> +/* { dg-final { scan-ipa-dump-not "strub_update" "strub" } } */
> diff --git a/gcc/testsuite/gnat.dg/strub_access.adb b/gcc/testsuite/gnat.dg/strub_access.adb
> new file mode 100644
> index 0000000000000..29e6996ecf61c
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_access.adb
> @@ -0,0 +1,21 @@
> +--  { dg-do compile }
> +--  { dg-options "-fstrub=relaxed -fdump-ipa-strubm" }
> +
> +--  The main subprogram doesn't read from the automatic variable, but
> +--  being an automatic variable, its presence should be enough for the
> +--  procedure to get strub enabled.
> +
> +procedure Strub_Access is
> +   type Strub_Int is new Integer;
> +   pragma Machine_Attribute (Strub_Int, "strub");
> +
> +   X : aliased Strub_Int := 0;
> +
> +   function F (P : access Strub_Int) return Strub_Int is (P.all);
> +
> +begin
> +   X := F (X'Access);
> +end Strub_Access;
> +
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub \[(\]internal\[)\]\[)\]" 1 "strubm" } }
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub \[(\]at-calls-opt\[)\]\[)\]" 1 "strubm" } }
> diff --git a/gcc/testsuite/gnat.dg/strub_access1.adb b/gcc/testsuite/gnat.dg/strub_access1.adb
> new file mode 100644
> index 0000000000000..dae4706016436
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_access1.adb
> @@ -0,0 +1,16 @@
> +--  { dg-do compile }
> +--  { dg-options "-fstrub=relaxed" }
> +
> +--  Check that we reject 'Access of a strub variable whose type does
> +--  not carry a strub modifier.
> +
> +procedure Strub_Access1 is
> +   X : aliased Integer := 0;
> +   pragma Machine_Attribute (X, "strub");
> +
> +   function F (P : access Integer) return Integer is (P.all);
> +
> +begin
> +   X := F (X'Unchecked_access); -- OK.
> +   X := F (X'Access); -- { dg-error "target access type drops .strub. mode" }
> +end Strub_Access1;
> diff --git a/gcc/testsuite/gnat.dg/strub_attr.adb b/gcc/testsuite/gnat.dg/strub_attr.adb
> new file mode 100644
> index 0000000000000..10445d7cf8451
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_attr.adb
> @@ -0,0 +1,37 @@
> +--  { dg-do compile }
> +--  { dg-options "-fstrub=strict -fdump-ipa-strubm -fdump-ipa-strub" }
> +
> +package body Strub_Attr is
> +   E : exception;
> +
> +   procedure P (X : Integer) is
> +   begin
> +      raise E;
> +   end;
> +
> +   function F (X : Integer) return Integer is
> +   begin
> +      return X * X;
> +   end;
> +
> +   function G return Integer is (F (X));
> +   --  function G return Integer is (FP (X));
> +   --  Calling G would likely raise an exception, because although FP
> +   --  carries the strub at-calls attribute needed to call F, the
> +   --  attribute is dropped from the type used for the call proper.
> +end Strub_Attr;
> +
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub \[(\]internal\[)\]\[)\]" 2 "strubm" } }
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub \[(\]at-calls\[)\]\[)\]" 0 "strubm" } }
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub\[)\]" 1 "strubm" } }
> +
> +--  { dg-final { scan-ipa-dump-times "strub.watermark_ptr" 6 "strub" } }
> +--  We have 1 at-calls subprogram (F) and 2 wrapped (P and G).
> +--  For each of them, there's one match for the wrapped signature,
> +--  and one for the update call.
> +
> +--  { dg-final { scan-ipa-dump-times "strub.watermark" 27 "strub" } }
> +--  The 6 matches above, plus:
> +--  5*2: wm var decl, enter, call, leave and clobber for each wrapper;
> +--  2*1: an extra leave and clobber for the exception paths in the wrappers.
> +--  7*1: for the F call in G, including EH path.
> diff --git a/gcc/testsuite/gnat.dg/strub_attr.ads b/gcc/testsuite/gnat.dg/strub_attr.ads
> new file mode 100644
> index 0000000000000..a94c23bf41833
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_attr.ads
> @@ -0,0 +1,12 @@
> +package Strub_Attr is
> +   procedure P (X : Integer);
> +   pragma Machine_Attribute (P, "strub", "internal");
> +
> +   function F (X : Integer) return Integer;
> +   pragma Machine_Attribute (F, "strub");
> +
> +   X : Integer := 0;
> +   pragma Machine_Attribute (X, "strub");
> +
> +   function G return Integer;
> +end Strub_Attr;
> diff --git a/gcc/testsuite/gnat.dg/strub_disp.adb b/gcc/testsuite/gnat.dg/strub_disp.adb
> new file mode 100644
> index 0000000000000..3dbcc4a357cba
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_disp.adb
> @@ -0,0 +1,64 @@
> +--  { dg-do compile }
> +
> +procedure Strub_Disp is
> +   package Foo is
> +      type A is tagged null record;
> +
> +      procedure P (I : Integer; X : A);
> +      pragma Machine_Attribute (P, "strub", "at-calls");
> +
> +      function F (X : access A) return Integer;
> +
> +      type B is new A with null record;
> +
> +      overriding
> +      procedure P (I : Integer; X : B); -- { dg-error "requires the same .strub. mode" }
> +
> +      overriding
> +      function F (X : access B) return Integer;
> +      pragma Machine_Attribute (F, "strub", "at-calls"); -- { dg-error "requires the same .strub. mode" }
> +
> +   end Foo;
> +
> +   package body Foo is
> +      procedure P (I : Integer; X : A) is
> +      begin
> +        null;
> +      end;
> +
> +      function F (X : access A) return Integer is (0);
> +
> +      overriding
> +      procedure P (I : Integer; X : B) is
> +      begin
> +        P (I, A (X));
> +      end;
> +
> +      overriding
> +      function F (X : access B) return Integer is (1);
> +   end Foo;
> +
> +   use Foo;
> +
> +   procedure Q (X : A'Class) is
> +   begin
> +      P (-1, X);
> +   end;
> +
> +   XA : aliased A;
> +   XB : aliased B;
> +   I : Integer := 0;
> +   XC : access A'Class;
> +begin
> +   Q (XA);
> +   Q (XB);
> +
> +   I := I + F (XA'Access);
> +   I := I + F (XB'Access);
> +
> +   XC := XA'Access;
> +   I := I + F (XC);
> +
> +   XC := XB'Access;
> +   I := I + F (XC);
> +end Strub_Disp;
> diff --git a/gcc/testsuite/gnat.dg/strub_disp1.adb b/gcc/testsuite/gnat.dg/strub_disp1.adb
> new file mode 100644
> index 0000000000000..09756a74b7d81
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_disp1.adb
> @@ -0,0 +1,79 @@
> +--  { dg-do compile }
> +--  { dg-options "-fdump-ipa-strub" }
> +
> +-- Check that at-calls dispatching calls are transformed.
> +
> +procedure Strub_Disp1 is
> +   package Foo is
> +      type A is tagged null record;
> +
> +      procedure P (I : Integer; X : A);
> +      pragma Machine_Attribute (P, "strub", "at-calls");
> +
> +      function F (X : access A) return Integer;
> +      pragma Machine_Attribute (F, "strub", "at-calls");
> +
> +      type B is new A with null record;
> +
> +      overriding
> +      procedure P (I : Integer; X : B);
> +      pragma Machine_Attribute (P, "strub", "at-calls");
> +
> +      overriding
> +      function F (X : access B) return Integer;
> +      pragma Machine_Attribute (F, "strub", "at-calls");
> +
> +   end Foo;
> +
> +   package body Foo is
> +      procedure P (I : Integer; X : A) is
> +      begin
> +        null;
> +      end;
> +
> +      function F (X : access A) return Integer is (0);
> +
> +      overriding
> +      procedure P (I : Integer; X : B) is
> +      begin
> +        P (I, A (X)); -- strub-at-calls non-dispatching call
> +      end;
> +
> +      overriding
> +      function F (X : access B) return Integer is (1);
> +   end Foo;
> +
> +   use Foo;
> +
> +   procedure Q (X : A'Class) is
> +   begin
> +      P (-1, X); -- strub-at-calls dispatching call.
> +   end;
> +
> +   XA : aliased A;
> +   XB : aliased B;
> +   I : Integer := 0;
> +   XC : access A'Class;
> +begin
> +   Q (XA);
> +   Q (XB);
> +
> +   I := I + F (XA'Access); -- strub-at-calls non-dispatching call
> +   I := I + F (XB'Access); -- strub-at-calls non-dispatching call
> +
> +   XC := XA'Access;
> +   I := I + F (XC); -- strub-at-calls dispatching call.
> +
> +   XC := XB'Access;
> +   I := I + F (XC); -- strub-at-calls dispatching call.
> +end Strub_Disp1;
> +
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub \[(\]at-calls\[)\]\[)\]" 4 "strub" } }
> +
> +--  Count the strub-at-calls non-dispatching calls
> +--  (+ 2 each, for the matching prototypes)
> +--  { dg-final { scan-ipa-dump-times "foo\.p \[(\]\[^\n\]*watermark" 3 "strub" } }
> +--  { dg-final { scan-ipa-dump-times "foo\.f \[(\]\[^\n\]*watermark" 4 "strub" } }
> +
> +--  Count the strub-at-calls dispatching calls.
> +--  { dg-final { scan-ipa-dump-times "_\[0-9\]* \[(\]\[^\n\]*watermark" 3 "strub" } }
> diff --git a/gcc/testsuite/gnat.dg/strub_ind.adb b/gcc/testsuite/gnat.dg/strub_ind.adb
> new file mode 100644
> index 0000000000000..da56acaa957d2
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_ind.adb
> @@ -0,0 +1,33 @@
> +--  { dg-do compile }
> +--  { dg-options "-fstrub=strict" }
> +
> +--  This is essentially the same test as strub_attr.adb,
> +--  but applying attributes to access types as well.
> +--  That doesn't quite work yet, so we get an error we shouldn't get.
> +
> +package body Strub_Ind is
> +   E : exception;
> +
> +   function G return Integer;
> +
> +   procedure P (X : Integer) is
> +   begin
> +      raise E;
> +   end;
> +
> +   function F (X : Integer) return Integer is
> +   begin
> +      return X * X;
> +   end;
> +
> +   function G return Integer is (FP (X));
> +
> +   type GT is access function return Integer;
> +
> +   type GT_SAC is access function return Integer;
> +   pragma Machine_Attribute (GT_SAC, "strub", "at-calls");
> +
> +   GP : GT_SAC := GT_SAC (GT'(G'Access)); -- { dg-error "incompatible" }
> +   -- pragma Machine_Attribute (GP, "strub", "at-calls");
> +
> +end Strub_Ind;
> diff --git a/gcc/testsuite/gnat.dg/strub_ind.ads b/gcc/testsuite/gnat.dg/strub_ind.ads
> new file mode 100644
> index 0000000000000..99a65fc24b1ec
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_ind.ads
> @@ -0,0 +1,17 @@
> +package Strub_Ind is
> +   procedure P (X : Integer);
> +   pragma Machine_Attribute (P, "strub", "internal");
> +
> +   function F (X : Integer) return Integer;
> +   pragma Machine_Attribute (F, "strub");
> +
> +   X : Integer := 0;
> +   pragma Machine_Attribute (X, "strub");
> +
> +   type FT is access function (X : Integer) return Integer;
> +   pragma Machine_Attribute (FT, "strub", "at-calls");
> +
> +   FP : FT := F'Access;
> +   -- pragma Machine_Attribute (FP, "strub", "at-calls"); -- not needed
> +
> +end Strub_Ind;
> diff --git a/gcc/testsuite/gnat.dg/strub_ind1.adb b/gcc/testsuite/gnat.dg/strub_ind1.adb
> new file mode 100644
> index 0000000000000..825e395e6819c
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_ind1.adb
> @@ -0,0 +1,41 @@
> +--  { dg-do compile }
> +--  { dg-options "-fstrub=strict -fdump-ipa-strubm" }
> +
> +--  This is essentially the same test as strub_attr.adb,
> +--  but with an explicit conversion.
> +
> +package body Strub_Ind1 is
> +   E : exception;
> +
> +   type Strub_Int is New Integer;
> +   pragma Machine_Attribute (Strub_Int, "strub");
> +
> +   function G return Integer;
> +   pragma Machine_Attribute (G, "strub", "disabled");
> +
> +   procedure P (X : Integer) is
> +   begin
> +      raise E;
> +   end;
> +
> +   function G return Integer is (FP (X));
> +
> +   type GT is access function return Integer;
> +   pragma Machine_Attribute (GT, "strub", "disabled");
> +
> +   type GT_SC is access function return Integer;
> +   pragma Machine_Attribute (GT_SC, "strub", "callable");
> +
> +   GP : GT_SC := GT_SC (GT'(G'Access));
> +   --  pragma Machine_Attribute (GP, "strub", "callable"); -- not needed.
> +
> +   function F (X : Integer) return Integer is
> +   begin
> +      return X * GP.all;
> +   end;
> +
> +end Strub_Ind1;
> +
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub \[(\]disabled\[)\]\[)\]" 1 "strubm" } }
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub \[(\]internal\[)\]\[)\]" 1 "strubm" } }
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub\[)\]" 1 "strubm" } }
> diff --git a/gcc/testsuite/gnat.dg/strub_ind1.ads b/gcc/testsuite/gnat.dg/strub_ind1.ads
> new file mode 100644
> index 0000000000000..d3f1273b3a6b9
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_ind1.ads
> @@ -0,0 +1,17 @@
> +package Strub_Ind1 is
> +   procedure P (X : Integer);
> +   pragma Machine_Attribute (P, "strub", "internal");
> +
> +   function F (X : Integer) return Integer;
> +   pragma Machine_Attribute (F, "strub");
> +
> +   X : aliased Integer := 0;
> +   pragma Machine_Attribute (X, "strub");
> +
> +   type FT is access function (X : Integer) return Integer;
> +   pragma Machine_Attribute (FT, "strub", "at-calls");
> +
> +   FP : FT := F'Access;
> +   pragma Machine_Attribute (FP, "strub", "at-calls");
> +
> +end Strub_Ind1;
> diff --git a/gcc/testsuite/gnat.dg/strub_ind2.adb b/gcc/testsuite/gnat.dg/strub_ind2.adb
> new file mode 100644
> index 0000000000000..e918b39263117
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_ind2.adb
> @@ -0,0 +1,34 @@
> +--  { dg-do compile }
> +--  { dg-options "-fstrub=strict" }
> +
> +--  This is essentially the same test as strub_attr.adb,
> +--  but with an explicit conversion.
> +
> +package body Strub_Ind2 is
> +   E : exception;
> +
> +   function G return Integer;
> +   pragma Machine_Attribute (G, "strub", "callable");
> +
> +   procedure P (X : Integer) is
> +   begin
> +      raise E;
> +   end;
> +
> +   function G return Integer is (FP (X));
> +
> +   type GT is access function return Integer;
> +   pragma Machine_Attribute (GT, "strub", "callable");
> +
> +   type GT_SD is access function return Integer;
> +   pragma Machine_Attribute (GT_SD, "strub", "disabled");
> +
> +   GP : GT_SD := GT_SD (GT'(G'Access));
> +   --  pragma Machine_Attribute (GP, "strub", "disabled"); -- not needed.
> +
> +   function F (X : Integer) return Integer is
> +   begin
> +      return X * GP.all; --  { dg-error "using non-.strub. type" }
> +   end;
> +
> +end Strub_Ind2;
> diff --git a/gcc/testsuite/gnat.dg/strub_ind2.ads b/gcc/testsuite/gnat.dg/strub_ind2.ads
> new file mode 100644
> index 0000000000000..e13865ec49c38
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_ind2.ads
> @@ -0,0 +1,17 @@
> +package Strub_Ind2 is
> +   procedure P (X : Integer);
> +   pragma Machine_Attribute (P, "strub", "internal");
> +
> +   function F (X : Integer) return Integer;
> +   pragma Machine_Attribute (F, "strub");
> +
> +   X : Integer := 0;
> +   pragma Machine_Attribute (X, "strub");
> +
> +   type FT is access function (X : Integer) return Integer;
> +   pragma Machine_Attribute (FT, "strub", "at-calls");
> +
> +   FP : FT := F'Access;
> +   pragma Machine_Attribute (FP, "strub", "at-calls");
> +
> +end Strub_Ind2;
> diff --git a/gcc/testsuite/gnat.dg/strub_intf.adb b/gcc/testsuite/gnat.dg/strub_intf.adb
> new file mode 100644
> index 0000000000000..8f0212a75866f
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_intf.adb
> @@ -0,0 +1,93 @@
> +--  { dg-do compile }
> +
> +--  Check that strub mode mismatches between overrider and overridden
> +--  subprograms are reported.
> +
> +procedure Strub_Intf is
> +   package Foo is
> +      type TP is interface;
> +      procedure P (I : Integer; X : TP) is abstract;
> +      pragma Machine_Attribute (P, "strub", "at-calls"); -- { dg-error "requires the same .strub. mode" }
> +
> +      type TF is interface;
> +      function F (X : access TF) return Integer is abstract;
> +
> +      type TX is interface;
> +      procedure P (I : Integer; X : TX) is abstract;
> +
> +      type TI is interface and TP and TF and TX;
> +      --  When we freeze TI, we detect the mismatch between the
> +      --  inherited P and another parent's P.  Because TP appears
> +      --  before TX, we inherit P from TP, and report the mismatch at
> +      --  the pragma inherited from TP against TX's P.  In contrast,
> +      --  when we freeze TII below, since TX appears before TP, we
> +      --  report the error at the line in which the inherited
> +      --  subprogram is synthesized, namely the line below, against
> +      --  the line of the pragma.
> +
> +      type TII is interface and TX and TP and TF; -- { dg-error "requires the same .strub. mode" }
> +
> +      function F (X : access TI) return Integer is abstract;
> +      pragma Machine_Attribute (F, "strub", "at-calls"); -- { dg-error "requires the same .strub. mode" }
> +
> +      type A is new TI with null record;
> +
> +      procedure P (I : Integer; X : A);
> +      pragma Machine_Attribute (P, "strub", "at-calls"); -- { dg-error "requires the same .strub. mode" }
> +
> +      function F (X : access A) return Integer; -- { dg-error "requires the same .strub. mode" }
> +
> +      type B is new TI with null record;
> +
> +      overriding
> +      procedure P (I : Integer; X : B); -- { dg-error "requires the same .strub. mode" }
> +
> +      overriding
> +      function F (X : access B) return Integer;
> +      pragma Machine_Attribute (F, "strub", "at-calls"); -- { dg-error "requires the same .strub. mode" }
> +
> +   end Foo;
> +
> +   package body Foo is
> +      procedure P (I : Integer; X : A) is
> +      begin
> +        null;
> +      end;
> +
> +      function F (X : access A) return Integer is (0);
> +
> +      overriding
> +      procedure P (I : Integer; X : B) is
> +      begin
> +        null;
> +      end;
> +
> +      overriding
> +      function F (X : access B) return Integer is (1);
> +
> +   end Foo;
> +
> +   use Foo;
> +
> +   procedure Q (X : TX'Class) is
> +   begin
> +      P (-1, X);
> +   end;
> +
> +   XA : aliased A;
> +   XB : aliased B;
> +   I : Integer := 0;
> +   XC : access TI'Class;
> +begin
> +   Q (XA);
> +   Q (XB);
> +
> +   I := I + F (XA'Access);
> +   I := I + F (XB'Access);
> +
> +   XC := XA'Access;
> +   I := I + F (XC);
> +
> +   XC := XB'Access;
> +   I := I + F (XC);
> +end Strub_Intf;
> diff --git a/gcc/testsuite/gnat.dg/strub_intf1.adb b/gcc/testsuite/gnat.dg/strub_intf1.adb
> new file mode 100644
> index 0000000000000..bf77321cef790
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_intf1.adb
> @@ -0,0 +1,86 @@
> +--  { dg-do compile }
> +--  { dg-options "-fdump-ipa-strub" }
> +
> +-- Check that at-calls dispatching calls to interfaces are transformed.
> +
> +procedure Strub_Intf1 is
> +   package Foo is
> +      type TX is Interface;
> +      procedure P (I : Integer; X : TX) is abstract;
> +      pragma Machine_Attribute (P, "strub", "at-calls");
> +      function F (X : access TX) return Integer is abstract;
> +      pragma Machine_Attribute (F, "strub", "at-calls");
> +
> +      type A is new TX with null record;
> +
> +      procedure P (I : Integer; X : A);
> +      pragma Machine_Attribute (P, "strub", "at-calls");
> +
> +      function F (X : access A) return Integer;
> +      pragma Machine_Attribute (F, "strub", "at-calls");
> +
> +      type B is new TX with null record;
> +
> +      overriding
> +      procedure P (I : Integer; X : B);
> +      pragma Machine_Attribute (P, "strub", "at-calls");
> +
> +      overriding
> +      function F (X : access B) return Integer;
> +      pragma Machine_Attribute (F, "strub", "at-calls");
> +
> +   end Foo;
> +
> +   package body Foo is
> +      procedure P (I : Integer; X : A) is
> +      begin
> +        null;
> +      end;
> +
> +      function F (X : access A) return Integer is (0);
> +
> +      overriding
> +      procedure P (I : Integer; X : B) is
> +      begin
> +        null;
> +      end;
> +
> +      overriding
> +      function F (X : access B) return Integer is (1);
> +
> +   end Foo;
> +
> +   use Foo;
> +
> +   procedure Q (X : TX'Class) is
> +   begin
> +      P (-1, X);
> +   end;
> +
> +   XA : aliased A;
> +   XB : aliased B;
> +   I : Integer := 0;
> +   XC : access TX'Class;
> +begin
> +   Q (XA);
> +   Q (XB);
> +
> +   I := I + F (XA'Access);
> +   I := I + F (XB'Access);
> +
> +   XC := XA'Access;
> +   I := I + F (XC);
> +
> +   XC := XB'Access;
> +   I := I + F (XC);
> +end Strub_Intf1;
> +
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub \[(\]at-calls\[)\]\[)\]" 4 "strub" } }
> +
> +--  Count the strub-at-calls non-dispatching calls
> +--  (+ 2 each, for the matching prototypes)
> +--  { dg-final { scan-ipa-dump-times "foo\.p \[(\]\[^\n\]*watermark" 2 "strub" } }
> +--  { dg-final { scan-ipa-dump-times "foo\.f \[(\]\[^\n\]*watermark" 4 "strub" } }
> +
> +--  Count the strub-at-calls dispatching calls.
> +--  { dg-final { scan-ipa-dump-times "_\[0-9\]* \[(\]\[^\n\]*watermark" 3 "strub" } }
> diff --git a/gcc/testsuite/gnat.dg/strub_intf2.adb b/gcc/testsuite/gnat.dg/strub_intf2.adb
> new file mode 100644
> index 0000000000000..e8880dbc43730
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_intf2.adb
> @@ -0,0 +1,55 @@
> +--  { dg-do compile }
> +
> +--  Check that strub mode mismatches between overrider and overridden
> +--  subprograms are reported even when the overriders for an
> +--  interface's subprograms are inherited from a type that is not a
> +--  descendent of the interface.
> +
> +procedure Strub_Intf2 is
> +   package Foo is
> +      type A is tagged null record;
> +
> +      procedure P (I : Integer; X : A);
> +      pragma Machine_Attribute (P, "strub", "at-calls"); -- { dg-error "requires the same .strub. mode" }
> +
> +      function F (X : access A) return Integer;
> +
> +      type TX is Interface;
> +
> +      procedure P (I : Integer; X : TX) is abstract;
> +
> +      function F (X : access TX) return Integer is abstract;
> +      pragma Machine_Attribute (F, "strub", "at-calls");
> +
> +      type B is new A and TX with null record; -- { dg-error "requires the same .strub. mode" }
> +
> +   end Foo;
> +
> +   package body Foo is
> +      procedure P (I : Integer; X : A) is
> +      begin
> +        null;
> +      end;
> +
> +      function F (X : access A) return Integer is (0);
> +
> +   end Foo;
> +
> +   use Foo;
> +
> +   procedure Q (X : TX'Class) is
> +   begin
> +      P (-1, X);
> +   end;
> +
> +   XB : aliased B;
> +   I : Integer := 0;
> +   XC : access TX'Class;
> +begin
> +   Q (XB);
> +
> +   I := I + F (XB'Access);
> +
> +   XC := XB'Access;
> +   I := I + F (XC);
> +end Strub_Intf2;
> diff --git a/gcc/testsuite/gnat.dg/strub_renm.adb b/gcc/testsuite/gnat.dg/strub_renm.adb
> new file mode 100644
> index 0000000000000..217367e712d82
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_renm.adb
> @@ -0,0 +1,21 @@
> +--  { dg-do compile }
> +
> +procedure Strub_Renm is
> +   procedure P (X : Integer);
> +   pragma Machine_Attribute (P, "strub", "at-calls");
> +
> +   function F return Integer;
> +   pragma Machine_Attribute (F, "strub", "internal");
> +
> +   procedure Q (X : Integer) renames P; -- { dg-error "requires the same .strub. mode" }
> +
> +   function G return Integer renames F;
> +   pragma Machine_Attribute (G, "strub", "callable"); -- { dg-error "requires the same .strub. mode" }
> +
> +   procedure P (X : Integer) is null;
> +   function F return Integer is (0);
> +
> +begin
> +   P (F);
> +   Q (G);
> +end Strub_Renm;
> diff --git a/gcc/testsuite/gnat.dg/strub_renm1.adb b/gcc/testsuite/gnat.dg/strub_renm1.adb
> new file mode 100644
> index 0000000000000..a11adbfb5a9d6
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_renm1.adb
> @@ -0,0 +1,32 @@
> +--  { dg-do compile }
> +--  { dg-options "-fstrub=relaxed -fdump-ipa-strub" }
> +
> +procedure Strub_Renm1 is
> +   V : Integer := 0;
> +   pragma Machine_Attribute (V, "strub");
> +
> +   procedure P (X : Integer);
> +   pragma Machine_Attribute (P, "strub", "at-calls");
> +
> +   function F return Integer;
> +
> +   procedure Q (X : Integer) renames P;
> +   pragma Machine_Attribute (Q, "strub", "at-calls");
> +
> +   function G return Integer renames F;
> +   pragma Machine_Attribute (G, "strub", "internal");
> +
> +   procedure P (X : Integer) is null;
> +   function F return Integer is (0);
> +
> +begin
> +   P (F);
> +   Q (G);
> +end Strub_Renm1;
> +
> +--  This is for P; Q is an alias.
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub \[(\]at-calls\[)\]\[)\]" 1 "strub" } }
> +
> +--  This is *not* for G, but for Strub_Renm1.
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub \[(\]wrapped\[)\]\[)\]" 1 "strub" } }
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub \[(\]wrapper\[)\]\[)\]" 1 "strub" } }
> diff --git a/gcc/testsuite/gnat.dg/strub_renm2.adb b/gcc/testsuite/gnat.dg/strub_renm2.adb
> new file mode 100644
> index 0000000000000..c488c20826fdb
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_renm2.adb
> @@ -0,0 +1,32 @@
> +--  { dg-do compile }
> +--  { dg-options "-fstrub=strict -fdump-ipa-strub" }
> +
> +procedure Strub_Renm2 is
> +   V : Integer := 0;
> +   pragma Machine_Attribute (V, "strub");
> +
> +   procedure P (X : Integer);
> +   pragma Machine_Attribute (P, "strub", "at-calls");
> +
> +   function F return Integer;
> +
> +   procedure Q (X : Integer) renames P;
> +   pragma Machine_Attribute (Q, "strub", "at-calls");
> +
> +   type T is access function return Integer;
> +
> +   type TC is access function return Integer;
> +   pragma Machine_Attribute (TC, "strub", "callable");
> +
> +   FCptr : constant TC := TC (T'(F'Access));
> +
> +   function G return Integer renames FCptr.all;
> +   pragma Machine_Attribute (G, "strub", "callable");
> +
> +   procedure P (X : Integer) is null;
> +   function F return Integer is (0);
> +
> +begin
> +   P (F);  -- { dg-error "calling non-.strub." }
> +   Q (G);  -- ok, G is callable.
> +end Strub_Renm2;
> diff --git a/gcc/testsuite/gnat.dg/strub_var.adb b/gcc/testsuite/gnat.dg/strub_var.adb
> new file mode 100644
> index 0000000000000..3d158de28031f
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_var.adb
> @@ -0,0 +1,16 @@
> +--  { dg-do compile }
> +--  { dg-options "-fstrub=strict -fdump-ipa-strubm" }
> +
> +-- We don't read from the automatic variable, but being an automatic
> +--  variable, its presence should be enough for the procedure to get
> +--  strub enabled.
> +
> +with Strub_Attr;
> +procedure Strub_Var is
> +   X : Integer := 0;
> +   pragma Machine_Attribute (X, "strub");
> +begin
> +   X := Strub_Attr.F (0);
> +end Strub_Var;
> +
> +--  { dg-final { scan-ipa-dump-times "\[(\]strub \[(\]internal\[)\]\[)\]" 1 "strubm" } }
> diff --git a/gcc/testsuite/gnat.dg/strub_var1.adb b/gcc/testsuite/gnat.dg/strub_var1.adb
> new file mode 100644
> index 0000000000000..6a504e09198b6
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/strub_var1.adb
> @@ -0,0 +1,20 @@
> +--  { dg-do compile }
> +
> +with Strub_Attr;
> +procedure Strub_Var1 is
> +   type TA  -- { dg-warning "does not apply to elements" }
> +      is array (1..2) of Integer;
> +   pragma Machine_Attribute (TA, "strub");
> +
> +   A : TA := (0, 0);  -- { dg-warning "does not apply to elements" }
> +
> +   type TR is record  -- { dg-warning "does not apply to fields" }
> +      M, N : Integer;
> +   end record;
> +   pragma Machine_Attribute (TR, "strub");
> +
> +   R : TR := (0, 0);
> +
> +begin
> +   A(2) := Strub_Attr.F (A(1));
> +end Strub_Var1;
> diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
> index a30a2de33a106..cefbb86be7bb4 100644
> --- a/gcc/tree-cfg.cc
> +++ b/gcc/tree-cfg.cc
> @@ -5790,6 +5790,7 @@ gimple_verify_flow_info (void)
>         {
>           gimple *stmt = gsi_stmt (gsi);
>
> +         /* Do NOT disregard debug stmts after found_ctrl_stmt.  */
>           if (found_ctrl_stmt)
>             {
>               error ("control flow in the middle of basic block %d",
> diff --git a/gcc/tree-pass.h b/gcc/tree-pass.h
> index 09e6ada5b2f91..36f955a0b37ee 100644
> --- a/gcc/tree-pass.h
> +++ b/gcc/tree-pass.h
> @@ -510,8 +510,9 @@ extern gimple_opt_pass *make_pass_adjust_alignment (gcc::context *ctxt);
>
>  /* IPA Passes */
>  extern simple_ipa_opt_pass *make_pass_ipa_lower_emutls (gcc::context *ctxt);
> -extern simple_ipa_opt_pass
> -                                                             *make_pass_ipa_function_and_variable_visibility (gcc::context *ctxt);
> +extern simple_ipa_opt_pass *make_pass_ipa_function_and_variable_visibility (gcc::context *ctxt);
> +extern simple_ipa_opt_pass *make_pass_ipa_strub_mode (gcc::context *ctxt);
> +extern simple_ipa_opt_pass *make_pass_ipa_strub (gcc::context *ctxt);
>  extern simple_ipa_opt_pass *make_pass_ipa_tree_profile (gcc::context *ctxt);
>  extern simple_ipa_opt_pass *make_pass_ipa_auto_profile (gcc::context *ctxt);
>
> diff --git a/gcc/tree-ssa-ccp.cc b/gcc/tree-ssa-ccp.cc
> index 1a555ae682638..03ff88afadddd 100644
> --- a/gcc/tree-ssa-ccp.cc
> +++ b/gcc/tree-ssa-ccp.cc
> @@ -3073,7 +3073,9 @@ optimize_stack_restore (gimple_stmt_iterator i)
>        if (!callee
>           || !fndecl_built_in_p (callee, BUILT_IN_NORMAL)
>           /* All regular builtins are ok, just obviously not alloca.  */
> -         || ALLOCA_FUNCTION_CODE_P (DECL_FUNCTION_CODE (callee)))
> +         || ALLOCA_FUNCTION_CODE_P (DECL_FUNCTION_CODE (callee))
> +         /* Do not remove stack updates before strub leave.  */
> +         || fndecl_built_in_p (callee, BUILT_IN___STRUB_LEAVE))
>         return NULL_TREE;
>
>        if (fndecl_built_in_p (callee, BUILT_IN_STACK_RESTORE))
> diff --git a/libgcc/Makefile.in b/libgcc/Makefile.in
> index 8dedd10f79a30..d8163c5af9903 100644
> --- a/libgcc/Makefile.in
> +++ b/libgcc/Makefile.in
> @@ -433,6 +433,9 @@ LIB2ADD += enable-execute-stack.c
>  # Control Flow Redundancy hardening out-of-line checker.
>  LIB2ADD += $(srcdir)/hardcfr.c
>
> +# Stack scrubbing infrastructure.
> +LIB2ADD += $(srcdir)/strub.c
> +
>  # While emutls.c has nothing to do with EH, it is in LIB2ADDEH*
>  # instead of LIB2ADD because that's the way to be sure on some targets
>  # (e.g. *-*-darwin*) only one copy of it is linked.
> diff --git a/libgcc/libgcc-std.ver.in b/libgcc/libgcc-std.ver.in
> index de00db647570c..a6b89632cae3e 100644
> --- a/libgcc/libgcc-std.ver.in
> +++ b/libgcc/libgcc-std.ver.in
> @@ -1957,4 +1957,7 @@ GCC_14.0.0 {
>    __PFX__floatbitintsf
>    __PFX__floatbitintdf
>    __PFX__hardcfr_check
> +  __PFX__strub_enter
> +  __PFX__strub_update
> +  __PFX__strub_leave
>  }
> diff --git a/libgcc/libgcc2.h b/libgcc/libgcc2.h
> index 7e6696d7ab14a..750670e8caaf3 100644
> --- a/libgcc/libgcc2.h
> +++ b/libgcc/libgcc2.h
> @@ -554,6 +554,10 @@ extern int __parityDI2 (UDWtype);
>
>  extern void __enable_execute_stack (void *);
>
> +extern void __strub_enter (void **);
> +extern void __strub_update (void**);
> +extern void __strub_leave (void **);
> +
>  #ifndef HIDE_EXPORTS
>  #pragma GCC visibility pop
>  #endif
> diff --git a/libgcc/strub.c b/libgcc/strub.c
> new file mode 100644
> index 0000000000000..b0f990d9deebb
> --- /dev/null
> +++ b/libgcc/strub.c
> @@ -0,0 +1,149 @@
> +/* Stack scrubbing infrastructure
> +   Copyright (C) 2021-2023 Free Software Foundation, Inc.
> +   Contributed by Alexandre Oliva <oliva@adacore.com>
> +
> +This file is part of GCC.
> +
> +GCC is free software; you can redistribute it and/or modify it under
> +the terms of the GNU General Public License as published by the Free
> +Software Foundation; either version 3, or (at your option) any later
> +version.
> +
> +GCC is distributed in the hope that it will be useful, but WITHOUT ANY
> +WARRANTY; without even the implied warranty of MERCHANTABILITY or
> +FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
> +for more details.
> +
> +Under Section 7 of GPL version 3, you are granted additional
> +permissions described in the GCC Runtime Library Exception, version
> +3.1, as published by the Free Software Foundation.
> +
> +You should have received a copy of the GNU General Public License and
> +a copy of the GCC Runtime Library Exception along with this program;
> +see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
> +<http://www.gnu.org/licenses/>.  */
> +
> +#include "tconfig.h"
> +#include "tsystem.h"
> +#include "coretypes.h"
> +#include "tm.h"
> +#include "libgcc_tm.h"
> +#include "libgcc2.h"
> +
> +#if ! STACK_GROWS_DOWNWARD
> +# define TOPS >
> +#else
> +# define TOPS <
> +#endif
> +
> +#define ATTRIBUTE_STRUB_CALLABLE __attribute__ ((__strub__ ("callable")))
> +
> +/* Enter a stack scrubbing context, initializing the watermark to the caller's
> +   stack address.  */
> +void ATTRIBUTE_STRUB_CALLABLE
> +__strub_enter (void **watermark)
> +{
> +  *watermark = __builtin_frame_address (0);
> +}
> +
> +/* Update the watermark within a stack scrubbing context with the current stack
> +   pointer.  */
> +void ATTRIBUTE_STRUB_CALLABLE
> +__strub_update (void **watermark)
> +{
> +  void *sp = __builtin_frame_address (0);
> +
> +  if (sp TOPS *watermark)
> +    *watermark = sp;
> +}
> +
> +#if TARGET_STRUB_USE_DYNAMIC_ARRAY && ! defined TARGET_STRUB_MAY_USE_MEMSET
> +# define TARGET_STRUB_MAY_USE_MEMSET 1
> +#endif
> +
> +#if defined __x86_64__ && __OPTIMIZE__
> +# define TARGET_STRUB_DISABLE_RED_ZONE \
> +  /* __attribute__ ((__target__ ("no-red-zone"))) // not needed when optimizing */
> +#elif !defined RED_ZONE_SIZE || defined __i386__
> +# define TARGET_STRUB_DISABLE_RED_ZONE
> +#endif
> +
> +#ifndef TARGET_STRUB_DISABLE_RED_ZONE
> +/* Dummy function, called to force the caller to not be a leaf function, so
> +   that it can't use the red zone.  */
> +static void ATTRIBUTE_STRUB_CALLABLE
> +__attribute__ ((__noinline__, __noipa__))
> +__strub_dummy_force_no_leaf (void)
> +{
> +}
> +#endif
> +
> +/* Leave a stack scrubbing context, clearing the stack between its top and
> +   *MARK.  */
> +void ATTRIBUTE_STRUB_CALLABLE
> +#if ! TARGET_STRUB_MAY_USE_MEMSET
> +__attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
> +#endif
> +#ifdef TARGET_STRUB_DISABLE_RED_ZONE
> +TARGET_STRUB_DISABLE_RED_ZONE
> +#endif
> +__strub_leave (void **mark)
> +{
> +  void *sp = __builtin_stack_address ();
> +
> +  void **base, **end;
> +#if ! STACK_GROWS_DOWNWARD
> +  base = sp; /* ??? Do we need an offset here?  */
> +  end = *mark;
> +#else
> +  base = *mark;
> +  end = sp; /* ??? Does any platform require an offset here?  */
> +#endif
> +
> +  if (! (base < end))
> +    return;
> +
> +#if TARGET_STRUB_USE_DYNAMIC_ARRAY
> +  /* Compute the length without assuming the pointers are both sufficiently
> +     aligned.  They should be, but pointer differences expected to be exact may
> +     yield unexpected results when the assumption doesn't hold.  Given the
> +     potential security implications, compute the length without that
> +     expectation.  If the pointers are misaligned, we may leave a partial
> +     unscrubbed word behind.  */
> +  ptrdiff_t len = ((char *)end - (char *)base) / sizeof (void *);
> +  /* Allocate a dynamically-sized array covering the desired range, so that we
> +     can safely call memset on it.  */
> +  void *ptr[len];
> +  base = &ptr[0];
> +  end = &ptr[len];
> +#elifndef TARGET_STRUB_DISABLE_RED_ZONE
> +  /* Prevent the use of the red zone, by making this function non-leaf through
> +     an unreachable call that, because of the asm stmt, the compiler will
> +     consider reachable.  */
> +  asm goto ("" : : : : no_leaf);
> +  if (0)
> +    {
> +    no_leaf:
> +      __strub_dummy_force_no_leaf ();
> +      return;
> +    }
> +#endif
> +
> +  /* ldist may turn these loops into a memset (thus the conditional
> +     -fno-tree-loop-distribute-patterns above).  Without the dynamic array
> +     above, that call would likely be unsafe: possibly tail-called, and likely
> +     scribbling over its own stack frame.  */
> +#if ! STACK_GROWS_DOWNWARD
> +  do
> +    *base++ = 0;
> +  while (base < end);
> +  /* Make sure the stack overwrites are not optimized away.  */
> +  asm ("" : : "m" (end[0]));
> +#else
> +  do
> +    *--end = 0;
> +  while (base < end);
> +  /* Make sure the stack overwrites are not optimized away.  */
> +  asm ("" : : "m" (base[0]));
> +#endif
> +}
>
>
> --
> Alexandre Oliva, happy hacker            https://FSFLA.org/blogs/lxo/
>    Free Software Activist                   GNU Toolchain Engineer
> More tolerance and less prejudice are key for inclusion and diversity
> Excluding neuro-others for not behaving ""normal"" is *not* inclusive

  parent reply	other threads:[~2023-12-05  9:05 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <ormtqpsbuc.fsf@lxoliva.fsfla.org>
2021-09-09  7:11 ` [PATCH] " Alexandre Oliva
2022-07-29  6:16   ` [PATCH v2 00/10] Introduce " Alexandre Oliva
2022-07-29  6:24     ` [PATCH v2 01/10] Introduce strub: documentation, and new command-line options Alexandre Oliva
2022-07-29  6:25     ` [PATCH v2 02/10] Introduce strub: torture tests for C and C++ Alexandre Oliva
2022-08-09 13:34       ` Alexandre Oliva
2022-07-29  6:25     ` [PATCH v2 03/10] Introduce strub: non-torture " Alexandre Oliva
2022-07-29  6:26     ` [PATCH v2 04/10] Introduce strub: tests for C++ and Ada Alexandre Oliva
2022-07-29  6:26     ` [PATCH v2 05/10] Introduce strub: builtins and runtime Alexandre Oliva
2022-07-29  6:27     ` [PATCH v2 06/10] Introduce strub: attributes Alexandre Oliva
2022-07-29  6:28     ` [PATCH v2 07/10] Introduce strub: infrastructure interfaces and adjustments Alexandre Oliva
2022-07-29  6:28     ` [PATCH v2 08/10] Introduce strub: strub modes Alexandre Oliva
2022-07-29  6:30     ` [PATCH v2 09/10] Introduce strub: strubm (mode assignment) pass Alexandre Oliva
2022-07-29  6:34     ` [PATCH v2 10/10] Introduce strub: strub pass Alexandre Oliva
2022-07-29  6:36     ` [PATCH v2 00/10] Introduce strub: machine-independent stack scrubbing Alexandre Oliva
2022-10-10  8:48       ` Richard Biener
2022-10-11 11:57         ` Alexandre Oliva
2022-10-11 11:59           ` Richard Biener
2022-10-11 13:33             ` Alexandre Oliva
2022-10-13 11:38               ` Richard Biener
2022-10-13 13:15                 ` Alexandre Oliva
2023-06-16  6:09     ` [PATCH v3] " Alexandre Oliva
2023-06-27 21:28       ` Qing Zhao
2023-06-28  8:20         ` Alexandre Oliva
2023-10-20  6:03       ` [PATCH v4] " Alexandre Oliva
2023-10-26  6:15         ` Alexandre Oliva
2023-11-20 12:40           ` Alexandre Oliva
2023-11-22 14:14             ` Richard Biener
2023-11-23 10:56               ` Alexandre Oliva
2023-11-23 12:05                 ` Richard Biener
2023-11-29  8:53                   ` Alexandre Oliva
2023-11-29 12:48                     ` Richard Biener
2023-11-30  4:13                       ` Alexandre Oliva
2023-11-30 12:00                         ` Richard Biener
2023-12-02 17:56                           ` [PATCH v5] " Alexandre Oliva
2023-12-05  6:25                             ` Alexandre Oliva
2023-12-06  1:04                               ` Alexandre Oliva
2023-12-05  9:01                             ` Richard Biener [this message]
2023-12-06  8:36                             ` Causes to nvptx bootstrap fail: " Tobias Burnus
2023-12-06 11:32                               ` Thomas Schwinge
2023-12-06 22:12                                 ` Alexandre Oliva
2023-12-07  3:33                                   ` [PATCH] strub: enable conditional support Alexandre Oliva
2023-12-07  7:24                                     ` Richard Biener
2023-12-07 16:44                                     ` Thomas Schwinge
2023-12-07 17:52                                       ` [PATCH] Alexandre Oliva
2023-12-08  6:46                                         ` [PATCH] Richard Biener
2023-12-08  9:33                                         ` [PATCH] strub: skip emutls after strubm errors Thomas Schwinge
2023-12-10  9:16                                           ` FX Coudert
2023-12-07  7:21                                   ` Causes to nvptx bootstrap fail: [PATCH v5] Introduce strub: machine-independent stack scrubbing Richard Biener
2023-12-06 10:22                             ` Jan Hubicka
2023-12-07 21:19                               ` Alexandre Oliva
2023-12-07 21:39                               ` Alexandre Oliva
2023-12-09  2:08                                 ` [PATCH] strub: add note on attribute access Alexandre Oliva
2023-12-11  7:26                                   ` Richard Biener
2023-12-12 14:21                                   ` Jan Hubicka
2023-12-11  8:40                             ` [PATCH] testsuite: Disable -fstack-protector* for some strub tests Jakub Jelinek
2023-12-11  8:59                               ` Richard Biener
2023-12-20  8:15                           ` [PATCH FYI] www: new AdaCore-contributed hardening features in gcc 13 and 14 Alexandre Oliva
2023-11-30  5:04                       ` [PATCH v4] Introduce strub: machine-independent stack scrubbing Alexandre Oliva
2023-11-30 11:56                         ` Richard Biener

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