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From: Alexandre Oliva <aoliva@gcc.gnu.org>
To: gcc-cvs@gcc.gnu.org
Subject: [gcc(refs/users/aoliva/heads/testme)] strub: enable conditional
 support
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X-Git-Author: Alexandre Oliva <oliva@adacore.com>
X-Git-Refname: refs/users/aoliva/heads/testme
X-Git-Oldrev: 951a5afea86c7e6b81959108fa2014ceb5d3a612
X-Git-Newrev: 015082195d5223ce14421ba747ebbc4028b0fc84
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Date: Thu,  7 Dec 2023 01:48:08 +0000 (GMT)
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https://gcc.gnu.org/g:015082195d5223ce14421ba747ebbc4028b0fc84

commit 015082195d5223ce14421ba747ebbc4028b0fc84
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Wed Dec 6 19:36:02 2023 -0300

    strub: enable conditional support
    
    Targets that don't expose callee stacks to callers, such as nvptx, as
    well as -fsplit-stack compilations, violate fundamental assumptions of
    the current strub implementation.  This patch enables targets to
    disable strub, and disables it when -fsplit-stack is enabled.
    
    When strub support is disabled, the testsuite will now skip strub
    tests, and libgcc will not build the strub runtime components.
    
    
    for  gcc/ChangeLog
    
            * target.def (have_strub_support_for): New hook.
            * doc/tm.texi.in: Document it.
            * doc/tm.texi: Rebuild.
            * ipa-strub.cc: Include target.h.
            (strub_target_support_p): New.
            (can_strub_p): Call it.  Test for no flag_split_stack.
            (pass_ipa_strub::adjust_at_calls_call): Check for target
            support.
            * config/nvptx/nvptx.cc (TARGET_HAVE_STRUB_SUPPORT_FOR):
            Disable.
            * doc/sourcebuild.texi (strub): Document new effective
            target.
    
    for  gcc/testsuite/ChangeLog
    
            * gcc.dg/strub-split-stack.c: New.
            * gcc.dg/strub-unsupported.c: New.
            * gcc.dg/strub-unsupported-2.c: New.
            * gcc.dg/strub-unsupported-3.c: New.
            * lib/target-supports.exp (check_effective_target_strub): New.
            * c-c++-common/strub-O0.c: Require effective target strub.
            * c-c++-common/strub-O1.c: Likewise.
            * c-c++-common/strub-O2.c: Likewise.
            * c-c++-common/strub-O2fni.c: Likewise.
            * c-c++-common/strub-O3.c: Likewise.
            * c-c++-common/strub-O3fni.c: Likewise.
            * c-c++-common/strub-Og.c: Likewise.
            * c-c++-common/strub-Os.c: Likewise.
            * c-c++-common/strub-all1.c: Likewise.
            * c-c++-common/strub-all2.c: Likewise.
            * c-c++-common/strub-apply1.c: Likewise.
            * c-c++-common/strub-apply2.c: Likewise.
            * c-c++-common/strub-apply3.c: Likewise.
            * c-c++-common/strub-apply4.c: Likewise.
            * c-c++-common/strub-at-calls1.c: Likewise.
            * c-c++-common/strub-at-calls2.c: Likewise.
            * c-c++-common/strub-defer-O1.c: Likewise.
            * c-c++-common/strub-defer-O2.c: Likewise.
            * c-c++-common/strub-defer-O3.c: Likewise.
            * c-c++-common/strub-defer-Os.c: Likewise.
            * c-c++-common/strub-internal1.c: Likewise.
            * c-c++-common/strub-internal2.c: Likewise.
            * c-c++-common/strub-parms1.c: Likewise.
            * c-c++-common/strub-parms2.c: Likewise.
            * c-c++-common/strub-parms3.c: Likewise.
            * c-c++-common/strub-relaxed1.c: Likewise.
            * c-c++-common/strub-relaxed2.c: Likewise.
            * c-c++-common/strub-short-O0-exc.c: Likewise.
            * c-c++-common/strub-short-O0.c: Likewise.
            * c-c++-common/strub-short-O1.c: Likewise.
            * c-c++-common/strub-short-O2.c: Likewise.
            * c-c++-common/strub-short-O3.c: Likewise.
            * c-c++-common/strub-short-Os.c: Likewise.
            * c-c++-common/strub-strict1.c: Likewise.
            * c-c++-common/strub-strict2.c: Likewise.
            * c-c++-common/strub-tail-O1.c: Likewise.
            * c-c++-common/strub-tail-O2.c: Likewise.
            * c-c++-common/strub-var1.c: Likewise.
            * c-c++-common/torture/strub-callable1.c: Likewise.
            * c-c++-common/torture/strub-callable2.c: Likewise.
            * c-c++-common/torture/strub-const1.c: Likewise.
            * c-c++-common/torture/strub-const2.c: Likewise.
            * c-c++-common/torture/strub-const3.c: Likewise.
            * c-c++-common/torture/strub-const4.c: Likewise.
            * c-c++-common/torture/strub-data1.c: Likewise.
            * c-c++-common/torture/strub-data2.c: Likewise.
            * c-c++-common/torture/strub-data3.c: Likewise.
            * c-c++-common/torture/strub-data4.c: Likewise.
            * c-c++-common/torture/strub-data5.c: Likewise.
            * c-c++-common/torture/strub-indcall1.c: Likewise.
            * c-c++-common/torture/strub-indcall2.c: Likewise.
            * c-c++-common/torture/strub-indcall3.c: Likewise.
            * c-c++-common/torture/strub-inlinable1.c: Likewise.
            * c-c++-common/torture/strub-inlinable2.c: Likewise.
            * c-c++-common/torture/strub-ptrfn1.c: Likewise.
            * c-c++-common/torture/strub-ptrfn2.c: Likewise.
            * c-c++-common/torture/strub-ptrfn3.c: Likewise.
            * c-c++-common/torture/strub-ptrfn4.c: Likewise.
            * c-c++-common/torture/strub-pure1.c: Likewise.
            * c-c++-common/torture/strub-pure2.c: Likewise.
            * c-c++-common/torture/strub-pure3.c: Likewise.
            * c-c++-common/torture/strub-pure4.c: Likewise.
            * c-c++-common/torture/strub-run1.c: Likewise.
            * c-c++-common/torture/strub-run2.c: Likewise.
            * c-c++-common/torture/strub-run3.c: Likewise.
            * c-c++-common/torture/strub-run4.c: Likewise.
            * c-c++-common/torture/strub-run4c.c: Likewise.
            * c-c++-common/torture/strub-run4d.c: Likewise.
            * c-c++-common/torture/strub-run4i.c: Likewise.
            * g++.dg/strub-run1.C: Likewise.
            * g++.dg/torture/strub-init1.C: Likewise.
            * g++.dg/torture/strub-init2.C: Likewise.
            * g++.dg/torture/strub-init3.C: Likewise.
            * gnat.dg/strub_attr.adb: Likewise.
            * gnat.dg/strub_ind.adb: Likewise.
            * gnat.dg/strub_access.adb: Likewise.
            * gnat.dg/strub_access1.adb: Likewise.
            * gnat.dg/strub_disp.adb: Likewise.
            * gnat.dg/strub_disp1.adb: Likewise.
            * gnat.dg/strub_ind1.adb: Likewise.
            * gnat.dg/strub_ind2.adb: Likewise.
            * gnat.dg/strub_intf.adb: Likewise.
            * gnat.dg/strub_intf1.adb: Likewise.
            * gnat.dg/strub_intf2.adb: Likewise.
            * gnat.dg/strub_renm.adb: Likewise.
            * gnat.dg/strub_renm1.adb: Likewise.
            * gnat.dg/strub_renm2.adb: Likewise.
            * gnat.dg/strub_var.adb: Likewise.
            * gnat.dg/strub_var1.adb: Likewise.
    
    for  libgcc/ChangeLog
    
            * configure.ac: Check for strub support.
            * configure: Rebuilt.
            * Makefile.in: Compile strub.c conditionally.

Diff:
---
 gcc/config/nvptx/nvptx.cc                          |  3 ++
 gcc/doc/sourcebuild.texi                           |  3 ++
 gcc/doc/tm.texi                                    |  6 +++
 gcc/doc/tm.texi.in                                 |  2 +
 gcc/ipa-strub.cc                                   | 54 +++++++++++++++++++++-
 gcc/target.def                                     |  8 ++++
 gcc/testsuite/c-c++-common/strub-O0.c              |  1 +
 gcc/testsuite/c-c++-common/strub-O1.c              |  1 +
 gcc/testsuite/c-c++-common/strub-O2.c              |  1 +
 gcc/testsuite/c-c++-common/strub-O2fni.c           |  1 +
 gcc/testsuite/c-c++-common/strub-O3.c              |  1 +
 gcc/testsuite/c-c++-common/strub-O3fni.c           |  1 +
 gcc/testsuite/c-c++-common/strub-Og.c              |  1 +
 gcc/testsuite/c-c++-common/strub-Os.c              |  1 +
 gcc/testsuite/c-c++-common/strub-all1.c            |  1 +
 gcc/testsuite/c-c++-common/strub-all2.c            |  1 +
 gcc/testsuite/c-c++-common/strub-apply1.c          |  1 +
 gcc/testsuite/c-c++-common/strub-apply2.c          |  1 +
 gcc/testsuite/c-c++-common/strub-apply3.c          |  1 +
 gcc/testsuite/c-c++-common/strub-apply4.c          |  1 +
 gcc/testsuite/c-c++-common/strub-at-calls1.c       |  1 +
 gcc/testsuite/c-c++-common/strub-at-calls2.c       |  1 +
 gcc/testsuite/c-c++-common/strub-defer-O1.c        |  1 +
 gcc/testsuite/c-c++-common/strub-defer-O2.c        |  1 +
 gcc/testsuite/c-c++-common/strub-defer-O3.c        |  1 +
 gcc/testsuite/c-c++-common/strub-defer-Os.c        |  1 +
 gcc/testsuite/c-c++-common/strub-internal1.c       |  1 +
 gcc/testsuite/c-c++-common/strub-internal2.c       |  1 +
 gcc/testsuite/c-c++-common/strub-parms1.c          |  1 +
 gcc/testsuite/c-c++-common/strub-parms2.c          |  1 +
 gcc/testsuite/c-c++-common/strub-parms3.c          |  1 +
 gcc/testsuite/c-c++-common/strub-relaxed1.c        |  1 +
 gcc/testsuite/c-c++-common/strub-relaxed2.c        |  1 +
 gcc/testsuite/c-c++-common/strub-short-O0-exc.c    |  1 +
 gcc/testsuite/c-c++-common/strub-short-O0.c        |  1 +
 gcc/testsuite/c-c++-common/strub-short-O1.c        |  1 +
 gcc/testsuite/c-c++-common/strub-short-O2.c        |  1 +
 gcc/testsuite/c-c++-common/strub-short-O3.c        |  1 +
 gcc/testsuite/c-c++-common/strub-short-Os.c        |  1 +
 gcc/testsuite/c-c++-common/strub-split-stack.c     | 10 ++++
 gcc/testsuite/c-c++-common/strub-strict1.c         |  1 +
 gcc/testsuite/c-c++-common/strub-strict2.c         |  1 +
 gcc/testsuite/c-c++-common/strub-tail-O1.c         |  1 +
 gcc/testsuite/c-c++-common/strub-tail-O2.c         |  1 +
 gcc/testsuite/c-c++-common/strub-unsupported-2.c   | 13 ++++++
 gcc/testsuite/c-c++-common/strub-unsupported-3.c   | 18 ++++++++
 gcc/testsuite/c-c++-common/strub-unsupported.c     | 21 +++++++++
 gcc/testsuite/c-c++-common/strub-var1.c            |  1 +
 .../c-c++-common/torture/strub-callable1.c         |  1 +
 .../c-c++-common/torture/strub-callable2.c         |  1 +
 gcc/testsuite/c-c++-common/torture/strub-const1.c  |  1 +
 gcc/testsuite/c-c++-common/torture/strub-const2.c  |  1 +
 gcc/testsuite/c-c++-common/torture/strub-const3.c  |  1 +
 gcc/testsuite/c-c++-common/torture/strub-const4.c  |  1 +
 gcc/testsuite/c-c++-common/torture/strub-data1.c   |  1 +
 gcc/testsuite/c-c++-common/torture/strub-data2.c   |  1 +
 gcc/testsuite/c-c++-common/torture/strub-data3.c   |  1 +
 gcc/testsuite/c-c++-common/torture/strub-data4.c   |  1 +
 gcc/testsuite/c-c++-common/torture/strub-data5.c   |  1 +
 .../c-c++-common/torture/strub-indcall1.c          |  1 +
 .../c-c++-common/torture/strub-indcall2.c          |  1 +
 .../c-c++-common/torture/strub-indcall3.c          |  1 +
 .../c-c++-common/torture/strub-inlinable1.c        |  1 +
 .../c-c++-common/torture/strub-inlinable2.c        |  1 +
 gcc/testsuite/c-c++-common/torture/strub-ptrfn1.c  |  1 +
 gcc/testsuite/c-c++-common/torture/strub-ptrfn2.c  |  1 +
 gcc/testsuite/c-c++-common/torture/strub-ptrfn3.c  |  1 +
 gcc/testsuite/c-c++-common/torture/strub-ptrfn4.c  |  1 +
 gcc/testsuite/c-c++-common/torture/strub-pure1.c   |  1 +
 gcc/testsuite/c-c++-common/torture/strub-pure2.c   |  1 +
 gcc/testsuite/c-c++-common/torture/strub-pure3.c   |  1 +
 gcc/testsuite/c-c++-common/torture/strub-pure4.c   |  1 +
 gcc/testsuite/c-c++-common/torture/strub-run1.c    |  1 +
 gcc/testsuite/c-c++-common/torture/strub-run2.c    |  1 +
 gcc/testsuite/c-c++-common/torture/strub-run3.c    |  1 +
 gcc/testsuite/c-c++-common/torture/strub-run4.c    |  1 +
 gcc/testsuite/c-c++-common/torture/strub-run4c.c   |  1 +
 gcc/testsuite/c-c++-common/torture/strub-run4d.c   |  1 +
 gcc/testsuite/c-c++-common/torture/strub-run4i.c   |  1 +
 gcc/testsuite/g++.dg/strub-run1.C                  |  1 +
 gcc/testsuite/g++.dg/torture/strub-init1.C         |  1 +
 gcc/testsuite/g++.dg/torture/strub-init2.C         |  1 +
 gcc/testsuite/g++.dg/torture/strub-init3.C         |  1 +
 gcc/testsuite/gnat.dg/strub_access.adb             |  1 +
 gcc/testsuite/gnat.dg/strub_access1.adb            |  1 +
 gcc/testsuite/gnat.dg/strub_attr.adb               |  1 +
 gcc/testsuite/gnat.dg/strub_disp.adb               |  1 +
 gcc/testsuite/gnat.dg/strub_disp1.adb              |  1 +
 gcc/testsuite/gnat.dg/strub_ind.adb                |  1 +
 gcc/testsuite/gnat.dg/strub_ind1.adb               |  1 +
 gcc/testsuite/gnat.dg/strub_ind2.adb               |  1 +
 gcc/testsuite/gnat.dg/strub_intf.adb               |  1 +
 gcc/testsuite/gnat.dg/strub_intf1.adb              |  1 +
 gcc/testsuite/gnat.dg/strub_intf2.adb              |  1 +
 gcc/testsuite/gnat.dg/strub_renm.adb               |  1 +
 gcc/testsuite/gnat.dg/strub_renm1.adb              |  1 +
 gcc/testsuite/gnat.dg/strub_renm2.adb              |  1 +
 gcc/testsuite/gnat.dg/strub_var.adb                |  1 +
 gcc/testsuite/gnat.dg/strub_var1.adb               |  1 +
 gcc/testsuite/lib/target-supports.exp              |  7 +++
 libgcc/Makefile.in                                 |  2 +-
 libgcc/configure                                   | 26 +++++++++++
 libgcc/configure.ac                                | 13 ++++++
 103 files changed, 272 insertions(+), 3 deletions(-)

diff --git a/gcc/config/nvptx/nvptx.cc b/gcc/config/nvptx/nvptx.cc
index ae20802c879..3fb1deb70fd 100644
--- a/gcc/config/nvptx/nvptx.cc
+++ b/gcc/config/nvptx/nvptx.cc
@@ -7789,6 +7789,9 @@ nvptx_asm_output_def_from_decls (FILE *stream, tree name, tree value)
 #undef TARGET_LIBC_HAS_FUNCTION
 #define TARGET_LIBC_HAS_FUNCTION nvptx_libc_has_function
 
+#undef TARGET_HAVE_STRUB_SUPPORT_FOR
+#define TARGET_HAVE_STRUB_SUPPORT_FOR hook_bool_tree_false
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 #include "gt-nvptx.h"
diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi
index c9909026854..26a7e9c3507 100644
--- a/gcc/doc/sourcebuild.texi
+++ b/gcc/doc/sourcebuild.texi
@@ -2983,6 +2983,9 @@ Target supports statically linking @samp{libgfortran}.
 @item string_merging
 Target supports merging string constants at link time.
 
+@item strub
+Target supports attribute @code{strub} for stack scrubbing.
+
 @item ucn
 Target supports compiling and assembling UCN.
 
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 89a1735dd79..768ada0af52 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -3450,6 +3450,12 @@ in DWARF 2 debug information.  The default is zero.  A different value
 may reduce the size of debug information on some ports.
 @end defmac
 
+@deftypefn {Target Hook} bool TARGET_HAVE_STRUB_SUPPORT_FOR (tree)
+Returns true if the target supports stack scrubbing for the given function
+or type, otherwise return false.  The default implementation always returns
+true.
+@end deftypefn
+
 @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.
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index ebc1d3de5ca..4fe0805394e 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -2686,6 +2686,8 @@ in DWARF 2 debug information.  The default is zero.  A different value
 may reduce the size of debug information on some ports.
 @end defmac
 
+@hook TARGET_HAVE_STRUB_SUPPORT_FOR
+
 @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.
diff --git a/gcc/ipa-strub.cc b/gcc/ipa-strub.cc
index 293bec132b8..2afb7a45575 100644
--- a/gcc/ipa-strub.cc
+++ b/gcc/ipa-strub.cc
@@ -60,6 +60,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "ipa-strub.h"
 #include "symtab-thunks.h"
 #include "attr-fnspec.h"
+#include "target.h"
 
 /* This file introduces two passes that, together, implement
    machine-independent stack scrubbing, strub for short.  It arranges
@@ -631,17 +632,60 @@ strub_always_inline_p (cgraph_node *node)
   return lookup_attribute ("always_inline", DECL_ATTRIBUTES (node->decl));
 }
 
+/* Return TRUE iff the target has strub support for T, a function
+   decl, or a type used in an indirect call, and optionally REPORT the
+   reasons for ineligibility.  If T is a type and error REPORTing is
+   enabled, the LOCation (of the indirect call) should be provided.  */
+static inline bool
+strub_target_support_p (tree t, bool report = false,
+			location_t loc = UNKNOWN_LOCATION)
+{
+  bool result = true;
+
+  if (!targetm.have_strub_support_for (t))
+    {
+      result = false;
+
+      if (!report)
+	return result;
+
+      if (DECL_P (t))
+	sorry_at (DECL_SOURCE_LOCATION (t),
+		  "%qD is not eligible for %<strub%>"
+		  " on the target system", t);
+      else
+	sorry_at (loc,
+		  "unsupported %<strub%> call"
+		  " on the target system");
+    }
+
+  return result;
+}
+
 /* 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;
+  bool result = strub_target_support_p (node->decl, report);
 
-  if (!report && strub_always_inline_p (node))
+  if (!report && (!result || strub_always_inline_p (node)))
     return result;
 
+  if (flag_split_stack)
+    {
+      result = false;
+
+      if (!report)
+	return result;
+
+      sorry_at (DECL_SOURCE_LOCATION (node->decl),
+		"%qD is not eligible for %<strub%>"
+		" because %<-fsplit-stack%> is enabled",
+		node->decl);
+    }
+
   if (lookup_attribute ("noipa", DECL_ATTRIBUTES (node->decl)))
     {
       result = false;
@@ -2417,6 +2461,12 @@ pass_ipa_strub::adjust_at_calls_call (cgraph_edge *e, int named_args,
 			 && (TREE_TYPE (gimple_call_arg (ocall, named_args))
 			     == get_pwmt ())));
 
+  tree tsup;
+  if (!(tsup = gimple_call_fndecl (ocall)))
+    tsup = TREE_TYPE (TREE_TYPE (gimple_call_fn (ocall)));
+  if (!strub_target_support_p (tsup, true, gimple_location (ocall)))
+    return;
+
   /* 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.  */
diff --git a/gcc/target.def b/gcc/target.def
index 52b83e091b9..08218f3a42a 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -4457,6 +4457,14 @@ otherwise return false.  The default implementation always returns true.",
  bool, (void),
  hook_bool_void_true)
 
+DEFHOOK
+(have_strub_support_for,
+ "Returns true if the target supports stack scrubbing for the given function\n\
+or type, otherwise return false.  The default implementation always returns\n\
+true.",
+ bool, (tree),
+ hook_bool_tree_true)
+
 DEFHOOK
 (have_speculation_safe_value,
 "This hook is used to determine the level of target support for\n\
diff --git a/gcc/testsuite/c-c++-common/strub-O0.c b/gcc/testsuite/c-c++-common/strub-O0.c
index c7a79a6ea0d..f0a3f7b4c6f 100644
--- a/gcc/testsuite/c-c++-common/strub-O0.c
+++ b/gcc/testsuite/c-c++-common/strub-O0.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O0 -fstrub=strict -fdump-rtl-expand" } */
+/* { dg-require-effective-target strub } */
 
 /* At -O0, none of the strub builtins are expanded inline.  */
 
diff --git a/gcc/testsuite/c-c++-common/strub-O1.c b/gcc/testsuite/c-c++-common/strub-O1.c
index 96285c975d9..50403426b18 100644
--- a/gcc/testsuite/c-c++-common/strub-O1.c
+++ b/gcc/testsuite/c-c++-common/strub-O1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O1 -fstrub=strict -fdump-rtl-expand" } */
+/* { dg-require-effective-target strub } */
 
 /* At -O1, without -fno-inline, we fully expand enter, but neither update nor
    leave.  */
diff --git a/gcc/testsuite/c-c++-common/strub-O2.c b/gcc/testsuite/c-c++-common/strub-O2.c
index 8edc0d8aa13..37e02998e31 100644
--- a/gcc/testsuite/c-c++-common/strub-O2.c
+++ b/gcc/testsuite/c-c++-common/strub-O2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O2 -fstrub=strict -fdump-rtl-expand" } */
+/* { dg-require-effective-target strub } */
 
 /* At -O2, without -fno-inline, we fully expand enter and update, and add a test
    around the leave call.  */
diff --git a/gcc/testsuite/c-c++-common/strub-O2fni.c b/gcc/testsuite/c-c++-common/strub-O2fni.c
index c6d900cf3c4..905e2c6b2ff 100644
--- a/gcc/testsuite/c-c++-common/strub-O2fni.c
+++ b/gcc/testsuite/c-c++-common/strub-O2fni.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O2 -fstrub=strict -fdump-rtl-expand -fno-inline" } */
+/* { dg-require-effective-target strub } */
 
 /* With -fno-inline, none of the strub builtins are inlined.  */
 
diff --git a/gcc/testsuite/c-c++-common/strub-O3.c b/gcc/testsuite/c-c++-common/strub-O3.c
index 33ee465e51c..3bbf132bdf1 100644
--- a/gcc/testsuite/c-c++-common/strub-O3.c
+++ b/gcc/testsuite/c-c++-common/strub-O3.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O3 -fstrub=strict -fdump-rtl-expand" } */
+/* { dg-require-effective-target strub } */
 
 int __attribute__ ((__strub__)) var;
 
diff --git a/gcc/testsuite/c-c++-common/strub-O3fni.c b/gcc/testsuite/c-c++-common/strub-O3fni.c
index 2936f82079e..c46fce38e5c 100644
--- a/gcc/testsuite/c-c++-common/strub-O3fni.c
+++ b/gcc/testsuite/c-c++-common/strub-O3fni.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O3 -fstrub=strict -fdump-rtl-expand -fno-inline" } */
+/* { dg-require-effective-target strub } */
 
 /* With -fno-inline, none of the strub builtins are inlined.  */
 
diff --git a/gcc/testsuite/c-c++-common/strub-Og.c b/gcc/testsuite/c-c++-common/strub-Og.c
index 479746e57d8..3b8eb19765c 100644
--- a/gcc/testsuite/c-c++-common/strub-Og.c
+++ b/gcc/testsuite/c-c++-common/strub-Og.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-Og -fstrub=strict -fdump-rtl-expand" } */
+/* { dg-require-effective-target strub } */
 
 /* At -Og, without -fno-inline, we fully expand enter, but neither update nor
    leave.  */
diff --git a/gcc/testsuite/c-c++-common/strub-Os.c b/gcc/testsuite/c-c++-common/strub-Os.c
index 2241d4ea07f..8cfb253d676 100644
--- a/gcc/testsuite/c-c++-common/strub-Os.c
+++ b/gcc/testsuite/c-c++-common/strub-Os.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-Os -fstrub=strict -fdump-rtl-expand" } */
+/* { dg-require-effective-target strub } */
 
 /* 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
diff --git a/gcc/testsuite/c-c++-common/strub-all1.c b/gcc/testsuite/c-c++-common/strub-all1.c
index a322bcc5da6..2037f681f29 100644
--- a/gcc/testsuite/c-c++-common/strub-all1.c
+++ b/gcc/testsuite/c-c++-common/strub-all1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=all -fdump-ipa-strubm -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* h becomes STRUB_CALLABLE, rather than STRUB_INLINABLE, because of the
    strub-enabling -fstrub flag, and gets inlined before pass_ipa_strub.  */
diff --git a/gcc/testsuite/c-c++-common/strub-all2.c b/gcc/testsuite/c-c++-common/strub-all2.c
index db60026d0e0..c026e7d9d28 100644
--- a/gcc/testsuite/c-c++-common/strub-all2.c
+++ b/gcc/testsuite/c-c++-common/strub-all2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=all -fdump-ipa-strubm -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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
diff --git a/gcc/testsuite/c-c++-common/strub-apply1.c b/gcc/testsuite/c-c++-common/strub-apply1.c
index 2f462adc1ef..3edc89c54ee 100644
--- a/gcc/testsuite/c-c++-common/strub-apply1.c
+++ b/gcc/testsuite/c-c++-common/strub-apply1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict" } */
+/* { dg-require-effective-target strub } */
 
 void __attribute__ ((__strub__ ("callable")))
 apply_function (void *args)
diff --git a/gcc/testsuite/c-c++-common/strub-apply2.c b/gcc/testsuite/c-c++-common/strub-apply2.c
index a5d7551f5da..838fc752734 100644
--- a/gcc/testsuite/c-c++-common/strub-apply2.c
+++ b/gcc/testsuite/c-c++-common/strub-apply2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict" } */
+/* { dg-require-effective-target strub } */
 
 extern void __attribute__ ((__strub__))
 apply_function (void *args);
diff --git a/gcc/testsuite/c-c++-common/strub-apply3.c b/gcc/testsuite/c-c++-common/strub-apply3.c
index 64422a0d1e8..0206e4d930e 100644
--- a/gcc/testsuite/c-c++-common/strub-apply3.c
+++ b/gcc/testsuite/c-c++-common/strub-apply3.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict" } */
+/* { dg-require-effective-target strub } */
 
 void __attribute__ ((__strub__))
 apply_function (void *args)
diff --git a/gcc/testsuite/c-c++-common/strub-apply4.c b/gcc/testsuite/c-c++-common/strub-apply4.c
index 15ffaa031b8..e82504728b2 100644
--- a/gcc/testsuite/c-c++-common/strub-apply4.c
+++ b/gcc/testsuite/c-c++-common/strub-apply4.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O2 -fstrub=strict -fdump-ipa-strubm" } */
+/* { dg-require-effective-target strub } */
 
 /* Check that implicit enabling of strub mode selects internal strub when the
    function uses __builtin_apply_args, that prevents the optimization to
diff --git a/gcc/testsuite/c-c++-common/strub-at-calls1.c b/gcc/testsuite/c-c++-common/strub-at-calls1.c
index b70843b4215..a20acc0a48a 100644
--- a/gcc/testsuite/c-c++-common/strub-at-calls1.c
+++ b/gcc/testsuite/c-c++-common/strub-at-calls1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=at-calls -fdump-ipa-strubm -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* h becomes STRUB_CALLABLE, rather than STRUB_INLINABLE, because of the
    strub-enabling -fstrub flag, and gets inlined before pass_ipa_strub.  */
diff --git a/gcc/testsuite/c-c++-common/strub-at-calls2.c b/gcc/testsuite/c-c++-common/strub-at-calls2.c
index 97a3988a6b9..7915b33a39a 100644
--- a/gcc/testsuite/c-c++-common/strub-at-calls2.c
+++ b/gcc/testsuite/c-c++-common/strub-at-calls2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=at-calls -fdump-ipa-strubm -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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
diff --git a/gcc/testsuite/c-c++-common/strub-defer-O1.c b/gcc/testsuite/c-c++-common/strub-defer-O1.c
index 3d73431b3dc..3689998b5a3 100644
--- a/gcc/testsuite/c-c++-common/strub-defer-O1.c
+++ b/gcc/testsuite/c-c++-common/strub-defer-O1.c
@@ -1,5 +1,6 @@
 /* { dg-do run } */
 /* { dg-options "-fstrub=strict -O1" } */
+/* { dg-require-effective-target strub } */
 
 /* Check that a strub function called by another strub function does NOT defer
    the strubbing to its caller at -O1.  */
diff --git a/gcc/testsuite/c-c++-common/strub-defer-O2.c b/gcc/testsuite/c-c++-common/strub-defer-O2.c
index fddf3c745e7..9e01949db6b 100644
--- a/gcc/testsuite/c-c++-common/strub-defer-O2.c
+++ b/gcc/testsuite/c-c++-common/strub-defer-O2.c
@@ -1,5 +1,6 @@
 /* { dg-do run } */
 /* { dg-options "-fstrub=strict -O2" } */
+/* { dg-require-effective-target strub } */
 
 /* Check that a strub function called by another strub function does NOT defer
    the strubbing to its caller at -O2.  */
diff --git a/gcc/testsuite/c-c++-common/strub-defer-O3.c b/gcc/testsuite/c-c++-common/strub-defer-O3.c
index 7ebc65b58dd..40ee8edd1e0 100644
--- a/gcc/testsuite/c-c++-common/strub-defer-O3.c
+++ b/gcc/testsuite/c-c++-common/strub-defer-O3.c
@@ -1,5 +1,6 @@
 /* { dg-do run } */
 /* { dg-options "-fstrub=strict -O3" } */
+/* { dg-require-effective-target strub } */
 
 /* Check that a strub function called by another strub function defers the
    strubbing to its caller at -O3.  */
diff --git a/gcc/testsuite/c-c++-common/strub-defer-Os.c b/gcc/testsuite/c-c++-common/strub-defer-Os.c
index fbaf85fe0fa..67ea9f04639 100644
--- a/gcc/testsuite/c-c++-common/strub-defer-Os.c
+++ b/gcc/testsuite/c-c++-common/strub-defer-Os.c
@@ -1,5 +1,6 @@
 /* { dg-do run } */
 /* { dg-options "-fstrub=strict -Os" } */
+/* { dg-require-effective-target strub } */
 
 /* Check that a strub function called by another strub function defers the
    strubbing to its caller at -Os.  */
diff --git a/gcc/testsuite/c-c++-common/strub-internal1.c b/gcc/testsuite/c-c++-common/strub-internal1.c
index e9d7b7b9ee0..d17254904e5 100644
--- a/gcc/testsuite/c-c++-common/strub-internal1.c
+++ b/gcc/testsuite/c-c++-common/strub-internal1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=internal -fdump-ipa-strubm -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* h becomes STRUB_CALLABLE, rather than STRUB_INLINABLE, because of the
    strub-enabling -fstrub flag, and gets inlined before pass_ipa_strub.  */
diff --git a/gcc/testsuite/c-c++-common/strub-internal2.c b/gcc/testsuite/c-c++-common/strub-internal2.c
index 8b8e15a51c7..afc9189701f 100644
--- a/gcc/testsuite/c-c++-common/strub-internal2.c
+++ b/gcc/testsuite/c-c++-common/strub-internal2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=internal -fdump-ipa-strubm -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* g becomes STRUB_INTERNAL, because of the flag.  */
 static void
diff --git a/gcc/testsuite/c-c++-common/strub-parms1.c b/gcc/testsuite/c-c++-common/strub-parms1.c
index 0a4a7539d34..f410b268971 100644
--- a/gcc/testsuite/c-c++-common/strub-parms1.c
+++ b/gcc/testsuite/c-c++-common/strub-parms1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 #include <stdarg.h>
 
diff --git a/gcc/testsuite/c-c++-common/strub-parms2.c b/gcc/testsuite/c-c++-common/strub-parms2.c
index 147171d96d5..6f572115a88 100644
--- a/gcc/testsuite/c-c++-common/strub-parms2.c
+++ b/gcc/testsuite/c-c++-common/strub-parms2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 #include <stdarg.h>
 
diff --git a/gcc/testsuite/c-c++-common/strub-parms3.c b/gcc/testsuite/c-c++-common/strub-parms3.c
index 4e92682895a..7383fea9ce8 100644
--- a/gcc/testsuite/c-c++-common/strub-parms3.c
+++ b/gcc/testsuite/c-c++-common/strub-parms3.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* Check that uses of a strub variable implicitly enables internal strub for
    publicly-visible functions, and causes the same transformations to their
diff --git a/gcc/testsuite/c-c++-common/strub-relaxed1.c b/gcc/testsuite/c-c++-common/strub-relaxed1.c
index e2f9d8aebca..d2b4b52c51e 100644
--- a/gcc/testsuite/c-c++-common/strub-relaxed1.c
+++ b/gcc/testsuite/c-c++-common/strub-relaxed1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=relaxed -fdump-ipa-strubm -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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,
diff --git a/gcc/testsuite/c-c++-common/strub-relaxed2.c b/gcc/testsuite/c-c++-common/strub-relaxed2.c
index 98474435d2e..9e5a8e76b6c 100644
--- a/gcc/testsuite/c-c++-common/strub-relaxed2.c
+++ b/gcc/testsuite/c-c++-common/strub-relaxed2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=relaxed -fdump-ipa-strubm -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* The difference between relaxed and strict in this case is that we accept the
    call from one internal-strub function to another.  */
diff --git a/gcc/testsuite/c-c++-common/strub-short-O0-exc.c b/gcc/testsuite/c-c++-common/strub-short-O0-exc.c
index 1de15342595..aaeba2a2159 100644
--- a/gcc/testsuite/c-c++-common/strub-short-O0-exc.c
+++ b/gcc/testsuite/c-c++-common/strub-short-O0-exc.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O0 -fstrub=strict -fexceptions -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* Check that the expected strub calls are issued.  */
 
diff --git a/gcc/testsuite/c-c++-common/strub-short-O0.c b/gcc/testsuite/c-c++-common/strub-short-O0.c
index f9209c81900..30cbdd819f1 100644
--- a/gcc/testsuite/c-c++-common/strub-short-O0.c
+++ b/gcc/testsuite/c-c++-common/strub-short-O0.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O0 -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* Check that the expected strub calls are issued.  */
 
diff --git a/gcc/testsuite/c-c++-common/strub-short-O1.c b/gcc/testsuite/c-c++-common/strub-short-O1.c
index bed1dcfb54a..911fdfb6db9 100644
--- a/gcc/testsuite/c-c++-common/strub-short-O1.c
+++ b/gcc/testsuite/c-c++-common/strub-short-O1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O1 -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* Check that the expected strub calls are issued.  */
 
diff --git a/gcc/testsuite/c-c++-common/strub-short-O2.c b/gcc/testsuite/c-c++-common/strub-short-O2.c
index 6bf0071f52b..9b23ee3ac33 100644
--- a/gcc/testsuite/c-c++-common/strub-short-O2.c
+++ b/gcc/testsuite/c-c++-common/strub-short-O2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O2 -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* Check that the expected strub calls are issued.  */
 
diff --git a/gcc/testsuite/c-c++-common/strub-short-O3.c b/gcc/testsuite/c-c++-common/strub-short-O3.c
index 4732f515bf7..4b3a8f843ea 100644
--- a/gcc/testsuite/c-c++-common/strub-short-O3.c
+++ b/gcc/testsuite/c-c++-common/strub-short-O3.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O3 -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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
diff --git a/gcc/testsuite/c-c++-common/strub-short-Os.c b/gcc/testsuite/c-c++-common/strub-short-Os.c
index 8d6424c479a..3627a240600 100644
--- a/gcc/testsuite/c-c++-common/strub-short-Os.c
+++ b/gcc/testsuite/c-c++-common/strub-short-Os.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-Os -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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
diff --git a/gcc/testsuite/c-c++-common/strub-split-stack.c b/gcc/testsuite/c-c++-common/strub-split-stack.c
new file mode 100644
index 00000000000..7a030cdb9e9
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/strub-split-stack.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-fsplit-stack" } */
+/* { dg-require-effective-target strub } */
+/* { dg-require-effective-target split_stack } */
+
+void __attribute__ ((__strub__))
+f () {} /* { dg-message "not eligible|requested" } */
+
+void __attribute__ ((__strub__ ("internal")))
+g () {} /* { dg-message "not eligible|requested" } */
diff --git a/gcc/testsuite/c-c++-common/strub-strict1.c b/gcc/testsuite/c-c++-common/strub-strict1.c
index 36852244206..503eb1734e3 100644
--- a/gcc/testsuite/c-c++-common/strub-strict1.c
+++ b/gcc/testsuite/c-c++-common/strub-strict1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strubm" } */
+/* { dg-require-effective-target strub } */
 
 static int __attribute__ ((__strub__)) var;
 
diff --git a/gcc/testsuite/c-c++-common/strub-strict2.c b/gcc/testsuite/c-c++-common/strub-strict2.c
index b4f28883218..3bf1aa30b4a 100644
--- a/gcc/testsuite/c-c++-common/strub-strict2.c
+++ b/gcc/testsuite/c-c++-common/strub-strict2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strubm" } */
+/* { dg-require-effective-target strub } */
 
 static int __attribute__ ((__strub__)) var;
 
diff --git a/gcc/testsuite/c-c++-common/strub-tail-O1.c b/gcc/testsuite/c-c++-common/strub-tail-O1.c
index e48e0610e07..ba4b1623e28 100644
--- a/gcc/testsuite/c-c++-common/strub-tail-O1.c
+++ b/gcc/testsuite/c-c++-common/strub-tail-O1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O1 -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 #include "strub-tail-O2.c"
 
diff --git a/gcc/testsuite/c-c++-common/strub-tail-O2.c b/gcc/testsuite/c-c++-common/strub-tail-O2.c
index 87cda7ab21b..043813b1de4 100644
--- a/gcc/testsuite/c-c++-common/strub-tail-O2.c
+++ b/gcc/testsuite/c-c++-common/strub-tail-O2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O2 -fstrub=strict -fno-exceptions -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* Check that the expected strub calls are issued.
    Tail calls are short-circuited at -O2+.  */
diff --git a/gcc/testsuite/c-c++-common/strub-unsupported-2.c b/gcc/testsuite/c-c++-common/strub-unsupported-2.c
new file mode 100644
index 00000000000..3586f4f679d
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/strub-unsupported-2.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+
+/* Check that, when strub is not supported (so no dg-required-effective-target
+   strub above), we report when pointers to strub functions are called.  This
+   cannot be part of strub-unsupported.c because errors in the strub-mode pass
+   prevent the main strub pass, where errors at calls are detected, from
+   running.  */
+
+void __attribute__ ((__strub__ ("at-calls"))) (*p) (void);
+
+void m () {
+  p (); /* { dg-message "unsupported" "" { target { ! strub } } } */
+}
diff --git a/gcc/testsuite/c-c++-common/strub-unsupported-3.c b/gcc/testsuite/c-c++-common/strub-unsupported-3.c
new file mode 100644
index 00000000000..d6fb4c525c4
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/strub-unsupported-3.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+
+/* Check that, when strub is not supported (so no dg-required-effective-target
+   strub above), we report when strub functions that are not defined are
+   called.  This cannot be part of strub-unsupported-2.c because errors in the
+   strub-mode pass prevent the main strub pass, where errors at calls are
+   detected, from running.  */
+
+extern void __attribute__ ((__strub__))
+s (void); /* { dg-message "not eligible|requested" "" { target { ! strub } } } */
+
+extern void __attribute__ ((__strub__ ("internal")))
+t (void); /* { dg-message "not eligible|requested" "" { target { ! strub } } } */
+
+void m () {
+  s ();
+  t ();
+}
diff --git a/gcc/testsuite/c-c++-common/strub-unsupported.c b/gcc/testsuite/c-c++-common/strub-unsupported.c
new file mode 100644
index 00000000000..cb5c4049495
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/strub-unsupported.c
@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+
+/* Check that, when strub is not supported (so no dg-required-effective-target
+   strub above), we report when strub functions are defined, and when they're
+   called in ways that would require changes.  */
+
+void __attribute__ ((__strub__))
+f (void) {} /* { dg-message "not eligible|requested" "" { target { ! strub } } } */
+
+void __attribute__ ((__strub__ ("internal")))
+g (void) {} /* { dg-message "not eligible|requested" "" { target { ! strub } } } */
+
+/* This only gets an error when called, see strub-unsupported-2.c.  */
+void __attribute__ ((__strub__ ("at-calls"))) (*p) (void);
+
+/* These too, see strub-unsupported-3.c.  */
+extern void __attribute__ ((__strub__))
+s (void);
+
+extern void __attribute__ ((__strub__ ("internal")))
+t (void);
diff --git a/gcc/testsuite/c-c++-common/strub-var1.c b/gcc/testsuite/c-c++-common/strub-var1.c
index eb6250fd39c..67014aa5de8 100644
--- a/gcc/testsuite/c-c++-common/strub-var1.c
+++ b/gcc/testsuite/c-c++-common/strub-var1.c
@@ -1,4 +1,5 @@
 /* { dg-do compile } */
+/* { dg-require-effective-target strub } */
 
 int __attribute__ ((strub)) x;
 float __attribute__ ((strub)) f;
diff --git a/gcc/testsuite/c-c++-common/torture/strub-callable1.c b/gcc/testsuite/c-c++-common/torture/strub-callable1.c
index b5e45ab0525..86dbee6746d 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-callable1.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-callable1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict" } */
+/* { dg-require-effective-target strub } */
 
 /* 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
diff --git a/gcc/testsuite/c-c++-common/torture/strub-callable2.c b/gcc/testsuite/c-c++-common/torture/strub-callable2.c
index 96aa7fe4b07..9da120f6156 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-callable2.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-callable2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict" } */
+/* { dg-require-effective-target strub } */
 
 /* Check that impermissible (cross-strub-context) calls are reported.  */
 
diff --git a/gcc/testsuite/c-c++-common/torture/strub-const1.c b/gcc/testsuite/c-c++-common/torture/strub-const1.c
index 5e956cb1a9b..22056713cce 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-const1.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-const1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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
diff --git a/gcc/testsuite/c-c++-common/torture/strub-const2.c b/gcc/testsuite/c-c++-common/torture/strub-const2.c
index 73d650292df..a105c66d7a9 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-const2.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-const2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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
diff --git a/gcc/testsuite/c-c++-common/torture/strub-const3.c b/gcc/testsuite/c-c++-common/torture/strub-const3.c
index 2584f1f974a..386200c2784 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-const3.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-const3.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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,
diff --git a/gcc/testsuite/c-c++-common/torture/strub-const4.c b/gcc/testsuite/c-c++-common/torture/strub-const4.c
index d819f54ec02..817e9fa2118 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-const4.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-const4.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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
diff --git a/gcc/testsuite/c-c++-common/torture/strub-data1.c b/gcc/testsuite/c-c++-common/torture/strub-data1.c
index 7c27a2a1a6d..132ab63ef73 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-data1.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-data1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* The pointed-to data enables strubbing if accessed.  */
 int __attribute__ ((__strub__)) var;
diff --git a/gcc/testsuite/c-c++-common/torture/strub-data2.c b/gcc/testsuite/c-c++-common/torture/strub-data2.c
index e66d903780a..b660702d26e 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-data2.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-data2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 /* The pointer itself is a strub variable, enabling internal strubbing when
    its value is used.  */
diff --git a/gcc/testsuite/c-c++-common/torture/strub-data3.c b/gcc/testsuite/c-c++-common/torture/strub-data3.c
index 5e08e0e58c6..fc44eef6f8f 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-data3.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-data3.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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.  */
diff --git a/gcc/testsuite/c-c++-common/torture/strub-data4.c b/gcc/testsuite/c-c++-common/torture/strub-data4.c
index a818e7a38bb..85e2f59055b 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-data4.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-data4.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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.  */
diff --git a/gcc/testsuite/c-c++-common/torture/strub-data5.c b/gcc/testsuite/c-c++-common/torture/strub-data5.c
index ddb0b5c0543..0a5edac414d 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-data5.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-data5.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict" } */
+/* { dg-require-effective-target strub } */
 
 /* It would be desirable to issue at least warnings for these.  */
 
diff --git a/gcc/testsuite/c-c++-common/torture/strub-indcall1.c b/gcc/testsuite/c-c++-common/torture/strub-indcall1.c
index c165f312f16..988954e7ed6 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-indcall1.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-indcall1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 typedef void __attribute__ ((__strub__)) fntype ();
 fntype (*ptr);
diff --git a/gcc/testsuite/c-c++-common/torture/strub-indcall2.c b/gcc/testsuite/c-c++-common/torture/strub-indcall2.c
index 69fcff8d376..d3ca91389a7 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-indcall2.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-indcall2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 typedef void __attribute__ ((__strub__)) fntype (int, int);
 fntype (*ptr);
diff --git a/gcc/testsuite/c-c++-common/torture/strub-indcall3.c b/gcc/testsuite/c-c++-common/torture/strub-indcall3.c
index ff006224909..89b5979cf7b 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-indcall3.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-indcall3.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target strub } */
 
 typedef void __attribute__ ((__strub__)) fntype (int, int, ...);
 fntype (*ptr);
diff --git a/gcc/testsuite/c-c++-common/torture/strub-inlinable1.c b/gcc/testsuite/c-c++-common/torture/strub-inlinable1.c
index 614b02228ba..4917dda8826 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-inlinable1.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-inlinable1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=relaxed" } */
+/* { dg-require-effective-target strub } */
 
 inline void __attribute__ ((strub ("internal"), always_inline))
 inl_int_ali (void)
diff --git a/gcc/testsuite/c-c++-common/torture/strub-inlinable2.c b/gcc/testsuite/c-c++-common/torture/strub-inlinable2.c
index f9a6b4a16fa..c45903856d4 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-inlinable2.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-inlinable2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=all" } */
+/* { dg-require-effective-target strub } */
 
 #include "strub-inlinable1.c"
 
diff --git a/gcc/testsuite/c-c++-common/torture/strub-ptrfn1.c b/gcc/testsuite/c-c++-common/torture/strub-ptrfn1.c
index b4a7f3992bb..b0d6139f0a8 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-ptrfn1.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-ptrfn1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict" } */
+/* { dg-require-effective-target strub } */
 
 typedef void ft (void);
 typedef void ft2 (int, int);
diff --git a/gcc/testsuite/c-c++-common/torture/strub-ptrfn2.c b/gcc/testsuite/c-c++-common/torture/strub-ptrfn2.c
index ef634d35126..1148c246f20 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-ptrfn2.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-ptrfn2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=relaxed -Wpedantic" } */
+/* { dg-require-effective-target strub } */
 
 /* C++ does not warn about the partial incompatibilities.
 
diff --git a/gcc/testsuite/c-c++-common/torture/strub-ptrfn3.c b/gcc/testsuite/c-c++-common/torture/strub-ptrfn3.c
index e1f179e160e..06a72d86d2c 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-ptrfn3.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-ptrfn3.c
@@ -1,6 +1,7 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=relaxed -Wpedantic -fpermissive" } */
 /* { dg-prune-output "command-line option .-fpermissive." } */
+/* { dg-require-effective-target strub } */
 
 /* See strub-ptrfn2.c.  */
 
diff --git a/gcc/testsuite/c-c++-common/torture/strub-ptrfn4.c b/gcc/testsuite/c-c++-common/torture/strub-ptrfn4.c
index 70b558afad0..83ea1af7056 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-ptrfn4.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-ptrfn4.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=relaxed" } */
+/* { dg-require-effective-target strub } */
 
 /* This is strub-ptrfn2.c without -Wpedantic.
 
diff --git a/gcc/testsuite/c-c++-common/torture/strub-pure1.c b/gcc/testsuite/c-c++-common/torture/strub-pure1.c
index a262a086837..2643136f178 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-pure1.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-pure1.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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.  */
diff --git a/gcc/testsuite/c-c++-common/torture/strub-pure2.c b/gcc/testsuite/c-c++-common/torture/strub-pure2.c
index 4c4bd50c209..8bda129b77d 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-pure2.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-pure2.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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
diff --git a/gcc/testsuite/c-c++-common/torture/strub-pure3.c b/gcc/testsuite/c-c++-common/torture/strub-pure3.c
index ce195c6b1f1..00bcbdd097a 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-pure3.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-pure3.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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.  */
diff --git a/gcc/testsuite/c-c++-common/torture/strub-pure4.c b/gcc/testsuite/c-c++-common/torture/strub-pure4.c
index 75cd54ccb5b..ea7c40e7912 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-pure4.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-pure4.c
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+/* { dg-require-effective-target 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
diff --git a/gcc/testsuite/c-c++-common/torture/strub-run1.c b/gcc/testsuite/c-c++-common/torture/strub-run1.c
index 7458b3fb54d..fdf10042863 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-run1.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-run1.c
@@ -1,5 +1,6 @@
 /* { dg-do run } */
 /* { dg-options "-fstrub=strict" } */
+/* { dg-require-effective-target strub } */
 
 /* 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
diff --git a/gcc/testsuite/c-c++-common/torture/strub-run2.c b/gcc/testsuite/c-c++-common/torture/strub-run2.c
index 5d60a7775f4..1228a665997 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-run2.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-run2.c
@@ -1,5 +1,6 @@
 /* { dg-do run } */
 /* { dg-options "-fstrub=strict" } */
+/* { dg-require-effective-target strub } */
 
 /* 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.  */
diff --git a/gcc/testsuite/c-c++-common/torture/strub-run3.c b/gcc/testsuite/c-c++-common/torture/strub-run3.c
index c2ad710858e..e5047a988f5 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-run3.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-run3.c
@@ -1,6 +1,7 @@
 /* { dg-do run } */
 /* { dg-options "-fstrub=strict" } */
 /* { dg-require-effective-target alloca } */
+/* { dg-require-effective-target strub } */
 
 /* Check that a non-strub function leaves a string behind in the stack, and that
    equivalent strub functions don't.  */
diff --git a/gcc/testsuite/c-c++-common/torture/strub-run4.c b/gcc/testsuite/c-c++-common/torture/strub-run4.c
index 3b36b8e5d68..0e84a4bab80 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-run4.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-run4.c
@@ -1,6 +1,7 @@
 /* { dg-do run } */
 /* { dg-options "-fstrub=all" } */
 /* { dg-require-effective-target alloca } */
+/* { dg-require-effective-target strub } */
 
 /* Check that multi-level, multi-inlined functions still get cleaned up as
    expected, without overwriting temporary stack allocations while they should
diff --git a/gcc/testsuite/c-c++-common/torture/strub-run4c.c b/gcc/testsuite/c-c++-common/torture/strub-run4c.c
index 57f9baf758d..edc98486dc9 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-run4c.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-run4c.c
@@ -1,5 +1,6 @@
 /* { dg-do run } */
 /* { dg-options "-fstrub=at-calls" } */
 /* { dg-require-effective-target alloca } */
+/* { dg-require-effective-target strub } */
 
 #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
index 08de3f1c3b1..487ed08bb66 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-run4d.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-run4d.c
@@ -1,6 +1,7 @@
 /* { dg-do run } */
 /* { dg-options "-fstrub=strict" } */
 /* { dg-require-effective-target alloca } */
+/* { dg-require-effective-target strub } */
 
 #define ATTR_STRUB_AT_CALLS __attribute__ ((__strub__ ("at-calls")))
 
diff --git a/gcc/testsuite/c-c++-common/torture/strub-run4i.c b/gcc/testsuite/c-c++-common/torture/strub-run4i.c
index 459f6886c54..a85447ffabf 100644
--- a/gcc/testsuite/c-c++-common/torture/strub-run4i.c
+++ b/gcc/testsuite/c-c++-common/torture/strub-run4i.c
@@ -1,5 +1,6 @@
 /* { dg-do run } */
 /* { dg-options "-fstrub=internal" } */
 /* { dg-require-effective-target alloca } */
+/* { dg-require-effective-target strub } */
 
 #include "strub-run4.c"
diff --git a/gcc/testsuite/g++.dg/strub-run1.C b/gcc/testsuite/g++.dg/strub-run1.C
index 0d367fb83d0..beb8b811f8f 100644
--- a/gcc/testsuite/g++.dg/strub-run1.C
+++ b/gcc/testsuite/g++.dg/strub-run1.C
@@ -1,5 +1,6 @@
 // { dg-do run }
 // { dg-options "-fstrub=internal" }
+// { dg-require-effective-target strub }
 
 // Check that we don't get extra copies.
 
diff --git a/gcc/testsuite/g++.dg/torture/strub-init1.C b/gcc/testsuite/g++.dg/torture/strub-init1.C
index c226ab10ff6..6ae45fadd70 100644
--- a/gcc/testsuite/g++.dg/torture/strub-init1.C
+++ b/gcc/testsuite/g++.dg/torture/strub-init1.C
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+// { dg-require-effective-target strub }
 
 extern int __attribute__((__strub__)) initializer ();
 
diff --git a/gcc/testsuite/g++.dg/torture/strub-init2.C b/gcc/testsuite/g++.dg/torture/strub-init2.C
index a7911f1fa72..8f4849c7fde 100644
--- a/gcc/testsuite/g++.dg/torture/strub-init2.C
+++ b/gcc/testsuite/g++.dg/torture/strub-init2.C
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+// { dg-require-effective-target strub }
 
 extern int __attribute__((__strub__)) initializer ();
 
diff --git a/gcc/testsuite/g++.dg/torture/strub-init3.C b/gcc/testsuite/g++.dg/torture/strub-init3.C
index 6ebebcd01e8..14f28e3c276 100644
--- a/gcc/testsuite/g++.dg/torture/strub-init3.C
+++ b/gcc/testsuite/g++.dg/torture/strub-init3.C
@@ -1,5 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-fstrub=strict -fdump-ipa-strub" } */
+// { dg-require-effective-target strub }
 
 extern int __attribute__((__strub__)) initializer ();
 
diff --git a/gcc/testsuite/gnat.dg/strub_access.adb b/gcc/testsuite/gnat.dg/strub_access.adb
index 29e6996ecf6..488a2d64afe 100644
--- a/gcc/testsuite/gnat.dg/strub_access.adb
+++ b/gcc/testsuite/gnat.dg/strub_access.adb
@@ -1,5 +1,6 @@
 --  { dg-do compile }
 --  { dg-options "-fstrub=relaxed -fdump-ipa-strubm" }
+--  { dg-require-effective-target strub }
 
 --  The main subprogram doesn't read from the automatic variable, but
 --  being an automatic variable, its presence should be enough for the
diff --git a/gcc/testsuite/gnat.dg/strub_access1.adb b/gcc/testsuite/gnat.dg/strub_access1.adb
index dae47060164..4a8653c4d84 100644
--- a/gcc/testsuite/gnat.dg/strub_access1.adb
+++ b/gcc/testsuite/gnat.dg/strub_access1.adb
@@ -1,5 +1,6 @@
 --  { dg-do compile }
 --  { dg-options "-fstrub=relaxed" }
+--  { dg-require-effective-target strub }
 
 --  Check that we reject 'Access of a strub variable whose type does
 --  not carry a strub modifier.
diff --git a/gcc/testsuite/gnat.dg/strub_attr.adb b/gcc/testsuite/gnat.dg/strub_attr.adb
index 10445d7cf84..eb7826dc990 100644
--- a/gcc/testsuite/gnat.dg/strub_attr.adb
+++ b/gcc/testsuite/gnat.dg/strub_attr.adb
@@ -1,5 +1,6 @@
 --  { dg-do compile }
 --  { dg-options "-fstrub=strict -fdump-ipa-strubm -fdump-ipa-strub" }
+--  { dg-require-effective-target strub }
 
 package body Strub_Attr is
    E : exception;
diff --git a/gcc/testsuite/gnat.dg/strub_disp.adb b/gcc/testsuite/gnat.dg/strub_disp.adb
index 3dbcc4a357c..f23d4675def 100644
--- a/gcc/testsuite/gnat.dg/strub_disp.adb
+++ b/gcc/testsuite/gnat.dg/strub_disp.adb
@@ -1,4 +1,5 @@
 --  { dg-do compile }
+--  { dg-require-effective-target strub }
 
 procedure Strub_Disp is
    package Foo is
diff --git a/gcc/testsuite/gnat.dg/strub_disp1.adb b/gcc/testsuite/gnat.dg/strub_disp1.adb
index 09756a74b7d..9c4c7f69637 100644
--- a/gcc/testsuite/gnat.dg/strub_disp1.adb
+++ b/gcc/testsuite/gnat.dg/strub_disp1.adb
@@ -1,5 +1,6 @@
 --  { dg-do compile }
 --  { dg-options "-fdump-ipa-strub" }
+--  { dg-require-effective-target strub }
 
 -- Check that at-calls dispatching calls are transformed.
 
diff --git a/gcc/testsuite/gnat.dg/strub_ind.adb b/gcc/testsuite/gnat.dg/strub_ind.adb
index da56acaa957..613db69305e 100644
--- a/gcc/testsuite/gnat.dg/strub_ind.adb
+++ b/gcc/testsuite/gnat.dg/strub_ind.adb
@@ -1,5 +1,6 @@
 --  { dg-do compile }
 --  { dg-options "-fstrub=strict" }
+--  { dg-require-effective-target strub }
 
 --  This is essentially the same test as strub_attr.adb, 
 --  but applying attributes to access types as well.
diff --git a/gcc/testsuite/gnat.dg/strub_ind1.adb b/gcc/testsuite/gnat.dg/strub_ind1.adb
index 825e395e681..245b0a830f6 100644
--- a/gcc/testsuite/gnat.dg/strub_ind1.adb
+++ b/gcc/testsuite/gnat.dg/strub_ind1.adb
@@ -1,5 +1,6 @@
 --  { dg-do compile }
 --  { dg-options "-fstrub=strict -fdump-ipa-strubm" }
+--  { dg-require-effective-target strub }
 
 --  This is essentially the same test as strub_attr.adb, 
 --  but with an explicit conversion.
diff --git a/gcc/testsuite/gnat.dg/strub_ind2.adb b/gcc/testsuite/gnat.dg/strub_ind2.adb
index e918b392631..b9bfe50e929 100644
--- a/gcc/testsuite/gnat.dg/strub_ind2.adb
+++ b/gcc/testsuite/gnat.dg/strub_ind2.adb
@@ -1,5 +1,6 @@
 --  { dg-do compile }
 --  { dg-options "-fstrub=strict" }
+--  { dg-require-effective-target strub }
 
 --  This is essentially the same test as strub_attr.adb, 
 --  but with an explicit conversion.
diff --git a/gcc/testsuite/gnat.dg/strub_intf.adb b/gcc/testsuite/gnat.dg/strub_intf.adb
index 8f0212a7586..f43854705d0 100644
--- a/gcc/testsuite/gnat.dg/strub_intf.adb
+++ b/gcc/testsuite/gnat.dg/strub_intf.adb
@@ -1,4 +1,5 @@
 --  { dg-do compile }
+--  { dg-require-effective-target strub }
 
 --  Check that strub mode mismatches between overrider and overridden
 --  subprograms are reported.
diff --git a/gcc/testsuite/gnat.dg/strub_intf1.adb b/gcc/testsuite/gnat.dg/strub_intf1.adb
index bf77321cef7..7a38a4c49ba 100644
--- a/gcc/testsuite/gnat.dg/strub_intf1.adb
+++ b/gcc/testsuite/gnat.dg/strub_intf1.adb
@@ -1,5 +1,6 @@
 --  { dg-do compile }
 --  { dg-options "-fdump-ipa-strub" }
+--  { dg-require-effective-target strub }
 
 -- Check that at-calls dispatching calls to interfaces are transformed.
 
diff --git a/gcc/testsuite/gnat.dg/strub_intf2.adb b/gcc/testsuite/gnat.dg/strub_intf2.adb
index e8880dbc437..7992b7344fb 100644
--- a/gcc/testsuite/gnat.dg/strub_intf2.adb
+++ b/gcc/testsuite/gnat.dg/strub_intf2.adb
@@ -1,4 +1,5 @@
 --  { dg-do compile }
+--  { dg-require-effective-target strub }
 
 --  Check that strub mode mismatches between overrider and overridden
 --  subprograms are reported even when the overriders for an
diff --git a/gcc/testsuite/gnat.dg/strub_renm.adb b/gcc/testsuite/gnat.dg/strub_renm.adb
index 217367e712d..abfb120b514 100644
--- a/gcc/testsuite/gnat.dg/strub_renm.adb
+++ b/gcc/testsuite/gnat.dg/strub_renm.adb
@@ -1,4 +1,5 @@
 --  { dg-do compile }
+--  { dg-require-effective-target strub }
 
 procedure Strub_Renm is
    procedure P (X : Integer);
diff --git a/gcc/testsuite/gnat.dg/strub_renm1.adb b/gcc/testsuite/gnat.dg/strub_renm1.adb
index a11adbfb5a9..68d3230b535 100644
--- a/gcc/testsuite/gnat.dg/strub_renm1.adb
+++ b/gcc/testsuite/gnat.dg/strub_renm1.adb
@@ -1,5 +1,6 @@
 --  { dg-do compile }
 --  { dg-options "-fstrub=relaxed -fdump-ipa-strub" }
+--  { dg-require-effective-target strub }
 
 procedure Strub_Renm1 is
    V : Integer := 0;
diff --git a/gcc/testsuite/gnat.dg/strub_renm2.adb b/gcc/testsuite/gnat.dg/strub_renm2.adb
index c488c20826f..3cb81ea03f7 100644
--- a/gcc/testsuite/gnat.dg/strub_renm2.adb
+++ b/gcc/testsuite/gnat.dg/strub_renm2.adb
@@ -1,5 +1,6 @@
 --  { dg-do compile }
 --  { dg-options "-fstrub=strict -fdump-ipa-strub" }
+--  { dg-require-effective-target strub }
 
 procedure Strub_Renm2 is
    V : Integer := 0;
diff --git a/gcc/testsuite/gnat.dg/strub_var.adb b/gcc/testsuite/gnat.dg/strub_var.adb
index 3d158de2803..7c6affa06d4 100644
--- a/gcc/testsuite/gnat.dg/strub_var.adb
+++ b/gcc/testsuite/gnat.dg/strub_var.adb
@@ -1,5 +1,6 @@
 --  { dg-do compile }
 --  { dg-options "-fstrub=strict -fdump-ipa-strubm" }
+--  { dg-require-effective-target strub }
 
 -- We don't read from the automatic variable, but being an automatic
 --  variable, its presence should be enough for the procedure to get
diff --git a/gcc/testsuite/gnat.dg/strub_var1.adb b/gcc/testsuite/gnat.dg/strub_var1.adb
index 6a504e09198..64b7e65fe9b 100644
--- a/gcc/testsuite/gnat.dg/strub_var1.adb
+++ b/gcc/testsuite/gnat.dg/strub_var1.adb
@@ -1,4 +1,5 @@
 --  { dg-do compile }
+--  { dg-require-effective-target strub }
 
 with Strub_Attr;
 procedure Strub_Var1 is
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index 3fcce6be49d..40a60c198cf 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -1302,6 +1302,13 @@ proc check_stack_check_available { stack_kind } {
     } "$stack_opt"]
 }
 
+# Return 1 if the target supports stack scrubbing.
+proc check_effective_target_strub {} {
+    return [check_no_compiler_messages strub assembly {
+	void __attribute__ ((__strub__)) fn (void) {}
+    } ""]
+}
+
 # Return 1 if compilation with -freorder-blocks-and-partition is error-free
 # for trivial code, 0 otherwise.  As some targets (ARM for example) only
 # warn when -fprofile-use is also supplied we test that combination too.
diff --git a/libgcc/Makefile.in b/libgcc/Makefile.in
index d8163c5af99..3f77283490e 100644
--- a/libgcc/Makefile.in
+++ b/libgcc/Makefile.in
@@ -434,7 +434,7 @@ LIB2ADD += enable-execute-stack.c
 LIB2ADD += $(srcdir)/hardcfr.c
 
 # Stack scrubbing infrastructure.
-LIB2ADD += $(srcdir)/strub.c
+@HAVE_STRUB_SUPPORT@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
diff --git a/libgcc/configure b/libgcc/configure
index cf149209652..567158955a3 100755
--- a/libgcc/configure
+++ b/libgcc/configure
@@ -593,6 +593,7 @@ asm_hidden_op
 extra_parts
 cpu_type
 get_gcc_base_ver
+HAVE_STRUB_SUPPORT
 thread_header
 tm_defines
 tm_file
@@ -5702,6 +5703,31 @@ esac
 
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for strub support" >&5
+$as_echo_n "checking for strub support... " >&6; }
+if ${libgcc_cv_strub_support+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void __attribute__ ((__strub__)) fn (void) {}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  libgcc_cv_strub_support=yes
+else
+  libgcc_cv_strub_support=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libgcc_cv_strub_support" >&5
+$as_echo "$libgcc_cv_strub_support" >&6; }
+if test "x$libgcc_cv_strub_support" != xno; then
+  HAVE_STRUB_SUPPORT=
+else
+  HAVE_STRUB_SUPPORT='# '
+fi
+
+
 # Determine what GCC version number to use in filesystem paths.
 
   get_gcc_base_ver="cat"
diff --git a/libgcc/configure.ac b/libgcc/configure.ac
index 2fc9d5d7c93..9c0e415501a 100644
--- a/libgcc/configure.ac
+++ b/libgcc/configure.ac
@@ -694,6 +694,19 @@ AC_SUBST(tm_defines)
 # Map from thread model to thread header.
 GCC_AC_THREAD_HEADER([$target_thread_file])
 
+AC_CACHE_CHECK([for strub support],
+  [libgcc_cv_strub_support],
+  [AC_COMPILE_IFELSE(
+    [AC_LANG_SOURCE([void __attribute__ ((__strub__)) fn (void) {}])],
+    [libgcc_cv_strub_support=yes],
+    [libgcc_cv_strub_support=no])])
+if test "x$libgcc_cv_strub_support" != xno; then
+  HAVE_STRUB_SUPPORT=
+else
+  HAVE_STRUB_SUPPORT='# '
+fi
+AC_SUBST(HAVE_STRUB_SUPPORT)
+
 # Determine what GCC version number to use in filesystem paths.
 GCC_BASE_VER