[Bug tree-optimization/64950] New: postpone expanding va_arg till pass_stdarg

[Bug tree-optimization/64950] New: postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

            Bug ID: 64950
           Summary: postpone expanding va_arg till pass_stdarg
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vries at gcc dot gnu.org

pass_stdarg optimizes cfun->va_list_gpr/fpr_size by detecting va_args.

However, va_args are expanded at gimple level, so pass_stdarg detects them by
matching what the expansion of va_arg looks like after running through the
passes between gimplification and pass_stdarg.

This is known to be fragile (see f.i. PR 41089). It makes more sense to do the
pass_stdarg optimization while va_arg is still intact. And we want to run
optimization passes before pass_stdarg to be able to eliminate some unwanted
va_args. So, it makes sense to postpone expansion of va_arg untill pass_stdarg.

Michael Matz posted a prototype patch (
https://gcc.gnu.org/ml/gcc/2015-01/msg00304.html ). Latest version availabe at
vries/expand-va-arg-at-pass-stdarg. Testing status of latest version available
at https://gcc.gnu.org/ml/gcc/2015-02/msg00020.html .

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch

--- Comment #1 from vries at gcc dot gnu.org ---
stage 1 patch submitted:
https://gcc.gnu.org/ml/gcc-patches/2015-02/msg01166.html

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2015-02-24
     Ever confirmed|0                           |1

--- Comment #2 from vries at gcc dot gnu.org ---
STATUS:

0001-Disable-lang_hooks.gimplify_expr-in-free_lang_data.patch
OK for stage1: https://gcc.gnu.org/ml/gcc-patches/2015-02/msg01182.html

0002-Add-gimple_find_sub_bbs.patch
OK for stage1: https://gcc.gnu.org/ml/gcc-patches/2015-02/msg01183.html
Updated with comment: https://gcc.gnu.org/ml/gcc-patches/2015-02/msg01330.html

0003-Factor-optimize_va_list_gpr_fpr_size-out-of-pass_std.patch
OK for stage1: https://gcc.gnu.org/ml/gcc-patches/2015-02/msg01184.html

0004-Handle-internal_fn-in-operand_equal_p.patch
OK for stage1: https://gcc.gnu.org/ml/gcc-patches/2015-02/msg01408.html

0005-Postpone-expanding-va_arg-until-pass_stdarg.patch
Submitted for stage1: https://gcc.gnu.org/ml/gcc-patches/2015-02/msg01332.html

0006-Set-PROP_gimple_lva-for-functions-without-IFN_VA_ARG.patch
Submitted for stage1: https://gcc.gnu.org/ml/gcc-patches/2015-02/msg01402.html

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

--- Comment #3 from vries at gcc dot gnu.org ---
> 0005-Postpone-expanding-va_arg-until-pass_stdarg.patch
> Submitted for stage1:
> https://gcc.gnu.org/ml/gcc-patches/2015-02/msg01332.html

Pinged: https://gcc.gnu.org/ml/gcc-patches/2015-03/msg00570.html

> 0006-Set-PROP_gimple_lva-for-functions-without-IFN_VA_ARG.patch
> Submitted for stage1:
> https://gcc.gnu.org/ml/gcc-patches/2015-02/msg01402.html

Pinged: https://gcc.gnu.org/ml/gcc-patches/2015-03/msg00571.html

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

--- Comment #4 from vries at gcc dot gnu.org ---
ping^2:
- https://gcc.gnu.org/ml/gcc-patches/2015-04/msg00796.html
- https://gcc.gnu.org/ml/gcc-patches/2015-04/msg00797.html

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

--- Comment #5 from vries at gcc dot gnu.org ---
https://gcc.gnu.org/ml/gcc-cvs/2015-04/msg00371.html :

Author: vries
Date: Fri Apr 17 09:26:59 2015
New Revision: 222173

URL: https://gcc.gnu.org/viewcvs?rev=222173&root=gcc&view=rev
Log:
Postpone expanding va_arg until pass_stdarg

2015-04-17  Tom de Vries  <tom@codesourcery.com>
        Michael Matz  <matz@suse.de>

    * gimple-iterator.c (update_modified_stmts): Remove static.
    * gimple-iterator.h (update_modified_stmts): Declare.
    * gimplify.c (gimplify_modify_expr): Handle IFN_VA_ARG.
    (gimplify_va_arg_internal): New function.
    (gimplify_va_arg_expr): Use IFN_VA_ARG.
    * gimplify.h (gimplify_va_arg_internal): Declare.
    * internal-fn.c (expand_VA_ARG): New unreachable function.
    * internal-fn.def (VA_ARG): New DEF_INTERNAL_FN.
    * tree-stdarg.c (gimple_call_ifn_va_arg_p, expand_ifn_va_arg_1)
    (expand_ifn_va_arg): New function.
    (pass_data_stdarg): Add PROP_gimple_lva to properties_provided field.
    (pass_stdarg::execute): Call expand_ifn_va_arg.
    (pass_data_lower_vaarg): New pass_data.
    (pass_lower_vaarg): New gimple_opt_pass.
    (pass_lower_vaarg::gate, pass_lower_vaarg::execute)
    (make_pass_lower_vaarg): New function.
    * cfgexpand.c (pass_data_expand): Add PROP_gimple_lva to
    properties_required field.
    * passes.def (all_passes): Add pass_lower_vaarg.
    * tree-pass.h (PROP_gimple_lva): Add define.
    (make_pass_lower_vaarg): Declare.

    * gcc.dg/tree-ssa/stdarg-2.c: Change f15 scan-tree-dump for target
    x86_64-*-*.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/cfgexpand.c
    trunk/gcc/gimple-iterator.c
    trunk/gcc/gimple-iterator.h
    trunk/gcc/gimplify.c
    trunk/gcc/gimplify.h
    trunk/gcc/internal-fn.c
    trunk/gcc/internal-fn.def
    trunk/gcc/passes.def
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/tree-ssa/stdarg-2.c
    trunk/gcc/tree-pass.h
    trunk/gcc/tree-stdarg.c

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

--- Comment #6 from vries at gcc dot gnu.org ---
https://gcc.gnu.org/ml/gcc-cvs/2015-04/msg00372.html :

Author: vries
Date: Fri Apr 17 09:27:08 2015
New Revision: 222174

URL: https://gcc.gnu.org/viewcvs?rev=222174&root=gcc&view=rev
Log:
Set PROP_gimple_lva for functions without IFN_VA_ARG

2015-04-17  Tom de Vries  <tom@codesourcery.com>

    * gimplify.c (gimplify_function_tree): Tentatively set PROP_gimple_lva
    in cfun->curr_properties.
    (gimplify_va_arg_expr): Clear PROP_gimple_lva in cfun->curr_properties
    if we generate an IFN_VA_ARG.
    * tree-inline.c (expand_call_inline): Reset PROP_gimple_lva in dest
    function if PROP_gimple_lva is not set in src function.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/gimplify.c
    trunk/gcc/tree-inline.c

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #7 from vries at gcc dot gnu.org ---
Patch series retested and committed.

Filed spinoff PR 65791 - Postpone expand_ifn_va_arg till after
optimize_va_list_gpr_fpr_size, for the TODO to rewrite
optimize_va_list_gpr_fpr_size to work on ifn_va_arg.

Marking resolved, fixed.

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

--- Comment #8 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to vries from comment #7)

> Marking resolved, fixed.

So, can PR41089 hack [1] finally be reverted?

[1] https://gcc.gnu.org/ml/gcc-patches/2010-08/msg00072.html
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https://gcc.gnu.org/bugzilla/show_bug.cgi?ide549

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org

--- Comment #29 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #17)
> Lambda functions aren't really nested functions in the tree-nested.c sense,
> but still are so closely related to the functions they are nested in that
> IMHO it would be desirable not to split them off into separate partitions,
> not just temporarily for GCC 5 for debug info reasons.

Agreed.  decl_function_context of the lambda function should give you the
containing function.

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rth at gcc dot gnu.org

--- Comment #9 from vries at gcc dot gnu.org ---
(In reply to Uroš Bizjak from comment #8)
> (In reply to vries from comment #7)
> 
> > Marking resolved, fixed.
> 
> So, can PR41089 hack [1] finally be reverted?
> 
> [1] https://gcc.gnu.org/ml/gcc-patches/2010-08/msg00072.html

[ Adding alpha maintainer to cc. ]

AFAIU, yes.

Thanks,
- Tom
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https://gcc.gnu.org/bugzilla/show_bug.cgi?ide296

Georg-Johann Lay <gjl at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |5.2

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[uros at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

--- Comment #10 from uros at gcc dot gnu.org ---
Author: uros
Date: Tue Apr 21 06:29:37 2015
New Revision: 222257

URL: https://gcc.gnu.org/viewcvs?rev=222257&root=gcc&view=rev
Log:
    PR tree-optimization/64950
    Revert:
    2010-08-02  Uros Bizjak  <ubizjak@gmail.com>

    PR target/41089
    * config/alpha/alpha.c (alpha_build_builtin_va_list): Mark __offset
    as volatile.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/alpha/alpha.c

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[ro at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

Rainer Orth <ro at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
                 CC|                            |ro at gcc dot gnu.org
         Resolution|FIXED                       |---

--- Comment #11 from Rainer Orth <ro at gcc dot gnu.org> ---
Unfortunately, the gcc.dg/tree-ssa/stdarg-2.c part of the patch is wrong: the
test
now FAILs on i686-unknown-linux-gnu, i686-apple-darwin, and i386-pc-solaris
with
-m64: both dumps (i.e. -m32 and -m64) contain

m32/stdarg-2.c.084t.stdarg:f15: va_list escapes 1, needs to save all GPR units
and all FPR units.
m64/stdarg-2.c.084t.stdarg:f15: va_list escapes 1, needs to save all GPR units
and all FPR units.

  Rainer

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

--- Comment #12 from vries at gcc dot gnu.org ---
(In reply to Rainer Orth from comment #11)
> Unfortunately, the gcc.dg/tree-ssa/stdarg-2.c part of the patch is wrong:
> the test
> now FAILs on i686-unknown-linux-gnu, i686-apple-darwin, and i386-pc-solaris
> with
> -m64: both dumps (i.e. -m32 and -m64) contain
> 
> m32/stdarg-2.c.084t.stdarg:f15: va_list escapes 1, needs to save all GPR
> units and all FPR units.
> m64/stdarg-2.c.084t.stdarg:f15: va_list escapes 1, needs to save all GPR
> units and all FPR units.
> 
>   Rainer

Proposed patch: https://gcc.gnu.org/ml/gcc-patches/2015-05/msg00294.html

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

--- Comment #13 from vries at gcc dot gnu.org ---
Author: vries
Date: Tue May  5 10:32:28 2015
New Revision: 222802

URL: https://gcc.gnu.org/viewcvs?rev=222802&root=gcc&view=rev
Log:
Xfail gcc.dg/tree-ssa/stdarg-2.c f15 scans

2015-05-05  Tom de Vries  <tom@codesourcery.com>

        * gcc.dg/tree-ssa/stdarg-2.c: Xfail f15 scans which test for presence
of
        'va_list escapes 0'.

Modified:
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gcc.dg/tree-ssa/stdarg-2.c

[Bug tree-optimization/64950] postpone expanding va_arg till pass_stdarg

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64950

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #14 from vries at gcc dot gnu.org ---
patch committed adding xfails in stdarg-2.c.

xfails tracked in spin-off PRs:
- PR66010 '[6 Regression] Missed optimization after inlining va_list parameter'
- PR66013 'Missed optimization after inlining va_list parameter, -m32 case'

Re-marking resolved, fixed.