[Bug tree-optimization/111039] New: Unable to coalesce ssa_names

[Bug tree-optimization/111039] New: Unable to coalesce ssa_names

[krebbel at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111039

            Bug ID: 111039
           Summary: Unable to coalesce ssa_names
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: krebbel at gcc dot gnu.org
  Target Milestone: ---

compiler_corruption_function(flags) {
  int nowait = flags & 1048576, isexpand = flags & 8388608;
  abcd();
  _setjmp(flags);
  if (nowait && isexpand)
    flags &= 0;
  abcde();
}

gcc -mbranch-cost=0 -O t.c
verified with recent GCC: 02ecc9a2632

t.c: In function ‘compiler_corruption_function’:
t.c:1:1: internal compiler error: SSA corruption
    1 | compiler_corruption_function(flags) {
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
0x15a657c fail_abnormal_edge_coalesce
        /home/andreas/build/../gcc/gcc/tree-ssa-coalesce.cc:1003
0x15a657c coalesce_partitions
        /home/andreas/build/../gcc/gcc/tree-ssa-coalesce.cc:1425
0x15a657c coalesce_ssa_name(_var_map*)
        /home/andreas/build/../gcc/gcc/tree-ssa-coalesce.cc:1755
0x153d6cf remove_ssa_form
        /home/andreas/build/../gcc/gcc/tree-outof-ssa.cc:1065
0x153d6cf rewrite_out_of_ssa(ssaexpand*)
        /home/andreas/build/../gcc/gcc/tree-outof-ssa.cc:1323
0xf42073 execute
        /home/andreas/build/../gcc/gcc/cfgexpand.cc:6610

This very much looks like another instance of PR71020.

[Bug tree-optimization/111039] [11/12/13/14 Regression] Unable to coalesce ssa_names

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111039

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Target Milestone|---                         |11.5
      Known to work|                            |4.8.5
   Last reconfirmed|                            |2023-08-16
            Summary|Unable to coalesce          |[11/12/13/14 Regression]
                   |ssa_names                   |Unable to coalesce
                   |                            |ssa_names

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andreas Krebbel from comment #0)
> This very much looks like another instance of PR71020.

It is much older than that though.

Confirmed.

[Bug tree-optimization/111039] [11/12/13/14 Regression] Unable to coalesce ssa_names

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111039

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
  # flags_1(ab) = PHI <flags_6(D)(ab)(2), flags_2(ab)(4)>
  _setjmp (flags_1(ab));
  _14 = flags_6(D)(ab) & 9437184;

The use of _6 is the issue here.

The problem shows up in ifcombine pass:
optimizing double bit test to flags_6(D)(ab) & T == T
with temporary T = (1 << 23) | (1 << 20)

[Bug tree-optimization/111039] [11/12/13/14 Regression] Unable to coalesce ssa_names

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111039

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I suspect the issue is recognize_single_bit_test does not check
SSA_NAME_OCCURS_IN_ABNORMAL_PHI at all ...

[Bug tree-optimization/111039] [11/12/13/14 Regression] Unable to coalesce ssa_names

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111039

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org

[Bug tree-optimization/111039] [11/12/13/14 Regression] Unable to coalesce ssa_names

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111039

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:482551a79a3d3f107f6239679ee74655cfe8707e

commit r14-3288-g482551a79a3d3f107f6239679ee74655cfe8707e
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Aug 17 13:10:14 2023 +0200

    tree-optimization/111039 - abnormals and bit test merging

    The following guards the bit test merging code in if-combine against
    the appearance of SSA names used in abnormal PHIs.

            PR tree-optimization/111039
            * tree-ssa-ifcombine.cc (ifcombine_ifandif): Check for
            SSA_NAME_OCCURS_IN_ABNORMAL_PHI.

            * gcc.dg/pr111039.c: New testcase.

[Bug tree-optimization/111039] [11/12/13 Regression] Unable to coalesce ssa_names

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111039

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |14.0
           Priority|P3                          |P2
            Summary|[11/12/13/14 Regression]    |[11/12/13 Regression]
                   |Unable to coalesce          |Unable to coalesce
                   |ssa_names                   |ssa_names

[Bug tree-optimization/111039] [11/12/13 Regression] Unable to coalesce ssa_names

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111039

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-13 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:e150cbf591759af10f3d57acbe0eb381aafa00de

commit r13-7754-ge150cbf591759af10f3d57acbe0eb381aafa00de
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Aug 17 13:10:14 2023 +0200

    tree-optimization/111039 - abnormals and bit test merging

    The following guards the bit test merging code in if-combine against
    the appearance of SSA names used in abnormal PHIs.

            PR tree-optimization/111039
            * tree-ssa-ifcombine.cc (ifcombine_ifandif): Check for
            SSA_NAME_OCCURS_IN_ABNORMAL_PHI.

            * gcc.dg/pr111039.c: New testcase.

    (cherry picked from commit 482551a79a3d3f107f6239679ee74655cfe8707e)

[Bug tree-optimization/111039] [11/12 Regression] Unable to coalesce ssa_names

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111039

--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:47e6bff94d980e2fcb6bcb42df04d3b73bd67da7

commit r12-10457-g47e6bff94d980e2fcb6bcb42df04d3b73bd67da7
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Aug 17 13:10:14 2023 +0200

    tree-optimization/111039 - abnormals and bit test merging

    The following guards the bit test merging code in if-combine against
    the appearance of SSA names used in abnormal PHIs.

            PR tree-optimization/111039
            * tree-ssa-ifcombine.cc (ifcombine_ifandif): Check for
            SSA_NAME_OCCURS_IN_ABNORMAL_PHI.

            * gcc.dg/pr111039.c: New testcase.

    (cherry picked from commit 482551a79a3d3f107f6239679ee74655cfe8707e)

[Bug tree-optimization/111039] [11 Regression] Unable to coalesce ssa_names

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111039

--- Comment #7 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:bae5dcf29c6cb1f0da437858aa7214811ece53a5

commit r11-11528-gbae5dcf29c6cb1f0da437858aa7214811ece53a5
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Aug 17 13:10:14 2023 +0200

    tree-optimization/111039 - abnormals and bit test merging

    The following guards the bit test merging code in if-combine against
    the appearance of SSA names used in abnormal PHIs.

            PR tree-optimization/111039
            * tree-ssa-ifcombine.c (ifcombine_ifandif): Check for
            SSA_NAME_OCCURS_IN_ABNORMAL_PHI.

            * gcc.dg/pr111039.c: New testcase.

[Bug tree-optimization/111039] [11 Regression] Unable to coalesce ssa_names

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111039

Richard Biener <rguenth at gcc dot gnu.org> changed:

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

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.