[Bug tree-optimization/104676] New: [12 Regression] ICE in verify_loop_structure, at cfgloop.cc:1748 (error: loop 3's number of iterations '(unsigned int) + 4294967295' references the released SSA name '<unknown>')

[Bug tree-optimization/104676] New: [12 Regression] ICE in verify_loop_structure, at cfgloop.cc:1748 (error: loop 3's number of iterations '(unsigned int) + 4294967295' references the released SSA name '<unknown>')

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104676

            Bug ID: 104676
           Summary: [12 Regression] ICE in verify_loop_structure, at
                    cfgloop.cc:1748 (error: loop 3's number of iterations
                    '(unsigned int) + 4294967295' references the released
                    SSA name '<unknown>')
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

gcc 12.0.1 20220220 snapshot (g:e49508ac6b36adb8a2056c5a1fb6e0178de2439d) ICEs
when compiling the following testcase w/ -O1 -ftree-loop-distribution
-ftree-parallelize-loops=2:

struct S {
  int f;
};

int n;

int
foo (struct S *s)
{
  int arr[3];
  int v = 0;

  for (n = 0; n < 2; ++n)
    {
      int i;

      for (i = 0; i < 2; ++i)
        {
          int j;

          for (j = 0; j < s->f; ++j)
            ++v;
        }

      if (v)
        arr[0] = 0;

      arr[n + 1] = 0;
    }

  return arr[0];
}

% gcc-12.0.1 -O1 -ftree-loop-distribution -ftree-parallelize-loops=2 -c
opcatmkb.c
opcatmkb.c: In function 'foo':
opcatmkb.c:8:1: error: loop 3's number of iterations '(unsigned int) +
4294967295' references the released SSA name '<unknown>'
    8 | foo (struct S *s)
      | ^~~
during GIMPLE pass: ldist
opcatmkb.c:8:1: internal compiler error: in verify_loop_structure, at
cfgloop.cc:1748
0x68eb89 verify_loop_structure()
       
/var/tmp/portage/sys-devel/gcc-12.0.1_p20220220/work/gcc-12-20220220/gcc/cfgloop.cc:1748
0xf752ee checking_verify_loop_structure
       
/var/tmp/portage/sys-devel/gcc-12.0.1_p20220220/work/gcc-12-20220220/gcc/cfgloop.h:646
0xf752ee loop_distribution::execute(function*)
       
/var/tmp/portage/sys-devel/gcc-12.0.1_p20220220/work/gcc-12-20220220/gcc/tree-loop-distribution.cc:3861
0xf7551b execute
       
/var/tmp/portage/sys-devel/gcc-12.0.1_p20220220/work/gcc-12-20220220/gcc/tree-loop-distribution.cc:3905

[Bug tree-optimization/104676] [12 Regression] ICE in verify_loop_structure, at cfgloop.cc:1748 (error: loop 3's number of iterations '(unsigned int) + 4294967295' references the released SSA name '<unknown>')

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104676

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-02-24
   Target Milestone|---                         |12.0
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |rguenth at gcc dot gnu.org
           Priority|P3                          |P1
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Started with r12-7228-g0a1a3afb5fb36e2d10ad92bf788e16d837451571

[Bug tree-optimization/104676] [12 Regression] ICE in verify_loop_structure, at cfgloop.cc:1748 (error: loop 3's number of iterations '(unsigned int) + 4294967295' references the released SSA name '<unknown>')

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104676

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

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

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
I will have a look.

[Bug tree-optimization/104676] [12 Regression] ICE in verify_loop_structure, at cfgloop.cc:1748 (error: loop 3's number of iterations '(unsigned int) + 4294967295' references the released SSA name '<unknown>')

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104676

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
loop distribution removes

_31 = s_18(D)->f;

releasing SSA name 31 but loop 3 still has nb_iterations == (unsigned int) _31
+ 4294967295

loop distribution already does scev_reset_htab but should just use scev_reset
here.

[Bug tree-optimization/104676] [12 Regression] ICE in verify_loop_structure, at cfgloop.cc:1748 (error: loop 3's number of iterations '(unsigned int) + 4294967295' references the released SSA name '<unknown>')

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104676

--- 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:a4066d3a5097333f17c0d7be1630a98f3a5b1c1d

commit r12-7372-ga4066d3a5097333f17c0d7be1630a98f3a5b1c1d
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Feb 24 14:34:52 2022 +0100

    tree-optimization/104676 - free nb_iterations after loop distribution

    Loop distribution can release SSA names used in nb_iterations, make
    sure to release those.

    2022-02-24  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/104676
            * tree-loop-distribution.cc (loop_distribution::execute):
            Do a full scev_reset.

            * gcc.dg/torture/pr104676.c: New testcase.

[Bug tree-optimization/104676] [12 Regression] ICE in verify_loop_structure, at cfgloop.cc:1748 (error: loop 3's number of iterations '(unsigned int) + 4294967295' references the released SSA name '<unknown>')

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104676

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

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

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.

[Bug tree-optimization/104676] [12 Regression] ICE in verify_loop_structure, at cfgloop.cc:1748 (error: loop 3's number of iterations '(unsigned int) + 4294967295' references the released SSA name '<unknown>')

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104676

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Kito Cheng <kito@gcc.gnu.org>:

https://gcc.gnu.org/g:d5b66a905322262483af5c4ca6cb6676c24e1f3f

commit r12-8295-gd5b66a905322262483af5c4ca6cb6676c24e1f3f
Author: Jia-Wei Chen <jiawei@iscas.ac.cn>
Date:   Tue Apr 19 11:11:24 2022 +0800

    testsuite: Skip target not support -pthread [PR104676].

    The "ftree-parallelize-loops=" imply -pthread option in gcc/gcc.cc,
    some target are not support pthread like elf target use newlib,
    and will get an error:

    "*-*-elf-gcc: error: unrecognized command-line option '-pthread'"

    so we add an additional condition "{target pthread}" to make sure the
    dg-additional-options runs on support targets.

    gcc/testsuite/ChangeLog

            PR target/104676
            * gcc.dg/torture/pr104676.c: Add "{target pthread}" check.