[Bug tree-optimization/111727] New: wrong code at -O3 on x86_64-linux-gnu

[Bug tree-optimization/111727] New: wrong code at -O3 on x86_64-linux-gnu

[zhendong.su at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111727

            Bug ID: 111727
           Summary: wrong code at -O3 on x86_64-linux-gnu
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

Compiler Explorer: https://godbolt.org/z/xherWE8x6

It might be related to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111652.

[508] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 20231008 (experimental) (GCC) 
[509] % 
[509] % gcctk -O2 small.c; ./a.out
[510] % 
[510] % gcctk -O3 small.c
[511] % ./a.out
Aborted
[512] % cat small.c
int a, b, c;
int main() {
  for (; a < 2; a += 2) {
    for (b = 0; b < 1; b++)
      if (a < 1)
        c = 0;
    for (; c < 1; c++)
      ;
    }
  if (a != 2)
    __builtin_abort();
  return 0;
}

[Bug tree-optimization/111727] [14 Regression] wrong code at -O3 on x86_64-linux-gnu

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111727

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
            Version|unknown                     |14.0
           Keywords|                            |wrong-code
   Target Milestone|---                         |14.0
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-10-08
            Summary|wrong code at -O3 on        |[14 Regression] wrong code
                   |x86_64-linux-gnu            |at -O3 on x86_64-linux-gnu

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

[Bug tree-optimization/111727] [14 Regression] wrong code at -O3 on x86_64-linux-gnu

[zhendong.su at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111727

--- Comment #2 from Zhendong Su <zhendong.su at inf dot ethz.ch> ---
Another similar/related test:

[553] % gcctk -O2 small.c; ./a.out
[554] % 
[554] % gcctk -O3 small.c
[555] % ./a.out
Aborted
[556] % cat small.c
int a, b;
int main() {
  for (; a < 4; a += 2)
    if (a > 2)
      while (b++);
        ;
  if (a != 4)
    __builtin_abort();
  return 0;
}

[Bug tree-optimization/111727] [14 Regression] wrong code at -O3 on x86_64-linux-gnu

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111727

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hubicka at gcc dot gnu.org,
                   |                            |rguenth at gcc dot gnu.org
           Priority|P3                          |P1

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
t.c:5:10: optimized: loop split

so maybe a duplicate of the other splitting issues

[Bug tree-optimization/111727] [14 Regression] wrong code at -O3 on x86_64-linux-gnu

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111727

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|needs-bisection             |
                 CC|                            |ppalka at gcc dot gnu.org

--- Comment #4 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Started with r14-2944-g3d48c11ad082de (for both testcases)

[Bug tree-optimization/111727] [14 Regression] wrong code at -O3 on x86_64-linux-gnu since r14-2944-g3d48c11ad082de

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111727

--- Comment #5 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:2066c29bf8dea87c9810eb261e342d941a6b2059

commit r14-5446-g2066c29bf8dea87c9810eb261e342d941a6b2059
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Nov 14 14:26:17 2023 +0100

    tree-optimization/111233 - loop splitting miscompile

    The change in r14-2852-gf5fb9ff2396fd4 failed to update patch_loop_exit
    to compensate for rewriting of a NE/EQ_EXPR to a new code.  Fixed
    with the following.

            PR tree-optimization/111233
            PR tree-optimization/111652
            PR tree-optimization/111727
            PR tree-optimization/111838
            PR tree-optimization/112113
            * tree-ssa-loop-split.cc (patch_loop_exit): Get the new
            guard code instead of the old guard stmt.
            (split_loop): Adjust.

            * gcc.dg/torture/pr111233.c: New testcase.
            * gcc.dg/torture/pr111652.c: Likewise.
            * gcc.dg/torture/pr111727.c: Likewise.
            * gcc.dg/torture/pr111838.c: Likewise.
            * gcc.dg/torture/pr112113.c: Likewise.

[Bug tree-optimization/111727] [14 Regression] wrong code at -O3 on x86_64-linux-gnu since r14-2944-g3d48c11ad082de

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111727

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

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

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.