[Bug tree-optimization/111792] New: wrong code at -O3 on x86_64-linux-gnu

[Bug tree-optimization/111792] 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=111792

            Bug ID: 111792
           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: ---

It appears to be a recent regression.

compiler Explorer: https://godbolt.org/z/7vfzPYTrn

[537] % 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 20231013 (experimental) (GCC) 
[538] % 
[538] % gcctk -O2 small.c; ./a.out
[539] % 
[539] % gcctk -O3 small.c
[540] % ./a.out
Aborted
[541] % cat small.c
int c, d, h, i, j, l, *n = &h;
short e, f, g, *k, m;
long o;
short p(short p1, int q) { return q >= 32 || p1 > 5 >> q ? 1 : p1 << q; }
long u(unsigned p1) {
  int r = 50, s, *t = &c;
 L:
  m && (*k = 0);
  for (d = 1; d; d--)
    for (s = 0; s < 3; s++) {
      *n = i ^ p1;
      *t = p1 > (unsigned)p((unsigned)(o = 4073709551615) >= p1 && 5, r);
      if (f)
        goto L;
    }
  for (; e < 1;)
    return j;
  int *b[2] = {&s, &r};
  for (; l; l--) {
    long a[1];
    for (r = 0; r < 1; r++) {
      h = a[0];
      if (g)
        goto L;
    }
  }
  return 0;
}
int main() {
  u(6);
  if (c != 1)
    __builtin_abort();
  return 0;
}

[Bug tree-optimization/111792] [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=111792

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|wrong code at -O3 on        |[14 Regression] wrong code
                   |x86_64-linux-gnu            |at -O3 on x86_64-linux-gnu
   Target Milestone|---                         |14.0
                 CC|                            |rguenth at gcc dot gnu.org
           Keywords|                            |needs-bisection, wrong-code
             Status|UNCONFIRMED                 |NEW
            Version|unknown                     |14.0
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-10-13

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  -fno-tree-loop-vectorize fixes it.  We vectorize

  for (; l; l--) {
    long a[1];
    for (r = 0; r < 1; r++) {
      h = a[0];
      if (g)
        goto L;
    }
  }

[Bug tree-optimization/111792] [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=111792

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1

[Bug tree-optimization/111792] [14 Regression] wrong code at -O3 on x86_64-linux-gnu since r14-3414-g0cfc9c953d0221

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111792

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|needs-bisection             |
                 CC|                            |amacleod at redhat dot com,
                   |                            |ppalka at gcc dot gnu.org
            Summary|[14 Regression] wrong code  |[14 Regression] wrong code
                   |at -O3 on x86_64-linux-gnu  |at -O3 on x86_64-linux-gnu
                   |                            |since
                   |                            |r14-3414-g0cfc9c953d0221

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Started with r14-3414-g0cfc9c953d0221

[Bug tree-optimization/111792] [14 Regression] wrong code at -O3 on x86_64-linux-gnu since r14-3414-g0cfc9c953d0221

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111792

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |needs-bisection

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I can no longer reproduce this on the trunk.

[Bug tree-optimization/111792] [14 Regression] wrong code at -O3 on x86_64-linux-gnu since r14-3414-g0cfc9c953d0221

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111792

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

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

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Indeed, doesn't reproduce since
r14-4786-gd118738e71cf4615f170fff8dabe66442206d008
Was that a fix for this or just made the bug latent?
In any case, we should add the testcase to the testsuite...

[Bug tree-optimization/111792] [14 Regression] wrong code at -O3 on x86_64-linux-gnu since r14-3414-g0cfc9c953d0221

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111792

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
             Status|NEW                         |ASSIGNED

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
I doubt that it was a proper fix, but I'll have a look.

[Bug tree-optimization/111792] [14 Regression] wrong code at -O3 on x86_64-linux-gnu since r14-3414-g0cfc9c953d0221

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111792

--- Comment #6 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:a0b2abef4e62d816f669df478a3cc320647c3b31

commit r14-5391-ga0b2abef4e62d816f669df478a3cc320647c3b31
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Nov 13 13:38:57 2023 +0100

    tree-optimization/111792 - new testcase

    This was fixed as part of the PR111000 fix.

            PR tree-optimization/111792
            PR tree-optimization/111000
            * gcc.dg/torture/pr111792.c: New testcase.

[Bug tree-optimization/111792] [14 Regression] wrong code at -O3 on x86_64-linux-gnu since r14-3414-g0cfc9c953d0221

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111792

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

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

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
It was indeed a proper fix, will add the testcase.