[Bug c/107293] New: Wrong code at -Os on x86_64-linux-gnu

[Bug c/107293] New: Wrong code at -Os on x86_64-linux-gnu

[shaohua.li at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107293

            Bug ID: 107293
           Summary: Wrong code at -Os on x86_64-linux-gnu
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shaohua.li at inf dot ethz.ch
  Target Milestone: ---

% gcc-tk -v
Using built-in specs.
COLLECT_GCC=gcc-tk
COLLECT_LTO_WRAPPER=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-acdb24166d13d87c374e578d2ad5d58249171930/libexec/gcc/x86_64-pc-linux-gnu/13.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure --disable-multilib --disable-bootstrap
--enable-languages=c,c++
--prefix=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-acdb24166d13d87c374e578d2ad5d58249171930
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.0.0 20221017 (experimental) (GCC)
%
% gcc-tk -w -O0 a.c && ./a.out
1
% gcc-tk -w -Os a.c && ./a.out
0
% cat a.c
short a;
int b[1];

int c(int p) {
  return (p < 0) ? 0 : 10 + ((p / 100 - 16) / 4);
}

void f(int n) {
  while (1) {
    int m = n;
    while ((m ) )
      m /= 2;
    break;
  }
}

void g() {
  int h = a = 0;
  for (; h + a <= 0; a++) {
    if (b[c(a - 6)])
      break;
    f(a);
  }
}
int main() {
  g();
  __builtin_printf("%d\n", a);
}

%

Compiler explorer: https://godbolt.org/z/e7sssT7cq

[Bug tree-optimization/107293] Wrong code at -Os on x86_64-linux-gnu since r13-2876-g2460f7cdef7ef9c9

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107293

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Wrong code at -Os on        |Wrong code at -Os on
                   |x86_64-linux-gnu            |x86_64-linux-gnu since
                   |                            |r13-2876-g2460f7cdef7ef9c9
     Ever confirmed|0                           |1
                 CC|                            |aldyh at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org
          Component|c                           |tree-optimization
   Target Milestone|---                         |13.0
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-10-17

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Started with r13-2876-g2460f7cdef7ef9c9.

[Bug tree-optimization/107293] Wrong code at -Os on x86_64-linux-gnu since r13-2876-g2460f7cdef7ef9c9

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107293

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
           Priority|P3                          |P1

[Bug tree-optimization/107293] Wrong code at -Os on x86_64-linux-gnu since r13-2876-g2460f7cdef7ef9c9

[aldyh at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107293

--- Comment #2 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
Created attachment 53717
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53717&action=edit
patch in testing

[Bug tree-optimization/107293] Wrong code at -Os on x86_64-linux-gnu since r13-2876-g2460f7cdef7ef9c9

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107293

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Aldy Hernandez <aldyh@gcc.gnu.org>:

https://gcc.gnu.org/g:c9b840db504d15db01f06fe1fec38282dbafee07

commit r13-3341-gc9b840db504d15db01f06fe1fec38282dbafee07
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Mon Oct 17 18:56:24 2022 +0200

    Make sure exported range for SSA post-dominates the DEF in
set_global_ranges_from_unreachable_edges.

    The problem here is that we're exporting a range for an SSA range that
    happens on the other side of a __builtin_unreachable, but the SSA does
    not post-dominate the definition point.  This is causing ivcanon to
    unroll things incorrectly.

    This was a snafu when converting the code from evrp.

            PR tree-optimization/107293

    gcc/ChangeLog:

            * tree-ssa-dom.cc
            (dom_opt_dom_walker::set_global_ranges_from_unreachable_edges):
            Check that condition post-dominates the definition point.

    gcc/testsuite/ChangeLog:

            * gcc.dg/tree-ssa/pr107293.c: New test.

[Bug tree-optimization/107293] Wrong code at -Os on x86_64-linux-gnu since r13-2876-g2460f7cdef7ef9c9

[aldyh at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107293

Aldy Hernandez <aldyh at gcc dot gnu.org> changed:

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

--- Comment #4 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
fixed

[Bug tree-optimization/107293] Wrong code at -Os on x86_64-linux-gnu since r13-2876-g2460f7cdef7ef9c9

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107293

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

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

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 107196 has been marked as a duplicate of this bug. ***