[Bug tree-optimization/111572] New: Wrong code at -O2 on x86_64-linux-gnu since r14-301-gf2d6beb7a4d

[Bug tree-optimization/111572] New: Wrong code at -O2 on x86_64-linux-gnu since r14-301-gf2d6beb7a4d

[shaohua.li at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111572

            Bug ID: 111572
           Summary: Wrong code at -O2 on x86_64-linux-gnu since
                    r14-301-gf2d6beb7a4d
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shaohua.li at inf dot ethz.ch
                CC: jh at suse dot cz
  Target Milestone: ---

gcc at -O2 produces the wrong code.

Bisected to r14-301-gf2d6beb7a4d

Compiler explorer: https://godbolt.org/z/reETd3ee4

$ cat a.c
int printf(const char *, ...);
int a, b = -8, e, f, h;
char c, d, g;
static int i(long k) {
  e = 8;
  for (; e; e = f) {
    d = 6;
    for (; d<7; d++) {
      unsigned char j = 0;
      for (; (unsigned char)(1 + k) + j <= 3; j++)
        printf("%u\n", (unsigned char)(1 + k) + j);
    }
    for (; g; g++)
      ;
  }
  return 0;
}
int main() {
  h = 26 & b;
  i((short)(h - 65557) + 65535);
}
$
$ gcc -O0 a.c && ./a.out
3
$ gcc -O2 a.c && ./a.out
3
3
3
3
(Truncated)
$

[Bug tree-optimization/111572] Wrong code at -O2 on x86_64-linux-gnu since r14-301-gf2d6beb7a4d

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111572

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

  __builtin_printf ("%u\n", _79);
  __builtin_unreachable ();

[Bug tree-optimization/111572] [14 Regression] Wrong code at -O2 on x86_64-linux-gnu since r14-301-gf2d6beb7a4d

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111572

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2023-09-24
     Ever confirmed|0                           |1
   Target Milestone|---                         |14.0
             Status|UNCONFIRMED                 |NEW
            Summary|Wrong code at -O2 on        |[14 Regression] Wrong code
                   |x86_64-linux-gnu since      |at -O2 on x86_64-linux-gnu
                   |r14-301-gf2d6beb7a4d        |since r14-301-gf2d6beb7a4d

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

[Bug tree-optimization/111572] [14 Regression] Wrong code at -O2 on x86_64-linux-gnu since r14-301-gf2d6beb7a4d

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111572

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Self contained testcase:
```

void gg(void)
{
        static int t = 0;
        if (t != 0) __builtin_abort();
        t++;
}
int a, b = -8, e, f, h;
char c, d, g;
static int i(long k) {
  e = 8;
  for (; e; e = f) {
    d = 6;
    for (; d<7; d++) {
      unsigned char j = 0;
      for (; (unsigned char)(1 + k) + j <= 3; j++)
       gg();
    }
    for (; g; g++)
      ;
  }
  return 0;
}
int main() {
  h = 26 & b;
  i((short)(h - 65557) + 65535);
}
```

[Bug tree-optimization/111572] [14 Regression] Wrong code at -O2 on x86_64-linux-gnu since r14-301-gf2d6beb7a4d

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111572

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
                 CC|                            |hubicka at gcc dot gnu.org
   Last reconfirmed|2023-09-24 00:00:00         |2023-10-17

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Re-confirmed.

[Bug tree-optimization/111572] [14 Regression] Wrong code at -O2 on x86_64-linux-gnu since r14-301-gf2d6beb7a4d

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111572

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

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

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Hmm, this works on the trunk now. Would be a good idea to figure out what
"fixed" it.

[Bug tree-optimization/111572] [14 Regression] Wrong code at -O2 on x86_64-linux-gnu since r14-301-gf2d6beb7a4d

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111572

--- Comment #6 from Martin Jambor <jamborm at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #5)
> Hmm, this works on the trunk now. Would be a good idea to figure out what
> "fixed" it.

If my simple test is correct, the error disappeared with
r14-4790-g9692309ed6b625 (Richi's: tree-optimization/111445 - simple_iv
simplification fault)

[Bug tree-optimization/111572] [14 Regression] Wrong code at -O2 on x86_64-linux-gnu since r14-301-gf2d6beb7a4d

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111572

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

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

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
Yep, the testcase looks very related.

*** This bug has been marked as a duplicate of bug 111445 ***