[Bug tree-optimization/118623] [12/13/14/15 regression] Miscompile with -O2/3 and -O0/1

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118623

Richard Biener  changed:

   What|Removed |Added

   Keywords||needs-bisection
   Last reconfirmed||2025-01-23
 CC||rguenth at gcc dot gnu.org
   Priority|P3  |P2
 Ever confirmed|0   |1
 Status|UNCONFIRMED |NEW

--- Comment #5 from Richard Biener  ---
Further reduced, not analyzed.

static int c(int f, int g)
{
  int e = 1 << f;
  if (g & e)
return 0;
  return 5;
}

__attribute__((noipa))
void h(int g)
{
  if (((c(g - 50, g) + g + g) & 1) == 0)
__builtin_abort ();
}

int main()
{
  h(63);
  return 0;
}

[Bug tree-optimization/118623] [12/13/14/15 regression] Miscompile with -O2/3 and -O0/1

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118623

--- Comment #4 from Andrew Pinski  ---
Created attachment 60247
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=60247&action=edit
self testing testcase

[Bug tree-optimization/118623] [12/13/14/15 regression] Miscompile with -O2/3 and -O0/1

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118623

--- Comment #3 from Andrew Pinski  ---
(In reply to Sam James from comment #2)
> Changing it to:
> ```
> int a, b;
> 
> int c(int f, int g) {
>   for (int d = 0; d <= 4; d++) {
> int e = 1 << f;
> if (g & e)
>   return d;
>   }
>   return 5;
> }
> 
> int h(int f, int g) {
>   if ((c(g - 50, g) + g + g) & 1);
>   else if (f)
>   a = 1;
>   return a;
> }
> 
> int main() {
>   if (h(b + 5, b + 63) != 0)
>   __builtin_abort();
>   return 0;
> }
> ```
> 
> it works at -O3.
Just mark h as noinline.

[Bug tree-optimization/118623] [12/13/14/15 regression] Miscompile with -O2/3 and -O0/1

[sjames at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118623

--- Comment #2 from Sam James  ---
Changing it to:
```
int a, b;

int c(int f, int g) {
  for (int d = 0; d <= 4; d++) {
int e = 1 << f;
if (g & e)
  return d;
  }
  return 5;
}

int h(int f, int g) {
  if ((c(g - 50, g) + g + g) & 1);
  else if (f)
  a = 1;
  return a;
}

int main() {
  if (h(b + 5, b + 63) != 0)
  __builtin_abort();
  return 0;
}
```

it works at -O3.

[Bug tree-optimization/118623] [12/13/14/15 regression] Miscompile with -O2/3 and -O0/1

[sjames at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118623

Sam James  changed:

   What|Removed |Added

  Component|c   |tree-optimization

--- Comment #1 from Sam James  ---
-O2 -fno-tree-pre works