[Bug tree-optimization/102676] Failure to optimize out malloc/nothrow allocation that's only used for bool checking

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102676

Richard Biener  changed:

   What|Removed |Added

   Last reconfirmed||2021-10-11
 Ever confirmed|0   |1
 Status|UNCONFIRMED |NEW

--- Comment #3 from Richard Biener  ---
We don't eliminate a malloc that's just used in a conditional, I think there's
a related bugreport with

  p = malloc (n)
  if (!p)
abort ();
  free (p);

or sth like that where we fail to elide the allocation.  Note in this case
failing allocation _would_ have a side-effect.

[Bug tree-optimization/102676] Failure to optimize out malloc/nothrow allocation that's only used for bool checking

[gabravier at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102676

--- Comment #2 from Gabriel Ravier  ---
Well, I think the assumption LLVM is making is that the allocation, being
unused, can just be eliminated and considered to have always succeeded. I don't
see how that would contradict the standard, although I suppose some would
consider it a bad thing to do for the compiler (although in that case you might
as well rule out all optimizations that elide allocations).

[Bug tree-optimization/102676] Failure to optimize out malloc/nothrow allocation that's only used for bool checking

[schwab--- via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102676

--- Comment #1 from Andreas Schwab  ---
Why is malloc(1) always true?