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From: "krebbel at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/114676] [12/13/14 Regression] DSE removes assignment
 that is used later
Date: Wed, 17 Apr 2024 17:01:26 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114676

--- Comment #13 from Andreas Krebbel <krebbel at gcc dot gnu.org> ---
We will go and fix PyTorch instead. Although it is not clearly documented, =
the
way PyTorch uses the builtin right now is probably not what was intended. I=
t is
pretty clear that the element type pointer needs to alias vectors of the sa=
me
element type, but there is no saying about aliasing everything.

I'm just wondering how to improve the diagnostics in our backend to catch t=
his.
The example below is similar to what PyTorch does today. Casting mem to
(float*) prevents our builtin code from complaining about the type mismatch=
 and
by that opens the door for the much harder to debug TBAA problem.

#include <vecintrin.h>

void __attribute__((noinline)) foo (int *mem)
{
  vec_xst ((vector float){ 1.0f, 2.0f, 3.0f, 4.0f }, 0, (float*)mem);
}

int
main ()
{
  int m[4] =3D { 0 };
  foo (m);
  if (m[3] =3D=3D 0)
    __builtin_abort ();
  return 0;
}=