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From: "linkw at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/106322] [12/13 Regression] tree-vectorize:
 Wrong code at O2 level (-fno-tree-vectorize is working) since
 r12-2404-ga1d27560770818c5
Date: Mon, 15 Aug 2022 06:51:40 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106322

Kewen Lin <linkw at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED

--- Comment #45 from Kewen Lin <linkw at gcc dot gnu.org> ---
One reduced C test case:

#define N 64
typedef unsigned short int uh;
typedef unsigned short int uw;
uh a[N];
uh b[N];
uh c[N];
uh e[N];

__attribute__ ((noipa)) void
foo ()
{
  for (int i =3D 0; i < N; i++)
    c[i] =3D ((uw) b[i] * (uw) a[i]) >> 16;
}

__attribute__ ((optimize ("-O0"))) void
init ()
{
  for (int i =3D 0; i < N; i++)
    {
      a[i] =3D (uh) (0x7ABC - 0x5 * i);
      b[i] =3D (uh) (0xEAB + 0xF * i);
      e[i] =3D ((uw) b[i] * (uw) a[i]) >> 16;
    }
}

__attribute__ ((optimize ("-O0"))) void
check ()
{
  for (int i =3D 0; i < N; i++)
    {
      if (c[i] !=3D e[i])
        __builtin_abort ();
    }
}

int
main ()
{
  init ();
  foo ();
  check ();

  return 0;
}=