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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/105219] [12 Regression] SVE: Wrong code with -O3
 -msve-vector-bits=128 -mtune=thunderx
Date: Wed, 20 Apr 2022 07:07:33 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105219

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|aarch64                     |aarch64, x86_64-*-*

--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
int data[128];

void __attribute((noipa))
foo (int *data, int n)
{
  for (int i =3D 0; i < n; ++i)
    data[i] =3D i;
}

int main()
{
  for (int start =3D 0; start < 16; ++start)
    for (int n =3D 1; n < 3*16; ++n)
      {
        __builtin_memset (data, 0, sizeof (data));
        foo (&data[start], n);
        for (int j =3D 0; j < n; ++j)
          if (data[start + j] !=3D j)
            __builtin_abort ();
      }
  return 0;
}

for example aborts with -O3 -mtune=3Dintel -fno-vect-cost-model on x86_64,
the cost model disabling is necessary to have the epilogue vectorized.
Without a cost model we peel for the maximum number of aligned refs
but still use the target cost to decide whether peeling is worth at all.=