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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/114908] fails to optimize avx2 in-register
 permute written with std::experimental::simd
Date: Mon, 06 May 2024 10:12:53 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114908

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
Thanks, and it might be enough to handle

typedef unsigned long V [[gnu::vector_size(32)]];

V load3(const unsigned long* ptr)
{
  V ret =3D {};
  __builtin_memcpy(&ret, ptr, 3 * sizeof(unsigned long));
  return ret;
}

where with -O2 .optimized still has

  <bb 2> [local count: 1073741824]:
  ret =3D { 0, 0, 0, 0 };
  __builtin_memcpy (&ret, ptr_3(D), 24);
  _5 =3D ret;
  ret =3D{v} {CLOBBER(eos)};
  return _5;

and thus 'ret' not promoted to a register.=