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From: "mkretz at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/111302] New: aligned std::experimental::simd loads
 and stores are not constant expressions
Date: Wed, 06 Sep 2023 06:33:37 +0000
X-Bugzilla-Reason: CC
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 14.0
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: mkretz at gcc dot gnu.org
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X-Bugzilla-Priority: P3
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111302

            Bug ID: 111302
           Summary: aligned std::experimental::simd loads and stores are
                    not constant expressions
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: mkretz at gcc dot gnu.org
          Reporter: mkretz at gcc dot gnu.org
  Target Milestone: ---

Test case (https://godbolt.org/z/d16rvjjsK):

#include <experimental/simd>

namespace stdx =3D std::experimental;
using V =3D stdx::native_simd<float>;
alignas(64) constexpr float mem[32] =3D {};
constexpr V zero1 =3D V(mem, stdx::element_aligned);
constexpr V zero2 =3D V(mem, stdx::vector_aligned);
constexpr V zero3 =3D V(mem, stdx::overaligned<64>);

constexpr float tmp1 =3D [](){
  float buf[V::size()] =3D {};
  V().copy_to(buf, stdx::element_aligned);
  return buf[0];
}();
constexpr float tmp2 =3D [](){
  alignas(stdx::memory_alignment_v<V>) float buf[V::size()] =3D {};
  V().copy_to(buf, stdx::vector_aligned);
  return buf[0];
}();
constexpr float tmp3 =3D [](){
  alignas(64) float buf[V::size()] =3D {};
  V().copy_to(buf, stdx::overaligned<64>);
  return buf[0];
}();

The element_aligned variants compile. The others don't, but they should.=