https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104665
Bug ID: 104665
Summary: Failure to recognize memcpy
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: monad at posteo dot net
Target Milestone: ---
The following serialization code:
void serialize_le(std::byte* __restrict dst, const std::uint32_t* __restrict
src)
{
for (int i = 0; i < 32; ++i, ++src)
{
*dst++ = static_cast<std::byte>((*src >> 0) & 0xff);
*dst++ = static_cast<std::byte>((*src >> 8) & 0xff);
*dst++ = static_cast<std::byte>((*src >> 16) & 0xff);
*dst++ = static_cast<std::byte>((*src >> 24) & 0xff);
}
}
is not recognized as just copying memory.
Both clang and gcc fail to optimize it properly, however gcc creates an
"interesting" mess.
Flags used are `-std=c++17 -O3 -march=haswell`
<https://godbolt.org/z/GM8jqssYd>
