https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65197
Bug ID: 65197
Summary: static initialization via intel intrinsics
Product: gcc
Version: 5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: glisse at gcc dot gnu.org
Target: x86_64-linux-gnu
I am compiling the following with: g++ -std=gnu++11 -Ofast
#include <x86intrin.h>
extern const __m128i x = { -1, 0 };
extern const __m128i y = _mm_set_epi64x (0, -1);
While x becomes a nice constant in .rodata, y is initialized by
_GLOBAL__sub_I_x (copying a constant that is in .rodata). For this specific
case, marking _mm_set_epi64x as constexpr gives y the same treatment as x, and
I believe we should do that, i.e. mark all intrinsics that can be constexpr in
C++11/C++14. However, I believe we are missing an optimization in the general
case that would notice (late, after many optimizations) when the initialization
function has become unnecessary.
Some possibly related bugs: PR4131, PR18399, PR24928, PR37949.
