https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94866
Bug ID: 94866
Summary: Failure to optimize pinsrq of 0 with index 1 into movq
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
typedef int64_t v2di __attribute__((vector_size(16)));
typedef int32_t v2si __attribute__((vector_size(8)));
v2di _mm_move_epi64(v2di a)
{
return v2di{a[0], 0LL};
}
LLVM with `-O3 -msse4.1` compiles this to this :
_mm_move_epi64(long __vector(2)): # @_mm_move_epi64(long __vector(2))
movq xmm0, xmm0 # xmm0 = xmm0[0],zero
ret
GCC gives :
_mm_move_epi64(long __vector(2)):
xor eax, eax
pinsrq xmm0, rax, 1
ret
GCC's output seems like it would naturally be much slower, so unless there is
something seriously messed up with x86 chips that I've missed, LLVM's version
should be faster
