https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72782
Bug ID: 72782
Summary: AVX512: No support for scalar broadcasts
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: wen...@mitsuba-renderer.org
Target Milestone: ---
AVX512 introduces the ability to do scalar broadcasts, which significantly cuts
down on the number of explicit broadcast instructions in vectorized code. It
looks like the AVX512 code generation backend on GCC does not recognize/make
use of this instruction set feature:
Consider the following snippet:
__m512 addConstant(__m512 arg) {
return _mm512_add_ps(arg, _mm512_set1_ps(1.f));
}
This is the assembly generated by GCC (HEAD):
__Z11addConstantDv16_f:
LFB4589:
vbroadcastss LC0(%rip), %zmm1
vaddps %zmm1, %zmm0, %zmm0
ret
For reference, this is the output generated by Clang:
_Z11addConstantDv16_f: ## @_Z11addConstantDv16_f
vaddps LCPI0_0(%rip){1to16}, %zmm0, %zmm0
retq
