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[X86] Use GFNI to materialize a vXi8 uniform vector constant #239960
Description
GFNI targets can create any vXi8 uniform constant with the vgf2p8affineqb instruction, zero inputs and the required constant immediate:
_mm512_gf2p8affine_epi64_epi8(_mm512_setzero_si512(), _mm512_setzero_si512(), CONSTANT) vpxor %xmm0, %xmm0, %xmm0
vgf2p8affineqb $CONSTANT, %zmm0, %zmm0, %zmm0Reacted by Andarwinux
Activity
llvmorg-github-actions commentedon Nov 7, 2026
@llvm/issue-subscribers-backend-x86
Author: Simon Pilgrim (RKSimon)
Details
GFNI targets can create any vXi8 uniform constant with the vgf2p8affineqb instruction, zero inputs and the required constant immediate: ```c _mm512_gf2p8affine_epi64_epi8(_mm512_setzero_si512(), _mm512_setzero_si512(), CONSTANT) ``` ```s vpxor %xmm0, %xmm0, %xmm0 vgf2p8affineqb $CONSTANT, %zmm0, %zmm0, %zmm0 ```