[llvm] [WIP][X86] lowerBuildVectorAsBroadcast - don't convert constant vectors to broadcasts on AVX512VL targets (PR #73509)

[Simon Pilgrim via llvm-commits]

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@@ -948,7 +948,8 @@ define void @load_i8_stride4_vf32(ptr %in.vec, ptr %out.vec0, ptr %out.vec1, ptr
 ; AVX512F-NEXT:    vpshufb %ymm0, %ymm1, %ymm2
 ; AVX512F-NEXT:    vmovdqa 64(%rdi), %ymm3
 ; AVX512F-NEXT:    vpshufb %ymm0, %ymm3, %ymm0
-; AVX512F-NEXT:    vmovdqa {{.*#+}} ymm4 = [0,4,0,4,0,4,8,12]
+; AVX512F-NEXT:    vbroadcasti128 {{.*#+}} ymm4 = [0,4,8,12,0,4,8,12]
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RKSimon wrote:

Yes - still addressing regressions, that's why its still a draft :) 

https://github.com/llvm/llvm-project/pull/73509