[PATCH] D81548: [X86][AVX512] Avoid bitcasts between scalar and vXi1 bool vectors

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


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Comment at: llvm/lib/Target/X86/X86ISelLowering.cpp:37953
+  case ISD::SHL: {
+    // If we find a suitable source, a SHL becomes a KSHIFTR (little endian).
+    SDValue Src0 = V.getOperand(0);
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Why does a SHL become KSHIFTR?


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Comment at: llvm/test/CodeGen/X86/vector-shuffle-v1.ll:893
+; AVX512F-NEXT:    kshiftrw $8, %k0, %k0
+; AVX512F-NEXT:    kshiftrw $8, %k0, %k1
+; AVX512F-NEXT:    korw %k0, %k1, %k1
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Isn't k1 zero after this kshiftr? The two kshiftrs back to back add up to 16. So there are no bits left.


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  https://reviews.llvm.org/D81548/new/

https://reviews.llvm.org/D81548