[PATCH] D66456: [DAGCombiner][X86] Teach visitCONCAT_VECTORS to combine (concat_vectors (concat_vectors X, Y), undef)) -> (concat_vectors X, Y, undef, undef)

[Craig Topper via Phabricator via llvm-commits]

craig.topper marked an inline comment as done.
craig.topper added inline comments.


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Comment at: llvm/test/CodeGen/X86/vec_umulo.ll:2516
+; AVX512-NEXT:    movq %r10, 8(%r14)
 ; AVX512-NEXT:    popq %rbx
 ; AVX512-NEXT:    popq %r12
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By instruction count this is a regression, but I'm not sure exactly what the difference is.


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  https://reviews.llvm.org/D66456/new/

https://reviews.llvm.org/D66456