[PATCH] D158063: [GISel][AArch64] Combine G_BUILD_VECTOR(G_UNMERGE) with undef elements

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


================
Comment at: llvm/include/llvm/CodeGen/GlobalISel/LegalizationArtifactCombiner.h:972
+            Register UndefReg = MIB.buildUndef(DstTy)->getOperand(0).getReg();
+            MIB.buildShuffleVector(Dst, UnmergeSrc, UndefReg, Mask);
+            UpdatedDefs.push_back(Dst);
----------------
shuffle vector isn't defined as a legalization artifact. Probably best if the artifact combiner avoids introducing something that isn't an artifact


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D158063/new/

https://reviews.llvm.org/D158063