[PATCH] D91655: [AArch64][GlobalISel] Fix crash during legalization of a vector G_SELECT with scalar mask.

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


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Comment at: llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp:6226
+      MaskElt = MIRBuilder.buildSExt(DstTy.getElementType(), MaskElt).getReg(0);
+    // Generate a vector splat idiom to be pattern matched later.
+    auto UndefVec = MIRBuilder.buildUndef(DstTy);
----------------
Maybe should have a buildSplat helper too


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Comment at: llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp:6231-6233
+    SmallVector<int, 16> ZeroMask;
+    for (int I = 0; I < DstTy.getNumElements(); ++I)
+      ZeroMask.push_back(0);
----------------
This is the same as the ZeroMask(DstTy.getNumElements())


================
Comment at: llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp:6235-6238
+    auto ShufSplat = MIRBuilder
+                         .buildInstr(TargetOpcode::G_SHUFFLE_VECTOR, {DstTy},
+                                     {InsElt, UndefVec})
+                         .addShuffleMask(MaskAlloc);
----------------
We should have a buildShuffleVector


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D91655/new/

https://reviews.llvm.org/D91655