commit 71ca53b6cf097c88de5cd03232d1ccd47cf72b08
author Jay Foad <jay.foad@amd.com> Mon Sep 04 18:32:43 2023 +0100
committer GitHub <noreply@github.com> Mon Sep 04 13:32:43 2023 -0400
tree 4764918e56e795ed12ccb3c57e3de7d93b5b7a70
parent f1162fb677bf6641928a2390edac5a8d62cf1250

[GlobalISel] Lower G_SHUFFLE_VECTOR with scalar result (#65275)

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 6044634..cfb9595 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -6779,26 +6779,9 @@
   LLT IdxTy = LLT::scalar(32);
 
   ArrayRef<int> Mask = MI.getOperand(3).getShuffleMask();
-
-  if (DstTy.isScalar()) {
-    if (Src0Ty.isVector())
-      return UnableToLegalize;
-
-    // This is just a SELECT.
-    assert(Mask.size() == 1 && "Expected a single mask element");
-    Register Val;
-    if (Mask[0] < 0 || Mask[0] > 1)
-      Val = MIRBuilder.buildUndef(DstTy).getReg(0);
-    else
-      Val = Mask[0] == 0 ? Src0Reg : Src1Reg;
-    MIRBuilder.buildCopy(DstReg, Val);
-    MI.eraseFromParent();
-    return Legalized;
-  }
-
   Register Undef;
   SmallVector<Register, 32> BuildVec;
-  LLT EltTy = DstTy.getElementType();
+  LLT EltTy = DstTy.getScalarType();
 
   for (int Idx : Mask) {
     if (Idx < 0) {
@@ -6820,7 +6803,10 @@
     }
   }
 
-  MIRBuilder.buildBuildVector(DstReg, BuildVec);
+  if (DstTy.isScalar())
+    MIRBuilder.buildCopy(DstReg, BuildVec[0]);
+  else
+    MIRBuilder.buildBuildVector(DstReg, BuildVec);
   MI.eraseFromParent();
   return Legalized;
 }