Use original return type's element type for return type

Fixes crashes with scmp where the element types aren't necessarily the same.

Author: lukel97

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -1453,8 +1453,12 @@ InstCombinerImpl::foldShuffledIntrinsicOperands(IntrinsicInst *II) {
 
   // intrinsic (shuf X, M), (shuf Y, M), ... --> shuf (intrinsic X, Y, ...), M
   Instruction *FPI = isa<FPMathOperator>(II) ? II : nullptr;
+  // Result type might be a different vector width.
+  // TODO: Check that the result type isn't widened?
+  VectorType *ResTy =
+      VectorType::get(II->getType()->getScalarType(), cast<VectorType>(SrcTy));
   Value *NewIntrinsic =
-      Builder.CreateIntrinsic(SrcTy, II->getIntrinsicID(), NewArgs, FPI);
+      Builder.CreateIntrinsic(ResTy, II->getIntrinsicID(), NewArgs, FPI);
   return new ShuffleVectorInst(NewIntrinsic, Mask);
 }
 

llvm/test/Transforms/InstCombine/scmp.ll

@@ -423,6 +423,19 @@ define i8 @scmp_from_select_eq_and_gt_commuted3(i32 %x, i32 %y) {
   ret i8 %r
 }
 
+define <3 x i2> @scmp_unary_shuffle_ops(<3 x i8> %x, <3 x i8> %y) {
+; CHECK-LABEL: define <3 x i2> @scmp_unary_shuffle_ops(
+; CHECK-SAME: <3 x i8> [[X:%.*]], <3 x i8> [[Y:%.*]]) {
+; CHECK-NEXT:    [[TMP1:%.*]] = call <3 x i2> @llvm.scmp.v3i2.v3i8(<3 x i8> [[X]], <3 x i8> [[Y]])
+; CHECK-NEXT:    [[R:%.*]] = shufflevector <3 x i2> [[TMP1]], <3 x i2> poison, <3 x i32> <i32 1, i32 0, i32 2>
+; CHECK-NEXT:    ret <3 x i2> [[R]]
+;
+  %sx = shufflevector <3 x i8> %x, <3 x i8> poison, <3 x i32> <i32 1, i32 0, i32 2>
+  %sy = shufflevector <3 x i8> %y, <3 x i8> poison, <3 x i32> <i32 1, i32 0, i32 2>
+  %r = call <3 x i2> @llvm.scmp(<3 x i8> %sx, <3 x i8> %sy)
+  ret <3 x i2> %r
+}
+
 ; Negative test: true value of outer select is not zero
 define i8 @scmp_from_select_eq_and_gt_neg1(i32 %x, i32 %y) {
 ; CHECK-LABEL: define i8 @scmp_from_select_eq_and_gt_neg1(