InstructionSimplify: Simplify a shuffle with a undef mask to undef
Summary:
Following the discussion in pr32486, adding the simplification:
shuffle %x, %y, undef -> undef
Reviewers: spatel, RKSimon, andreadb, davide
Reviewed By: spatel
Subscribers: jroelofs, davide, llvm-commits
Differential Revision: https://reviews.llvm.org/D32293
llvm-svn: 301764
diff --git a/llvm/test/Transforms/InstSimplify/shufflevector.ll b/llvm/test/Transforms/InstSimplify/shufflevector.ll
index e03916c..6af0db8 100644
--- a/llvm/test/Transforms/InstSimplify/shufflevector.ll
+++ b/llvm/test/Transforms/InstSimplify/shufflevector.ll
@@ -118,6 +118,14 @@
ret <4 x i32> %shuf
}
+define <4 x i32> @undef_mask_1(<4 x i32> %x, <4 x i32> %y) {
+; CHECK-LABEL: @undef_mask_1(
+; CHECK-NEXT: ret <4 x i32> undef
+;
+ %shuf = shufflevector <4 x i32> %x, <4 x i32> %y, <4 x i32> undef
+ ret <4 x i32> %shuf
+}
+
define <4 x i32> @identity_mask_0(<4 x i32> %x) {
; CHECK-LABEL: @identity_mask_0(
; CHECK-NEXT: ret <4 x i32> [[X:%.*]]