[WebAssembly] Use poison instead of undef for swizzle test

Author: valadaptive

llvm/test/Transforms/InstCombine/WebAssembly/fold-swizzle.ll

@@ -27,14 +27,14 @@ define <16 x i8> @swizzle_reverse(<16 x i8> %v) {
   ret <16 x i8> %result
 }
 
-; undef elements
-define <16 x i8> @swizzle_with_undef(<16 x i8> %v) {
-; CHECK-LABEL: define <16 x i8> @swizzle_with_undef(
+; poison elements
+define <16 x i8> @swizzle_with_poison(<16 x i8> %v) {
+; CHECK-LABEL: define <16 x i8> @swizzle_with_poison(
 ; CHECK-SAME: <16 x i8> [[V:%.*]]) {
 ; CHECK-NEXT:    [[RESULT:%.*]] = shufflevector <16 x i8> [[V]], <16 x i8> poison, <16 x i32> <i32 0, i32 poison, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
 ; CHECK-NEXT:    ret <16 x i8> [[RESULT]]
 ;
-  %result = tail call <16 x i8> @llvm.wasm.swizzle(<16 x i8> %v, <16 x i8> <i8 0, i8 undef, i8 2, i8 3, i8 4, i8 5, i8 6, i8 7, i8 8, i8 9, i8 10, i8 11, i8 12, i8 13, i8 14, i8 15>)
+  %result = tail call <16 x i8> @llvm.wasm.swizzle(<16 x i8> %v, <16 x i8> <i8 0, i8 poison, i8 2, i8 3, i8 4, i8 5, i8 6, i8 7, i8 8, i8 9, i8 10, i8 11, i8 12, i8 13, i8 14, i8 15>)
   ret <16 x i8> %result
 }