[llvm] [VectorCombine] Add support for zext/sext/trunc to shuffleToIdentity (PR #92696)

[David Green via llvm-commits]

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@@ -372,8 +370,7 @@ define <8 x i8> @inner_shuffle(<8 x i8> %a, <8 x i8> %b, <8 x i8> %c) {
 define <4 x i32> @extrause_add_same_operands(<4 x i32> %x) {
 ; CHECK-LABEL: @extrause_add_same_operands(
 ; CHECK-NEXT:    [[SHUF:%.*]] = shufflevector <4 x i32> [[X:%.*]], <4 x i32> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
-; CHECK-NEXT:    [[ADD:%.*]] = add <4 x i32> [[SHUF]], [[SHUF]]
-; CHECK-NEXT:    [[REVSHUF:%.*]] = shufflevector <4 x i32> [[ADD]], <4 x i32> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT:    [[REVSHUF:%.*]] = add <4 x i32> [[X]], [[X]]
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davemgreen wrote:

The resulting instructions can come from multiple original instructions, so it doesn't currently try to pick a variable name. The name is scavenged automatically by replaceValue.

https://github.com/llvm/llvm-project/pull/92696