[llvm] [AArch64] Optimize lowering of extending BUILD_VECTOR(EXTRACT_VECTOR_ELT()) (PR #212156)

[David Sherwood via llvm-commits]

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@@ -281,7 +281,8 @@ define void @insert_vec_v16i8_uaddlv_from_v8i8(ptr %0) {
 ; CHECK-NEXT:    movi.2d v2, #0000000000000000
 ; CHECK-NEXT:    uaddlv.8b h1, v0
 ; CHECK-NEXT:    stp q0, q0, [x0, #32]
-; CHECK-NEXT:    mov.h v2[0], v1[0]
+; CHECK-NEXT:    mov.b v2[0], v1[0]
+; CHECK-NEXT:    zip1.8b v2, v2, v2
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david-arm wrote:

Overall the codegen changes all look like decent improvements. However, these two test changes seem to be a regression. Do you know what's going on here?

https://github.com/llvm/llvm-project/pull/212156