[llvm] [SelectionDAG] Fold (avg x, 0) -> x >> 1 (PR #85581)

[David Green via llvm-commits]

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@@ -464,8 +464,7 @@ define <8 x i16> @rhaddu_i_const_lhs(<8 x i16> %src1) {
 define <8 x i16> @rhaddu_i_const_zero(<8 x i16> %src1) {
 ; CHECK-LABEL: rhaddu_i_const_zero:
 ; CHECK:       // %bb.0:
-; CHECK-NEXT:    movi v1.2d, #0000000000000000
-; CHECK-NEXT:    urhadd v0.8h, v0.8h, v1.8h
+; CHECK-NEXT:    ushr v0.8h, v0.8h, #1
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davemgreen wrote:

I think these would be incorrect for avgceil.

https://github.com/llvm/llvm-project/pull/85581