[llvm] [AArch64] Use sve instructions for fixed-width smulh/umulh. (PR #166168)

[David Sherwood via llvm-commits]

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@@ -1844,6 +1844,8 @@ AArch64TargetLowering::AArch64TargetLowering(const TargetMachine &TM,
                     MVT::v4i32, MVT::v1i64, MVT::v2i64}) {
       setOperationAction(ISD::SDIV, VT, Custom);
       setOperationAction(ISD::UDIV, VT, Custom);
+      setOperationAction(ISD::MULHS, VT, Custom);
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david-arm wrote:

nit: Perhaps worth updating the comment above the for loop?

https://github.com/llvm/llvm-project/pull/166168