[llvm] [mlir] [ADT] Add signed and unsigned mulh to APInt (PR #84719)

[Simon Pilgrim via llvm-commits]

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@@ -434,9 +434,7 @@ arith::MulSIExtendedOp::fold(FoldAdaptor adaptor,
     // Invoke the constant fold helper again to calculate the 'high' result.
     Attribute highAttr = constFoldBinaryOp<IntegerAttr>(
         adaptor.getOperands(), [](const APInt &a, const APInt &b) {
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RKSimon wrote:

I'd recommend any further refactor changes like that as followups for somebody (not necessarily @Atousa) - to ensure the changes in this PR are just the move to the APIntOps::mulh* helpers.

https://github.com/llvm/llvm-project/pull/84719