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

[Jakub Kuderski via llvm-commits]

https://github.com/kuhar approved this pull request.

LGTM, thanks for the changes.

Note that this could also be implement without sign extension, similar to https://github.com/llvm/llvm-project/pull/85212. I don't know if the performance of the implementation matters much here, these functions are not on any fast path on MLIR the mlir. If you need a faster implementation, I wrote one for WebGPU: https://github.com/llvm/llvm-project/blob/22eb8000d22efe1bf06518e84af84d34ff6375de/mlir/lib/Dialect/SPIRV/Transforms/SPIRVWebGPUTransforms.cpp#L50

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