[llvm] [X86] Truncate i64 add/sub/mul arithmetic to i32 with known zeros in upper 32 bits (PR #143313)

[Omkar Mohanty via llvm-commits]

omkar-mohanty wrote:

Hi @phoebewang , @RKSimon — apologies for the noise earlier. I wasn’t aware that I could run clang-format on just the diffs 😅. I’ve now marked this PR as a draft because I’m still uncertain about the `combineSub` and `combineMul` implementations. That said, I’ve updated the `combineAdd` function based on Phoebe’s suggestion.

Thanks for your patience!

https://github.com/llvm/llvm-project/pull/143313