[llvm] [MacroFusion] Support commutable instructions (PR #82751)

[Wang Pengcheng via llvm-commits]

wangpc-pp wrote:

I added a `IsCommutable` to control the generation of checking commutable operands, because we may not need it in all cases.
@arsenm WDYT?

https://github.com/llvm/llvm-project/pull/82751