[llvm] [AMDGPU][AggressiveInstCombine] Narrow 64 bit math to 32 bit if profitable (PR #130577)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> If `%x` is b'1000000 then sext(trunc(%x)) = b'11111...1000

It is guarded by the assumption `sext(trunc(%x)) == %x` in `@src`.


https://github.com/llvm/llvm-project/pull/130577