[llvm] [MCP] Bug fix for reverted patch #70778 (PR #74239)

[via llvm-commits]

LWenH wrote:

> > This seems to at least work for the test cases that failed downstream after #70778
> > I'll try to run some more testing with this new patch over night.
> 
> Can't say that I know much about this pass and the code diff. But I haven't seen any new failures when running tests this patch, so it's fine with me in that sense.

Seems like a corner case in MIR code pattern leading to this bug:-), thank you for your time to test this patch further.

https://github.com/llvm/llvm-project/pull/74239