[llvm] [Reland][ValueTracking] Improve Bitcast handling to match SDAG (PR #145223)

[Abhishek Kaushik via llvm-commits]

abhishek-kaushik22 wrote:

> @abhishek-kaushik22 Sorry I missed the reversion for this - have you been able to create additional test coverage?

Hey, I've managed to find the diff in the C file that was miscompiled, but the miscompile originated not in `instcombine` but `always-inline` pass.
As such what I've have is ~250 line module that I've extracted from the original ir, I'm currently trying to reduce it

https://github.com/llvm/llvm-project/pull/145223