[llvm] [TailCallElim] Add flow-sensitivity to alloca escape analysis (PR #176825)

[Antonio Frighetto via llvm-commits]

https://github.com/antoniofrighetto commented:

Thanks for the patch, this misses some negative tests though.

> * `alloca-temporal-alias.ll`: Verifies that storing a pointer in an alias slot used only locally is handled correctly. [Compiler Explorer](https://godbolt.org/z/GszMv6Y61)

I believe TRE AllocaDerivedValueTracker currently doesn't follow load/store chains. Consider the unoptimized IR where `ptr_storage` contains the address of `local_var`; the latter is loaded back from `ptr_storage` and passed to a function: https://llvm.godbolt.org/z/5sf8We8ee. I don't think we could perform TRE in this case, however the patch does?

https://github.com/llvm/llvm-project/pull/176825