[llvm] [GVN] Look through select/phi when determining underlying object (PR #99509)

[Nikita Popov via llvm-commits]

nikic wrote:

> > getUnderlyingObjectThroughPhisAndSelects() (let me know if you have a better name...)
> 
> maybe `getUnderlyingObjectAggressive` to leave more room for future extensions :)

Sounds reasonable, done!

https://github.com/llvm/llvm-project/pull/99509