[RS4GC] Fix algorithm to avoid setting vector BDV for scalar derived pointer
- updates isKnownBaseValue to account for base pointer and
derived pointer having differing types.
- This inturn allows us to populate the
lattice (States) for such derived pointers.
- It also updates all states where the base and derived pointers have
differing types (vector versus scalar) and conservatively marks these
states as conflictcs.
Note that in 59029b9eef23, we were just fixing existing lattice values
and that too, only for uses of extractelement.
Reviewers: reames, skatkov, dantrushin
Reviewed By: skatkov
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D76305