[llvm] [SeparateConstOffsetFromGEP] Decompose constant xor operand if possible (PR #135788)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm requested changes to this pull request.

InstCombine already removes these xors. Your examples have them all fold away when run through instcombine. In general we should not need to worry about non-canonical IR in late optimization passes 

https://github.com/llvm/llvm-project/pull/135788