[AMDGPU] setcc (select cc, CT, CF), CF, eq | ne -> xor cc, -1 | cc

This is the common case in the BE when we serialize condition and then
rematerialize it. Use either original or inverted condition.

Differential Revision: https://reviews.llvm.org/D48246

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334882 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed