Experimental re-land of [X86][BMI1] X86DAGToDAGISel: select BEXTR from x << (32 - y) >> (32 - y) pattern
This initially landed in rL345014, but was reverted in rL345017
due to sanitizer-x86_64-linux-fast buildbot failure in
check-lld (ELF/relocatable-versioned.s) test.
While i'm not yet quite sure what is the problem, one obvious
thing here is that extra truncation roundtrip.
Maybe that's it? If not, will re-revert.
Differential Revision: https://reviews.llvm.org/D53521
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345027
91177308-0d34-0410-b5e6-
96231b3b80d8