[DAGCombiner] add (sext i1 X), 1 --> zext (not i1 X)
Besides better codegen, the motivation is to be able to canonicalize this pattern
in IR (currently we don't) knowing that the backend is prepared for that.
This may also allow removing code for special constant cases in
DAGCombiner::foldSelectOfConstants() that was added in D30180.
Differential Revision: https://reviews.llvm.org/D31944
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301457 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed