[InstCombine] use m_APInt to allow shift-shift folds for vectors with splat constants

Some existing 'FIXME' tests are still not folded because of splat holes in value tracking.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@292151 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed