Summary: Both computeKnownBits and ComputeNumSignBits can now do a simple
look-through of EXTRACT_VECTOR_ELT. It will compute the result based
on the known bits (or known sign bits) for the vector that the element
is extracted from.
Reviewers: bogner, tstellarAMD, mkuper
Subscribers: wdng, RKSimon, jyknight, llvm-commits, nhaehnle
Differential Revision: https://reviews.llvm.org/D25007
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@283347 91177308-0d34-0410-b5e6-96231b3b80d8
