Pointer-comparison folding should look through returned-argument functions

For functions which are known to return a specific argument, pointer-comparison
folding can look through the function calls as part of its analysis.

Differential Revision: http://reviews.llvm.org/D9387

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275039 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed