[FunctionAttrs] Infer WriteOnly Function Attribute

These changes expand the FunctionAttr logic in order to mark functions as
WriteOnly when appropriate. This is done through an additional bool variable
and extended logic.

Reviewers: hfinkel, jdoerfert

Differential Revision: https://reviews.llvm.org/D48387


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@340537 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed