[FunctionAttrs] try to extend nonnull-ness of arguments from a callsite back to its parent function
As discussed here:
http://lists.llvm.org/pipermail/llvm-dev/2016-December/108182.html
...we should be able to propagate 'nonnull' info from a callsite back to its parent.
The original motivation for this patch is our botched optimization of "dyn_cast" (PR28430),
but this won't solve that problem.
The transform is currently disabled by default while we wait for clang to work-around
potential security problems:
http://lists.llvm.org/pipermail/cfe-dev/2017-January/052066.html
Differential Revision: https://reviews.llvm.org/D27855
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294998
91177308-0d34-0410-b5e6-
96231b3b80d8