2 Commits

Author SHA1 Message Date
Sanjay Patel
a771f08794 [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
2017-02-13 23:10:51 +00:00
Philip Reames
bf9ec6af48 [FunctionAttr] Infer nonnull attributes on returns
Teach FunctionAttr to infer the nonnull attribute on return values of functions which never return a potentially null value. This is done both via a conservative local analysis for the function itself and a optimistic per-SCC analysis. If no function in the SCC returns anything which could be null (other than values from other functions in the SCC), we can conclude no function returned a null pointer. Even if some function within the SCC returns a null pointer, we may be able to locally conclude that some don't.

Differential Revision: http://reviews.llvm.org/D9688



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@246476 91177308-0d34-0410-b5e6-96231b3b80d8
2015-08-31 19:44:38 +00:00