[FunctionAttr] Infer nonnull attributes on returns

Description

[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

Details

Committed
reamesAug 31 2015, 12:44 PM
Differential Revision
D9688: [FunctionAttr] Infer nonnull attributes on returns
Parents
rL246475: [fuzzer bot] fix flag syntax
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