troyj added a comment.

Hi, I got here via llvm-dev => https://reviews.llvm.org/D9375 => 
https://reviews.llvm.org/D9403 (this) and have read through everything.  I see 
that this patch has been stalled for about a year and I would like to know its 
status.  Is it waiting on a resolution in LLVM for this problem that Jeroen 
mentioned on llvm-dev?

  "One of the bigger problems is, that some optimization passes optimize away 
some (but not all) of the llvm.noalias intrinsics in a function. Because of 
that, the alias analysis can get confused and can identify two pointers as 
not-aliasing where they should be aliasing."

That's an improper optimization though, right?  If the semantics of the 
intrinsic are that all of them or none of them must be present for correctness, 
then any optimization that removes some but not all is defective.  Is the issue 
that these optimizations cannot tell that they are doing anything wrong?

I am interested in seeing this patch merged, so I would like to know what the 
obstacles are.  Thanks.


https://reviews.llvm.org/D9403



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