Commit Graph

2 Commits

Author SHA1 Message Date
Sanjay Patel fd24fb1b2b add checks for 'unpredictable' metadata preservation
llvm-svn: 263648
2016-03-16 18:15:34 +00:00
Sanjay Patel ee52b6e77d allow branch weight metadata on select instructions (PR26636)
As noted in:
https://llvm.org/bugs/show_bug.cgi?id=26636

This doesn't accomplish anything on its own. It's the first step towards preserving 
and using branch weights with selects.

The next step would be to make sure we're propagating the info in all of the other
places where we create selects (SimplifyCFG, InstCombine, etc). I don't think there's
an easy fix to make this happen; we have to look at each transform individually to 
determine how to correctly propagate the weights.

Along with that step, we need to then use the weights when making subsequent transform
decisions such as discussed in http://reviews.llvm.org/D16836.

The inliner test is independent but closely related. It verifies that metadata is
preserved when both branches and selects are cloned.

Differential Revision: http://reviews.llvm.org/D18133

llvm-svn: 263482
2016-03-14 20:18:59 +00:00