[PATCH] D20017: Aggressive choosing best loop top

[David Li via llvm-commits]

davidxl added a comment.

Sorry I missed this.

Chandler thanks for looping me in. I will take a look.

By briefly looking at the summary, it seems to me this is exactly the cost based loop rotation enhancement (by Cong) is supposed to solve. This option is currently off by default, and also guarded by Profile feedback.

Can you comment out the guard at line 1555 that checks profile data, and then use option -mllvm precise-rotation-cost=true to see if it solves your problem?  We have plan to turn that on by default at some point after more performance experiment.


http://reviews.llvm.org/D20017