[PATCH] D20017: Aggressive choosing best loop top

[David Li via llvm-commits]

davidxl added a comment.

I verified that cost based rotation algorithm handles the issue as expected.

See the new test case added in r269267.

A new internal option is also added to help enable this rotation llc -force-precise-rotation-cost without requiring PGO. I recommend exploring existing rotation strategy (i.e., help by testing your use cases with performance data so that we can turn it on by default if desired) instead of adding more redundant logic here.


http://reviews.llvm.org/D20017