[PATCH] D62989: [Unroll] Do NOT unroll a loop with small runtime upperbound

[Z. Zheng via Phabricator via llvm-commits]

zzheng added a comment.

> Wouldn't I want to (fully) unroll loops especially those with low trip count to reduce overhead/enable further optimizations?
> 
> Do you have performance/code size numbers?

The overhead of loop exit check will not be reduced after full unroll, that the reason computeUnrollCount() chooses not to fully unroll unless it's run MaxOrZero iterations.

``

  This loop was found from an internal workload, unrolling it impact performance negatively.


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https://reviews.llvm.org/D62989