[PATCH] D21560: Relax the clearance calculating for breaking partial register dependency.

[Sanjay Patel via llvm-commits]

spatel added a reviewer: joerg.
spatel added a comment.

Thanks.

Earlier in the thread, Joerg requested more general perf data. Has that request been fulfilled or cancelled?

It would be interesting to know what the optimal setting is for at least one benchmark, so you can leave a comment by the cl::opt definition to justify the default setting.

Also, we don't have to answer the MinSize question that I raised directly in this patch, but my perf data shows that we really shouldn't be adding xors in that situation - we hope these are free, but they are not in all cases. IMO, our documentation for -Oz is wrong. There shouldn't be any room for interpretation about the definition of "minimum"; this is the flag used by devs (embedded, boot code, etc) who require the smallest possible code, and perf shouldn't matter.


http://reviews.llvm.org/D21560