[PATCH] D18827: Rework/enhance stack coloring data flow analysis.

Wei Mi via llvm-commits llvm-commits at lists.llvm.org
Thu May 12 14:58:22 PDT 2016

wmi added a comment.

Thanks for the detailed implementation notes and spec2006 data. The spec2006 data is a overall number which looks good. I guess for individual file there is no regression anymore, right?

But I havn't understood quite well about the way to handle case with degenerate slot.  From my understanding, for case with degenerate slot, its liverange from startmarker to endmarker is smaller than actual, so it is possible for stackcoloring to generate incorrect code for such case (although I understand the case is never worse than without the patch).  The question is before this patch, since the case with degenerate slot always existed, why we didn't see error caused by it?

According to http://lists.llvm.org/pipermail/llvm-dev/2012-September/053458.html, letting ProtectFromEscapedAllocas stay off is to detect problematic case and fix it. Is the case with degenerate slot caused by LICM such a problematic case?



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