[PATCH] D27004: Set unroll remainder to epilog if profitable

Tue Feb 14 10:41:34 PST 2017

hfinkel accepted this revision.
hfinkel added a comment.
This revision is now accepted and ready to land.

In https://reviews.llvm.org/D27004#675251, @evstupac wrote:

> PING.
>  Are there any major concerns regarding epilogue, besides this: https://bugs.llvm.org//show_bug.cgi?id=30939?
>  It looks like we are accepting epilogue for vectorization for some reason and can not accept it for unroll.

I think that we should move forward with this. PR30939, as explained in the bug report, does not seem like something we can reasonably work around - it seems like a prototypical microarchitectural sensitivity - dealing with branch predictors on unpredictable branches is always hard.

================
Comment at: lib/Transforms/Utils/LoopUnroll.cpp:357
+      UnrollRuntimeEpilog.getNumOccurrences() ? UnrollRuntimeEpilog
+                                              : isEpilogProfitable (L);
+
----------------
No space before (L).

Repository:
  rL LLVM

https://reviews.llvm.org/D27004