[PATCH] D32166: Improve LoopVectorizers estimation of scalar loops by predicting LSR behaviour

[Jonas Paulsson via Phabricator via llvm-commits]

jonpa created this revision.
Herald added a subscriber: mzolotukhin.

I have experimented with collecting a set of instructions that LSR is likely to eliminate in the scalar version of the loop. This is e.g. an add of a PHI and a constant.

At this point, the patch is showing a general improvement of at least %5 in scalar estimates. The collectLikelyLSRed() can likely be improved.

At this point, I wonder what the response to this is? Is this a good or bad idea?

How much would we want a general improvement vs avoiding worst case degradation of estimates?


https://reviews.llvm.org/D32166

Files:
  lib/Transforms/Vectorize/LoopVectorize.cpp

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D32166.95567.patch
Type: text/x-patch
Size: 3349 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20170418/252d7be9/attachment.bin>