[PATCH] D57779: [SLP] Add support for throttling.

[Vasileios Porpodas via Phabricator via llvm-commits]

vporpo added inline comments.


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Comment at: lib/Transforms/Vectorize/SLPVectorizer.cpp:645
+  /// Save seed instructions to try partially vectorize later.
+  void recordSeeds(ArrayRef<Value *> Ops);
+
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dtemirbulatov wrote:
> vporpo wrote:
> > Why are we collecting the seeds specifically for partial vectorization? Is this really needed? Why don't you just call tryPartialVectorization(Seeds) within vectorizeStorChain() etc. ?
> Ok, Imagine that we could do partial vectorization with vector size 4 for 30% of the tree, but for the same tree, we could have full vectorization with vector size 2. I think that it would be serious regression if we could do it with just 30%. Or for example, for the same tree, we could do reduction later for the whole tree.
Yes, but this problem is not specific to throttling. As it is now, SLP will greedily accept 4-wide vectorization if profitable, without comparing it against 2x 2-wide. I think this problem should be addressed separately.


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  https://reviews.llvm.org/D57779/new/

https://reviews.llvm.org/D57779