[PATCH] D121940: [SLP] Support internal users of splat loads

[Alexey Bataev via Phabricator via llvm-commits]

ABataev added inline comments.


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Comment at: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:1184
+            static constexpr unsigned VectorUsesLimit = 3;
+            unsigned Limit = VectorUsesLimit * NumLanes + 1;
+            if (V1->hasNUsesOrMore(Limit) || V2->hasNUsesOrMore(Limit))
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vporpo wrote:
> ABataev wrote:
> > Same question here
> This sets the limit of users of a broadcast that will be checked. Instead of having a fixed hard limit of say 10 users, this is taking into account the number of lanes, because the more the lanes, the higher the limit should be to avoid it being over-conservative. For example, if we only have 2 lanes then this corresponds to a limit of 7, but if we have 4 lanes then this becomes 13.
> Anyway, I don't think this is super important, we could just set a hard limit of 10. What do you think?
The limit here is just to reduce number of checks, probably some hardcoded constant value would be better, otherwise we may have to many checks for very big `NumLanes` values.


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  https://reviews.llvm.org/D121940/new/

https://reviews.llvm.org/D121940