[PATCH] D71847: [OpenMP][Part 1] Reusable OpenMP context/traits handling

[Reid Kleckner via Phabricator via llvm-commits]

rnk added inline comments.


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Comment at: llvm/include/llvm/Frontend/OpenMP/OMPContext.h:119
+
+  SmallSet<TraitProperty, 8> RequiredTraits;
+  SmallVector<TraitProperty, 8> ConstructTraits;
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jdoerfert wrote:
> rnk wrote:
> > I'd suggest that you think about different data structures here. I noticed that this instantiation of SmallSet, which wraps std::set, takes ~20ms, and happens in every file that includes OMPContext.h.
> > 
> > Can you use a BitVector or std::bitset instead?
> TBH, I don't understand why this takes any time at all as it is just a type. Do you mean having `std::set` in the type is already slow?
> 
> I still run test but what do you think of D76170 ?
Basically, yes, all the time is spent instantiating std::set<>::insert. This is a set of enumerators, though, which are densely packed integers with some known fixed maximum, so a bit vector seems like a more natural representation.


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https://reviews.llvm.org/D71847