[PATCH] D116261: [Clang][OpenMP] Add support for compare capture in parser

[Alexey Bataev via Phabricator via llvm-commits]

ABataev added inline comments.


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Comment at: clang/lib/Sema/SemaOpenMP.cpp:11320
+  bool MutexClauseEncountered = false;
+  llvm::SmallSet<OpenMPClauseKind, 2> EncounteredAtomicKinds;
   for (const OMPClause *C : Clauses) {
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ABataev wrote:
> tianshilei1992 wrote:
> > ABataev wrote:
> > > tianshilei1992 wrote:
> > > > ABataev wrote:
> > > > > tianshilei1992 wrote:
> > > > > > ABataev wrote:
> > > > > > > SmallVector with 2 elements should be enough, no need to use SmallSet here.
> > > > > > `SmallVector` doesn't provide `contains`, which we use to check if `OMPC_compare` and `OMPC_capture` exist at the same time. Using `SmallVector` requires us to have a complicated comparison, for example:
> > > > > > ```
> > > > > > (EncounteredAtomicKinds[0] == OMPC_compare && EncounteredAtomicKinds[1] == OMPC_capture) || (EncounteredAtomicKinds[1] == OMPC_compare && EncounteredAtomicKinds[0] == OMPC_capture)
> > > > > > ```
> > > > > > which is not as neat as `SmallSet`.
> > > > > Use llvm::find
> > > > That is linear time. Why it is better than `SmallSet`?
> > > Because there are only 2 elements, no?
> > It could have more. If user writes it like `atomic compare compare capture capture capture`, then it will have 5 elements. `SmallSet<T>::insert` returns a `pair` and we know if it is already in the set, which I have not added it yet but I'll. `SmallVector` then is not that easy to use. Of course you could say do `llvm::find` beforehand but it's not neat.
> Is this correct at all?
You still can scan over the small vector and check if it has specified clause already. 


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https://reviews.llvm.org/D116261