[PATCH] D80708: Improve SmallPtrSetImpl::count implementation

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serge-sans-paille created this revision.
serge-sans-paille added reviewers: yaron.keren, dexonsmith, bkramer.
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Relying on the `find` method implies a roundtrip to the iterator world, which is not costless because iterator creation involves a few check to ensure the iterator is in a valid position (through the `SmallPtrSetIteratorImpl::AdvanceIfNotValid` method). It turns out that the result of ` SmallPtrSetImpl::find_imp` is either valid or the EndPointer, so there's no need to go through that abstraction, and the compiler cannot guess it.


https://reviews.llvm.org/D80708

Files:
  llvm/include/llvm/ADT/SmallPtrSet.h


Index: llvm/include/llvm/ADT/SmallPtrSet.h
===================================================================
--- llvm/include/llvm/ADT/SmallPtrSet.h
+++ llvm/include/llvm/ADT/SmallPtrSet.h
@@ -372,7 +372,9 @@
     return erase_imp(PtrTraits::getAsVoidPointer(Ptr));
   }
   /// count - Return 1 if the specified pointer is in the set, 0 otherwise.
-  size_type count(ConstPtrType Ptr) const { return find(Ptr) != end() ? 1 : 0; }
+  size_type count(ConstPtrType Ptr) const {
+    return find_imp(ConstPtrTraits::getAsVoidPointer(Ptr)) != EndPointer();
+  }
   iterator find(ConstPtrType Ptr) const {
     return makeIterator(find_imp(ConstPtrTraits::getAsVoidPointer(Ptr)));
   }


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