[llvm] r234589 - Microoptimize DenseMap::clear.

[Benjamin Kramer]

Author: d0k
Date: Fri Apr 10 07:46:44 2015
New Revision: 234589

URL: http://llvm.org/viewvc/llvm-project?rev=234589&view=rev
Log:
Microoptimize DenseMap::clear.

Cache NumEntries locally, it's only used in an assert and using the member
variable prevents the compiler from eliminating the tombstone check for types
with trivial destructors. No functionality change intended.

Modified:
    llvm/trunk/include/llvm/ADT/DenseMap.h

Modified: llvm/trunk/include/llvm/ADT/DenseMap.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/DenseMap.h?rev=234589&r1=234588&r2=234589&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/DenseMap.h (original)
+++ llvm/trunk/include/llvm/ADT/DenseMap.h Fri Apr 10 07:46:44 2015
@@ -100,16 +100,18 @@ public:
     }
 
     const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
+    unsigned NumEntries = getNumEntries();
     for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P) {
       if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey)) {
         if (!KeyInfoT::isEqual(P->getFirst(), TombstoneKey)) {
           P->getSecond().~ValueT();
-          decrementNumEntries();
+          --NumEntries;
         }
         P->getFirst() = EmptyKey;
       }
     }
-    assert(getNumEntries() == 0 && "Node count imbalance!");
+    assert(NumEntries == 0 && "Node count imbalance!");
+    setNumEntries(0);
     setNumTombstones(0);
   }
 
@@ -257,7 +259,7 @@ public:
   const void *getPointerIntoBucketsArray() const { return getBuckets(); }
 
 protected:
-  DenseMapBase() {}
+  DenseMapBase() = default;
 
   void destroyAll() {
     if (getNumBuckets() == 0) // Nothing to do.