1 files changed, 33 insertions, 9 deletions

diff --git a/include/llvm/ADT/DenseMap.h b/include/llvm/ADT/DenseMap.h
index 06a1575da4..dd341c6a75 100644
--- a/include/llvm/ADT/DenseMap.h
+++ b/include/llvm/ADT/DenseMap.h
@@ -18,6 +18,7 @@
 #include "llvm/Support/PointerLikeTypeTraits.h"
 #include "llvm/Support/type_traits.h"
 #include "llvm/ADT/DenseMapInfo.h"
+#include <algorithm>
 #include <iterator>
 #include <new>
 #include <utility>
@@ -52,13 +53,13 @@ public:
     CopyFrom(other);
   }
 
-  explicit DenseMap(unsigned NumInitBuckets = 64) {
+  explicit DenseMap(unsigned NumInitBuckets = 0) {
     init(NumInitBuckets);
   }
 
   template<typename InputIt>
   DenseMap(const InputIt &I, const InputIt &E) {
-    init(64);
+    init(NextPowerOf2(std::distance(I, E)));
     insert(I, E);
   }
   
@@ -97,7 +98,10 @@ public:
   unsigned size() const { return NumEntries; }
 
   /// Grow the densemap so that it has at least Size buckets. Does not shrink
-  void resize(size_t Size) { grow(Size); }
+  void resize(size_t Size) {
+    if (Size > NumBuckets)
+      grow(Size);
+  }
 
   void clear() {
     if (NumEntries == 0 && NumTombstones == 0) return;
@@ -251,19 +255,25 @@ private:
 #endif
       operator delete(Buckets);
     }
-    Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) *
-                                                 other.NumBuckets));
+
+    NumBuckets = other.NumBuckets;
+
+    if (NumBuckets == 0) {
+      Buckets = 0;
+      return;
+    }
+
+    Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT) * NumBuckets));
 
     if (isPodLike<KeyInfoT>::value && isPodLike<ValueInfoT>::value)
-      memcpy(Buckets, other.Buckets, other.NumBuckets * sizeof(BucketT));
+      memcpy(Buckets, other.Buckets, NumBuckets * sizeof(BucketT));
     else
-      for (size_t i = 0; i < other.NumBuckets; ++i) {
+      for (size_t i = 0; i < NumBuckets; ++i) {
         new (&Buckets[i].first) KeyT(other.Buckets[i].first);
         if (!KeyInfoT::isEqual(Buckets[i].first, getEmptyKey()) &&
             !KeyInfoT::isEqual(Buckets[i].first, getTombstoneKey()))
           new (&Buckets[i].second) ValueT(other.Buckets[i].second);
       }
-    NumBuckets = other.NumBuckets;
   }
 
   BucketT *InsertIntoBucket(const KeyT &Key, const ValueT &Value,
@@ -312,6 +322,11 @@ private:
     unsigned ProbeAmt = 1;
     BucketT *BucketsPtr = Buckets;
 
+    if (NumBuckets == 0) {
+      FoundBucket = 0;
+      return false;
+    }
+
     // FoundTombstone - Keep track of whether we find a tombstone while probing.
     BucketT *FoundTombstone = 0;
     const KeyT EmptyKey = getEmptyKey();
@@ -353,6 +368,12 @@ private:
     NumEntries = 0;
     NumTombstones = 0;
     NumBuckets = InitBuckets;
+
+    if (InitBuckets == 0) {
+      Buckets = 0;
+      return;
+    }
+
     assert(InitBuckets && (InitBuckets & (InitBuckets-1)) == 0 &&
            "# initial buckets must be a power of two!");
     Buckets = static_cast<BucketT*>(operator new(sizeof(BucketT)*InitBuckets));
@@ -366,6 +387,9 @@ private:
     unsigned OldNumBuckets = NumBuckets;
     BucketT *OldBuckets = Buckets;
 
+    if (NumBuckets < 64)
+      NumBuckets = 64;
+
     // Double the number of buckets.
     while (NumBuckets < AtLeast)
       NumBuckets <<= 1;
@@ -385,7 +409,7 @@ private:
         // Insert the key/value into the new table.
         BucketT *DestBucket;
         bool FoundVal = LookupBucketFor(B->first, DestBucket);
-        FoundVal = FoundVal; // silence warning.
+        (void)FoundVal; // silence warning.
         assert(!FoundVal && "Key already in new map?");
         DestBucket->first = B->first;
         new (&DestBucket->second) ValueT(B->second);