Enhancements to PartitionAlloc to support threading and arbitrary allocation sizes.

Source/wtf/PartitionAlloc.cpp

Index: Source/wtf/PartitionAlloc.cpp
diff --git a/Source/wtf/PartitionAlloc.cpp b/Source/wtf/PartitionAlloc.cpp
index f53b03a79ed2a7c4e740265c8bba758750a66ab1..9b9af0d6821f220f985029b9133e6d5e3f24920f 100644
--- a/Source/wtf/PartitionAlloc.cpp
+++ b/Source/wtf/PartitionAlloc.cpp
@@ -46,6 +46,7 @@ void partitionAllocInit(PartitionRoot* root)
 {
     ASSERT(!root->initialized);
     root->initialized = true;
+    root->lock = 0;
     size_t i;
     for (i = 0; i < kNumBuckets; ++i) {
         PartitionBucket* bucket = &root->buckets[i];
@@ -323,6 +324,36 @@ void partitionFreeSlowPath(PartitionPageHeader* page)
     }
 }
 
+void* partitionReallocGeneric(PartitionRoot* root, void* ptr, size_t oldSize, size_t newSize)
+{
+#if defined(MEMORY_TOOL_REPLACES_ALLOCATOR)
+    return realloc(ptr, newSize);
+#else
+    size_t oldIndex = oldSize >> kBucketShift;
+    if (oldIndex > kNumBuckets)
+        oldIndex = kNumBuckets;
+    size_t newIndex = newSize >> kBucketShift;
+    if (newIndex > kNumBuckets)
+        newIndex = kNumBuckets;
+
+    if (oldIndex == newIndex) {
+        // Same bucket. But kNumBuckets indicates the fastMalloc "bucket" so in
+        // that case we're not done; we have to forward to fastRealloc.
+        if (oldIndex == kNumBuckets)
+            return WTF::fastRealloc(ptr, newSize);
+        return ptr;
+    }
+    // This realloc cannot be resized in-place. Sadness.
+    void* ret = partitionAllocGeneric(root, newSize);
+    size_t copySize = oldSize;
+    if (newSize < oldSize)
+        copySize = newSize;
+    memcpy(ret, ptr, copySize);
+    partitionFreeGeneric(ptr, oldSize);
+    return ret;
+#endif
+}
+
 #ifndef NDEBUG
 
 void partitionDumpStats(const PartitionRoot& root)