Changeset 24059 in webkit for trunk/JavaScriptCore/wtf/FastMalloc.cpp

Timestamp:

Jul 6, 2007, 5:09:08 AM (18 years ago)

Author:

mjs

Message:

JavaScriptCore:

Reviewed by Antti.

• <rdar://problem/5311093> JavaScriptCore fails to build with strict-aliasing warnings

• Configurations/Base.xcconfig: Re-enable -Wstrict-aliasing
• bindings/jni/jni_utility.cpp: (KJS::Bindings::getJNIEnv): Type-pun via a union instead of a pointer cast.
• wtf/HashMap.h: (WTF::): Instead of doing type-punned assignments via pointer cast, do one of three things: (1) assign directly w/o cast if storage type matches real type; (2) assign using cast via union if type does not need reffing; (3) copy with memcpy and ref/deref manually if type needs reffing. This is ok peref-wise because memcpy of a constant length gets optomized. HashTraits are now expected to make ref()/deref() take the storage type, not the true type.
• wtf/HashSet.h: (WTF::): Same basic idea.
• wtf/HashTable.h: (WTF::): Added Assigner template for use by HashMap/HashSet. Change RefCounter to call ref() and deref() via storage type, avoiding the need to type-pun. (WTF::RefCounter::ref): ditto (WTF::RefCounter::deref): ditto
• wtf/HashTraits.h: (WTF::): Change ref() and deref() for RefPtr HashTraits to take the storage type; cast via union to pointer type.
• wtf/FastMalloc.cpp: (WTF::TCMalloc_PageHeap::init): Changed from constructor to init function so this can go in a union. (WTF::): redefine pageheap macro in terms of getPageHeap(). (WTF::getPageHeap): new inline function, helper for pageheap macro. This hides the cast in a union. (WTF::TCMalloc_ThreadCache::InitModule): Call init() instead of using placement new to initialize page heap.
• wtf/TCPageMap.h: (TCMalloc_PageMap1::init): Changed from constructor to init function. (TCMalloc_PageMap2::init): ditto (TCMalloc_PageMap3::init): ditto

WebCore:

Reviewed by Antti.

• <rdar://problem/5311093> JavaScriptCore fails to build with strict-aliasing warnings

• platform/StringHash.h: (WTF::): Adapt to newer way to do storage types.

File:

• trunk/JavaScriptCore/wtf/FastMalloc.cpp (modified) (4 diffs)

trunk/JavaScriptCore/wtf/FastMalloc.cpp

@@ -677 +677 @@
 class TCMalloc_PageHeap {
  public:
-  TCMalloc_PageHeap();
+  void init();
 
   // Allocate a run of "n" pages.  Returns zero if out of memory.
@@ -758 +758 @@
 };
 
-TCMalloc_PageHeap::TCMalloc_PageHeap() : pagemap_(MetaDataAlloc),
-                                         free_pages_(0),
-                                         system_bytes_(0) {
+void TCMalloc_PageHeap::init()
+{
+  pagemap_.init(MetaDataAlloc);
+  free_pages_ = 0;
+  system_bytes_ = 0;
+  
   DLL_Init(&large_);
   for (size_t i = 0; i < kMaxPages; i++) {
@@ -1174 +1177 @@
 // Avoid extra level of indirection by making "pageheap" be just an alias
 // of pageheap_memory.
-#define pageheap ((TCMalloc_PageHeap*) pageheap_memory)
+
+typedef union {
+    void* m_memory;
+    TCMalloc_PageHeap m_pageHeap;
+} PageHeapUnion;
+
+static inline TCMalloc_PageHeap* getPageHeap()
+{
+    return &reinterpret_cast<PageHeapUnion*>(&pageheap_memory[0])->m_pageHeap;
+}
+
+#define pageheap getPageHeap()
 
 // Thread-specific key.  Initialization here is somewhat tricky
@@ -1544 +1558 @@
       central_cache[i].Init(i);
     }
-    new ((void*)pageheap_memory) TCMalloc_PageHeap;
+    pageheap->init();
     phinited = 1;
   }