Changeset 36740 in webkit for trunk/JavaScriptCore/wtf/Vector.h

Timestamp:

Sep 21, 2008, 1:17:51 PM (17 years ago)

Author:

Darin Adler

Message:

2008-09-21 Paul Pedriana <​[email protected]>

Reviewed and tweaked by Darin Adler.

• ​https://bugs.webkit.org/show_bug.cgi?id=16925 Fixed lack of Vector buffer alignment for both GCC and MSVC. Since there's no portable way to do this, for now we don't support other compilers.

• wtf/Vector.h: Added WTF_ALIGH_ON, WTF_ALIGNED, AlignedBufferChar, and AlignedBuffer. Use AlignedBuffer insteadof an array of char in VectorBuffer.

File:

• trunk/JavaScriptCore/wtf/Vector.h (modified) (2 diffs)

trunk/JavaScriptCore/wtf/Vector.h

@@ -36 +36 @@
     using std::min;
     using std::max;
-    
+
+    // WTF_ALIGN_OF / WTF_ALIGNED
+    #if COMPILER(GCC) || COMPILER(MINGW)
+        #define WTF_ALIGN_OF(type) __alignof__(type)
+        #define WTF_ALIGNED(variable_type, variable, n) variable_type variable __attribute__((__aligned__(n)))
+    #elif COMPILER(MSVC)
+        #define WTF_ALIGN_OF(type) __alignof(type)
+        #define WTF_ALIGNED(variable_type, variable, n) __declspec(align(n)) variable_type variable
+    #else
+        #error WTF_ALIGN macros need alignment control.
+    #endif
+
+    #if COMPILER(GCC) && (((__GNUC__ * 100) + __GNUC_MINOR__) >= 303)
+        typedef char __attribute__((__may_alias__)) AlignedBufferChar; 
+    #else
+        typedef char AlignedBufferChar; 
+    #endif
+
+    template <size_t size, size_t alignment> struct AlignedBuffer;
+    template <size_t size> struct AlignedBuffer<size, 1> { AlignedBufferChar buffer[size]; };
+    template <size_t size> struct AlignedBuffer<size, 2> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 2);  };
+    template <size_t size> struct AlignedBuffer<size, 4> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 4);  };
+    template <size_t size> struct AlignedBuffer<size, 8> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 8);  };
+    template <size_t size> struct AlignedBuffer<size, 16> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 16); };
+    template <size_t size> struct AlignedBuffer<size, 32> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 32); };
+    template <size_t size> struct AlignedBuffer<size, 64> { WTF_ALIGNED(AlignedBufferChar, buffer[size], 64); };
+
     template <bool needsDestruction, typename T>
     class VectorDestructor;
@@ -385 +411 @@
 
         static const size_t m_inlineBufferSize = inlineCapacity * sizeof(T);
-        T* inlineBuffer() { return reinterpret_cast<T*>(&m_inlineBuffer); }
-
-        // FIXME: Nothing guarantees this buffer is appropriately aligned to hold objects of type T.
-        char m_inlineBuffer[m_inlineBufferSize];
+        T* inlineBuffer() { return reinterpret_cast<T*>(m_inlineBuffer.buffer); }
+
+        AlignedBuffer<m_inlineBufferSize, WTF_ALIGN_OF(T)> m_inlineBuffer;
     };