Defer slow branch of GetAlignedPointerFromInternalField

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 74 matching lines @@
 #endif
 
 #if defined(__GNUC__) && !V8_DISABLE_DEPRECATIONS
 #define V8_DEPRECATED(declarator) declarator __attribute__ ((deprecated))
 #elif defined(_MSC_VER) && !V8_DISABLE_DEPRECATIONS
 #define V8_DEPRECATED(declarator) __declspec(deprecated) declarator
 #else
 #define V8_DEPRECATED(declarator) declarator
 #endif
 
+#ifdef __GNUC__

[Sven Panne, 2013/04/26 07:09:28]

An undefined preprocessor symbol evaluates to 0 by definition, so you can
totally remove this #ifdef and its #else branch.

+  #if __GNUC__ > 2 || (__GNUC__ == 2 && (__GNUC_MINOR__ > 95))
+    #define V8_UNLIKELY(x) __builtin_expect(!!(x), 0)

[Sven Panne, 2013/04/26 07:09:28]

According to http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html you don't
need the !! here and below.

+    #define V8_LIKELY(x) __builtin_expect(!!(x), 1)
+  #else
+    #define V8_UNLIKELY(x) (x)
+    #define V8_LIKELY(x) (x)
+  #endif
+#else
+  #define V8_UNLIKELY(x) (x)
+  #define V8_LIKELY(x) (x)
+#endif
+
 /**
  * The v8 JavaScript engine.
  */
 namespace v8 {
 
 class AccessorInfo;
 class AccessorSignature;
 class Array;
 class Boolean;
 class BooleanObject;
@@ skipping 4767 matching lines @@
 }
 
 
 void* Object::GetAlignedPointerFromInternalField(int index) {
 #ifndef V8_ENABLE_CHECKS
   typedef internal::Object O;
   typedef internal::Internals I;
   O* obj = *reinterpret_cast<O**>(this);
   // Fast path: If the object is a plain JSObject, which is the common case, we
   // know where to find the internal fields and can return the value directly.
-  if (I::GetInstanceType(obj) == I::kJSObjectType) {
+  if (V8_LIKELY(I::GetInstanceType(obj) == I::kJSObjectType)) {
     int offset = I::kJSObjectHeaderSize + (internal::kApiPointerSize * index);
     return I::ReadField<void*>(obj, offset);
   }
 #endif
   return SlowGetAlignedPointerFromInternalField(index);
 }
 
 
 String* String::Cast(v8::Value* value) {
 #ifdef V8_ENABLE_CHECKS
@@ skipping 336 matching lines @@
 
 
 }  // namespace v8
 
 
 #undef V8EXPORT
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_