Create fewer local v8::TryCatch objects in generated bindings code

Source/bindings/v8/V8BindingMacros.h

 /*
  * Copyright (C) 2010 Google Inc. 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
@@ skipping 28 matching lines @@
 
 #define TONATIVE_EXCEPTION(type, var, value) \
     type var;                                \
     {                                        \
         v8::TryCatch block;                  \
         var = (value);                       \
         if (UNLIKELY(block.HasCaught()))     \
             return block.ReThrow();          \
     }
 
+#define TONATIVE_VOID_NO_DECL(var, value) \

[haraken, 2014/05/08 03:45:06]

Nit: _NO_DECL => _INTERNAL ?

It's dangerous to allow people to use this macro unless they understand what
they're doing.

[Jens Widell, 2014/05/08 16:38:05]

Renamed.

+    var = (value);                        \
+    if (UNLIKELY(block.HasCaught())) {    \
+        block.ReThrow();                  \
+        return;                           \
+    }
+
 #define TONATIVE_VOID(type, var, value)    \
     type var;                              \
     {                                      \
         v8::TryCatch block;                \
-        var = (value);                     \
-        if (UNLIKELY(block.HasCaught())) { \
-            block.ReThrow();               \
-            return;                        \
-        }                                  \
+        TONATIVE_VOID_NO_DECL(var, value); \
     }
 
 #define TONATIVE_DEFAULT(type, var, value, retVal) \
     type var;                                      \
     {                                              \
         v8::TryCatch block;                        \
         var = (value);                             \
         if (UNLIKELY(block.HasCaught())) {         \
             block.ReThrow();                       \
             return retVal;                         \
         }                                          \
     }
 
-#define TONATIVE_VOID_EXCEPTIONSTATE(type, var, value, exceptionState) \
-    type var;                                                          \
-    {                                                                  \
-        v8::TryCatch block;                                            \
-        var = (value);                                                 \
-        if (UNLIKELY(block.HasCaught()))                               \
-            exceptionState.rethrowV8Exception(block.Exception());      \
-        if (UNLIKELY(exceptionState.throwIfNeeded()))                  \
-            return;                                                    \
+#define TONATIVE_VOID_EXCEPTIONSTATE_NO_DECL(var, value, exceptionState) \
+    var = (value);                                                       \
+    if (UNLIKELY(block.HasCaught()))                                     \
+        exceptionState.rethrowV8Exception(block.Exception());            \
+    if (UNLIKELY(exceptionState.throwIfNeeded()))                        \
+        return;
+
+#define TONATIVE_VOID_EXCEPTIONSTATE(type, var, value, exceptionState)    \
+    type var;                                                             \
+    {                                                                     \
+        v8::TryCatch block;                                               \
+        TONATIVE_VOID_EXCEPTIONSTATE_NO_DECL(var, value, exceptionState); \
     }
 
 #define TONATIVE_DEFAULT_EXCEPTIONSTATE(type, var, value, exceptionState, retVal) \
     type var;                                                                 \
     {                                                                         \
         v8::TryCatch block;                                                   \
         var = (value);                                                        \
         if (UNLIKELY(block.HasCaught()))                                      \
             exceptionState.rethrowV8Exception(block.Exception());             \
         if (UNLIKELY(exceptionState.throwIfNeeded()))                         \
             return retVal;                                                    \
     }
 
 // type is an instance of class template V8StringResource<>,
 // but Mode argument varies; using type (not Mode) for consistency
 // with other macros and ease of code generation
 #define TOSTRING_VOID(type, var, value) \
     type var(value);                    \
     if (UNLIKELY(!var.prepare()))       \

[haraken, 2014/05/08 03:45:06]

Can we use TOSTRING_VOID_NO_DECL here?

[Jens Widell, 2014/05/08 06:22:06]

Make this

  type var;
  TOSTRING_VOID_NO_DECL(var, value);

you mean? Yes, that would work.

We've seen some indication that the splitting the declaration and
initialization/assignment of V8StringResource<> objects might lead to a small
increase in generated code, though. I'd consider it an acceptable cost in the
method case, but changing this macro that way might add the same cost to all
string attribute setters.

         return;
 
+#define TOSTRING_VOID_NO_DECL(var, value) \
+    var = value;                          \
+    if (UNLIKELY(!var.prepare()))         \
+        return;
+
 #define TOSTRING_DEFAULT(type, var, value, retVal) \
     type var(value);                               \
     if (UNLIKELY(!var.prepare()))                  \
         return retVal;
 
 } // namespace WebCore
 
 #endif // V8BindingMacros_h