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

Source/bindings/v8/V8BindingMacros.h

Index: Source/bindings/v8/V8BindingMacros.h
diff --git a/Source/bindings/v8/V8BindingMacros.h b/Source/bindings/v8/V8BindingMacros.h
index e5841c9beda84810daf9ed7ea80f01cb7aca48cd..269c5fa2f4f00421d340f8e58cc85357ddb283a2 100644
--- a/Source/bindings/v8/V8BindingMacros.h
+++ b/Source/bindings/v8/V8BindingMacros.h
@@ -46,15 +46,18 @@ namespace WebCore {
             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) \
@@ -68,15 +71,18 @@ namespace WebCore {
         }                                          \
     }
 
-#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) \
@@ -98,6 +104,11 @@ namespace WebCore {
     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()))                  \