Bug 93093 – [V8] Implement v8Undefined() and use it in CodeGeneratorV8.pm

• Status: RESOLVED
• Resolution: FIXED
• Component: WebCore JavaScript

[Kentaro Hara]

There are a couple of equivalent ways to create an undefined value, e.g. v8::Undefined(), v8::Undefined(isolate), v8::Handle<v8::Value>(), etc. We should implement v8Undefined() and use it everywhere.

In this bug, we implement v8Undefined() and use it in CodeGeneratorV8.pm.

We can implement v8Undefined() like this:

    v8::Handle<v8::Value> v8Undefined() { v8::Handle<v8::Value>(); }

This is based on the following performance results:

// 14.5 ns
v8::Handle<v8::Value> xxxAttrGetter(..., info) {
    return v8::Undefined();
}

// 8.24 ns (This cannot be used where isolate can be 0.)
v8::Handle<v8::Value> xxxAttrGetter(..., info) {
    return v8::Undefined(info.GetIsolate());
}

// 8.54 ns
v8::Handle<v8::Value> xxxAttrGetter(..., info) {
    v8::Isolate* isolate = info.GetIsolate();
    return isolate ? v8::Handle<v8::Value>(v8::Undefined(isolate)) : v8::Handle<v8::Value>();
}

// 8.52 ns
v8::Handle<v8::Value> xxxAttrGetter(..., info) {
    return v8::Handle<v8::Value>();
}

[Kentaro Hara]

Created attachment 156331 [details]
Patch

[WebKit Review Bot]

Comment on attachment 156331 [details]
Patch

Clearing flags on attachment: 156331

Committed r124629: <http://trac.webkit.org/changeset/124629>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.