[Webkit-unassigned] [Bug 172481] New: [WebIDL] Overloaded functions unnecessarily duplicate argument checks

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=172481

            Bug ID: 172481
           Summary: [WebIDL] Overloaded functions unnecessarily duplicate
                    argument checks
           Product: WebKit
           Version: WebKit Nightly Build
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Bindings
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: sam at webkit.org
                CC: cdumez at apple.com

Overloaded functions are currently unnecessarily duplicate argument checks. For example, let's take CanvasRenderingContext2d's stroke function. It has two overloads:

    void stroke(DOMPath path);
    void stroke();

This generates the main bindings function:

EncodedJSValue JSC_HOST_CALL jsCanvasRenderingContext2DPrototypeFunctionStroke(ExecState* state)
{
    VM& vm = state->vm();
    auto throwScope = DECLARE_THROW_SCOPE(vm);
    UNUSED_PARAM(throwScope);
    size_t argsCount = std::min<size_t>(1, state->argumentCount());
    if (argsCount == 0) {
        return jsCanvasRenderingContext2DPrototypeFunctionStroke2(state);
    }
    if (argsCount == 1) {
        return jsCanvasRenderingContext2DPrototypeFunctionStroke1(state);
    }
    return throwVMTypeError(state, throwScope);
}

and then two the helpers, jsCanvasRenderingContext2DPrototypeFunctionStroke1 and jsCanvasRenderingContext2DPrototypeFunctionStroke2.

Taking a look at jsCanvasRenderingContext2DPrototypeFunctionStroke1, we see the argumentCount is once again checked, despite it already having been done in the main function: 

static inline JSC::EncodedJSValue jsCanvasRenderingContext2DPrototypeFunctionStroke1Caller(JSC::ExecState* state, JSCanvasRenderingContext2D* castedThis, JSC::ThrowScope& throwScope)
{
    UNUSED_PARAM(state);
    UNUSED_PARAM(throwScope);
    auto& impl = castedThis->wrapped();
    if (UNLIKELY(state->argumentCount() < 1))
        return throwVMError(state, throwScope, createNotEnoughArgumentsError(state));
    auto path = convert<IDLInterface<DOMPath>>(*state, state->uncheckedArgument(0), [](JSC::ExecState& state, JSC::ThrowScope& scope) { throwArgumentTypeError(state, scope, 0, "path", "CanvasRenderingContext2D", "stroke", "DOMPath"); });
    RETURN_IF_EXCEPTION(throwScope, encodedJSValue());
    impl.stroke(*path);
    return JSValue::encode(jsUndefined());
}


We could further improve things by taking advantage of the cases where disambiguation takes place, and retain the type information into the helpers.

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.webkit.org/pipermail/webkit-unassigned/attachments/20170523/d9a6e7f2/attachment.html>