Source/JavaScriptCore/wasm/js/WebAssemblyWrapperFunction.cpp

/*
 * Copyright (C) 2017-2018 Apple Inc. All rights reserved.
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#include "config.h"
#include "WebAssemblyWrapperFunction.h"

#if ENABLE(WEBASSEMBLY)

#include "Error.h"
#include "FunctionPrototype.h"
#include "JSCInlines.h"
#include "JSWebAssemblyInstance.h"

namespace JSC {

const ClassInfo WebAssemblyWrapperFunction::s_info = { "WebAssemblyWrapperFunction", &Base::s_info, nullptr, nullptr, CREATE_METHOD_TABLE(WebAssemblyWrapperFunction) };

static EncodedJSValue JSC_HOST_CALL callWebAssemblyWrapperFunction(ExecState* exec)
{
    VM& vm = exec->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);
    WebAssemblyWrapperFunction* wasmFunction = jsDynamicCast<WebAssemblyWrapperFunction*>(vm, exec->jsCallee());
    if (!wasmFunction)
        return JSValue::encode(throwException(exec, scope, createTypeError(exec, "expected a WebAssembly function")));

    CallData callData;
    JSObject* function = wasmFunction->function();
    CallType callType = function->methodTable(vm)->getCallData(function, callData);
    RELEASE_ASSERT(callType != CallType::None);
    scope.release();
    return JSValue::encode(call(exec, function, callType, callData, jsUndefined(), ArgList(exec)));
}

WebAssemblyWrapperFunction::WebAssemblyWrapperFunction(VM& vm, JSGlobalObject* globalObject, Structure* structure, Wasm::WasmToWasmImportableFunction importableFunction)
    : Base(vm, globalObject, structure)
    , m_importableFunction(importableFunction)
{ }

WebAssemblyWrapperFunction* WebAssemblyWrapperFunction::create(VM& vm, JSGlobalObject* globalObject, JSObject* function, unsigned importIndex, JSWebAssemblyInstance* instance, Wasm::SignatureIndex signatureIndex)
{
    ASSERT_WITH_MESSAGE(!function->inherits<WebAssemblyWrapperFunction>(vm), "We should never double wrap a wrapper function.");
    String name = "";
    NativeExecutable* executable = vm.getHostFunction(callWebAssemblyWrapperFunction, NoIntrinsic, callHostFunctionAsConstructor, nullptr, name);
    WebAssemblyWrapperFunction* result = new (NotNull, allocateCell<WebAssemblyWrapperFunction>(vm.heap)) WebAssemblyWrapperFunction(vm, globalObject, globalObject->webAssemblyWrapperFunctionStructure(), Wasm::WasmToWasmImportableFunction { signatureIndex, &instance->instance().importFunctionInfo(importIndex)->wasmToEmbedderStub } );
    const Wasm::Signature& signature = Wasm::SignatureInformation::get(signatureIndex);
    result->finishCreation(vm, executable, signature.argumentCount(), name, function, instance);
    return result;
}

void WebAssemblyWrapperFunction::finishCreation(VM& vm, NativeExecutable* executable, unsigned length, const String& name, JSObject* function, JSWebAssemblyInstance* instance)
{
    Base::finishCreation(vm, executable, length, name, instance);
    RELEASE_ASSERT(JSValue(function).isFunction());
    m_function.set(vm, this, function);
}

Structure* WebAssemblyWrapperFunction::createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
{
    ASSERT(globalObject);
    return Structure::create(vm, globalObject, prototype, TypeInfo(JSFunctionType, StructureFlags), info());
}

void WebAssemblyWrapperFunction::visitChildren(JSCell* cell, SlotVisitor& visitor)
{
    WebAssemblyWrapperFunction* thisObject = jsCast<WebAssemblyWrapperFunction*>(cell);
    ASSERT_GC_OBJECT_INHERITS(thisObject, info());
    Base::visitChildren(thisObject, visitor);

    visitor.append(thisObject->m_function);
}

} // namespace JSC

#endif // ENABLE(WEBASSEMBLY)