Source/JavaScriptCore/wasm/js/JSWebAssemblyInstance.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2016-2019 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "config.h"
 #include "JSWebAssemblyInstance.h"

 #if ENABLE(WEBASSEMBLY)

 #include "AbstractModuleRecord.h"
 #include "JSCInlines.h"
 #include "JSModuleEnvironment.h"
 #include "JSModuleNamespaceObject.h"
 #include "JSWebAssemblyHelpers.h"
 #include "JSWebAssemblyLinkError.h"
 #include "JSWebAssemblyMemory.h"
 #include "JSWebAssemblyModule.h"
 #include "WebAssemblyModuleRecord.h"
 #include "WebAssemblyToJSCallee.h"
 #include <wtf/StdLibExtras.h>

 namespace JSC {

 const ClassInfo JSWebAssemblyInstance::s_info = { "WebAssembly.Instance", &Base::s_info, nullptr, nullptr, CREATE_METHOD_TABLE(JSWebAssemblyInstance) };

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

 JSWebAssemblyInstance::JSWebAssemblyInstance(VM& vm, Structure* structure, Ref<Wasm::Instance>&& instance)
     : Base(vm, structure)
     , m_instance(WTFMove(instance))
     , m_vm(&vm)
     , m_tables(m_instance->module().moduleInformation().tableCount())
 {
     for (unsigned i = 0; i < this->instance().numImportFunctions(); ++i)
         new (this->instance().importFunction<WriteBarrier<JSObject>>(i)) WriteBarrier<JSObject>();
 }

 void JSWebAssemblyInstance::finishCreation(VM& vm, JSWebAssemblyModule* module, JSModuleNamespaceObject* moduleNamespaceObject)
 {
     Base::finishCreation(vm);
     ASSERT(inherits(vm, info()));

     m_module.set(vm, this, module);
     m_moduleNamespaceObject.set(vm, this, moduleNamespaceObject);
     m_callee.set(vm, this, module->callee());

     vm.heap.reportExtraMemoryAllocated(m_instance->extraMemoryAllocated());
 }

 void JSWebAssemblyInstance::destroy(JSCell* cell)
 {
     static_cast<JSWebAssemblyInstance*>(cell)->JSWebAssemblyInstance::~JSWebAssemblyInstance();
 }

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

     Base::visitChildren(thisObject, visitor);
     visitor.append(thisObject->m_module);
     visitor.append(thisObject->m_codeBlock);
     visitor.append(thisObject->m_moduleNamespaceObject);
     visitor.append(thisObject->m_memory);
     for (unsigned i = 0; i < thisObject->instance().module().moduleInformation().tableCount(); ++i)
         visitor.append(thisObject->m_tables[i]);
     visitor.append(thisObject->m_callee);
     visitor.reportExtraMemoryVisited(thisObject->m_instance->extraMemoryAllocated());
     for (unsigned i = 0; i < thisObject->instance().numImportFunctions(); ++i)
         visitor.append(*thisObject->instance().importFunction<WriteBarrier<JSObject>>(i)); // This also keeps the functions' JSWebAssemblyInstance alive.

     for (size_t i : thisObject->instance().globalsToMark())
         visitor.appendUnbarriered(JSValue::decode(thisObject->instance().loadI64Global(i)));

     auto locker = holdLock(cell->cellLock());
     for (auto& wrapper : thisObject->instance().functionWrappers())
         visitor.appendUnbarriered(wrapper.get());
 }

 void JSWebAssemblyInstance::finalizeCreation(VM& vm, ExecState* exec, Ref<Wasm::CodeBlock>&& wasmCodeBlock, JSObject* importObject, Wasm::CreationMode creationMode)
 {
     m_instance->finalizeCreation(this, wasmCodeBlock.copyRef());

     auto scope = DECLARE_THROW_SCOPE(vm);

     if (!wasmCodeBlock->runnable()) {
         throwException(exec, scope, JSWebAssemblyLinkError::create(exec, vm, globalObject(vm)->webAssemblyLinkErrorStructure(), wasmCodeBlock->errorMessage()));
         return;
     }

     RELEASE_ASSERT(wasmCodeBlock->isSafeToRun(memoryMode()));
     JSWebAssemblyCodeBlock* jsCodeBlock = m_module->codeBlock(memoryMode());
     if (jsCodeBlock) {
         // A CodeBlock might have already been compiled. If so, it means
         // that the CodeBlock we are trying to compile must be the same
         // because we will never compile a CodeBlock again once it's
         // runnable.
         ASSERT(&jsCodeBlock->codeBlock() == wasmCodeBlock.ptr());
         m_codeBlock.set(vm, this, jsCodeBlock);
     } else {
         jsCodeBlock = JSWebAssemblyCodeBlock::create(vm, WTFMove(wasmCodeBlock), module()->module().moduleInformation());
         if (UNLIKELY(!jsCodeBlock->runnable())) {
             throwException(exec, scope, JSWebAssemblyLinkError::create(exec, vm, globalObject(vm)->webAssemblyLinkErrorStructure(), jsCodeBlock->errorMessage()));
             return;
         }
         m_codeBlock.set(vm, this, jsCodeBlock);
         m_module->setCodeBlock(vm, memoryMode(), jsCodeBlock);
     }

     for (unsigned importFunctionNum = 0; importFunctionNum < instance().numImportFunctions(); ++importFunctionNum) {
         auto* info = instance().importFunctionInfo(importFunctionNum);
         info->wasmToEmbedderStub = m_codeBlock->wasmToEmbedderStub(importFunctionNum);
     }

     auto* moduleRecord = jsCast<WebAssemblyModuleRecord*>(m_moduleNamespaceObject->moduleRecord());
     moduleRecord->prepareLink(vm, this);

     if (creationMode == Wasm::CreationMode::FromJS) {
         moduleRecord->link(exec, jsNull(), importObject, creationMode);
         RETURN_IF_EXCEPTION(scope, void());

         JSValue startResult = moduleRecord->evaluate(exec);
         UNUSED_PARAM(startResult);
         RETURN_IF_EXCEPTION(scope, void());
     }
 }

 Identifier JSWebAssemblyInstance::createPrivateModuleKey()
 {
     return Identifier::fromUid(PrivateName(PrivateName::Description, "WebAssemblyInstance"));
 }

 JSWebAssemblyInstance* JSWebAssemblyInstance::create(VM& vm, ExecState* exec, const Identifier& moduleKey, JSWebAssemblyModule* jsModule, JSObject* importObject, Structure* instanceStructure, Ref<Wasm::Module>&& module, Wasm::CreationMode creationMode)
 {
     auto throwScope = DECLARE_THROW_SCOPE(vm);
     auto* globalObject = exec->lexicalGlobalObject();

     const Wasm::ModuleInformation& moduleInformation = jsModule->moduleInformation();

     auto exception = [&] (JSObject* error) {
         throwException(exec, throwScope, error);
         return nullptr;
     };

     if (!globalObject->webAssemblyEnabled())
         return exception(createEvalError(exec, globalObject->webAssemblyDisabledErrorMessage()));

     auto importFailMessage = [&] (const Wasm::Import& import, const char* before, const char* after) {
         return makeString(before, " ", String::fromUTF8(import.module), ":", String::fromUTF8(import.field), " ", after);
     };

     WebAssemblyModuleRecord* moduleRecord = WebAssemblyModuleRecord::create(exec, vm, globalObject->webAssemblyModuleRecordStructure(), moduleKey, moduleInformation);
     RETURN_IF_EXCEPTION(throwScope, nullptr);

     JSModuleNamespaceObject* moduleNamespace = moduleRecord->getModuleNamespace(exec);

     auto storeTopCallFrame = [&vm] (void* topCallFrame) {
         vm.topCallFrame = bitwise_cast<ExecState*>(topCallFrame);
     };

     // FIXME: These objects could be pretty big we should try to throw OOM here.
     auto* jsInstance = new (NotNull, allocateCell<JSWebAssemblyInstance>(vm.heap)) JSWebAssemblyInstance(vm, instanceStructure,
         Wasm::Instance::create(&vm.wasmContext, WTFMove(module), &vm.topEntryFrame, vm.addressOfSoftStackLimit(), WTFMove(storeTopCallFrame)));
     jsInstance->finishCreation(vm, jsModule, moduleNamespace);
     RETURN_IF_EXCEPTION(throwScope, nullptr);

     // Let funcs, memories and tables be initially-empty lists of callable JavaScript objects, WebAssembly.Memory objects and WebAssembly.Table objects, respectively.
     // Let imports be an initially-empty list of external values.
     bool hasMemoryImport = false;

     if (creationMode == Wasm::CreationMode::FromJS) {
         // If the list of module.imports is not empty and Type(importObject) is not Object, a TypeError is thrown.
         if (moduleInformation.imports.size() && !importObject)
             return exception(createTypeError(exec, "can't make WebAssembly.Instance because there is no imports Object and the WebAssembly.Module requires imports"_s));
     }

     // For each import i in module.imports:
     for (auto& import : moduleInformation.imports) {
         Identifier moduleName = Identifier::fromString(vm, String::fromUTF8(import.module));
         Identifier fieldName = Identifier::fromString(vm, String::fromUTF8(import.field));
         moduleRecord->appendRequestedModule(moduleName);
         moduleRecord->addImportEntry(WebAssemblyModuleRecord::ImportEntry {
             WebAssemblyModuleRecord::ImportEntryType::Single,
             moduleName,
             fieldName,
             Identifier::fromUid(PrivateName(PrivateName::Description, "WebAssemblyImportName")),
         });

         // Skip Wasm::ExternalKind::Function validation here. It will be done in WebAssemblyModuleRecord::link.
         // Eventually we will move all the linking code here to WebAssemblyModuleRecord::link.
         switch (import.kind) {
         case Wasm::ExternalKind::Function:
         case Wasm::ExternalKind::Global:
         case Wasm::ExternalKind::Table:
             continue;
         case Wasm::ExternalKind::Memory:
             break;
         }

         JSValue value;
         if (creationMode == Wasm::CreationMode::FromJS) {
             // 1. Let o be the resultant value of performing Get(importObject, i.module_name).
             JSValue importModuleValue = importObject->get(exec, moduleName);
             RETURN_IF_EXCEPTION(throwScope, nullptr);
             // 2. If Type(o) is not Object, throw a TypeError.
             if (!importModuleValue.isObject())
                 return exception(createTypeError(exec, importFailMessage(import, "import", "must be an object"), defaultSourceAppender, runtimeTypeForValue(vm, importModuleValue)));

             // 3. Let v be the value of performing Get(o, i.item_name)
             JSObject* object = jsCast<JSObject*>(importModuleValue);
             value = object->get(exec, fieldName);
             RETURN_IF_EXCEPTION(throwScope, nullptr);
         }
         if (!value)
             value = jsUndefined();

         switch (import.kind) {
         case Wasm::ExternalKind::Function:
         case Wasm::ExternalKind::Global:
         case Wasm::ExternalKind::Table:
             break;

         case Wasm::ExternalKind::Memory: {
             // 6. If i is a memory import:
             RELEASE_ASSERT(!hasMemoryImport); // This should be guaranteed by a validation failure.
             RELEASE_ASSERT(moduleInformation.memory);
             hasMemoryImport = true;
             JSWebAssemblyMemory* memory = jsDynamicCast<JSWebAssemblyMemory*>(vm, value);
             // i. If v is not a WebAssembly.Memory object, throw a WebAssembly.LinkError.
             if (!memory)
                 return exception(createJSWebAssemblyLinkError(exec, vm, importFailMessage(import, "Memory import", "is not an instance of WebAssembly.Memory")));

             Wasm::PageCount declaredInitial = moduleInformation.memory.initial();
             Wasm::PageCount importedInitial = memory->memory().initial();
             if (importedInitial < declaredInitial)
                 return exception(createJSWebAssemblyLinkError(exec, vm, importFailMessage(import, "Memory import", "provided an 'initial' that is smaller than the module's declared 'initial' import memory size")));

             if (Wasm::PageCount declaredMaximum = moduleInformation.memory.maximum()) {
                 Wasm::PageCount importedMaximum = memory->memory().maximum();
                 if (!importedMaximum)
                     return exception(createJSWebAssemblyLinkError(exec, vm, importFailMessage(import, "Memory import", "did not have a 'maximum' but the module requires that it does")));

                 if (importedMaximum > declaredMaximum)
                     return exception(createJSWebAssemblyLinkError(exec, vm, importFailMessage(import, "Memory import", "provided a 'maximum' that is larger than the module's declared 'maximum' import memory size")));
             }

             // ii. Append v to memories.
             // iii. Append v.[[Memory]] to imports.
             jsInstance->setMemory(vm, memory);
             RETURN_IF_EXCEPTION(throwScope, nullptr);
             break;
         }
         }
     }
     ASSERT(moduleRecord->importEntries().size() == moduleInformation.imports.size());

     {
         if (!!moduleInformation.memory && moduleInformation.memory.isImport()) {
             // We should either have a Memory import or we should have thrown an exception.
             RELEASE_ASSERT(hasMemoryImport);
         }

         if (moduleInformation.memory && !hasMemoryImport) {
             // We create a memory when it's a memory definition.
             RELEASE_ASSERT(!moduleInformation.memory.isImport());

             auto* jsMemory = JSWebAssemblyMemory::create(exec, vm, globalObject->webAssemblyMemoryStructure());
             RETURN_IF_EXCEPTION(throwScope, nullptr);

             RefPtr<Wasm::Memory> memory = Wasm::Memory::tryCreate(moduleInformation.memory.initial(), moduleInformation.memory.maximum(),
                 [&vm] (Wasm::Memory::NotifyPressure) { vm.heap.collectAsync(CollectionScope::Full); },
                 [&vm] (Wasm::Memory::SyncTryToReclaim) { vm.heap.collectSync(CollectionScope::Full); },
                 [&vm, jsMemory] (Wasm::Memory::GrowSuccess, Wasm::PageCount oldPageCount, Wasm::PageCount newPageCount) { jsMemory->growSuccessCallback(vm, oldPageCount, newPageCount); });
             if (!memory)
                 return exception(createOutOfMemoryError(exec));

             jsMemory->adopt(memory.releaseNonNull());
             jsInstance->setMemory(vm, jsMemory);
             RETURN_IF_EXCEPTION(throwScope, nullptr);
         }
     }

     if (!jsInstance->memory()) {
         // Make sure we have a dummy memory, so that wasm -> wasm thunks avoid checking for a nullptr Memory when trying to set pinned registers.
         auto* jsMemory = JSWebAssemblyMemory::create(exec, vm, globalObject->webAssemblyMemoryStructure());
         jsMemory->adopt(Wasm::Memory::create());
         jsInstance->setMemory(vm, jsMemory);
         RETURN_IF_EXCEPTION(throwScope, nullptr);
     }

     return jsInstance;
 }

 } // namespace JSC

 #endif // ENABLE(WEBASSEMBLY)
	/*
	* Copyright (C) 2016-2019 Apple 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:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
	* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
	* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "config.h"
	#include "JSWebAssemblyInstance.h"

	#if ENABLE(WEBASSEMBLY)

	#include "AbstractModuleRecord.h"
	#include "JSCInlines.h"
	#include "JSModuleEnvironment.h"
	#include "JSModuleNamespaceObject.h"
	#include "JSWebAssemblyHelpers.h"
	#include "JSWebAssemblyLinkError.h"
	#include "JSWebAssemblyMemory.h"
	#include "JSWebAssemblyModule.h"
	#include "WebAssemblyModuleRecord.h"
	#include "WebAssemblyToJSCallee.h"
	#include <wtf/StdLibExtras.h>

	namespace JSC {

	const ClassInfo JSWebAssemblyInstance::s_info = { "WebAssembly.Instance", &Base::s_info, nullptr, nullptr, CREATE_METHOD_TABLE(JSWebAssemblyInstance) };

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

	JSWebAssemblyInstance::JSWebAssemblyInstance(VM& vm, Structure* structure, Ref<Wasm::Instance>&& instance)
	: Base(vm, structure)
	, m_instance(WTFMove(instance))
	, m_vm(&vm)
	, m_tables(m_instance->module().moduleInformation().tableCount())
	{
	for (unsigned i = 0; i < this->instance().numImportFunctions(); ++i)
	new (this->instance().importFunction<WriteBarrier<JSObject>>(i)) WriteBarrier<JSObject>();
	}

	void JSWebAssemblyInstance::finishCreation(VM& vm, JSWebAssemblyModule* module, JSModuleNamespaceObject* moduleNamespaceObject)
	{
	Base::finishCreation(vm);
	ASSERT(inherits(vm, info()));

	m_module.set(vm, this, module);
	m_moduleNamespaceObject.set(vm, this, moduleNamespaceObject);
	m_callee.set(vm, this, module->callee());

	vm.heap.reportExtraMemoryAllocated(m_instance->extraMemoryAllocated());
	}

	void JSWebAssemblyInstance::destroy(JSCell* cell)
	{
	static_cast<JSWebAssemblyInstance*>(cell)->JSWebAssemblyInstance::~JSWebAssemblyInstance();
	}

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

	Base::visitChildren(thisObject, visitor);
	visitor.append(thisObject->m_module);
	visitor.append(thisObject->m_codeBlock);
	visitor.append(thisObject->m_moduleNamespaceObject);
	visitor.append(thisObject->m_memory);
	for (unsigned i = 0; i < thisObject->instance().module().moduleInformation().tableCount(); ++i)
	visitor.append(thisObject->m_tables[i]);
	visitor.append(thisObject->m_callee);
	visitor.reportExtraMemoryVisited(thisObject->m_instance->extraMemoryAllocated());
	for (unsigned i = 0; i < thisObject->instance().numImportFunctions(); ++i)
	visitor.append(*thisObject->instance().importFunction<WriteBarrier<JSObject>>(i)); // This also keeps the functions' JSWebAssemblyInstance alive.

	for (size_t i : thisObject->instance().globalsToMark())
	visitor.appendUnbarriered(JSValue::decode(thisObject->instance().loadI64Global(i)));

	auto locker = holdLock(cell->cellLock());
	for (auto& wrapper : thisObject->instance().functionWrappers())
	visitor.appendUnbarriered(wrapper.get());
	}

	void JSWebAssemblyInstance::finalizeCreation(VM& vm, ExecState* exec, Ref<Wasm::CodeBlock>&& wasmCodeBlock, JSObject* importObject, Wasm::CreationMode creationMode)
	{
	m_instance->finalizeCreation(this, wasmCodeBlock.copyRef());

	auto scope = DECLARE_THROW_SCOPE(vm);

	if (!wasmCodeBlock->runnable()) {
	throwException(exec, scope, JSWebAssemblyLinkError::create(exec, vm, globalObject(vm)->webAssemblyLinkErrorStructure(), wasmCodeBlock->errorMessage()));
	return;
	}

	RELEASE_ASSERT(wasmCodeBlock->isSafeToRun(memoryMode()));
	JSWebAssemblyCodeBlock* jsCodeBlock = m_module->codeBlock(memoryMode());
	if (jsCodeBlock) {
	// A CodeBlock might have already been compiled. If so, it means
	// that the CodeBlock we are trying to compile must be the same
	// because we will never compile a CodeBlock again once it's
	// runnable.
	ASSERT(&jsCodeBlock->codeBlock() == wasmCodeBlock.ptr());
	m_codeBlock.set(vm, this, jsCodeBlock);
	} else {
	jsCodeBlock = JSWebAssemblyCodeBlock::create(vm, WTFMove(wasmCodeBlock), module()->module().moduleInformation());
	if (UNLIKELY(!jsCodeBlock->runnable())) {
	throwException(exec, scope, JSWebAssemblyLinkError::create(exec, vm, globalObject(vm)->webAssemblyLinkErrorStructure(), jsCodeBlock->errorMessage()));
	return;
	}
	m_codeBlock.set(vm, this, jsCodeBlock);
	m_module->setCodeBlock(vm, memoryMode(), jsCodeBlock);
	}

	for (unsigned importFunctionNum = 0; importFunctionNum < instance().numImportFunctions(); ++importFunctionNum) {
	auto* info = instance().importFunctionInfo(importFunctionNum);
	info->wasmToEmbedderStub = m_codeBlock->wasmToEmbedderStub(importFunctionNum);
	}

	auto* moduleRecord = jsCast<WebAssemblyModuleRecord*>(m_moduleNamespaceObject->moduleRecord());
	moduleRecord->prepareLink(vm, this);

	if (creationMode == Wasm::CreationMode::FromJS) {
	moduleRecord->link(exec, jsNull(), importObject, creationMode);
	RETURN_IF_EXCEPTION(scope, void());

	JSValue startResult = moduleRecord->evaluate(exec);
	UNUSED_PARAM(startResult);
	RETURN_IF_EXCEPTION(scope, void());
	}
	}

	Identifier JSWebAssemblyInstance::createPrivateModuleKey()
	{
	return Identifier::fromUid(PrivateName(PrivateName::Description, "WebAssemblyInstance"));
	}

	JSWebAssemblyInstance* JSWebAssemblyInstance::create(VM& vm, ExecState* exec, const Identifier& moduleKey, JSWebAssemblyModule* jsModule, JSObject* importObject, Structure* instanceStructure, Ref<Wasm::Module>&& module, Wasm::CreationMode creationMode)
	{
	auto throwScope = DECLARE_THROW_SCOPE(vm);
	auto* globalObject = exec->lexicalGlobalObject();

	const Wasm::ModuleInformation& moduleInformation = jsModule->moduleInformation();

	auto exception = [&] (JSObject* error) {
	throwException(exec, throwScope, error);
	return nullptr;
	};

	if (!globalObject->webAssemblyEnabled())
	return exception(createEvalError(exec, globalObject->webAssemblyDisabledErrorMessage()));

	auto importFailMessage = [&] (const Wasm::Import& import, const char* before, const char* after) {
	return makeString(before, " ", String::fromUTF8(import.module), ":", String::fromUTF8(import.field), " ", after);
	};

	WebAssemblyModuleRecord* moduleRecord = WebAssemblyModuleRecord::create(exec, vm, globalObject->webAssemblyModuleRecordStructure(), moduleKey, moduleInformation);
	RETURN_IF_EXCEPTION(throwScope, nullptr);

	JSModuleNamespaceObject* moduleNamespace = moduleRecord->getModuleNamespace(exec);

	auto storeTopCallFrame = [&vm] (void* topCallFrame) {
	vm.topCallFrame = bitwise_cast<ExecState*>(topCallFrame);
	};

	// FIXME: These objects could be pretty big we should try to throw OOM here.
	auto* jsInstance = new (NotNull, allocateCell<JSWebAssemblyInstance>(vm.heap)) JSWebAssemblyInstance(vm, instanceStructure,
	Wasm::Instance::create(&vm.wasmContext, WTFMove(module), &vm.topEntryFrame, vm.addressOfSoftStackLimit(), WTFMove(storeTopCallFrame)));
	jsInstance->finishCreation(vm, jsModule, moduleNamespace);
	RETURN_IF_EXCEPTION(throwScope, nullptr);

	// Let funcs, memories and tables be initially-empty lists of callable JavaScript objects, WebAssembly.Memory objects and WebAssembly.Table objects, respectively.
	// Let imports be an initially-empty list of external values.
	bool hasMemoryImport = false;

	if (creationMode == Wasm::CreationMode::FromJS) {
	// If the list of module.imports is not empty and Type(importObject) is not Object, a TypeError is thrown.
	if (moduleInformation.imports.size() && !importObject)
	return exception(createTypeError(exec, "can't make WebAssembly.Instance because there is no imports Object and the WebAssembly.Module requires imports"_s));
	}

	// For each import i in module.imports:
	for (auto& import : moduleInformation.imports) {
	Identifier moduleName = Identifier::fromString(vm, String::fromUTF8(import.module));
	Identifier fieldName = Identifier::fromString(vm, String::fromUTF8(import.field));
	moduleRecord->appendRequestedModule(moduleName);
	moduleRecord->addImportEntry(WebAssemblyModuleRecord::ImportEntry {
	WebAssemblyModuleRecord::ImportEntryType::Single,
	moduleName,
	fieldName,
	Identifier::fromUid(PrivateName(PrivateName::Description, "WebAssemblyImportName")),
	});

	// Skip Wasm::ExternalKind::Function validation here. It will be done in WebAssemblyModuleRecord::link.
	// Eventually we will move all the linking code here to WebAssemblyModuleRecord::link.
	switch (import.kind) {
	case Wasm::ExternalKind::Function:
	case Wasm::ExternalKind::Global:
	case Wasm::ExternalKind::Table:
	continue;
	case Wasm::ExternalKind::Memory:
	break;
	}

	JSValue value;
	if (creationMode == Wasm::CreationMode::FromJS) {
	// 1. Let o be the resultant value of performing Get(importObject, i.module_name).
	JSValue importModuleValue = importObject->get(exec, moduleName);
	RETURN_IF_EXCEPTION(throwScope, nullptr);
	// 2. If Type(o) is not Object, throw a TypeError.
	if (!importModuleValue.isObject())
	return exception(createTypeError(exec, importFailMessage(import, "import", "must be an object"), defaultSourceAppender, runtimeTypeForValue(vm, importModuleValue)));

	// 3. Let v be the value of performing Get(o, i.item_name)
	JSObject* object = jsCast<JSObject*>(importModuleValue);
	value = object->get(exec, fieldName);
	RETURN_IF_EXCEPTION(throwScope, nullptr);
	}
	if (!value)
	value = jsUndefined();

	switch (import.kind) {
	case Wasm::ExternalKind::Function:
	case Wasm::ExternalKind::Global:
	case Wasm::ExternalKind::Table:
	break;

	case Wasm::ExternalKind::Memory: {
	// 6. If i is a memory import:
	RELEASE_ASSERT(!hasMemoryImport); // This should be guaranteed by a validation failure.
	RELEASE_ASSERT(moduleInformation.memory);
	hasMemoryImport = true;
	JSWebAssemblyMemory* memory = jsDynamicCast<JSWebAssemblyMemory*>(vm, value);
	// i. If v is not a WebAssembly.Memory object, throw a WebAssembly.LinkError.
	if (!memory)
	return exception(createJSWebAssemblyLinkError(exec, vm, importFailMessage(import, "Memory import", "is not an instance of WebAssembly.Memory")));

	Wasm::PageCount declaredInitial = moduleInformation.memory.initial();
	Wasm::PageCount importedInitial = memory->memory().initial();
	if (importedInitial < declaredInitial)
	return exception(createJSWebAssemblyLinkError(exec, vm, importFailMessage(import, "Memory import", "provided an 'initial' that is smaller than the module's declared 'initial' import memory size")));

	if (Wasm::PageCount declaredMaximum = moduleInformation.memory.maximum()) {
	Wasm::PageCount importedMaximum = memory->memory().maximum();
	if (!importedMaximum)
	return exception(createJSWebAssemblyLinkError(exec, vm, importFailMessage(import, "Memory import", "did not have a 'maximum' but the module requires that it does")));

	if (importedMaximum > declaredMaximum)
	return exception(createJSWebAssemblyLinkError(exec, vm, importFailMessage(import, "Memory import", "provided a 'maximum' that is larger than the module's declared 'maximum' import memory size")));
	}

	// ii. Append v to memories.
	// iii. Append v.[[Memory]] to imports.
	jsInstance->setMemory(vm, memory);
	RETURN_IF_EXCEPTION(throwScope, nullptr);
	break;
	}
	}
	}
	ASSERT(moduleRecord->importEntries().size() == moduleInformation.imports.size());

	{
	if (!!moduleInformation.memory && moduleInformation.memory.isImport()) {
	// We should either have a Memory import or we should have thrown an exception.
	RELEASE_ASSERT(hasMemoryImport);
	}

	if (moduleInformation.memory && !hasMemoryImport) {
	// We create a memory when it's a memory definition.
	RELEASE_ASSERT(!moduleInformation.memory.isImport());

	auto* jsMemory = JSWebAssemblyMemory::create(exec, vm, globalObject->webAssemblyMemoryStructure());
	RETURN_IF_EXCEPTION(throwScope, nullptr);

	RefPtr<Wasm::Memory> memory = Wasm::Memory::tryCreate(moduleInformation.memory.initial(), moduleInformation.memory.maximum(),
	[&vm] (Wasm::Memory::NotifyPressure) { vm.heap.collectAsync(CollectionScope::Full); },
	[&vm] (Wasm::Memory::SyncTryToReclaim) { vm.heap.collectSync(CollectionScope::Full); },
	[&vm, jsMemory] (Wasm::Memory::GrowSuccess, Wasm::PageCount oldPageCount, Wasm::PageCount newPageCount) { jsMemory->growSuccessCallback(vm, oldPageCount, newPageCount); });
	if (!memory)
	return exception(createOutOfMemoryError(exec));

	jsMemory->adopt(memory.releaseNonNull());
	jsInstance->setMemory(vm, jsMemory);
	RETURN_IF_EXCEPTION(throwScope, nullptr);
	}
	}

	if (!jsInstance->memory()) {
	// Make sure we have a dummy memory, so that wasm -> wasm thunks avoid checking for a nullptr Memory when trying to set pinned registers.
	auto* jsMemory = JSWebAssemblyMemory::create(exec, vm, globalObject->webAssemblyMemoryStructure());
	jsMemory->adopt(Wasm::Memory::create());
	jsInstance->setMemory(vm, jsMemory);
	RETURN_IF_EXCEPTION(throwScope, nullptr);
	}

	return jsInstance;
	}

	} // namespace JSC

	#endif // ENABLE(WEBASSEMBLY)