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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include "vm/GeneratorObject.h"
#include "frontend/ParserAtom.h"
#ifdef DEBUG
# include "js/friend/DumpFunctions.h" // js::DumpObject, js::DumpValue
#endif
#include "js/PropertySpec.h"
#include "vm/AsyncFunction.h"
#include "vm/AsyncIteration.h"
#include "vm/FunctionFlags.h" // js::FunctionFlags
#include "vm/GlobalObject.h"
#include "vm/JSObject.h"
#include "vm/PlainObject.h" // js::PlainObject
#include "debugger/DebugAPI-inl.h"
#include "vm/Stack-inl.h"
using namespace js;
AbstractGeneratorObject* AbstractGeneratorObject::create(
JSContext* cx, HandleFunction callee, HandleScript script,
HandleObject environmentChain, Handle<ArgumentsObject*> argsObject) {
Rooted<AbstractGeneratorObject*> genObj(cx);
if (!callee->isAsync()) {
genObj = GeneratorObject::create(cx, callee);
} else if (callee->isGenerator()) {
genObj = AsyncGeneratorObject::create(cx, callee);
} else {
genObj = AsyncFunctionGeneratorObject::create(cx, callee);
}
if (!genObj) {
return nullptr;
}
genObj->setCallee(*callee);
genObj->setEnvironmentChain(*environmentChain);
if (argsObject) {
genObj->setArgsObj(*argsObject.get());
}
ArrayObject* stack = NewDenseFullyAllocatedArray(cx, script->nslots());
if (!stack) {
return nullptr;
}
genObj->setStackStorage(*stack);
// Note: This assumes that a Warp frame cannot be the target of
// the debugger, as we do not call OnNewGenerator.
return genObj;
}
JSObject* AbstractGeneratorObject::createFromFrame(JSContext* cx,
AbstractFramePtr frame) {
MOZ_ASSERT(frame.isGeneratorFrame());
MOZ_ASSERT(!frame.isConstructing());
if (frame.isModuleFrame()) {
return createModuleGenerator(cx, frame);
}
RootedFunction fun(cx, frame.callee());
Rooted<ArgumentsObject*> maybeArgs(
cx, frame.script()->needsArgsObj() ? &frame.argsObj() : nullptr);
RootedObject environmentChain(cx, frame.environmentChain());
RootedScript script(cx, frame.script());
Rooted<AbstractGeneratorObject*> genObj(
cx, AbstractGeneratorObject::create(cx, fun, script, environmentChain,
maybeArgs));
if (!genObj) {
return nullptr;
}
if (!DebugAPI::onNewGenerator(cx, frame, genObj)) {
return nullptr;
}
return genObj;
}
JSObject* AbstractGeneratorObject::createModuleGenerator(
JSContext* cx, AbstractFramePtr frame) {
Rooted<ModuleObject*> module(cx, frame.script()->module());
Rooted<AbstractGeneratorObject*> genObj(cx);
genObj = AsyncFunctionGeneratorObject::create(cx, module);
if (!genObj) {
return nullptr;
}
// Create a handler function to wrap the module's script. This way
// we can access it later and restore the state.
Handle<PropertyName*> funName = cx->names().empty_;
RootedFunction handlerFun(
cx, NewFunctionWithProto(cx, nullptr, 0,
FunctionFlags::INTERPRETED_GENERATOR_OR_ASYNC,
nullptr, funName, nullptr,
gc::AllocKind::FUNCTION, GenericObject));
if (!handlerFun) {
return nullptr;
}
handlerFun->initScript(module->script());
genObj->setCallee(*handlerFun);
genObj->setEnvironmentChain(*frame.environmentChain());
ArrayObject* stack =
NewDenseFullyAllocatedArray(cx, module->script()->nslots());
if (!stack) {
return nullptr;
}
genObj->setStackStorage(*stack);
if (!DebugAPI::onNewGenerator(cx, frame, genObj)) {
return nullptr;
}
return genObj;
}
void AbstractGeneratorObject::trace(JSTracer* trc) {
DebugAPI::traceGeneratorFrame(trc, this);
}
bool AbstractGeneratorObject::suspend(JSContext* cx, HandleObject obj,
AbstractFramePtr frame,
const jsbytecode* pc, unsigned nvalues) {
MOZ_ASSERT(JSOp(*pc) == JSOp::InitialYield || JSOp(*pc) == JSOp::Yield ||
JSOp(*pc) == JSOp::Await);
auto genObj = obj.as<AbstractGeneratorObject>();
MOZ_ASSERT(!genObj->hasStackStorage() || genObj->isStackStorageEmpty());
MOZ_ASSERT_IF(JSOp(*pc) == JSOp::Await, genObj->callee().isAsync());
MOZ_ASSERT_IF(JSOp(*pc) == JSOp::Yield, genObj->callee().isGenerator());
if (nvalues > 0) {
ArrayObject* stack = nullptr;
MOZ_ASSERT(genObj->hasStackStorage());
stack = &genObj->stackStorage();
MOZ_ASSERT(stack->getDenseCapacity() >= nvalues);
if (!frame.saveGeneratorSlots(cx, nvalues, stack)) {
return false;
}
}
genObj->setResumeIndex(pc);
genObj->setEnvironmentChain(*frame.environmentChain());
return true;
}
#ifdef DEBUG
void AbstractGeneratorObject::dump() const {
fprintf(stderr, "(AbstractGeneratorObject*) %p {\n", (void*)this);
fprintf(stderr, " callee: (JSFunction*) %p,\n", (void*)&callee());
fprintf(stderr, " environmentChain: (JSObject*) %p,\n",
(void*)&environmentChain());
if (hasArgsObj()) {
fprintf(stderr, " argsObj: Some((ArgumentsObject*) %p),\n",
(void*)&argsObj());
} else {
fprintf(stderr, " argsObj: None,\n");
}
if (hasStackStorage()) {
fprintf(stderr, " stackStorage: Some(ArrayObject {\n");
ArrayObject& stack = stackStorage();
uint32_t denseLen = uint32_t(stack.getDenseInitializedLength());
fprintf(stderr, " denseInitializedLength: %u\n,", denseLen);
uint32_t len = stack.length();
fprintf(stderr, " length: %u\n,", len);
fprintf(stderr, " data: [\n");
const Value* elements = getDenseElements();
for (uint32_t i = 0; i < std::max(len, denseLen); i++) {
fprintf(stderr, " [%u]: ", i);
js::DumpValue(elements[i]);
}
fprintf(stderr, " ],\n");
fprintf(stderr, " }),\n");
} else {
fprintf(stderr, " stackStorage: None\n");
}
if (isSuspended()) {
fprintf(stderr, " resumeIndex: Some(%u),\n", resumeIndex());
} else {
fprintf(stderr, " resumeIndex: None, /* (not suspended) */\n");
}
fprintf(stderr, "}\n");
}
#endif
void AbstractGeneratorObject::finalSuspend(JSContext* cx, HandleObject obj) {
auto* genObj = &obj->as<AbstractGeneratorObject>();
MOZ_ASSERT(genObj->isRunning());
genObj->setClosed(cx);
}
static AbstractGeneratorObject* GetGeneratorObjectForCall(JSContext* cx,
CallObject& callObj) {
// The ".generator" binding is always present and always "aliased".
mozilla::Maybe<PropertyInfo> prop =
callObj.lookup(cx, cx->names().dot_generator_);
if (prop.isNothing()) {
return nullptr;
}
Value genValue = callObj.getSlot(prop->slot());
// If the `Generator; SetAliasedVar ".generator"; InitialYield` bytecode
// sequence has not run yet, genValue is undefined.
return genValue.isObject()
? &genValue.toObject().as<AbstractGeneratorObject>()
: nullptr;
}
AbstractGeneratorObject* js::GetGeneratorObjectForFrame(
JSContext* cx, AbstractFramePtr frame) {
cx->check(frame);
MOZ_ASSERT(frame.isGeneratorFrame());
if (frame.isModuleFrame()) {
ModuleEnvironmentObject* moduleEnv =
frame.script()->module()->environment();
mozilla::Maybe<PropertyInfo> prop =
moduleEnv->lookup(cx, cx->names().dot_generator_);
Value genValue = moduleEnv->getSlot(prop->slot());
return genValue.isObject()
? &genValue.toObject().as<AbstractGeneratorObject>()
: nullptr;
}
if (!frame.hasInitialEnvironment()) {
return nullptr;
}
return GetGeneratorObjectForCall(cx, frame.callObj());
}
AbstractGeneratorObject* js::GetGeneratorObjectForEnvironment(
JSContext* cx, HandleObject env) {
auto* call = CallObject::find(env);
return call ? GetGeneratorObjectForCall(cx, *call) : nullptr;
}
bool js::GeneratorThrowOrReturn(JSContext* cx, AbstractFramePtr frame,
Handle<AbstractGeneratorObject*> genObj,
HandleValue arg,
GeneratorResumeKind resumeKind) {
MOZ_ASSERT(genObj->isRunning());
if (resumeKind == GeneratorResumeKind::Throw) {
cx->setPendingException(arg, ShouldCaptureStack::Maybe);
} else {
MOZ_ASSERT(resumeKind == GeneratorResumeKind::Return);
MOZ_ASSERT_IF(genObj->is<GeneratorObject>(), arg.isObject());
frame.setReturnValue(arg);
RootedValue closing(cx, MagicValue(JS_GENERATOR_CLOSING));
cx->setPendingException(closing, nullptr);
}
return false;
}
bool AbstractGeneratorObject::resume(JSContext* cx,
InterpreterActivation& activation,
Handle<AbstractGeneratorObject*> genObj,
HandleValue arg, HandleValue resumeKind) {
MOZ_ASSERT(genObj->isSuspended());
RootedFunction callee(cx, &genObj->callee());
RootedObject envChain(cx, &genObj->environmentChain());
if (!activation.resumeGeneratorFrame(callee, envChain)) {
return false;
}
activation.regs().fp()->setResumedGenerator();
if (genObj->hasArgsObj()) {
activation.regs().fp()->initArgsObj(genObj->argsObj());
}
if (genObj->hasStackStorage() && !genObj->isStackStorageEmpty()) {
JSScript* script = activation.regs().fp()->script();
ArrayObject* storage = &genObj->stackStorage();
uint32_t len = storage->getDenseInitializedLength();
activation.regs().fp()->restoreGeneratorSlots(storage);
activation.regs().sp += len - script->nfixed();
storage->setDenseInitializedLength(0);
}
JSScript* script = callee->nonLazyScript();
uint32_t offset = script->resumeOffsets()[genObj->resumeIndex()];
activation.regs().pc = script->offsetToPC(offset);
// Push arg, generator, resumeKind Values on the generator's stack.
activation.regs().sp += 3;
MOZ_ASSERT(activation.regs().spForStackDepth(activation.regs().stackDepth()));
activation.regs().sp[-3] = arg;
activation.regs().sp[-2] = ObjectValue(*genObj);
activation.regs().sp[-1] = resumeKind;
genObj->setRunning();
return true;
}
GeneratorObject* GeneratorObject::create(JSContext* cx, HandleFunction fun) {
MOZ_ASSERT(fun->isGenerator() && !fun->isAsync());
// FIXME: This would be faster if we could avoid doing a lookup to get
RootedValue pval(cx);
if (!GetProperty(cx, fun, fun, cx->names().prototype, &pval)) {
return nullptr;
}
RootedObject proto(cx, pval.isObject() ? &pval.toObject() : nullptr);
if (!proto) {
proto = GlobalObject::getOrCreateGeneratorObjectPrototype(cx, cx->global());
if (!proto) {
return nullptr;
}
}
return NewObjectWithGivenProto<GeneratorObject>(cx, proto);
}
const JSClass GeneratorObject::class_ = {
"Generator",
JSCLASS_HAS_RESERVED_SLOTS(GeneratorObject::RESERVED_SLOTS),
&classOps_,
};
const JSClassOps GeneratorObject::classOps_ = {
nullptr, // addProperty
nullptr, // delProperty
nullptr, // enumerate
nullptr, // newEnumerate
nullptr, // resolve
nullptr, // mayResolve
nullptr, // finalize
nullptr, // call
nullptr, // construct
CallTraceMethod<AbstractGeneratorObject>, // trace
};
static const JSFunctionSpec generator_methods[] = {
JS_SELF_HOSTED_FN("next", "GeneratorNext", 1, 0),
JS_SELF_HOSTED_FN("throw", "GeneratorThrow", 1, 0),
JS_SELF_HOSTED_FN("return", "GeneratorReturn", 1, 0), JS_FS_END};
JSObject* js::NewTenuredObjectWithFunctionPrototype(
JSContext* cx, Handle<GlobalObject*> global) {
RootedObject proto(cx, &cx->global()->getFunctionPrototype());
return NewPlainObjectWithProto(cx, proto, TenuredObject);
}
static JSObject* CreateGeneratorFunction(JSContext* cx, JSProtoKey key) {
RootedObject proto(cx, &cx->global()->getFunctionConstructor());
Handle<PropertyName*> name = cx->names().GeneratorFunction;
return NewFunctionWithProto(cx, Generator, 1, FunctionFlags::NATIVE_CTOR,
nullptr, name, proto, gc::AllocKind::FUNCTION,
TenuredObject);
}
static JSObject* CreateGeneratorFunctionPrototype(JSContext* cx,
JSProtoKey key) {
return NewTenuredObjectWithFunctionPrototype(cx, cx->global());
}
static bool GeneratorFunctionClassFinish(JSContext* cx,
HandleObject genFunction,
HandleObject genFunctionProto) {
Handle<GlobalObject*> global = cx->global();
// Change the "constructor" property to non-writable before adding any other
// properties, so it's still the last property and can be modified without a
// dictionary-mode transition.
MOZ_ASSERT(genFunctionProto->as<NativeObject>().getLastProperty().key() ==
NameToId(cx->names().constructor));
MOZ_ASSERT(!genFunctionProto->as<NativeObject>().inDictionaryMode());
RootedValue genFunctionVal(cx, ObjectValue(*genFunction));
if (!DefineDataProperty(cx, genFunctionProto, cx->names().constructor,
genFunctionVal, JSPROP_READONLY)) {
return false;
}
MOZ_ASSERT(!genFunctionProto->as<NativeObject>().inDictionaryMode());
RootedObject iteratorProto(
cx, GlobalObject::getOrCreateIteratorPrototype(cx, global));
if (!iteratorProto) {
return false;
}
RootedObject genObjectProto(cx, GlobalObject::createBlankPrototypeInheriting(
cx, &PlainObject::class_, iteratorProto));
if (!genObjectProto) {
return false;
}
if (!DefinePropertiesAndFunctions(cx, genObjectProto, nullptr,
generator_methods) ||
!DefineToStringTag(cx, genObjectProto, cx->names().Generator)) {
return false;
}
if (!LinkConstructorAndPrototype(cx, genFunctionProto, genObjectProto,
JSPROP_READONLY, JSPROP_READONLY) ||
!DefineToStringTag(cx, genFunctionProto, cx->names().GeneratorFunction)) {
return false;
}
global->setGeneratorObjectPrototype(genObjectProto);
return true;
}
static const ClassSpec GeneratorFunctionClassSpec = {
CreateGeneratorFunction,
CreateGeneratorFunctionPrototype,
nullptr,
nullptr,
nullptr,
nullptr,
GeneratorFunctionClassFinish,
ClassSpec::DontDefineConstructor};
const JSClass js::GeneratorFunctionClass = {
"GeneratorFunction", 0, JS_NULL_CLASS_OPS, &GeneratorFunctionClassSpec};
const Value& AbstractGeneratorObject::getUnaliasedLocal(uint32_t slot) const {
MOZ_ASSERT(isSuspended());
MOZ_ASSERT(hasStackStorage());
MOZ_ASSERT(slot < callee().nonLazyScript()->nfixed());
return stackStorage().getDenseElement(slot);
}
void AbstractGeneratorObject::setUnaliasedLocal(uint32_t slot,
const Value& value) {
MOZ_ASSERT(isSuspended());
MOZ_ASSERT(hasStackStorage());
MOZ_ASSERT(slot < callee().nonLazyScript()->nfixed());
return stackStorage().setDenseElement(slot, value);
}
void AbstractGeneratorObject::setClosed(JSContext* cx) {
setFixedSlot(CALLEE_SLOT, NullValue());
setFixedSlot(ENV_CHAIN_SLOT, NullValue());
setFixedSlot(ARGS_OBJ_SLOT, NullValue());
setFixedSlot(STACK_STORAGE_SLOT, NullValue());
setFixedSlot(RESUME_INDEX_SLOT, NullValue());
DebugAPI::onGeneratorClosed(cx, this);
}
bool AbstractGeneratorObject::isAfterYield() {
return isAfterYieldOrAwait(JSOp::Yield);
}
bool AbstractGeneratorObject::isAfterAwait() {
return isAfterYieldOrAwait(JSOp::Await);
}
bool AbstractGeneratorObject::isAfterYieldOrAwait(JSOp op) {
if (isClosed() || isRunning()) {
return false;
}
JSScript* script = callee().nonLazyScript();
jsbytecode* code = script->code();
uint32_t nextOffset = script->resumeOffsets()[resumeIndex()];
if (JSOp(code[nextOffset]) != JSOp::AfterYield) {
return false;
}
static_assert(JSOpLength_Yield == JSOpLength_InitialYield,
"JSOp::Yield and JSOp::InitialYield must have the same length");
static_assert(JSOpLength_Yield == JSOpLength_Await,
"JSOp::Yield and JSOp::Await must have the same length");
uint32_t offset = nextOffset - JSOpLength_Yield;
JSOp prevOp = JSOp(code[offset]);
MOZ_ASSERT(prevOp == JSOp::InitialYield || prevOp == JSOp::Yield ||
prevOp == JSOp::Await);
return prevOp == op;
}
template <>
bool JSObject::is<js::AbstractGeneratorObject>() const {
return is<GeneratorObject>() || is<AsyncFunctionGeneratorObject>() ||
is<AsyncGeneratorObject>();
}
GeneratorResumeKind js::ParserAtomToResumeKind(
frontend::TaggedParserAtomIndex atom) {
if (atom == frontend::TaggedParserAtomIndex::WellKnown::next()) {
return GeneratorResumeKind::Next;
}
if (atom == frontend::TaggedParserAtomIndex::WellKnown::throw_()) {
return GeneratorResumeKind::Throw;
}
MOZ_ASSERT(atom == frontend::TaggedParserAtomIndex::WellKnown::return_());
return GeneratorResumeKind::Return;
}
JSAtom* js::ResumeKindToAtom(JSContext* cx, GeneratorResumeKind kind) {
switch (kind) {
case GeneratorResumeKind::Next:
return cx->names().next;
case GeneratorResumeKind::Throw:
return cx->names().throw_;
case GeneratorResumeKind::Return:
return cx->names().return_;
}
MOZ_CRASH("Invalid resume kind");
}