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-rw-r--r--js/src/vm/GeneratorObject.cpp508
1 files changed, 508 insertions, 0 deletions
diff --git a/js/src/vm/GeneratorObject.cpp b/js/src/vm/GeneratorObject.cpp
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+++ b/js/src/vm/GeneratorObject.cpp
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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
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#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(HandleObject obj) {
+ auto* genObj = &obj->as<AbstractGeneratorObject>();
+ MOZ_ASSERT(genObj->isRunning());
+ genObj->setClosed();
+}
+
+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
+ // the prototype for the instance. Bug 906600.
+ 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);
+}
+
+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");
+}