https://github.com/mozilla/gecko-dev
Tip revision: 717b1cdc7109767ac16cf4aaa0e6c4803352a9e8 authored by Ted Campbell on 07 November 2020, 05:36:31 UTC
Bug 1675905 - Simplify IonBuilder::createThisScripted. r=jandem,iain a=RyanVM
Bug 1675905 - Simplify IonBuilder::createThisScripted. r=jandem,iain a=RyanVM
Tip revision: 717b1cd
EmitterScope.cpp
/* -*- 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 "frontend/EmitterScope.h"
#include "frontend/AbstractScopePtr.h"
#include "frontend/BytecodeEmitter.h"
#include "frontend/ModuleSharedContext.h"
#include "frontend/TDZCheckCache.h"
#include "vm/GlobalObject.h"
using namespace js;
using namespace js::frontend;
using mozilla::DebugOnly;
using mozilla::Maybe;
using mozilla::Nothing;
using mozilla::Some;
EmitterScope::EmitterScope(BytecodeEmitter* bce)
: Nestable<EmitterScope>(&bce->innermostEmitterScope_),
nameCache_(bce->cx->frontendCollectionPool()),
hasEnvironment_(false),
environmentChainLength_(0),
nextFrameSlot_(0),
scopeIndex_(ScopeNote::NoScopeIndex),
noteIndex_(ScopeNote::NoScopeNoteIndex) {}
bool EmitterScope::ensureCache(BytecodeEmitter* bce) {
return nameCache_.acquire(bce->cx);
}
bool EmitterScope::checkSlotLimits(BytecodeEmitter* bce,
const BindingIter& bi) {
if (bi.nextFrameSlot() >= LOCALNO_LIMIT ||
bi.nextEnvironmentSlot() >= ENVCOORD_SLOT_LIMIT) {
bce->reportError(nullptr, JSMSG_TOO_MANY_LOCALS);
return false;
}
return true;
}
bool EmitterScope::checkEnvironmentChainLength(BytecodeEmitter* bce) {
uint32_t hops;
if (EmitterScope* emitterScope = enclosing(&bce)) {
hops = emitterScope->environmentChainLength_;
} else {
hops = bce->sc->compilationEnclosingScope()->environmentChainLength();
}
if (hops >= ENVCOORD_HOPS_LIMIT - 1) {
bce->reportError(nullptr, JSMSG_TOO_DEEP, js_function_str);
return false;
}
environmentChainLength_ = mozilla::AssertedCast<uint8_t>(hops + 1);
return true;
}
void EmitterScope::updateFrameFixedSlots(BytecodeEmitter* bce,
const BindingIter& bi) {
nextFrameSlot_ = bi.nextFrameSlot();
if (nextFrameSlot_ > bce->maxFixedSlots) {
bce->maxFixedSlots = nextFrameSlot_;
}
MOZ_ASSERT_IF(
bce->sc->isFunctionBox() && (bce->sc->asFunctionBox()->isGenerator() ||
bce->sc->asFunctionBox()->isAsync()),
bce->maxFixedSlots == 0);
}
bool EmitterScope::putNameInCache(BytecodeEmitter* bce, JSAtom* name,
NameLocation loc) {
NameLocationMap& cache = *nameCache_;
NameLocationMap::AddPtr p = cache.lookupForAdd(name);
MOZ_ASSERT(!p);
if (!cache.add(p, name, loc)) {
ReportOutOfMemory(bce->cx);
return false;
}
return true;
}
Maybe<NameLocation> EmitterScope::lookupInCache(BytecodeEmitter* bce,
JSAtom* name) {
if (NameLocationMap::Ptr p = nameCache_->lookup(name)) {
return Some(p->value().wrapped);
}
if (fallbackFreeNameLocation_ && nameCanBeFree(bce, name)) {
return fallbackFreeNameLocation_;
}
return Nothing();
}
EmitterScope* EmitterScope::enclosing(BytecodeEmitter** bce) const {
// There is an enclosing scope with access to the same frame.
if (EmitterScope* inFrame = enclosingInFrame()) {
return inFrame;
}
// We are currently compiling the enclosing script, look in the
// enclosing BCE.
if ((*bce)->parent) {
*bce = (*bce)->parent;
return (*bce)->innermostEmitterScopeNoCheck();
}
return nullptr;
}
AbstractScopePtr EmitterScope::enclosingScope(BytecodeEmitter* bce) const {
if (EmitterScope* es = enclosing(&bce)) {
return es->scope(bce);
}
// The enclosing script is already compiled or the current script is the
// global script.
return AbstractScopePtr(bce->sc->compilationEnclosingScope());
}
/* static */
bool EmitterScope::nameCanBeFree(BytecodeEmitter* bce, JSAtom* name) {
// '.generator' cannot be accessed by name.
return name != bce->cx->names().dotGenerator;
}
#ifdef DEBUG
static bool NameIsOnEnvironment(Scope* scope, JSAtom* name) {
for (BindingIter bi(scope); bi; bi++) {
// If found, the name must already be on the environment or an import,
// or else there is a bug in the closed-over name analysis in the
// Parser.
if (bi.name() == name) {
BindingLocation::Kind kind = bi.location().kind();
if (bi.hasArgumentSlot()) {
JSScript* script = scope->as<FunctionScope>().script();
if (script->functionAllowsParameterRedeclaration()) {
// Check for duplicate positional formal parameters.
for (BindingIter bi2(bi); bi2 && bi2.hasArgumentSlot(); bi2++) {
if (bi2.name() == name) {
kind = bi2.location().kind();
}
}
}
}
return kind == BindingLocation::Kind::Global ||
kind == BindingLocation::Kind::Environment ||
kind == BindingLocation::Kind::Import;
}
}
// If not found, assume it's on the global or dynamically accessed.
return true;
}
#endif
/* static */
NameLocation EmitterScope::searchInEnclosingScope(JSAtom* name, Scope* scope,
uint8_t hops) {
for (ScopeIter si(scope); si; si++) {
MOZ_ASSERT(NameIsOnEnvironment(si.scope(), name));
bool hasEnv = si.hasSyntacticEnvironment();
switch (si.kind()) {
case ScopeKind::Function:
if (hasEnv) {
JSScript* script = si.scope()->as<FunctionScope>().script();
if (script->funHasExtensibleScope()) {
return NameLocation::Dynamic();
}
for (BindingIter bi(si.scope()); bi; bi++) {
if (bi.name() != name) {
continue;
}
BindingLocation bindLoc = bi.location();
if (bi.hasArgumentSlot() &&
script->functionAllowsParameterRedeclaration()) {
// Check for duplicate positional formal parameters.
for (BindingIter bi2(bi); bi2 && bi2.hasArgumentSlot(); bi2++) {
if (bi2.name() == name) {
bindLoc = bi2.location();
}
}
}
MOZ_ASSERT(bindLoc.kind() == BindingLocation::Kind::Environment);
return NameLocation::EnvironmentCoordinate(bi.kind(), hops,
bindLoc.slot());
}
}
break;
case ScopeKind::FunctionBodyVar:
case ScopeKind::Lexical:
case ScopeKind::NamedLambda:
case ScopeKind::StrictNamedLambda:
case ScopeKind::SimpleCatch:
case ScopeKind::Catch:
case ScopeKind::FunctionLexical:
if (hasEnv) {
for (BindingIter bi(si.scope()); bi; bi++) {
if (bi.name() != name) {
continue;
}
// The name must already have been marked as closed
// over. If this assertion is hit, there is a bug in the
// name analysis.
BindingLocation bindLoc = bi.location();
MOZ_ASSERT(bindLoc.kind() == BindingLocation::Kind::Environment);
return NameLocation::EnvironmentCoordinate(bi.kind(), hops,
bindLoc.slot());
}
}
break;
case ScopeKind::Module:
if (hasEnv) {
for (BindingIter bi(si.scope()); bi; bi++) {
if (bi.name() != name) {
continue;
}
BindingLocation bindLoc = bi.location();
// Imports are on the environment but are indirect
// bindings and must be accessed dynamically instead of
// using an EnvironmentCoordinate.
if (bindLoc.kind() == BindingLocation::Kind::Import) {
MOZ_ASSERT(si.kind() == ScopeKind::Module);
return NameLocation::Import();
}
MOZ_ASSERT(bindLoc.kind() == BindingLocation::Kind::Environment);
return NameLocation::EnvironmentCoordinate(bi.kind(), hops,
bindLoc.slot());
}
}
break;
case ScopeKind::Eval:
case ScopeKind::StrictEval:
// As an optimization, if the eval doesn't have its own var
// environment and its immediate enclosing scope is a global
// scope, all accesses are global.
if (!hasEnv && si.scope()->enclosing()->is<GlobalScope>()) {
return NameLocation::Global(BindingKind::Var);
}
return NameLocation::Dynamic();
case ScopeKind::Global:
return NameLocation::Global(BindingKind::Var);
case ScopeKind::With:
case ScopeKind::NonSyntactic:
return NameLocation::Dynamic();
case ScopeKind::WasmInstance:
case ScopeKind::WasmFunction:
MOZ_CRASH("No direct eval inside wasm functions");
}
if (hasEnv) {
MOZ_ASSERT(hops < ENVCOORD_HOPS_LIMIT - 1);
hops++;
}
}
MOZ_CRASH("Malformed scope chain");
}
NameLocation EmitterScope::searchAndCache(BytecodeEmitter* bce, JSAtom* name) {
Maybe<NameLocation> loc;
uint8_t hops = hasEnvironment() ? 1 : 0;
DebugOnly<bool> inCurrentScript = enclosingInFrame();
// Start searching in the current compilation.
for (EmitterScope* es = enclosing(&bce); es; es = es->enclosing(&bce)) {
loc = es->lookupInCache(bce, name);
if (loc) {
if (loc->kind() == NameLocation::Kind::EnvironmentCoordinate) {
*loc = loc->addHops(hops);
}
break;
}
if (es->hasEnvironment()) {
hops++;
}
#ifdef DEBUG
if (!es->enclosingInFrame()) {
inCurrentScript = false;
}
#endif
}
// If the name is not found in the current compilation, walk the Scope
// chain encompassing the compilation.
if (!loc) {
inCurrentScript = false;
loc = Some(searchInEnclosingScope(
name, bce->sc->compilationEnclosingScope(), hops));
}
// Each script has its own frame. A free name that is accessed
// from an inner script must not be a frame slot access. If this
// assertion is hit, it is a bug in the free name analysis in the
// parser.
MOZ_ASSERT_IF(!inCurrentScript, loc->kind() != NameLocation::Kind::FrameSlot);
// It is always correct to not cache the location. Ignore OOMs to make
// lookups infallible.
if (!putNameInCache(bce, name, *loc)) {
bce->cx->recoverFromOutOfMemory();
}
return *loc;
}
bool EmitterScope::internEmptyGlobalScopeAsBody(BytecodeEmitter* bce) {
Scope* scope = &bce->cx->global()->emptyGlobalScope();
hasEnvironment_ = scope->hasEnvironment();
bce->bodyScopeIndex = bce->perScriptData().gcThingList().length();
return bce->perScriptData().gcThingList().appendEmptyGlobalScope(
&scopeIndex_);
}
template <typename ScopeCreator>
bool EmitterScope::internScopeCreationData(BytecodeEmitter* bce,
ScopeCreator createScope) {
Rooted<AbstractScopePtr> enclosing(bce->cx, enclosingScope(bce));
ScopeIndex index;
if (!createScope(bce->cx, enclosing, &index)) {
return false;
}
auto scope = bce->compilationInfo.scopeCreationData[index.index];
hasEnvironment_ = scope.get().hasEnvironment();
return bce->perScriptData().gcThingList().append(index, &scopeIndex_);
}
template <typename ScopeCreator>
bool EmitterScope::internBodyScopeCreationData(BytecodeEmitter* bce,
ScopeCreator createScope) {
MOZ_ASSERT(bce->bodyScopeIndex == UINT32_MAX,
"There can be only one body scope");
bce->bodyScopeIndex = bce->perScriptData().gcThingList().length();
return internScopeCreationData(bce, createScope);
}
bool EmitterScope::appendScopeNote(BytecodeEmitter* bce) {
MOZ_ASSERT(ScopeKindIsInBody(scope(bce).kind()) && enclosingInFrame(),
"Scope notes are not needed for body-level scopes.");
noteIndex_ = bce->bytecodeSection().scopeNoteList().length();
return bce->bytecodeSection().scopeNoteList().append(
index(), bce->bytecodeSection().offset(),
enclosingInFrame() ? enclosingInFrame()->noteIndex()
: ScopeNote::NoScopeNoteIndex);
}
bool EmitterScope::deadZoneFrameSlotRange(BytecodeEmitter* bce,
uint32_t slotStart,
uint32_t slotEnd) const {
// Lexical bindings throw ReferenceErrors if they are used before
// initialization. See ES6 8.1.1.1.6.
//
// For completeness, lexical bindings are initialized in ES6 by calling
// InitializeBinding, after which touching the binding will no longer
// throw reference errors. See 13.1.11, 9.2.13, 13.6.3.4, 13.6.4.6,
// 13.6.4.8, 13.14.5, 15.1.8, and 15.2.0.15.
if (slotStart != slotEnd) {
if (!bce->emit1(JSOp::Uninitialized)) {
return false;
}
for (uint32_t slot = slotStart; slot < slotEnd; slot++) {
if (!bce->emitLocalOp(JSOp::InitLexical, slot)) {
return false;
}
}
if (!bce->emit1(JSOp::Pop)) {
return false;
}
}
return true;
}
void EmitterScope::dump(BytecodeEmitter* bce) {
fprintf(stdout, "EmitterScope [%s] %p\n", ScopeKindString(scope(bce).kind()),
this);
for (NameLocationMap::Range r = nameCache_->all(); !r.empty(); r.popFront()) {
const NameLocation& l = r.front().value();
UniqueChars bytes = AtomToPrintableString(bce->cx, r.front().key());
if (!bytes) {
return;
}
if (l.kind() != NameLocation::Kind::Dynamic) {
fprintf(stdout, " %s %s ", BindingKindString(l.bindingKind()),
bytes.get());
} else {
fprintf(stdout, " %s ", bytes.get());
}
switch (l.kind()) {
case NameLocation::Kind::Dynamic:
fprintf(stdout, "dynamic\n");
break;
case NameLocation::Kind::Global:
fprintf(stdout, "global\n");
break;
case NameLocation::Kind::Intrinsic:
fprintf(stdout, "intrinsic\n");
break;
case NameLocation::Kind::NamedLambdaCallee:
fprintf(stdout, "named lambda callee\n");
break;
case NameLocation::Kind::Import:
fprintf(stdout, "import\n");
break;
case NameLocation::Kind::ArgumentSlot:
fprintf(stdout, "arg slot=%u\n", l.argumentSlot());
break;
case NameLocation::Kind::FrameSlot:
fprintf(stdout, "frame slot=%u\n", l.frameSlot());
break;
case NameLocation::Kind::EnvironmentCoordinate:
fprintf(stdout, "environment hops=%u slot=%u\n",
l.environmentCoordinate().hops(),
l.environmentCoordinate().slot());
break;
case NameLocation::Kind::DynamicAnnexBVar:
fprintf(stdout, "dynamic annex b var\n");
break;
}
}
fprintf(stdout, "\n");
}
bool EmitterScope::enterLexical(BytecodeEmitter* bce, ScopeKind kind,
Handle<LexicalScope::Data*> bindings) {
MOZ_ASSERT(kind != ScopeKind::NamedLambda &&
kind != ScopeKind::StrictNamedLambda);
MOZ_ASSERT(this == bce->innermostEmitterScopeNoCheck());
if (!ensureCache(bce)) {
return false;
}
// Resolve bindings.
TDZCheckCache* tdzCache = bce->innermostTDZCheckCache;
uint32_t firstFrameSlot = frameSlotStart();
BindingIter bi(*bindings, firstFrameSlot, /* isNamedLambda = */ false);
for (; bi; bi++) {
if (!checkSlotLimits(bce, bi)) {
return false;
}
NameLocation loc = NameLocation::fromBinding(bi.kind(), bi.location());
if (!putNameInCache(bce, bi.name(), loc)) {
return false;
}
if (!tdzCache->noteTDZCheck(bce, bi.name(), CheckTDZ)) {
return false;
}
}
updateFrameFixedSlots(bce, bi);
auto createScope = [kind, bindings, firstFrameSlot, bce](
JSContext* cx, Handle<AbstractScopePtr> enclosing,
ScopeIndex* index) {
return ScopeCreationData::create(cx, bce->compilationInfo, kind, bindings,
firstFrameSlot, enclosing, index);
};
if (!internScopeCreationData(bce, createScope)) {
return false;
}
if (ScopeKindIsInBody(kind) && hasEnvironment()) {
// After interning the VM scope we can get the scope index.
if (!bce->emitInternedScopeOp(index(), JSOp::PushLexicalEnv)) {
return false;
}
}
// Lexical scopes need notes to be mapped from a pc.
if (!appendScopeNote(bce)) {
return false;
}
// Put frame slots in TDZ. Environment slots are poisoned during
// environment creation.
//
// This must be done after appendScopeNote to be considered in the extent
// of the scope.
if (!deadZoneFrameSlotRange(bce, firstFrameSlot, frameSlotEnd())) {
return false;
}
return checkEnvironmentChainLength(bce);
}
bool EmitterScope::enterNamedLambda(BytecodeEmitter* bce, FunctionBox* funbox) {
MOZ_ASSERT(this == bce->innermostEmitterScopeNoCheck());
MOZ_ASSERT(funbox->namedLambdaBindings());
if (!ensureCache(bce)) {
return false;
}
BindingIter bi(*funbox->namedLambdaBindings(), LOCALNO_LIMIT,
/* isNamedLambda = */ true);
MOZ_ASSERT(bi.kind() == BindingKind::NamedLambdaCallee);
// The lambda name, if not closed over, is accessed via JSOp::Callee and
// not a frame slot. Do not update frame slot information.
NameLocation loc = NameLocation::fromBinding(bi.kind(), bi.location());
if (!putNameInCache(bce, bi.name(), loc)) {
return false;
}
bi++;
MOZ_ASSERT(!bi, "There should be exactly one binding in a NamedLambda scope");
ScopeKind scopeKind =
funbox->strict() ? ScopeKind::StrictNamedLambda : ScopeKind::NamedLambda;
auto createScope = [funbox, scopeKind, bce](
JSContext* cx, Handle<AbstractScopePtr> enclosing,
ScopeIndex* index) {
return ScopeCreationData::create(cx, bce->compilationInfo, scopeKind,
funbox->namedLambdaBindings(),
LOCALNO_LIMIT, enclosing, index);
};
if (!internScopeCreationData(bce, createScope)) {
return false;
}
return checkEnvironmentChainLength(bce);
}
bool EmitterScope::enterFunction(BytecodeEmitter* bce, FunctionBox* funbox) {
MOZ_ASSERT(this == bce->innermostEmitterScopeNoCheck());
// If there are parameter expressions, there is an extra var scope.
if (!funbox->functionHasExtraBodyVarScope()) {
bce->setVarEmitterScope(this);
}
if (!ensureCache(bce)) {
return false;
}
// Resolve body-level bindings, if there are any.
auto bindings = funbox->functionScopeBindings();
if (bindings) {
NameLocationMap& cache = *nameCache_;
BindingIter bi(*bindings, funbox->hasParameterExprs);
for (; bi; bi++) {
if (!checkSlotLimits(bce, bi)) {
return false;
}
NameLocation loc = NameLocation::fromBinding(bi.kind(), bi.location());
NameLocationMap::AddPtr p = cache.lookupForAdd(bi.name());
// The only duplicate bindings that occur are simple formal
// parameters, in which case the last position counts, so update the
// location.
if (p) {
MOZ_ASSERT(bi.kind() == BindingKind::FormalParameter);
MOZ_ASSERT(!funbox->hasDestructuringArgs);
MOZ_ASSERT(!funbox->hasRest());
p->value() = loc;
continue;
}
if (!cache.add(p, bi.name(), loc)) {
ReportOutOfMemory(bce->cx);
return false;
}
}
updateFrameFixedSlots(bce, bi);
} else {
nextFrameSlot_ = 0;
}
// If the function's scope may be extended at runtime due to sloppy direct
// eval, any names beyond the function scope must be accessed dynamically as
// we don't know if the name will become a 'var' binding due to direct eval.
if (funbox->funHasExtensibleScope()) {
fallbackFreeNameLocation_ = Some(NameLocation::Dynamic());
}
// In case of parameter expressions, the parameters are lexical
// bindings and have TDZ.
if (funbox->hasParameterExprs && nextFrameSlot_) {
uint32_t paramFrameSlotEnd = 0;
for (BindingIter bi(*bindings, true); bi; bi++) {
if (!BindingKindIsLexical(bi.kind())) {
break;
}
NameLocation loc = NameLocation::fromBinding(bi.kind(), bi.location());
if (loc.kind() == NameLocation::Kind::FrameSlot) {
MOZ_ASSERT(paramFrameSlotEnd <= loc.frameSlot());
paramFrameSlotEnd = loc.frameSlot() + 1;
}
}
if (!deadZoneFrameSlotRange(bce, 0, paramFrameSlotEnd)) {
return false;
}
}
auto createScope = [funbox, bce](JSContext* cx,
Handle<AbstractScopePtr> enclosing,
ScopeIndex* index) {
return ScopeCreationData::create(
cx, bce->compilationInfo, funbox->functionScopeBindings(),
funbox->hasParameterExprs,
funbox->needsCallObjectRegardlessOfBindings(), funbox, enclosing,
index);
};
if (!internBodyScopeCreationData(bce, createScope)) {
return false;
}
return checkEnvironmentChainLength(bce);
}
bool EmitterScope::enterFunctionExtraBodyVar(BytecodeEmitter* bce,
FunctionBox* funbox) {
MOZ_ASSERT(funbox->hasParameterExprs);
MOZ_ASSERT(funbox->extraVarScopeBindings() ||
funbox->needsExtraBodyVarEnvironmentRegardlessOfBindings());
MOZ_ASSERT(this == bce->innermostEmitterScopeNoCheck());
// The extra var scope is never popped once it's entered. It replaces the
// function scope as the var emitter scope.
bce->setVarEmitterScope(this);
if (!ensureCache(bce)) {
return false;
}
// Resolve body-level bindings, if there are any.
uint32_t firstFrameSlot = frameSlotStart();
if (auto bindings = funbox->extraVarScopeBindings()) {
BindingIter bi(*bindings, firstFrameSlot);
for (; bi; bi++) {
if (!checkSlotLimits(bce, bi)) {
return false;
}
NameLocation loc = NameLocation::fromBinding(bi.kind(), bi.location());
if (!putNameInCache(bce, bi.name(), loc)) {
return false;
}
}
updateFrameFixedSlots(bce, bi);
} else {
nextFrameSlot_ = firstFrameSlot;
}
// If the extra var scope may be extended at runtime due to sloppy
// direct eval, any names beyond the var scope must be accessed
// dynamically as we don't know if the name will become a 'var' binding
// due to direct eval.
if (funbox->funHasExtensibleScope()) {
fallbackFreeNameLocation_ = Some(NameLocation::Dynamic());
}
// Create and intern the VM scope.
auto createScope = [funbox, firstFrameSlot, bce](
JSContext* cx, Handle<AbstractScopePtr> enclosing,
ScopeIndex* index) {
return ScopeCreationData::create(
cx, bce->compilationInfo, ScopeKind::FunctionBodyVar,
funbox->extraVarScopeBindings(), firstFrameSlot,
funbox->needsExtraBodyVarEnvironmentRegardlessOfBindings(), enclosing,
index);
};
if (!internScopeCreationData(bce, createScope)) {
return false;
}
if (hasEnvironment()) {
if (!bce->emitInternedScopeOp(index(), JSOp::PushVarEnv)) {
return false;
}
}
// The extra var scope needs a note to be mapped from a pc.
if (!appendScopeNote(bce)) {
return false;
}
return checkEnvironmentChainLength(bce);
}
class DynamicBindingIter : public BindingIter {
public:
explicit DynamicBindingIter(GlobalSharedContext* sc)
: BindingIter(*sc->bindings) {}
explicit DynamicBindingIter(EvalSharedContext* sc)
: BindingIter(*sc->bindings, /* strict = */ false) {
MOZ_ASSERT(!sc->strict());
}
JSOp bindingOp() const {
switch (kind()) {
case BindingKind::Var:
return JSOp::DefVar;
case BindingKind::Let:
return JSOp::DefLet;
case BindingKind::Const:
return JSOp::DefConst;
default:
MOZ_CRASH("Bad BindingKind");
}
}
};
bool EmitterScope::enterGlobal(BytecodeEmitter* bce,
GlobalSharedContext* globalsc) {
MOZ_ASSERT(this == bce->innermostEmitterScopeNoCheck());
bce->setVarEmitterScope(this);
if (!ensureCache(bce)) {
return false;
}
if (bce->emitterMode == BytecodeEmitter::SelfHosting) {
// In self-hosting, it is incorrect to consult the global scope because
// self-hosted scripts are cloned into their target compartments before
// they are run. Instead of Global, Intrinsic is used for all names.
//
// Intrinsic lookups are redirected to the special intrinsics holder
// in the global object, into which any missing values are cloned
// lazily upon first access.
fallbackFreeNameLocation_ = Some(NameLocation::Intrinsic());
return internEmptyGlobalScopeAsBody(bce);
}
auto createScope = [globalsc, bce](JSContext* cx,
Handle<AbstractScopePtr> enclosing,
ScopeIndex* index) {
MOZ_ASSERT(!enclosing.get());
return ScopeCreationData::create(cx, bce->compilationInfo,
globalsc->scopeKind(), globalsc->bindings,
index);
};
if (!internBodyScopeCreationData(bce, createScope)) {
return false;
}
// See: JSScript::outermostScope.
MOZ_ASSERT(bce->bodyScopeIndex == 0, "Global scope must be index 0");
// Resolve binding names and emit Def{Var,Let,Const} prologue ops.
if (globalsc->bindings) {
// Check for declaration conflicts before the Def* ops.
if (!bce->emit1(JSOp::CheckGlobalOrEvalDecl)) {
return false;
}
for (DynamicBindingIter bi(globalsc); bi; bi++) {
NameLocation loc = NameLocation::fromBinding(bi.kind(), bi.location());
JSAtom* name = bi.name();
if (!putNameInCache(bce, name, loc)) {
return false;
}
// Define the name in the prologue. Do not emit DefVar for
// functions that we'll emit DefFun for.
if (bi.isTopLevelFunction()) {
continue;
}
if (!bce->emitAtomOp(bi.bindingOp(), name)) {
return false;
}
}
}
// Note that to save space, we don't add free names to the cache for
// global scopes. They are assumed to be global vars in the syntactic
// global scope, dynamic accesses under non-syntactic global scope.
if (globalsc->scopeKind() == ScopeKind::Global) {
fallbackFreeNameLocation_ = Some(NameLocation::Global(BindingKind::Var));
} else {
fallbackFreeNameLocation_ = Some(NameLocation::Dynamic());
}
return true;
}
bool EmitterScope::enterEval(BytecodeEmitter* bce, EvalSharedContext* evalsc) {
MOZ_ASSERT(this == bce->innermostEmitterScopeNoCheck());
bce->setVarEmitterScope(this);
if (!ensureCache(bce)) {
return false;
}
// For simplicity, treat all free name lookups in eval scripts as dynamic.
fallbackFreeNameLocation_ = Some(NameLocation::Dynamic());
// Create the `var` scope. Note that there is also a lexical scope, created
// separately in emitScript().
auto createScope = [evalsc, bce](JSContext* cx,
Handle<AbstractScopePtr> enclosing,
ScopeIndex* index) {
ScopeKind scopeKind =
evalsc->strict() ? ScopeKind::StrictEval : ScopeKind::Eval;
return ScopeCreationData::create(cx, bce->compilationInfo, scopeKind,
evalsc->bindings, enclosing, index);
};
if (!internBodyScopeCreationData(bce, createScope)) {
return false;
}
if (hasEnvironment()) {
if (!bce->emitInternedScopeOp(index(), JSOp::PushVarEnv)) {
return false;
}
} else {
// Resolve binding names and emit DefVar prologue ops if we don't have
// an environment (i.e., a sloppy eval).
// Eval scripts always have their own lexical scope, but non-strict
// scopes may introduce 'var' bindings to the nearest var scope.
//
// TODO: We may optimize strict eval bindings in the future to be on
// the frame. For now, handle everything dynamically.
if (!hasEnvironment() && evalsc->bindings) {
// Check for declaration conflicts before the DefVar ops.
if (!bce->emit1(JSOp::CheckGlobalOrEvalDecl)) {
return false;
}
for (DynamicBindingIter bi(evalsc); bi; bi++) {
MOZ_ASSERT(bi.bindingOp() == JSOp::DefVar);
if (bi.isTopLevelFunction()) {
continue;
}
if (!bce->emitAtomOp(JSOp::DefVar, bi.name())) {
return false;
}
}
}
// As an optimization, if the eval does not have its own var
// environment and is directly enclosed in a global scope, then all
// free name lookups are global.
if (scope(bce).enclosing().is<GlobalScope>()) {
fallbackFreeNameLocation_ = Some(NameLocation::Global(BindingKind::Var));
}
}
return true;
}
bool EmitterScope::enterModule(BytecodeEmitter* bce,
ModuleSharedContext* modulesc) {
MOZ_ASSERT(this == bce->innermostEmitterScopeNoCheck());
bce->setVarEmitterScope(this);
if (!ensureCache(bce)) {
return false;
}
// Resolve body-level bindings, if there are any.
TDZCheckCache* tdzCache = bce->innermostTDZCheckCache;
Maybe<uint32_t> firstLexicalFrameSlot;
if (ModuleScope::Data* bindings = modulesc->bindings) {
BindingIter bi(*bindings);
for (; bi; bi++) {
if (!checkSlotLimits(bce, bi)) {
return false;
}
NameLocation loc = NameLocation::fromBinding(bi.kind(), bi.location());
if (!putNameInCache(bce, bi.name(), loc)) {
return false;
}
if (BindingKindIsLexical(bi.kind())) {
if (loc.kind() == NameLocation::Kind::FrameSlot &&
!firstLexicalFrameSlot) {
firstLexicalFrameSlot = Some(loc.frameSlot());
}
if (!tdzCache->noteTDZCheck(bce, bi.name(), CheckTDZ)) {
return false;
}
}
}
updateFrameFixedSlots(bce, bi);
} else {
nextFrameSlot_ = 0;
}
// Modules are toplevel, so any free names are global.
fallbackFreeNameLocation_ = Some(NameLocation::Global(BindingKind::Var));
// Put lexical frame slots in TDZ. Environment slots are poisoned during
// environment creation.
if (firstLexicalFrameSlot) {
if (!deadZoneFrameSlotRange(bce, *firstLexicalFrameSlot, frameSlotEnd())) {
return false;
}
}
// Create and intern the VM scope creation data.
auto createScope = [modulesc, bce](JSContext* cx,
Handle<AbstractScopePtr> enclosing,
ScopeIndex* index) {
return ScopeCreationData::create(cx, bce->compilationInfo,
modulesc->bindings, modulesc->module(),
enclosing, index);
};
if (!internBodyScopeCreationData(bce, createScope)) {
return false;
}
return checkEnvironmentChainLength(bce);
}
bool EmitterScope::enterWith(BytecodeEmitter* bce) {
MOZ_ASSERT(this == bce->innermostEmitterScopeNoCheck());
if (!ensureCache(bce)) {
return false;
}
// 'with' make all accesses dynamic and unanalyzable.
fallbackFreeNameLocation_ = Some(NameLocation::Dynamic());
auto createScope = [bce](JSContext* cx, Handle<AbstractScopePtr> enclosing,
ScopeIndex* index) {
return ScopeCreationData::create(cx, bce->compilationInfo, enclosing,
index);
};
if (!internScopeCreationData(bce, createScope)) {
return false;
}
if (!bce->emitInternedScopeOp(index(), JSOp::EnterWith)) {
return false;
}
if (!appendScopeNote(bce)) {
return false;
}
return checkEnvironmentChainLength(bce);
}
bool EmitterScope::deadZoneFrameSlots(BytecodeEmitter* bce) const {
return deadZoneFrameSlotRange(bce, frameSlotStart(), frameSlotEnd());
}
bool EmitterScope::leave(BytecodeEmitter* bce, bool nonLocal) {
// If we aren't leaving the scope due to a non-local jump (e.g., break),
// we must be the innermost scope.
MOZ_ASSERT_IF(!nonLocal, this == bce->innermostEmitterScopeNoCheck());
ScopeKind kind = scope(bce).kind();
switch (kind) {
case ScopeKind::Lexical:
case ScopeKind::SimpleCatch:
case ScopeKind::Catch:
case ScopeKind::FunctionLexical:
if (!bce->emit1(hasEnvironment() ? JSOp::PopLexicalEnv
: JSOp::DebugLeaveLexicalEnv)) {
return false;
}
break;
case ScopeKind::With:
if (!bce->emit1(JSOp::LeaveWith)) {
return false;
}
break;
case ScopeKind::Function:
case ScopeKind::FunctionBodyVar:
case ScopeKind::NamedLambda:
case ScopeKind::StrictNamedLambda:
case ScopeKind::Eval:
case ScopeKind::StrictEval:
case ScopeKind::Global:
case ScopeKind::NonSyntactic:
case ScopeKind::Module:
break;
case ScopeKind::WasmInstance:
case ScopeKind::WasmFunction:
MOZ_CRASH("No wasm function scopes in JS");
}
// Finish up the scope if we are leaving it in LIFO fashion.
if (!nonLocal) {
// Popping scopes due to non-local jumps generate additional scope
// notes. See NonLocalExitControl::prepareForNonLocalJump.
if (ScopeKindIsInBody(kind)) {
if (kind == ScopeKind::FunctionBodyVar) {
// The extra function var scope is never popped once it's pushed,
// so its scope note extends until the end of any possible code.
bce->bytecodeSection().scopeNoteList().recordEndFunctionBodyVar(
noteIndex_);
} else {
bce->bytecodeSection().scopeNoteList().recordEnd(
noteIndex_, bce->bytecodeSection().offset());
}
}
}
return true;
}
AbstractScopePtr EmitterScope::scope(const BytecodeEmitter* bce) const {
return bce->perScriptData().gcThingList().getScope(index());
}
NameLocation EmitterScope::lookup(BytecodeEmitter* bce, JSAtom* name) {
if (Maybe<NameLocation> loc = lookupInCache(bce, name)) {
return *loc;
}
return searchAndCache(bce, name);
}
Maybe<NameLocation> EmitterScope::locationBoundInScope(JSAtom* name,
EmitterScope* target) {
// The target scope must be an intra-frame enclosing scope of this
// one. Count the number of extra hops to reach it.
uint8_t extraHops = 0;
for (EmitterScope* es = this; es != target; es = es->enclosingInFrame()) {
if (es->hasEnvironment()) {
extraHops++;
}
}
// Caches are prepopulated with bound names. So if the name is bound in a
// particular scope, it must already be in the cache. Furthermore, don't
// consult the fallback location as we only care about binding names.
Maybe<NameLocation> loc;
if (NameLocationMap::Ptr p = target->nameCache_->lookup(name)) {
NameLocation l = p->value().wrapped;
if (l.kind() == NameLocation::Kind::EnvironmentCoordinate) {
loc = Some(l.addHops(extraHops));
} else {
loc = Some(l);
}
}
return loc;
}