inline bool JSLexicalEnvironment::symbolTableGet(PropertyName propertyName, PropertySlot& slot)
{
SymbolTableEntry entry = symbolTable()->inlineGet(propertyName.uid());
if (entry.isNull())
return false;
ScopeOffset offset = entry.scopeOffset();
// Defend against the inspector asking for a var after it has been optimized out.
if (!isValid(offset))
return false;
slot.setValue(this, DontEnum, variableAt(offset).get());
return true;
}
inline bool JSLexicalEnvironment::symbolTableGet(PropertyName propertyName, PropertyDescriptor& descriptor)
{
SymbolTableEntry entry = symbolTable()->inlineGet(propertyName.uid());
if (entry.isNull())
return false;
ScopeOffset offset = entry.scopeOffset();
// Defend against the inspector asking for a var after it has been optimized out.
if (!isValid(offset))
return false;
descriptor.setDescriptor(variableAt(offset).get(), entry.getAttributes());
return true;
}
// Returns true if we found enough information to terminate optimization.
static inline bool abstractAccess(ExecState* exec, JSScope* scope, const Identifier& ident, GetOrPut getOrPut, size_t depth, bool& needsVarInjectionChecks, ResolveOp& op, InitializationMode initializationMode)
{
if (scope->isJSLexicalEnvironment()) {
JSLexicalEnvironment* lexicalEnvironment = jsCast<JSLexicalEnvironment*>(scope);
if (ident == exec->propertyNames().arguments) {
// We know the property will be at this lexical environment scope, but we don't know how to cache it.
op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
return true;
}
SymbolTableEntry entry = lexicalEnvironment->symbolTable()->get(ident.impl());
if (entry.isReadOnly() && getOrPut == Put) {
// We know the property will be at this lexical environment scope, but we don't know how to cache it.
op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
return true;
}
if (!entry.isNull()) {
op = ResolveOp(makeType(ClosureVar, needsVarInjectionChecks), depth, 0, lexicalEnvironment, entry.watchpointSet(), entry.scopeOffset().offset());
return true;
}
if (scope->type() == ModuleEnvironmentType) {
JSModuleEnvironment* moduleEnvironment = jsCast<JSModuleEnvironment*>(scope);
JSModuleRecord* moduleRecord = moduleEnvironment->moduleRecord();
JSModuleRecord::Resolution resolution = moduleRecord->resolveImport(exec, ident);
if (resolution.type == JSModuleRecord::Resolution::Type::Resolved) {
JSModuleRecord* importedRecord = resolution.moduleRecord;
JSModuleEnvironment* importedEnvironment = importedRecord->moduleEnvironment();
SymbolTableEntry entry = importedEnvironment->symbolTable()->get(resolution.localName.impl());
ASSERT(!entry.isNull());
op = ResolveOp(makeType(ModuleVar, needsVarInjectionChecks), depth, 0, importedEnvironment, entry.watchpointSet(), entry.scopeOffset().offset(), resolution.localName.impl());
return true;
}
}
if (lexicalEnvironment->symbolTable()->usesNonStrictEval())
needsVarInjectionChecks = true;
return false;
}
if (scope->isGlobalLexicalEnvironment()) {
JSGlobalLexicalEnvironment* globalLexicalEnvironment = jsCast<JSGlobalLexicalEnvironment*>(scope);
SymbolTableEntry entry = globalLexicalEnvironment->symbolTable()->get(ident.impl());
if (!entry.isNull()) {
if (getOrPut == Put && entry.isReadOnly() && initializationMode != Initialization) {
// We know the property will be at global lexical environment, but we don't know how to cache it.
op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
return true;
}
// We can try to force const Initialization to always go down the fast path. It is provably impossible to construct
// a program that needs a var injection check here. You can convince yourself of this as follows:
// Any other let/const/class would be a duplicate of this in the global scope, so we would never get here in that situation.
// Also, if we had an eval in the global scope that defined a const, it would also be a duplicate of this const, and so it would
// also throw an error. Therefore, we're *the only* thing that can assign to this "const" slot for the first (and only) time. Also,
// we will never have a Dynamic ResolveType here because if we were inside a "with" statement, that would mean the "const" definition
// isn't a global, it would be a local to the "with" block.
// We still need to make the slow path correct for when we need to fire a watchpoint.
ResolveType resolveType = initializationMode == Initialization ? GlobalLexicalVar : makeType(GlobalLexicalVar, needsVarInjectionChecks);
op = ResolveOp(
resolveType, depth, 0, 0, entry.watchpointSet(),
reinterpret_cast<uintptr_t>(globalLexicalEnvironment->variableAt(entry.scopeOffset()).slot()));
return true;
}
return false;
}
if (scope->isGlobalObject()) {
JSGlobalObject* globalObject = jsCast<JSGlobalObject*>(scope);
SymbolTableEntry entry = globalObject->symbolTable()->get(ident.impl());
if (!entry.isNull()) {
if (getOrPut == Put && entry.isReadOnly()) {
// We know the property will be at global scope, but we don't know how to cache it.
op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
return true;
}
op = ResolveOp(
makeType(GlobalVar, needsVarInjectionChecks), depth, 0, 0, entry.watchpointSet(),
reinterpret_cast<uintptr_t>(globalObject->variableAt(entry.scopeOffset()).slot()));
return true;
}
PropertySlot slot(globalObject, PropertySlot::InternalMethodType::VMInquiry);
bool hasOwnProperty = globalObject->getOwnPropertySlot(globalObject, exec, ident, slot);
if (!hasOwnProperty) {
op = ResolveOp(makeType(UnresolvedProperty, needsVarInjectionChecks), 0, 0, 0, 0, 0);
return true;
}
if (!slot.isCacheableValue()
|| !globalObject->structure()->propertyAccessesAreCacheable()
|| (globalObject->structure()->hasReadOnlyOrGetterSetterPropertiesExcludingProto() && getOrPut == Put)) {
// We know the property will be at global scope, but we don't know how to cache it.
ASSERT(!scope->next());
op = ResolveOp(makeType(GlobalProperty, needsVarInjectionChecks), 0, 0, 0, 0, 0);
return true;
}
WatchpointState state = globalObject->structure()->ensurePropertyReplacementWatchpointSet(exec->vm(), slot.cachedOffset())->state();
if (state == IsWatched && getOrPut == Put) {
// The field exists, but because the replacement watchpoint is still intact. This is
// kind of dangerous. We have two options:
// 1) Invalidate the watchpoint set. That would work, but it's possible that this code
// path never executes - in which case this would be unwise.
// 2) Have the invalidation happen at run-time. All we have to do is leave the code
// uncached. The only downside is slightly more work when this does execute.
// We go with option (2) here because it seems less evil.
op = ResolveOp(makeType(GlobalProperty, needsVarInjectionChecks), depth, 0, 0, 0, 0);
} else
op = ResolveOp(makeType(GlobalProperty, needsVarInjectionChecks), depth, globalObject->structure(), 0, 0, slot.cachedOffset());
return true;
}
op = ResolveOp(Dynamic, 0, 0, 0, 0, 0);
return true;
}