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LibJS: Make DeclarativeEnvironment store bindings in a Vector

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The previous storage for DeclarativeEnvironment looked like this:

    HashMap<FlyString, Binding> m_bindings;

This patch changes that to:

    HashMap<FlyString, size_t> m_names;
    Vector<Binding> m_bindings;

The main goal here is to give each binding an index that can ultimately
be cached and used for optimized environment accesses.
This commit is contained in:
Andreas Kling 2021-10-06 23:38:46 +02:00
parent 7aa3cfda09
commit 6ef5464015
2 changed files with 52 additions and 44 deletions
Download patch file Download diff file Expand all files Collapse all files

93
Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.cpp
View file

@ -30,59 +30,60 @@ DeclarativeEnvironment::~DeclarativeEnvironment()
void DeclarativeEnvironment::visit_edges(Visitor& visitor)
{
Base::visit_edges(visitor);
for (auto& it : m_bindings)
visitor.visit(it.value.value);
for (auto& binding : m_bindings)
visitor.visit(binding.value);
}
// 9.1.1.1.1 HasBinding ( N ), https://tc39.es/ecma262/#sec-declarative-environment-records-hasbinding-n
bool DeclarativeEnvironment::has_binding(FlyString const& name) const
{
return m_bindings.contains(name);
return m_names.contains(name);
}
// 9.1.1.1.2 CreateMutableBinding ( N, D ), https://tc39.es/ecma262/#sec-declarative-environment-records-createmutablebinding-n-d
void DeclarativeEnvironment::create_mutable_binding(GlobalObject&, FlyString const& name, bool can_be_deleted)
{
auto result = m_bindings.set(name,
Binding {
.value = {},
.strict = false,
.mutable_ = true,
.can_be_deleted = can_be_deleted,
.initialized = false,
});
m_bindings.append(Binding {
.value = {},
.strict = false,
.mutable_ = true,
.can_be_deleted = can_be_deleted,
.initialized = false,
});
auto result = m_names.set(name, m_bindings.size() - 1);
VERIFY(result == AK::HashSetResult::InsertedNewEntry);
}
// 9.1.1.1.3 CreateImmutableBinding ( N, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-createimmutablebinding-n-s
void DeclarativeEnvironment::create_immutable_binding(GlobalObject&, FlyString const& name, bool strict)
{
auto result = m_bindings.set(name,
Binding {
.value = {},
.strict = strict,
.mutable_ = false,
.can_be_deleted = false,
.initialized = false,
});
m_bindings.append(Binding {
.value = {},
.strict = strict,
.mutable_ = false,
.can_be_deleted = false,
.initialized = false,
});
auto result = m_names.set(name, m_bindings.size() - 1);
VERIFY(result == AK::HashSetResult::InsertedNewEntry);
}
// 9.1.1.1.4 InitializeBinding ( N, V ), https://tc39.es/ecma262/#sec-declarative-environment-records-initializebinding-n-v
void DeclarativeEnvironment::initialize_binding(GlobalObject&, FlyString const& name, Value value)
{
auto it = m_bindings.find(name);
VERIFY(it != m_bindings.end());
VERIFY(it->value.initialized == false);
it->value.value = value;
it->value.initialized = true;
auto it = m_names.find(name);
VERIFY(it != m_names.end());
auto& binding = m_bindings[it->value];
VERIFY(binding.initialized == false);
binding.value = value;
binding.initialized = true;
}
// 9.1.1.1.5 SetMutableBinding ( N, V, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-setmutablebinding-n-v-s
void DeclarativeEnvironment::set_mutable_binding(GlobalObject& global_object, FlyString const& name, Value value, bool strict)
{
auto it = m_bindings.find(name);
if (it == m_bindings.end()) {
auto it = m_names.find(name);
if (it == m_names.end()) {
if (strict) {
global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::UnknownIdentifier, name);
return;
@ -92,16 +93,17 @@ void DeclarativeEnvironment::set_mutable_binding(GlobalObject& global_object, Fl
return;
}
if (it->value.strict)
auto& binding = m_bindings[it->value];
if (binding.strict)
strict = true;
if (!it->value.initialized) {
if (!binding.initialized) {
global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::BindingNotInitialized, name);
return;
}
if (it->value.mutable_) {
it->value.value = value;
if (binding.mutable_) {
binding.value = value;
} else {
if (strict) {
global_object.vm().throw_exception<TypeError>(global_object, ErrorType::InvalidAssignToConst);
@ -112,31 +114,36 @@ void DeclarativeEnvironment::set_mutable_binding(GlobalObject& global_object, Fl
// 9.1.1.1.6 GetBindingValue ( N, S ), https://tc39.es/ecma262/#sec-declarative-environment-records-getbindingvalue-n-s
Value DeclarativeEnvironment::get_binding_value(GlobalObject& global_object, FlyString const& name, bool)
{
auto it = m_bindings.find(name);
VERIFY(it != m_bindings.end());
if (!it->value.initialized) {
auto it = m_names.find(name);
VERIFY(it != m_names.end());
auto& binding = m_bindings[it->value];
if (!binding.initialized) {
global_object.vm().throw_exception<ReferenceError>(global_object, ErrorType::BindingNotInitialized, name);
return {};
}
return it->value.value;
return binding.value;
}
// 9.1.1.1.7 DeleteBinding ( N ), https://tc39.es/ecma262/#sec-declarative-environment-records-deletebinding-n
bool DeclarativeEnvironment::delete_binding(GlobalObject&, FlyString const& name)
{
auto it = m_bindings.find(name);
VERIFY(it != m_bindings.end());
if (!it->value.can_be_deleted)
auto it = m_names.find(name);
VERIFY(it != m_names.end());
auto& binding = m_bindings[it->value];
if (!binding.can_be_deleted)
return false;
m_bindings.remove(it);
// NOTE: We keep the entry in m_bindings to avoid disturbing indices.
binding = {};
m_names.remove(it);
return true;
}
void DeclarativeEnvironment::initialize_or_set_mutable_binding(Badge<ScopeNode>, GlobalObject& global_object, FlyString const& name, Value value)
{
auto it = m_bindings.find(name);
VERIFY(it != m_bindings.end());
if (!it->value.initialized)
auto it = m_names.find(name);
VERIFY(it != m_names.end());
auto& binding = m_bindings[it->value];
if (!binding.initialized)
initialize_binding(global_object, name, value);
else
set_mutable_binding(global_object, name, value, false);
@ -145,8 +152,8 @@ void DeclarativeEnvironment::initialize_or_set_mutable_binding(Badge<ScopeNode>,
Vector<String> DeclarativeEnvironment::bindings() const
{
Vector<String> names;
for (auto& binding : m_bindings) {
names.empend(binding.key);
for (auto& it : m_names) {
names.append(it.key);
}
return names;
}

3
Userland/Libraries/LibJS/Runtime/DeclarativeEnvironment.h
View file

@ -48,7 +48,8 @@ private:
bool initialized { false };
};
HashMap<FlyString, Binding> m_bindings;
HashMap<FlyString, size_t> m_names;
Vector<Binding> m_bindings;
};
template<>