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LibJS: Make GetById and GetByValue avoid get_identifier() in common case

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We now defer looking up the various identifiers by IdentifierTableIndex
until the last moment. This allows us to avoid the retrieval in common
cases like when a property access is cached.

Knocks a ~12% item off the profile on https://ventrella.com/Clusters/
This commit is contained in:
Andreas Kling 2024-07-09 11:37:06 +02:00 • committed by Andreas Kling
parent ae0cfe4f2d
commit 509c10d14d
Notes: sideshowbarker 2024-07-17 01:27:18 +09:00
4 changed files with 57 additions and 22 deletions
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2
Userland/Libraries/LibJS/Bytecode/Executable.h
View file

@ -86,6 +86,8 @@ public:
Vector<DeprecatedFlyString> local_variable_names;
size_t local_index_base { 0 };
Optional<IdentifierTableIndex> length_identifier;
ByteString const& get_string(StringTableIndex index) const { return string_table->get(index); }
DeprecatedFlyString const& get_identifier(IdentifierTableIndex index) const { return identifier_table->get(index); }

2
Userland/Libraries/LibJS/Bytecode/Generator.cpp
View file

@ -453,6 +453,7 @@ CodeGenerationErrorOr<NonnullGCPtr<Executable>> Generator::compile(VM& vm, ASTNo
executable->source_map = move(source_map);
executable->local_variable_names = move(local_variable_names);
executable->local_index_base = number_of_registers + number_of_constants;
executable->length_identifier = generator.m_length_identifier;
generator.m_finished = true;
@ -1075,6 +1076,7 @@ CodeGenerationErrorOr<Optional<ScopedOperand>> Generator::emit_named_evaluation_
void Generator::emit_get_by_id(ScopedOperand dst, ScopedOperand base, IdentifierTableIndex property_identifier, Optional<IdentifierTableIndex> base_identifier)
{
if (m_identifier_table->get(property_identifier) == "length"sv) {
m_length_identifier = property_identifier;
emit<Op::GetLength>(dst, base, move(base_identifier), m_next_property_lookup_cache++);
return;
}

2
Userland/Libraries/LibJS/Bytecode/Generator.h
View file

@ -402,6 +402,8 @@ private:
bool m_must_propagate_completion { true };
GCPtr<ECMAScriptFunctionObject const> m_function;
Optional<IdentifierTableIndex> m_length_identifier;
};
}

73
Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
View file

@ -876,6 +876,24 @@ inline void fast_typed_array_set_element(TypedArrayBase& typed_array, u32 index,
*slot = value;
}
Completion throw_null_or_undefined_property_get(VM& vm, Value base_value, Optional<IdentifierTableIndex> base_identifier, IdentifierTableIndex property_identifier, Executable const& executable)
{
VERIFY(base_value.is_nullish());
if (base_identifier.has_value())
return vm.throw_completion<TypeError>(ErrorType::ToObjectNullOrUndefinedWithPropertyAndName, executable.get_identifier(property_identifier), base_value, executable.get_identifier(base_identifier.value()));
return vm.throw_completion<TypeError>(ErrorType::ToObjectNullOrUndefinedWithProperty, executable.get_identifier(property_identifier), base_value);
}
Completion throw_null_or_undefined_property_get(VM& vm, Value base_value, Optional<IdentifierTableIndex> base_identifier, Value property, Executable const& executable)
{
VERIFY(base_value.is_nullish());
if (base_identifier.has_value())
return vm.throw_completion<TypeError>(ErrorType::ToObjectNullOrUndefinedWithPropertyAndName, property, base_value, executable.get_identifier(base_identifier.value()));
return vm.throw_completion<TypeError>(ErrorType::ToObjectNullOrUndefinedWithProperty, property, base_value);
}
template<typename BaseType, typename PropertyType>
ALWAYS_INLINE Completion throw_null_or_undefined_property_access(VM& vm, Value base_value, BaseType const& base_identifier, PropertyType const& property_identifier)
{
@ -898,8 +916,7 @@ ALWAYS_INLINE Completion throw_null_or_undefined_property_access(VM& vm, Value b
return vm.throw_completion<TypeError>(ErrorType::ToObjectNullOrUndefined);
}
template<typename BaseType, typename PropertyType>
ALWAYS_INLINE ThrowCompletionOr<NonnullGCPtr<Object>> base_object_for_get(VM& vm, Value base_value, BaseType const& base_identifier, PropertyType const& property_identifier)
ALWAYS_INLINE GCPtr<Object> base_object_for_get_impl(VM& vm, Value base_value)
{
if (base_value.is_object()) [[likely]]
return base_value.as_object();
@ -917,8 +934,25 @@ ALWAYS_INLINE ThrowCompletionOr<NonnullGCPtr<Object>> base_object_for_get(VM& vm
if (base_value.is_symbol())
return realm.intrinsics().symbol_prototype();
return nullptr;
}
ALWAYS_INLINE ThrowCompletionOr<NonnullGCPtr<Object>> base_object_for_get(VM& vm, Value base_value, Optional<IdentifierTableIndex> base_identifier, IdentifierTableIndex property_identifier, Executable const& executable)
{
if (auto base_object = base_object_for_get_impl(vm, base_value))
return NonnullGCPtr { *base_object };
// NOTE: At this point this is guaranteed to throw (null or undefined).
return throw_null_or_undefined_property_access(vm, base_value, base_identifier, property_identifier);
return throw_null_or_undefined_property_get(vm, base_value, base_identifier, property_identifier, executable);
}
ALWAYS_INLINE ThrowCompletionOr<NonnullGCPtr<Object>> base_object_for_get(VM& vm, Value base_value, Optional<IdentifierTableIndex> base_identifier, Value property, Executable const& executable)
{
if (auto base_object = base_object_for_get_impl(vm, base_value))
return NonnullGCPtr { *base_object };
// NOTE: At this point this is guaranteed to throw (null or undefined).
return throw_null_or_undefined_property_get(vm, base_value, base_identifier, property, executable);
}
enum class GetByIdMode {
@ -927,7 +961,7 @@ enum class GetByIdMode {
};
template<GetByIdMode mode = GetByIdMode::Normal>
inline ThrowCompletionOr<Value> get_by_id(VM& vm, Optional<DeprecatedFlyString const&> const& base_identifier, DeprecatedFlyString const& property, Value base_value, Value this_value, PropertyLookupCache& cache)
inline ThrowCompletionOr<Value> get_by_id(VM& vm, Optional<IdentifierTableIndex> base_identifier, IdentifierTableIndex property, Value base_value, Value this_value, PropertyLookupCache& cache, Executable const& executable)
{
if constexpr (mode == GetByIdMode::Length) {
if (base_value.is_string()) {
@ -935,7 +969,7 @@ inline ThrowCompletionOr<Value> get_by_id(VM& vm, Optional<DeprecatedFlyString c
}
}
auto base_obj = TRY(base_object_for_get(vm, base_value, base_identifier, property));
auto base_obj = TRY(base_object_for_get(vm, base_value, base_identifier, property, executable));
if constexpr (mode == GetByIdMode::Length) {
// OPTIMIZATION: Fast path for the magical "length" property on Array objects.
@ -965,7 +999,7 @@ inline ThrowCompletionOr<Value> get_by_id(VM& vm, Optional<DeprecatedFlyString c
}
CacheablePropertyMetadata cacheable_metadata;
auto value = TRY(base_obj->internal_get(property, this_value, &cacheable_metadata));
auto value = TRY(base_obj->internal_get(executable.get_identifier(property), this_value, &cacheable_metadata));
if (cacheable_metadata.type == CacheablePropertyMetadata::Type::OwnProperty) {
cache = {};
@ -982,7 +1016,7 @@ inline ThrowCompletionOr<Value> get_by_id(VM& vm, Optional<DeprecatedFlyString c
return value;
}
inline ThrowCompletionOr<Value> get_by_value(VM& vm, Optional<DeprecatedFlyString const&> const& base_identifier, Value base_value, Value property_key_value)
inline ThrowCompletionOr<Value> get_by_value(VM& vm, Optional<IdentifierTableIndex> base_identifier, Value base_value, Value property_key_value, Executable const& executable)
{
// OPTIMIZATION: Fast path for simple Int32 indexes in array-like objects.
if (base_value.is_object() && property_key_value.is_int32() && property_key_value.as_i32() >= 0) {
@ -1044,7 +1078,7 @@ inline ThrowCompletionOr<Value> get_by_value(VM& vm, Optional<DeprecatedFlyStrin
}
}
auto object = TRY(base_object_for_get(vm, base_value, base_identifier, property_key_value));
auto object = TRY(base_object_for_get(vm, base_value, base_identifier, property_key_value, executable));
auto property_key = TRY(property_key_value.to_property_key(vm));
@ -2309,13 +2343,10 @@ ThrowCompletionOr<void> SetVariableBinding::execute_impl(Bytecode::Interpreter&
ThrowCompletionOr<void> GetById::execute_impl(Bytecode::Interpreter& interpreter) const
{
auto base_identifier = interpreter.current_executable().get_identifier(m_base_identifier);
auto const& property_identifier = interpreter.current_executable().get_identifier(m_property);
auto base_value = interpreter.get(base());
auto& cache = interpreter.current_executable().property_lookup_caches[m_cache_index];
interpreter.set(dst(), TRY(get_by_id(interpreter.vm(), base_identifier, property_identifier, base_value, base_value, cache)));
interpreter.set(dst(), TRY(get_by_id(interpreter.vm(), m_base_identifier, m_property, base_value, base_value, cache, interpreter.current_executable())));
return {};
}
@ -2324,18 +2355,17 @@ ThrowCompletionOr<void> GetByIdWithThis::execute_impl(Bytecode::Interpreter& int
auto base_value = interpreter.get(m_base);
auto this_value = interpreter.get(m_this_value);
auto& cache = interpreter.current_executable().property_lookup_caches[m_cache_index];
interpreter.set(dst(), TRY(get_by_id(interpreter.vm(), {}, interpreter.current_executable().get_identifier(m_property), base_value, this_value, cache)));
interpreter.set(dst(), TRY(get_by_id(interpreter.vm(), {}, m_property, base_value, this_value, cache, interpreter.current_executable())));
return {};
}
ThrowCompletionOr<void> GetLength::execute_impl(Bytecode::Interpreter& interpreter) const
{
auto base_identifier = interpreter.current_executable().get_identifier(m_base_identifier);
auto base_value = interpreter.get(base());
auto& cache = interpreter.current_executable().property_lookup_caches[m_cache_index];
auto& executable = interpreter.current_executable();
auto& cache = executable.property_lookup_caches[m_cache_index];
interpreter.set(dst(), TRY(get_by_id<GetByIdMode::Length>(interpreter.vm(), base_identifier, interpreter.vm().names.length.as_string(), base_value, base_value, cache)));
interpreter.set(dst(), TRY(get_by_id<GetByIdMode::Length>(interpreter.vm(), m_base_identifier, *executable.length_identifier, base_value, base_value, cache, executable)));
return {};
}
@ -2343,8 +2373,9 @@ ThrowCompletionOr<void> GetLengthWithThis::execute_impl(Bytecode::Interpreter& i
{
auto base_value = interpreter.get(m_base);
auto this_value = interpreter.get(m_this_value);
auto& cache = interpreter.current_executable().property_lookup_caches[m_cache_index];
interpreter.set(dst(), TRY(get_by_id<GetByIdMode::Length>(interpreter.vm(), {}, interpreter.vm().names.length.as_string(), base_value, this_value, cache)));
auto& executable = interpreter.current_executable();
auto& cache = executable.property_lookup_caches[m_cache_index];
interpreter.set(dst(), TRY(get_by_id<GetByIdMode::Length>(interpreter.vm(), {}, *executable.length_identifier, base_value, this_value, cache, executable)));
return {};
}
@ -2699,9 +2730,7 @@ void Await::execute_impl(Bytecode::Interpreter& interpreter) const
ThrowCompletionOr<void> GetByValue::execute_impl(Bytecode::Interpreter& interpreter) const
{
auto base_identifier = interpreter.current_executable().get_identifier(m_base_identifier);
interpreter.set(dst(), TRY(get_by_value(interpreter.vm(), base_identifier, interpreter.get(m_base), interpreter.get(m_property))));
interpreter.set(dst(), TRY(get_by_value(interpreter.vm(), m_base_identifier, interpreter.get(m_base), interpreter.get(m_property), interpreter.current_executable())));
return {};
}