mirrors/ladybird
0
0
Fork 0
mirror of https://github.com/LadybirdBrowser/ladybird.git synced 2025-07-30 20:59:16 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 9

LibJS: Add cache for the string "[object Object]"

Browse source 
This is very frequently returned by Object.prototype.toString(),
so we benefit from caching it instead of recreating it every time.

Takes Speedometer2.1/EmberJS-Debug-TodoMVC from ~4000ms to ~3700ms
on my M3 MacBook Pro.
This commit is contained in:
Andreas Kling 2025-04-14 23:42:31 +02:00 • committed by Andreas Kling
commit 81d4ed27d8
Notes: github-actions[bot] 2025-04-15 11:09:47 +00:00
4 changed files with 27 additions and 20 deletions
Download patch file Download diff file Expand all files Collapse all files

4
Libraries/LibJS/Runtime/ObjectPrototype.cpp
View file

@ -193,6 +193,10 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectPrototype::to_string)
tag = to_string_tag.as_string().utf8_string_view();
// 17. Return the string-concatenation of "[object ", tag, and "]".
// OPTIMIZATION: The VM has a cache for the extremely common "[object Object]" string.
if (tag == "Object"sv)
return vm.cached_strings.object_Object;
return PrimitiveString::create(vm, MUST(String::formatted("[object {}]", tag)));
}

20
Libraries/LibJS/Runtime/VM.cpp
View file

@ -74,7 +74,7 @@ VM::VM(OwnPtr<CustomData> custom_data, ErrorMessages error_messages)
m_empty_string = m_heap.allocate<PrimitiveString>(String {});
typeof_strings = {
cached_strings = {
.number = m_heap.allocate<PrimitiveString>("number"_string),
.undefined = m_heap.allocate<PrimitiveString>("undefined"_string),
.object = m_heap.allocate<PrimitiveString>("object"_string),
@ -83,6 +83,7 @@ VM::VM(OwnPtr<CustomData> custom_data, ErrorMessages error_messages)
.boolean = m_heap.allocate<PrimitiveString>("boolean"_string),
.bigint = m_heap.allocate<PrimitiveString>("bigint"_string),
.function = m_heap.allocate<PrimitiveString>("function"_string),
.object_Object = m_heap.allocate<PrimitiveString>("[object Object]"_string),
};
for (size_t i = 0; i < single_ascii_character_strings.size(); ++i)
@ -239,14 +240,15 @@ void VM::gather_roots(HashMap<GC::Cell*, GC::HeapRoot>& roots)
for (auto string : m_single_ascii_character_strings)
roots.set(string, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(typeof_strings.number, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(typeof_strings.undefined, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(typeof_strings.object, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(typeof_strings.string, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(typeof_strings.symbol, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(typeof_strings.boolean, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(typeof_strings.bigint, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(typeof_strings.function, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(cached_strings.number, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(cached_strings.undefined, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(cached_strings.object, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(cached_strings.string, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(cached_strings.symbol, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(cached_strings.boolean, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(cached_strings.bigint, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(cached_strings.function, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
roots.set(cached_strings.object_Object, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });
#define __JS_ENUMERATE(SymbolName, snake_name) \
roots.set(m_well_known_symbols.snake_name, GC::HeapRoot { .type = GC::HeapRoot::Type::VM });

3
Libraries/LibJS/Runtime/VM.h
View file

@ -229,7 +229,8 @@ public:
GC::Ptr<PrimitiveString> boolean;
GC::Ptr<PrimitiveString> bigint;
GC::Ptr<PrimitiveString> function;
} typeof_strings;
GC::Ptr<PrimitiveString> object_Object;
} cached_strings;
void run_queued_promise_jobs();
void enqueue_promise_job(GC::Ref<GC::Function<ThrowCompletionOr<Value>()>> job, Realm*);

20
Libraries/LibJS/Runtime/Value.cpp
View file

@ -326,38 +326,38 @@ GC::Ref<PrimitiveString> Value::typeof_(VM& vm) const
{
// 9. If val is a Number, return "number".
if (is_number())
return *vm.typeof_strings.number;
return *vm.cached_strings.number;
switch (m_value.tag) {
// 4. If val is undefined, return "undefined".
case UNDEFINED_TAG:
return *vm.typeof_strings.undefined;
return *vm.cached_strings.undefined;
// 5. If val is null, return "object".
case NULL_TAG:
return *vm.typeof_strings.object;
return *vm.cached_strings.object;
// 6. If val is a String, return "string".
case STRING_TAG:
return *vm.typeof_strings.string;
return *vm.cached_strings.string;
// 7. If val is a Symbol, return "symbol".
case SYMBOL_TAG:
return *vm.typeof_strings.symbol;
return *vm.cached_strings.symbol;
// 8. If val is a Boolean, return "boolean".
case BOOLEAN_TAG:
return *vm.typeof_strings.boolean;
return *vm.cached_strings.boolean;
// 10. If val is a BigInt, return "bigint".
case BIGINT_TAG:
return *vm.typeof_strings.bigint;
return *vm.cached_strings.bigint;
// 11. Assert: val is an Object.
case OBJECT_TAG:
// B.3.6.3 Changes to the typeof Operator, https://tc39.es/ecma262/#sec-IsHTMLDDA-internal-slot-typeof
// 12. If val has an [[IsHTMLDDA]] internal slot, return "undefined".
if (as_object().is_htmldda())
return *vm.typeof_strings.undefined;
return *vm.cached_strings.undefined;
// 13. If val has a [[Call]] internal slot, return "function".
if (is_function())
return *vm.typeof_strings.function;
return *vm.cached_strings.function;
// 14. Return "object".
return *vm.typeof_strings.object;
return *vm.cached_strings.object;
default:
VERIFY_NOT_REACHED();
}