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LibJS: Use local variables to store function parameters in some cases

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Using local variables to store function parameters makes Kraken tests
run 7-10% faster.

For now this optimization is limited to only be applied if:
- Parameter does not use destructuring assignment
- None of the function params has default value
- There is no access to "arguments" variable inside function body
This commit is contained in:
Aliaksandr Kalenik 2023-07-06 21:25:13 +02:00 • committed by Andreas Kling
parent 2e81cc4cf7
commit b1af91d8c4
Notes: sideshowbarker 2024-07-17 00:47:29 +09:00
2 changed files with 28 additions and 6 deletions
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16
Userland/Libraries/LibJS/Parser.cpp
View file

@ -77,9 +77,15 @@ public:
{
ScopePusher scope_pusher(parser, &function_body, ScopeLevel::FunctionTopLevel, ScopeType::Function);
scope_pusher.m_function_parameters = parameters;
auto has_parameters_with_default_values = false;
for (auto& parameter : parameters) {
parameter.binding.visit(
[&](Identifier const& identifier) {
if (parameter.default_value)
has_parameters_with_default_values = true;
scope_pusher.register_identifier(identifier);
scope_pusher.m_function_parameters_candidates_for_local_variables.set(identifier.string());
scope_pusher.m_forbidden_lexical_names.set(identifier.string());
},
[&](NonnullRefPtr<BindingPattern const> const& binding_pattern) {
@ -89,6 +95,11 @@ public:
}));
});
}
if (has_parameters_with_default_values) {
scope_pusher.m_function_parameters_candidates_for_local_variables.clear();
}
return scope_pusher;
}
@ -313,6 +324,10 @@ public:
scope_has_declaration = false;
}
if (m_type == ScopeType::Function && !m_contains_access_to_arguments_object && m_function_parameters_candidates_for_local_variables.contains(identifier_group_name)) {
scope_has_declaration = true;
}
if (scope_has_declaration) {
if (function_declaration)
continue;
@ -413,6 +428,7 @@ private:
Vector<NonnullRefPtr<FunctionDeclaration const>> m_functions_to_hoist;
HashTable<DeprecatedFlyString> m_bound_names;
HashTable<DeprecatedFlyString> m_function_parameters_candidates_for_local_variables;
struct IdentifierGroup {
bool captured_by_nested_function { false };