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Code Issues Projects Releases Packages Wiki Activity Actions 10

LibJS: Use a local variable for arguments object when possible

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This allows us to skip allocating a function environment in cases where
it was previously impossible because the arguments object needed a
binding.

This change does not bring visible improvement in Kraken or Octane
benchmarks but seems useful to have anyway.
This commit is contained in:
Aliaksandr Kalenik 2024-05-21 09:32:51 +01:00 • committed by Andreas Kling
parent 777e84b09b
commit 210a5d77dc
Notes: sideshowbarker 2024-07-17 02:55:44 +09:00
5 changed files with 39 additions and 11 deletions
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9
Userland/Libraries/LibJS/Bytecode/Generator.cpp
View file

@ -45,10 +45,15 @@ CodeGenerationErrorOr<void> Generator::emit_function_declaration_instantiation(E
}
if (function.m_arguments_object_needed) {
Optional<Operand> dst;
auto local_var_index = function.m_local_variables_names.find_first_index("arguments"sv);
if (local_var_index.has_value())
dst = local(local_var_index.value());
if (function.m_strict || !function.has_simple_parameter_list()) {
emit<Op::CreateArguments>(Op::CreateArguments::Kind::Unmapped, function.m_strict);
emit<Op::CreateArguments>(dst, Op::CreateArguments::Kind::Unmapped, function.m_strict);
} else {
emit<Op::CreateArguments>(Op::CreateArguments::Kind::Mapped, function.m_strict);
emit<Op::CreateArguments>(dst, Op::CreateArguments::Kind::Mapped, function.m_strict);
}
}

14
Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
View file

@ -1373,6 +1373,11 @@ ThrowCompletionOr<void> CreateArguments::execute_impl(Bytecode::Interpreter& int
arguments_object = create_unmapped_arguments_object(interpreter.vm(), passed_arguments);
}
if (m_dst.has_value()) {
interpreter.set(*m_dst, arguments_object);
return {};
}
if (m_is_immutable) {
MUST(environment->create_immutable_binding(interpreter.vm(), interpreter.vm().names.arguments.as_string(), false));
} else {
@ -2110,9 +2115,14 @@ ByteString CreateRestParams::to_byte_string_impl(Bytecode::Executable const& exe
return ByteString::formatted("CreateRestParams {}, rest_index:{}", format_operand("dst"sv, m_dst, executable), m_rest_index);
}
ByteString CreateArguments::to_byte_string_impl(Bytecode::Executable const&) const
ByteString CreateArguments::to_byte_string_impl(Bytecode::Executable const& executable) const
{
return ByteString::formatted("CreateArguments {} immutable:{}", m_kind == Kind::Mapped ? "mapped"sv : "unmapped"sv, m_is_immutable);
StringBuilder builder;
builder.appendff("CreateArguments");
if (m_dst.has_value())
builder.appendff(" {}", format_operand("dst"sv, *m_dst, executable));
builder.appendff(" {} immutable:{}", m_kind == Kind::Mapped ? "mapped"sv : "unmapped"sv, m_is_immutable);
return builder.to_byte_string();
}
ByteString EnterObjectEnvironment::to_byte_string_impl(Executable const& executable) const

9
Userland/Libraries/LibJS/Bytecode/Op.h
View file

@ -60,8 +60,9 @@ public:
Unmapped,
};
CreateArguments(Kind kind, bool is_immutable)
CreateArguments(Optional<Operand> dst, Kind kind, bool is_immutable)
: Instruction(Type::CreateArguments)
, m_dst(dst)
, m_kind(kind)
, m_is_immutable(is_immutable)
{
@ -69,8 +70,14 @@ public:
ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
ByteString to_byte_string_impl(Bytecode::Executable const&) const;
void visit_operands_impl(Function<void(Operand&)> visitor)
{
if (m_dst.has_value())
visitor(m_dst.value());
}
private:
Optional<Operand> m_dst;
Kind m_kind;
bool m_is_immutable { false };
};