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LibJS: Let invokers (callers) of [[Call]] allocate ExecutionContext

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Instead of letting every [[Call]] implementation allocate an
ExecutionContext, we now make that a responsibility of the caller.

The main point of this exercise is to allow the Call instruction
to write function arguments directly into the callee ExecutionContext
instead of copying them later.

This makes function calls significantly faster:
- 10-20% faster on micro-benchmarks (depending on argument count)
- 4% speedup on Kraken
- 2% speedup on Octane
- 5% speedup on JetStream
This commit is contained in:
Andreas Kling
2025-04-27 11:53:11 +02:00
committed by Andreas Kling
parent 93788f8057
commit a05be67e4a
Notes: github-actions[bot] 2025-04-27 23:24:56 +00:00 
Author: https://github.com/awesomekling
Commit: https://github.com/LadybirdBrowser/ladybird/commit/a05be67e4ae
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4497
Reviewed-by: https://github.com/Hendiadyoin1
18 changed files with 139 additions and 84 deletions
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43
Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp
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@@ -481,46 +481,39 @@ void ECMAScriptFunctionObject::initialize(Realm& realm)
}
}
// 10.2.1 [[Call]] ( thisArgument, argumentsList ), https://tc39.es/ecma262/#sec-ecmascript-function-objects-call-thisargument-argumentslist
ThrowCompletionOr<Value> ECMAScriptFunctionObject::internal_call(Value this_argument, ReadonlySpan<Value> arguments_list)
ThrowCompletionOr<void> ECMAScriptFunctionObject::get_stack_frame_size(size_t& registers_and_constants_and_locals_count, size_t& argument_count)
{
auto& vm = this->vm();
// 1. Let callerContext be the running execution context.
// NOTE: No-op, kept by the VM in its execution context stack.
if (!m_bytecode_executable) {
if (!ecmascript_code().bytecode_executable()) {
if (is_module_wrapper()) {
const_cast<Statement&>(ecmascript_code()).set_bytecode_executable(TRY(Bytecode::compile(vm, ecmascript_code(), kind(), name())));
const_cast<Statement&>(ecmascript_code()).set_bytecode_executable(TRY(Bytecode::compile(vm(), ecmascript_code(), kind(), name())));
} else {
const_cast<Statement&>(ecmascript_code()).set_bytecode_executable(TRY(Bytecode::compile(vm, *this)));
const_cast<Statement&>(ecmascript_code()).set_bytecode_executable(TRY(Bytecode::compile(vm(), *this)));
}
}
m_bytecode_executable = ecmascript_code().bytecode_executable();
}
registers_and_constants_and_locals_count = m_bytecode_executable->number_of_registers + m_bytecode_executable->constants.size() + m_bytecode_executable->local_variable_names.size();
argument_count = max(argument_count, formal_parameters().size());
return {};
}
u32 arguments_count = max(arguments_list.size(), formal_parameters().size());
auto registers_and_constants_and_locals_count = m_bytecode_executable->number_of_registers + m_bytecode_executable->constants.size() + m_bytecode_executable->local_variable_names.size();
ExecutionContext* callee_context = nullptr;
ALLOCATE_EXECUTION_CONTEXT_ON_NATIVE_STACK(callee_context, registers_and_constants_and_locals_count, arguments_count);
// 10.2.1 [[Call]] ( thisArgument, argumentsList ), https://tc39.es/ecma262/#sec-ecmascript-function-objects-call-thisargument-argumentslist
ThrowCompletionOr<Value> ECMAScriptFunctionObject::internal_call(ExecutionContext& callee_context, Value this_argument)
{
auto& vm = this->vm();
// Non-standard
auto arguments = callee_context->arguments;
if (!arguments_list.is_empty())
arguments.overwrite(0, arguments_list.data(), arguments_list.size() * sizeof(Value));
callee_context->passed_argument_count = arguments_list.size();
if (arguments_list.size() < formal_parameters().size()) {
for (size_t i = arguments_list.size(); i < formal_parameters().size(); ++i)
arguments[i] = js_undefined();
}
VERIFY(m_bytecode_executable);
// 1. Let callerContext be the running execution context.
// NOTE: No-op, kept by the VM in its execution context stack.
// 2. Let calleeContext be PrepareForOrdinaryCall(F, undefined).
// NOTE: We throw if the end of the native stack is reached, so unlike in the spec this _does_ need an exception check.
TRY(prepare_for_ordinary_call(*callee_context, nullptr));
TRY(prepare_for_ordinary_call(callee_context, nullptr));
// 3. Assert: calleeContext is now the running execution context.
VERIFY(&vm.running_execution_context() == callee_context);
VERIFY(&vm.running_execution_context() == &callee_context);
// 4. If F.[[IsClassConstructor]] is true, then
if (is_class_constructor()) {
@@ -537,7 +530,7 @@ ThrowCompletionOr<Value> ECMAScriptFunctionObject::internal_call(Value this_argu
// 5. Perform OrdinaryCallBindThis(F, calleeContext, thisArgument).
if (uses_this())
ordinary_call_bind_this(*callee_context, this_argument);
ordinary_call_bind_this(callee_context, this_argument);
// 6. Let result be Completion(OrdinaryCallEvaluateBody(F, argumentsList)).
auto result = ordinary_call_evaluate_body();