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/*
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Debug.h>
#include <AK/TemporaryChange.h>
#include <LibJS/Bytecode/BasicBlock.h>
#include <LibJS/Bytecode/Instruction.h>
#include <LibJS/Bytecode/Interpreter.h>
#include <LibJS/Bytecode/Op.h>
#include <LibJS/Interpreter.h>
#include <LibJS/Runtime/GlobalEnvironment.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/Realm.h>
namespace JS::Bytecode {
static Interpreter* s_current;
bool g_dump_bytecode = false;
Interpreter* Interpreter::current()
{
return s_current;
}
Interpreter::Interpreter(GlobalObject& global_object, Realm& realm)
: m_vm(global_object.vm())
, m_global_object(global_object)
, m_realm(realm)
{
VERIFY(!s_current);
s_current = this;
}
Interpreter::~Interpreter()
{
VERIFY(s_current == this);
s_current = nullptr;
}
Interpreter::ValueAndFrame Interpreter::run_and_return_frame(Executable const& executable, BasicBlock const* entry_point, RegisterWindow* in_frame)
{
dbgln_if(JS_BYTECODE_DEBUG, "Bytecode::Interpreter will run unit {:p}", &executable);
TemporaryChange restore_executable { m_current_executable, &executable };
VERIFY(m_saved_exception.is_null());
bool pushed_execution_context = false;
ExecutionContext execution_context(vm().heap());
if (vm().execution_context_stack().is_empty() || !vm().running_execution_context().lexical_environment) {
// The "normal" interpreter pushes an execution context without environment so in that case we also want to push one.
execution_context.this_value = &global_object();
static FlyString global_execution_context_name = "(*BC* global execution context)";
execution_context.function_name = global_execution_context_name;
execution_context.lexical_environment = &m_realm.global_environment();
execution_context.variable_environment = &m_realm.global_environment();
execution_context.realm = &m_realm;
execution_context.is_strict_mode = executable.is_strict_mode;
vm().push_execution_context(execution_context);
pushed_execution_context = true;
}
auto block = entry_point ?: &executable.basic_blocks.first();
if (in_frame)
m_register_windows.append(in_frame);
else
m_register_windows.append(make<RegisterWindow>(MarkedVector<Value>(vm().heap()), MarkedVector<Environment*>(vm().heap()), MarkedVector<Environment*>(vm().heap())));
registers().resize(executable.number_of_registers);
registers()[Register::global_object_index] = Value(&global_object());
for (;;) {
Bytecode::InstructionStreamIterator pc(block->instruction_stream());
bool will_jump = false;
bool will_return = false;
while (!pc.at_end()) {
auto& instruction = *pc;
auto ran_or_error = instruction.execute(*this);
if (ran_or_error.is_error()) {
auto exception_value = *ran_or_error.throw_completion().value();
m_saved_exception = make_handle(exception_value);
if (m_unwind_contexts.is_empty())
break;
auto& unwind_context = m_unwind_contexts.last();
if (unwind_context.executable != m_current_executable)
break;
if (unwind_context.handler) {
block = unwind_context.handler;
unwind_context.handler = nullptr;
// If there's no finalizer, there's nowhere for the handler block to unwind to, so the unwind context is no longer needed.
if (!unwind_context.finalizer)
m_unwind_contexts.take_last();
accumulator() = exception_value;
m_saved_exception = {};
will_jump = true;
break;
}
if (unwind_context.finalizer) {
block = unwind_context.finalizer;
m_unwind_contexts.take_last();
will_jump = true;
break;
}
// An unwind context with no handler or finalizer? We have nowhere to jump, and continuing on will make us crash on the next `Call` to a non-native function if there's an exception! So let's crash here instead.
// If you run into this, you probably forgot to remove the current unwind_context somewhere.
VERIFY_NOT_REACHED();
}
if (m_pending_jump.has_value()) {
block = m_pending_jump.release_value();
will_jump = true;
break;
}
if (!m_return_value.is_empty()) {
will_return = true;
break;
}
++pc;
}
if (will_return)
break;
if (pc.at_end() && !will_jump)
break;
if (!m_saved_exception.is_null())
break;
}
dbgln_if(JS_BYTECODE_DEBUG, "Bytecode::Interpreter did run unit {:p}", &executable);
if constexpr (JS_BYTECODE_DEBUG) {
for (size_t i = 0; i < registers().size(); ++i) {
String value_string;
if (registers()[i].is_empty())
value_string = "(empty)";
else
value_string = registers()[i].to_string_without_side_effects();
dbgln("[{:3}] {}", i, value_string);
}
}
auto frame = m_register_windows.take_last();
auto return_value = m_return_value.value_or(js_undefined());
m_return_value = {};
// NOTE: The return value from a called function is put into $0 in the caller context.
if (!m_register_windows.is_empty())
window().registers[0] = return_value;
// At this point we may have already run any queued promise jobs via on_call_stack_emptied,
// in which case this is a no-op.
vm().run_queued_promise_jobs();
if (pushed_execution_context) {
VERIFY(&vm().running_execution_context() == &execution_context);
vm().pop_execution_context();
}
vm().finish_execution_generation();
if (!m_saved_exception.is_null()) {
Value thrown_value = m_saved_exception.value();
m_saved_exception = {};
if (auto* register_window = frame.get_pointer<NonnullOwnPtr<RegisterWindow>>())
return { throw_completion(thrown_value), move(*register_window) };
return { throw_completion(thrown_value), nullptr };
}
if (auto register_window = frame.get_pointer<NonnullOwnPtr<RegisterWindow>>())
return { return_value, move(*register_window) };
return { return_value, nullptr };
}
void Interpreter::enter_unwind_context(Optional<Label> handler_target, Optional<Label> finalizer_target)
{
m_unwind_contexts.empend(m_current_executable, handler_target.has_value() ? &handler_target->block() : nullptr, finalizer_target.has_value() ? &finalizer_target->block() : nullptr);
}
void Interpreter::leave_unwind_context()
{
m_unwind_contexts.take_last();
}
ThrowCompletionOr<void> Interpreter::continue_pending_unwind(Label const& resume_label)
{
if (!m_saved_exception.is_null()) {
auto result = throw_completion(m_saved_exception.value());
m_saved_exception = {};
return result;
}
jump(resume_label);
return {};
}
VM::InterpreterExecutionScope Interpreter::ast_interpreter_scope()
{
if (!m_ast_interpreter)
m_ast_interpreter = JS::Interpreter::create_with_existing_realm(m_realm);
return { *m_ast_interpreter };
}
AK::Array<OwnPtr<PassManager>, static_cast<UnderlyingType<Interpreter::OptimizationLevel>>(Interpreter::OptimizationLevel::__Count)> Interpreter::s_optimization_pipelines {};
Bytecode::PassManager& Interpreter::optimization_pipeline(Interpreter::OptimizationLevel level)
{
auto underlying_level = to_underlying(level);
VERIFY(underlying_level <= to_underlying(Interpreter::OptimizationLevel::__Count));
auto& entry = s_optimization_pipelines[underlying_level];
if (entry)
return *entry;
auto pm = make<PassManager>();
if (level == OptimizationLevel::Default) {
pm->add<Passes::GenerateCFG>();
pm->add<Passes::UnifySameBlocks>();
pm->add<Passes::GenerateCFG>();
pm->add<Passes::MergeBlocks>();
pm->add<Passes::GenerateCFG>();
pm->add<Passes::UnifySameBlocks>();
pm->add<Passes::GenerateCFG>();
pm->add<Passes::MergeBlocks>();
pm->add<Passes::GenerateCFG>();
pm->add<Passes::PlaceBlocks>();
} else {
VERIFY_NOT_REACHED();
}
auto& passes = *pm;
entry = move(pm);
return passes;
}
}
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