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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/Runtime/GlobalObject.h>
namespace JS::Bytecode {
static Interpreter* s_current;
Interpreter* Interpreter::current()
{
return s_current;
}
Interpreter::Interpreter(GlobalObject& global_object)
: m_vm(global_object.vm())
, m_global_object(global_object)
{
VERIFY(!s_current);
s_current = this;
}
Interpreter::~Interpreter()
{
VERIFY(s_current == this);
s_current = nullptr;
}
Value Interpreter::run(Executable const& executable, BasicBlock const* entry_point)
{
dbgln_if(JS_BYTECODE_DEBUG, "Bytecode::Interpreter will run unit {:p}", &executable);
TemporaryChange restore_executable { m_current_executable, &executable };
vm().set_last_value(Badge<Interpreter> {}, {});
CallFrame global_call_frame;
if (vm().call_stack().is_empty()) {
global_call_frame.this_value = &global_object();
static FlyString global_execution_context_name = "(*BC* global execution context)";
global_call_frame.function_name = global_execution_context_name;
global_call_frame.scope = &global_object();
VERIFY(!vm().exception());
// FIXME: How do we know if we're in strict mode? Maybe the Bytecode::Block should know this?
// global_call_frame.is_strict_mode = ???;
vm().push_call_frame(global_call_frame, global_object());
VERIFY(!vm().exception());
}
auto block = entry_point ?: &executable.basic_blocks.first();
if (m_manually_entered_frames) {
VERIFY(registers().size() >= executable.number_of_registers);
} else {
m_register_windows.append(make<RegisterWindow>());
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;
instruction.execute(*this);
if (vm().exception()) {
m_saved_exception = {};
if (m_unwind_contexts.is_empty())
break;
auto& unwind_context = m_unwind_contexts.last();
if (unwind_context.handler) {
block = unwind_context.handler;
unwind_context.handler = nullptr;
accumulator() = vm().exception()->value();
vm().clear_exception();
will_jump = true;
} else if (unwind_context.finalizer) {
block = unwind_context.finalizer;
m_unwind_contexts.take_last();
will_jump = true;
m_saved_exception = Handle<Exception>::create(vm().exception());
vm().clear_exception();
}
}
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 (vm().exception())
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);
}
}
vm().set_last_value(Badge<Interpreter> {}, accumulator());
if (!m_manually_entered_frames)
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())
m_register_windows.last()[0] = return_value;
if (vm().call_stack().size() == 1)
vm().pop_call_frame();
vm().finish_execution_generation();
return return_value;
}
void Interpreter::enter_unwind_context(Optional<Label> handler_target, Optional<Label> finalizer_target)
{
m_unwind_contexts.empend(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();
}
void Interpreter::continue_pending_unwind(Label const& resume_label)
{
if (!m_saved_exception.is_null()) {
vm().set_exception(*m_saved_exception.cell());
m_saved_exception = {};
} else {
jump(resume_label);
}
}
}
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