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ladybird/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
davidot 830ea0414c LibJS: Make scoping follow the spec 
Before this we used an ad-hoc combination of references and 'variables'
stored in a hashmap. This worked in most cases but is not spec like.
Additionally hoisting, dynamically naming functions and scope analysis
was not done properly.

This patch fixes all of that by:
  - Implement BindingInitialization for destructuring assignment.
  - Implementing a new ScopePusher which tracks the lexical and var
    scoped declarations. This hoists functions to the top level if no
    lexical declaration name overlaps. Furthermore we do checking of
    redeclarations in the ScopePusher now requiring less checks all over
    the place.
  - Add methods for parsing the directives and statement lists instead
    of having that code duplicated in multiple places. This allows
    declarations to pushed to the appropriate scope more easily.
  - Remove the non spec way of storing 'variables' in
    DeclarativeEnvironment and make Reference follow the spec instead of
    checking both the bindings and 'variables'.
  - Remove all scoping related things from the Interpreter. And instead
    use environments as specified by the spec. This also includes fixing
    that NativeFunctions did not produce a valid FunctionEnvironment
    which could cause issues with callbacks and eval. All
    FunctionObjects now have a valid NewFunctionEnvironment
    implementation.
  - Remove execute_statements from Interpreter and instead use
    ASTNode::execute everywhere this simplifies AST.cpp as you no longer
    need to worry about which method to call.
  - Make ScopeNodes setup their own environment. This uses four
    different methods specified by the spec
    {Block, Function, Eval, Global}DeclarationInstantiation with the
    annexB extensions.
  - Implement and use NamedEvaluation where specified.

Additionally there are fixes to things exposed by these changes to eval,
{for, for-in, for-of} loops and assignment.

Finally it also fixes some tests in test-js which where passing before
but not now that we have correct behavior :^).
2021-09-30 08:16:32 +01:00

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/*
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
* Copyright (c) 2021, Gunnar Beutner <gbeutner@serenityos.org>
* Copyright (c) 2021, Marcin Gasperowicz <xnooga@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Format.h>
#include <LibJS/AST.h>
#include <LibJS/Bytecode/Generator.h>
#include <LibJS/Bytecode/Instruction.h>
#include <LibJS/Bytecode/Op.h>
#include <LibJS/Bytecode/Register.h>
#include <LibJS/Bytecode/StringTable.h>
#include <LibJS/Runtime/Environment.h>
namespace JS {
void ASTNode::generate_bytecode(Bytecode::Generator&) const
{
dbgln("Missing generate_bytecode() in {}", class_name());
TODO();
}
void ScopeNode::generate_bytecode(Bytecode::Generator& generator) const
{
// FIXME: Register lexical and variable scope declarations
for (auto& child : children()) {
child.generate_bytecode(generator);
if (generator.is_current_block_terminated())
break;
}
}
void EmptyStatement::generate_bytecode(Bytecode::Generator&) const
{
}
void ExpressionStatement::generate_bytecode(Bytecode::Generator& generator) const
{
m_expression->generate_bytecode(generator);
}
void BinaryExpression::generate_bytecode(Bytecode::Generator& generator) const
{
m_lhs->generate_bytecode(generator);
auto lhs_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(lhs_reg);
m_rhs->generate_bytecode(generator);
switch (m_op) {
case BinaryOp::Addition:
generator.emit<Bytecode::Op::Add>(lhs_reg);
break;
case BinaryOp::Subtraction:
generator.emit<Bytecode::Op::Sub>(lhs_reg);
break;
case BinaryOp::Multiplication:
generator.emit<Bytecode::Op::Mul>(lhs_reg);
break;
case BinaryOp::Division:
generator.emit<Bytecode::Op::Div>(lhs_reg);
break;
case BinaryOp::Modulo:
generator.emit<Bytecode::Op::Mod>(lhs_reg);
break;
case BinaryOp::Exponentiation:
generator.emit<Bytecode::Op::Exp>(lhs_reg);
break;
case BinaryOp::GreaterThan:
generator.emit<Bytecode::Op::GreaterThan>(lhs_reg);
break;
case BinaryOp::GreaterThanEquals:
generator.emit<Bytecode::Op::GreaterThanEquals>(lhs_reg);
break;
case BinaryOp::LessThan:
generator.emit<Bytecode::Op::LessThan>(lhs_reg);
break;
case BinaryOp::LessThanEquals:
generator.emit<Bytecode::Op::LessThanEquals>(lhs_reg);
break;
case BinaryOp::LooselyInequals:
generator.emit<Bytecode::Op::LooselyInequals>(lhs_reg);
break;
case BinaryOp::LooselyEquals:
generator.emit<Bytecode::Op::LooselyEquals>(lhs_reg);
break;
case BinaryOp::StrictlyInequals:
generator.emit<Bytecode::Op::StrictlyInequals>(lhs_reg);
break;
case BinaryOp::StrictlyEquals:
generator.emit<Bytecode::Op::StrictlyEquals>(lhs_reg);
break;
case BinaryOp::BitwiseAnd:
generator.emit<Bytecode::Op::BitwiseAnd>(lhs_reg);
break;
case BinaryOp::BitwiseOr:
generator.emit<Bytecode::Op::BitwiseOr>(lhs_reg);
break;
case BinaryOp::BitwiseXor:
generator.emit<Bytecode::Op::BitwiseXor>(lhs_reg);
break;
case BinaryOp::LeftShift:
generator.emit<Bytecode::Op::LeftShift>(lhs_reg);
break;
case BinaryOp::RightShift:
generator.emit<Bytecode::Op::RightShift>(lhs_reg);
break;
case BinaryOp::UnsignedRightShift:
generator.emit<Bytecode::Op::UnsignedRightShift>(lhs_reg);
break;
case BinaryOp::In:
generator.emit<Bytecode::Op::In>(lhs_reg);
break;
case BinaryOp::InstanceOf:
generator.emit<Bytecode::Op::InstanceOf>(lhs_reg);
break;
default:
VERIFY_NOT_REACHED();
}
}
void LogicalExpression::generate_bytecode(Bytecode::Generator& generator) const
{
m_lhs->generate_bytecode(generator);
// lhs
// jump op (true) end (false) rhs
// rhs
// jump always (true) end
// end
auto& rhs_block = generator.make_block();
auto& end_block = generator.make_block();
switch (m_op) {
case LogicalOp::And:
generator.emit<Bytecode::Op::JumpConditional>().set_targets(
Bytecode::Label { rhs_block },
Bytecode::Label { end_block });
break;
case LogicalOp::Or:
generator.emit<Bytecode::Op::JumpConditional>().set_targets(
Bytecode::Label { end_block },
Bytecode::Label { rhs_block });
break;
case LogicalOp::NullishCoalescing:
generator.emit<Bytecode::Op::JumpNullish>().set_targets(
Bytecode::Label { rhs_block },
Bytecode::Label { end_block });
break;
default:
VERIFY_NOT_REACHED();
}
generator.switch_to_basic_block(rhs_block);
m_rhs->generate_bytecode(generator);
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { end_block },
{});
generator.switch_to_basic_block(end_block);
}
void UnaryExpression::generate_bytecode(Bytecode::Generator& generator) const
{
m_lhs->generate_bytecode(generator);
switch (m_op) {
case UnaryOp::BitwiseNot:
generator.emit<Bytecode::Op::BitwiseNot>();
break;
case UnaryOp::Not:
generator.emit<Bytecode::Op::Not>();
break;
case UnaryOp::Plus:
generator.emit<Bytecode::Op::UnaryPlus>();
break;
case UnaryOp::Minus:
generator.emit<Bytecode::Op::UnaryMinus>();
break;
case UnaryOp::Typeof:
generator.emit<Bytecode::Op::Typeof>();
break;
case UnaryOp::Void:
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
break;
default:
TODO();
}
}
void NumericLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::LoadImmediate>(m_value);
}
void BooleanLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::LoadImmediate>(Value(m_value));
}
void NullLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::LoadImmediate>(js_null());
}
void BigIntLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::NewBigInt>(Crypto::SignedBigInteger::from_base(10, m_value.substring(0, m_value.length() - 1)));
}
void StringLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::NewString>(generator.intern_string(m_value));
}
void RegExpLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
auto source_index = generator.intern_string(m_pattern);
auto flags_index = generator.intern_string(m_flags);
generator.emit<Bytecode::Op::NewRegExp>(source_index, flags_index);
}
void Identifier::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::GetVariable>(generator.intern_string(m_string));
}
void AssignmentExpression::generate_bytecode(Bytecode::Generator& generator) const
{
// FIXME: Implement this for BindingPatterns too.
auto& lhs = m_lhs.get<NonnullRefPtr<Expression>>();
if (is<Identifier>(*lhs)) {
auto& identifier = static_cast<Identifier const&>(*lhs);
if (m_op == AssignmentOp::Assignment) {
m_rhs->generate_bytecode(generator);
generator.emit<Bytecode::Op::SetVariable>(generator.intern_string(identifier.string()));
return;
}
lhs->generate_bytecode(generator);
Bytecode::BasicBlock* rhs_block_ptr { nullptr };
Bytecode::BasicBlock* end_block_ptr { nullptr };
// Logical assignments short circuit.
if (m_op == AssignmentOp::AndAssignment) { // &&=
rhs_block_ptr = &generator.make_block();
end_block_ptr = &generator.make_block();
generator.emit<Bytecode::Op::JumpConditional>().set_targets(
Bytecode::Label { *rhs_block_ptr },
Bytecode::Label { *end_block_ptr });
} else if (m_op == AssignmentOp::OrAssignment) { // ||=
rhs_block_ptr = &generator.make_block();
end_block_ptr = &generator.make_block();
generator.emit<Bytecode::Op::JumpConditional>().set_targets(
Bytecode::Label { *end_block_ptr },
Bytecode::Label { *rhs_block_ptr });
} else if (m_op == AssignmentOp::NullishAssignment) { // ??=
rhs_block_ptr = &generator.make_block();
end_block_ptr = &generator.make_block();
generator.emit<Bytecode::Op::JumpNullish>().set_targets(
Bytecode::Label { *rhs_block_ptr },
Bytecode::Label { *end_block_ptr });
}
if (rhs_block_ptr)
generator.switch_to_basic_block(*rhs_block_ptr);
// lhs_reg is a part of the rhs_block because the store isn't necessary
// if the logical assignment condition fails.
auto lhs_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(lhs_reg);
m_rhs->generate_bytecode(generator);
switch (m_op) {
case AssignmentOp::AdditionAssignment:
generator.emit<Bytecode::Op::Add>(lhs_reg);
break;
case AssignmentOp::SubtractionAssignment:
generator.emit<Bytecode::Op::Sub>(lhs_reg);
break;
case AssignmentOp::MultiplicationAssignment:
generator.emit<Bytecode::Op::Mul>(lhs_reg);
break;
case AssignmentOp::DivisionAssignment:
generator.emit<Bytecode::Op::Div>(lhs_reg);
break;
case AssignmentOp::ModuloAssignment:
generator.emit<Bytecode::Op::Mod>(lhs_reg);
break;
case AssignmentOp::ExponentiationAssignment:
generator.emit<Bytecode::Op::Exp>(lhs_reg);
break;
case AssignmentOp::BitwiseAndAssignment:
generator.emit<Bytecode::Op::BitwiseAnd>(lhs_reg);
break;
case AssignmentOp::BitwiseOrAssignment:
generator.emit<Bytecode::Op::BitwiseOr>(lhs_reg);
break;
case AssignmentOp::BitwiseXorAssignment:
generator.emit<Bytecode::Op::BitwiseXor>(lhs_reg);
break;
case AssignmentOp::LeftShiftAssignment:
generator.emit<Bytecode::Op::LeftShift>(lhs_reg);
break;
case AssignmentOp::RightShiftAssignment:
generator.emit<Bytecode::Op::RightShift>(lhs_reg);
break;
case AssignmentOp::UnsignedRightShiftAssignment:
generator.emit<Bytecode::Op::UnsignedRightShift>(lhs_reg);
break;
case AssignmentOp::AndAssignment:
case AssignmentOp::OrAssignment:
case AssignmentOp::NullishAssignment:
break; // These are handled above.
default:
TODO();
}
generator.emit<Bytecode::Op::SetVariable>(generator.intern_string(identifier.string()));
if (end_block_ptr) {
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { *end_block_ptr },
{});
generator.switch_to_basic_block(*end_block_ptr);
}
return;
}
if (is<MemberExpression>(*lhs)) {
auto& expression = static_cast<MemberExpression const&>(*lhs);
expression.object().generate_bytecode(generator);
auto object_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(object_reg);
if (expression.is_computed()) {
expression.property().generate_bytecode(generator);
auto property_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(property_reg);
m_rhs->generate_bytecode(generator);
generator.emit<Bytecode::Op::PutByValue>(object_reg, property_reg);
} else {
m_rhs->generate_bytecode(generator);
auto identifier_table_ref = generator.intern_string(verify_cast<Identifier>(expression.property()).string());
generator.emit<Bytecode::Op::PutById>(object_reg, identifier_table_ref);
}
return;
}
TODO();
}
void WhileStatement::generate_bytecode(Bytecode::Generator& generator) const
{
// test
// jump if_false (true) end (false) body
// body
// jump always (true) test
// end
auto& test_block = generator.make_block();
auto& body_block = generator.make_block();
auto& end_block = generator.make_block();
// Init result register
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
auto result_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(result_reg);
// jump to the test block
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { test_block },
{});
generator.switch_to_basic_block(test_block);
m_test->generate_bytecode(generator);
generator.emit<Bytecode::Op::JumpConditional>().set_targets(
Bytecode::Label { body_block },
Bytecode::Label { end_block });
generator.switch_to_basic_block(body_block);
generator.begin_continuable_scope(Bytecode::Label { test_block });
generator.begin_breakable_scope(Bytecode::Label { end_block });
m_body->generate_bytecode(generator);
if (!generator.is_current_block_terminated()) {
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { test_block },
{});
generator.end_continuable_scope();
generator.end_breakable_scope();
generator.switch_to_basic_block(end_block);
generator.emit<Bytecode::Op::Load>(result_reg);
}
}
void DoWhileStatement::generate_bytecode(Bytecode::Generator& generator) const
{
// jump always (true) body
// test
// jump if_false (true) end (false) body
// body
// jump always (true) test
// end
auto& test_block = generator.make_block();
auto& body_block = generator.make_block();
auto& end_block = generator.make_block();
// Init result register
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
auto result_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(result_reg);
// jump to the body block
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { body_block },
{});
generator.switch_to_basic_block(test_block);
m_test->generate_bytecode(generator);
generator.emit<Bytecode::Op::JumpConditional>().set_targets(
Bytecode::Label { body_block },
Bytecode::Label { end_block });
generator.switch_to_basic_block(body_block);
generator.begin_continuable_scope(Bytecode::Label { test_block });
generator.begin_breakable_scope(Bytecode::Label { end_block });
m_body->generate_bytecode(generator);
if (!generator.is_current_block_terminated()) {
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { test_block },
{});
generator.end_continuable_scope();
generator.end_breakable_scope();
generator.switch_to_basic_block(end_block);
generator.emit<Bytecode::Op::Load>(result_reg);
}
}
void ForStatement::generate_bytecode(Bytecode::Generator& generator) const
{
// init
// jump always (true) test
// test
// jump if_true (true) body (false) end
// body
// jump always (true) update
// update
// jump always (true) test
// end
// If 'test' is missing, fuse the 'test' and 'body' basic blocks
// If 'update' is missing, fuse the 'body' and 'update' basic blocks
Bytecode::BasicBlock* test_block_ptr { nullptr };
Bytecode::BasicBlock* body_block_ptr { nullptr };
Bytecode::BasicBlock* update_block_ptr { nullptr };
auto& end_block = generator.make_block();
if (m_init)
m_init->generate_bytecode(generator);
body_block_ptr = &generator.make_block();
if (m_test)
test_block_ptr = &generator.make_block();
else
test_block_ptr = body_block_ptr;
if (m_update)
update_block_ptr = &generator.make_block();
else
update_block_ptr = body_block_ptr;
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
auto result_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(result_reg);
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { *test_block_ptr },
{});
if (m_test) {
generator.switch_to_basic_block(*test_block_ptr);
m_test->generate_bytecode(generator);
generator.emit<Bytecode::Op::JumpConditional>().set_targets(
Bytecode::Label { *body_block_ptr },
Bytecode::Label { end_block });
}
generator.switch_to_basic_block(*body_block_ptr);
generator.begin_continuable_scope(Bytecode::Label { *update_block_ptr });
generator.begin_breakable_scope(Bytecode::Label { end_block });
m_body->generate_bytecode(generator);
generator.end_continuable_scope();
if (!generator.is_current_block_terminated()) {
if (m_update) {
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { *update_block_ptr },
{});
generator.switch_to_basic_block(*update_block_ptr);
m_update->generate_bytecode(generator);
}
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { *test_block_ptr },
{});
generator.end_breakable_scope();
generator.switch_to_basic_block(end_block);
generator.emit<Bytecode::Op::Load>(result_reg);
}
}
void ObjectExpression::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::NewObject>();
if (m_properties.is_empty())
return;
auto object_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(object_reg);
for (auto& property : m_properties) {
if (property.type() != ObjectProperty::Type::KeyValue)
TODO();
if (is<StringLiteral>(property.key())) {
auto& string_literal = static_cast<StringLiteral const&>(property.key());
Bytecode::StringTableIndex key_name = generator.intern_string(string_literal.value());
property.value().generate_bytecode(generator);
generator.emit<Bytecode::Op::PutById>(object_reg, key_name);
} else {
property.key().generate_bytecode(generator);
auto property_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(property_reg);
property.value().generate_bytecode(generator);
generator.emit<Bytecode::Op::PutByValue>(object_reg, property_reg);
}
}
generator.emit<Bytecode::Op::Load>(object_reg);
}
void ArrayExpression::generate_bytecode(Bytecode::Generator& generator) const
{
Vector<Bytecode::Register> element_regs;
for (auto& element : m_elements) {
if (element) {
element->generate_bytecode(generator);
if (is<SpreadExpression>(*element)) {
TODO();
continue;
}
} else {
generator.emit<Bytecode::Op::LoadImmediate>(Value {});
}
auto element_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(element_reg);
element_regs.append(element_reg);
}
generator.emit_with_extra_register_slots<Bytecode::Op::NewArray>(element_regs.size(), element_regs);
}
void MemberExpression::generate_bytecode(Bytecode::Generator& generator) const
{
object().generate_bytecode(generator);
if (is_computed()) {
auto object_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(object_reg);
property().generate_bytecode(generator);
generator.emit<Bytecode::Op::GetByValue>(object_reg);
} else {
auto identifier_table_ref = generator.intern_string(verify_cast<Identifier>(property()).string());
generator.emit<Bytecode::Op::GetById>(identifier_table_ref);
}
}
void FunctionDeclaration::generate_bytecode(Bytecode::Generator&) const
{
}
void FunctionExpression::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::NewFunction>(*this);
}
static void generate_binding_pattern_bytecode(Bytecode::Generator& generator, BindingPattern const& pattern, Bytecode::Register const& value_reg);
static void generate_object_binding_pattern_bytecode(Bytecode::Generator& generator, BindingPattern const& pattern, Bytecode::Register const& value_reg)
{
Vector<Bytecode::Register> excluded_property_names;
auto has_rest = false;
if (pattern.entries.size() > 0)
has_rest = pattern.entries[pattern.entries.size() - 1].is_rest;
for (auto& [name, alias, initializer, is_rest] : pattern.entries) {
if (is_rest) {
VERIFY(name.has<NonnullRefPtr<Identifier>>());
VERIFY(alias.has<Empty>());
VERIFY(!initializer);
auto identifier = name.get<NonnullRefPtr<Identifier>>()->string();
auto interned_identifier = generator.intern_string(identifier);
generator.emit_with_extra_register_slots<Bytecode::Op::CopyObjectExcludingProperties>(excluded_property_names.size(), value_reg, excluded_property_names);
generator.emit<Bytecode::Op::SetVariable>(interned_identifier);
return;
}
Bytecode::StringTableIndex name_index;
if (name.has<NonnullRefPtr<Identifier>>()) {
auto identifier = name.get<NonnullRefPtr<Identifier>>()->string();
name_index = generator.intern_string(identifier);
if (has_rest) {
auto excluded_name_reg = generator.allocate_register();
excluded_property_names.append(excluded_name_reg);
generator.emit<Bytecode::Op::NewString>(name_index);
generator.emit<Bytecode::Op::Store>(excluded_name_reg);
}
generator.emit<Bytecode::Op::Load>(value_reg);
generator.emit<Bytecode::Op::GetById>(name_index);
} else {
auto expression = name.get<NonnullRefPtr<Expression>>();
expression->generate_bytecode(generator);
if (has_rest) {
auto excluded_name_reg = generator.allocate_register();
excluded_property_names.append(excluded_name_reg);
generator.emit<Bytecode::Op::Store>(excluded_name_reg);
}
generator.emit<Bytecode::Op::GetByValue>(value_reg);
}
if (initializer) {
auto& if_undefined_block = generator.make_block();
auto& if_not_undefined_block = generator.make_block();
generator.emit<Bytecode::Op::JumpUndefined>().set_targets(
Bytecode::Label { if_undefined_block },
Bytecode::Label { if_not_undefined_block });
generator.switch_to_basic_block(if_undefined_block);
initializer->generate_bytecode(generator);
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { if_not_undefined_block },
{});
generator.switch_to_basic_block(if_not_undefined_block);
}
if (alias.has<NonnullRefPtr<BindingPattern>>()) {
auto& binding_pattern = *alias.get<NonnullRefPtr<BindingPattern>>();
auto nested_value_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(nested_value_reg);
generate_binding_pattern_bytecode(generator, binding_pattern, nested_value_reg);
} else if (alias.has<Empty>()) {
if (name.has<NonnullRefPtr<Expression>>()) {
// This needs some sort of SetVariableByValue opcode, as it's a runtime binding
TODO();
}
generator.emit<Bytecode::Op::SetVariable>(name_index);
} else {
auto& identifier = alias.get<NonnullRefPtr<Identifier>>()->string();
generator.emit<Bytecode::Op::SetVariable>(generator.intern_string(identifier));
}
}
}
static void generate_array_binding_pattern_bytecode(Bytecode::Generator& generator, BindingPattern const& pattern, Bytecode::Register const& value_reg)
{
/*
* Consider the following destructuring assignment:
*
* let [a, b, c, d, e] = o;
*
* It would be fairly trivial to just loop through this iterator, getting the value
* at each step and assigning them to the binding sequentially. However, this is not
* correct: once an iterator is exhausted, it must not be called again. This complicates
* the bytecode. In order to accomplish this, we do the following:
*
* - Reserve a special boolean register which holds 'true' if the iterator is exhausted,
* and false otherwise
* - When we are retrieving the value which should be bound, we first check this register.
* If it is 'true', we load undefined into the accumulator. Otherwise, we grab the next
* value from the iterator and store it into the accumulator.
*
* Note that the is_exhausted register does not need to be loaded with false because the
* first IteratorNext bytecode is _not_ proceeded by an exhausted check, as it is
* unnecessary.
*/
auto is_iterator_exhausted_register = generator.allocate_register();
auto iterator_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Load>(value_reg);
generator.emit<Bytecode::Op::GetIterator>();
generator.emit<Bytecode::Op::Store>(iterator_reg);
bool first = true;
auto temp_iterator_result_reg = generator.allocate_register();
auto assign_accumulator_to_alias = [&](auto& alias) {
alias.visit(
[&](Empty) {
// This element is an elision
},
[&](NonnullRefPtr<Identifier> const& identifier) {
auto interned_index = generator.intern_string(identifier->string());
generator.emit<Bytecode::Op::SetVariable>(interned_index);
},
[&](NonnullRefPtr<BindingPattern> const& pattern) {
// Store the accumulator value in a permanent register
auto target_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(target_reg);
generate_binding_pattern_bytecode(generator, pattern, target_reg);
},
[&](NonnullRefPtr<MemberExpression> const&) {
TODO();
});
};
for (auto& [name, alias, initializer, is_rest] : pattern.entries) {
VERIFY(name.has<Empty>());
if (is_rest) {
if (first) {
// The iterator has not been called, and is thus known to be not exhausted
generator.emit<Bytecode::Op::Load>(iterator_reg);
generator.emit<Bytecode::Op::IteratorToArray>();
} else {
auto& if_exhausted_block = generator.make_block();
auto& if_not_exhausted_block = generator.make_block();
auto& continuation_block = generator.make_block();
generator.emit<Bytecode::Op::Load>(is_iterator_exhausted_register);
generator.emit<Bytecode::Op::JumpConditional>().set_targets(
Bytecode::Label { if_exhausted_block },
Bytecode::Label { if_not_exhausted_block });
generator.switch_to_basic_block(if_exhausted_block);
generator.emit<Bytecode::Op::NewArray>();
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { continuation_block },
{});
generator.switch_to_basic_block(if_not_exhausted_block);
generator.emit<Bytecode::Op::Load>(iterator_reg);
generator.emit<Bytecode::Op::IteratorToArray>();
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { continuation_block },
{});
generator.switch_to_basic_block(continuation_block);
}
assign_accumulator_to_alias(alias);
return;
}
// In the first iteration of the loop, a few things are true which can save
// us some bytecode:
// - the iterator result is still in the accumulator, so we can avoid a load
// - the iterator is not yet exhausted, which can save us a jump and some
// creation
auto& iterator_is_exhausted_block = generator.make_block();
if (!first) {
auto& iterator_is_not_exhausted_block = generator.make_block();
generator.emit<Bytecode::Op::Load>(is_iterator_exhausted_register);
generator.emit<Bytecode::Op::JumpConditional>().set_targets(
Bytecode::Label { iterator_is_exhausted_block },
Bytecode::Label { iterator_is_not_exhausted_block });
generator.switch_to_basic_block(iterator_is_not_exhausted_block);
generator.emit<Bytecode::Op::Load>(iterator_reg);
}
generator.emit<Bytecode::Op::IteratorNext>();
generator.emit<Bytecode::Op::Store>(temp_iterator_result_reg);
generator.emit<Bytecode::Op::IteratorResultDone>();
generator.emit<Bytecode::Op::Store>(is_iterator_exhausted_register);
// We still have to check for exhaustion here. If the iterator is exhausted,
// we need to bail before trying to get the value
auto& no_bail_block = generator.make_block();
generator.emit<Bytecode::Op::JumpConditional>().set_targets(
Bytecode::Label { iterator_is_exhausted_block },
Bytecode::Label { no_bail_block });
generator.switch_to_basic_block(no_bail_block);
// Get the next value in the iterator
generator.emit<Bytecode::Op::Load>(temp_iterator_result_reg);
generator.emit<Bytecode::Op::IteratorResultValue>();
auto& create_binding_block = generator.make_block();
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { create_binding_block },
{});
// The iterator is exhausted, so we just load undefined and continue binding
generator.switch_to_basic_block(iterator_is_exhausted_block);
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { create_binding_block },
{});
// Create the actual binding. The value which this entry must bind is now in the
// accumulator. We can proceed, processing the alias as a nested destructuring
// pattern if necessary.
generator.switch_to_basic_block(create_binding_block);
assign_accumulator_to_alias(alias);
first = false;
}
}
static void generate_binding_pattern_bytecode(Bytecode::Generator& generator, BindingPattern const& pattern, Bytecode::Register const& value_reg)
{
if (pattern.kind == BindingPattern::Kind::Object) {
generate_object_binding_pattern_bytecode(generator, pattern, value_reg);
} else {
generate_array_binding_pattern_bytecode(generator, pattern, value_reg);
}
};
void VariableDeclaration::generate_bytecode(Bytecode::Generator& generator) const
{
for (auto& declarator : m_declarations) {
if (declarator.init())
declarator.init()->generate_bytecode(generator);
else
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
declarator.target().visit(
[&](NonnullRefPtr<Identifier> const& id) {
generator.emit<Bytecode::Op::SetVariable>(generator.intern_string(id->string()));
},
[&](NonnullRefPtr<BindingPattern> const& pattern) {
auto value_register = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(value_register);
generate_binding_pattern_bytecode(generator, pattern, value_register);
});
}
}
void CallExpression::generate_bytecode(Bytecode::Generator& generator) const
{
auto callee_reg = generator.allocate_register();
auto this_reg = generator.allocate_register();
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
generator.emit<Bytecode::Op::Store>(this_reg);
if (is<NewExpression>(this)) {
m_callee->generate_bytecode(generator);
generator.emit<Bytecode::Op::Store>(callee_reg);
} else if (is<SuperExpression>(*m_callee)) {
TODO();
} else if (is<MemberExpression>(*m_callee)) {
auto& member_expression = static_cast<const MemberExpression&>(*m_callee);
if (is<SuperExpression>(member_expression.object())) {
TODO();
} else {
member_expression.object().generate_bytecode(generator);
generator.emit<Bytecode::Op::Store>(this_reg);
// FIXME: Don't copy this logic here, make MemberExpression generate it.
if (!is<Identifier>(member_expression.property()))
TODO();
auto identifier_table_ref = generator.intern_string(static_cast<Identifier const&>(member_expression.property()).string());
generator.emit<Bytecode::Op::GetById>(identifier_table_ref);
generator.emit<Bytecode::Op::Store>(callee_reg);
}
} else {
// FIXME: this = global object in sloppy mode.
m_callee->generate_bytecode(generator);
generator.emit<Bytecode::Op::Store>(callee_reg);
}
Vector<Bytecode::Register> argument_registers;
for (auto& arg : m_arguments) {
arg.value->generate_bytecode(generator);
auto arg_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(arg_reg);
argument_registers.append(arg_reg);
}
Bytecode::Op::Call::CallType call_type;
if (is<NewExpression>(*this)) {
call_type = Bytecode::Op::Call::CallType::Construct;
} else {
call_type = Bytecode::Op::Call::CallType::Call;
}
generator.emit_with_extra_register_slots<Bytecode::Op::Call>(argument_registers.size(), call_type, callee_reg, this_reg, argument_registers);
}
void ReturnStatement::generate_bytecode(Bytecode::Generator& generator) const
{
if (m_argument)
m_argument->generate_bytecode(generator);
if (generator.is_in_generator_function())
generator.emit<Bytecode::Op::Yield>(nullptr);
else
generator.emit<Bytecode::Op::Return>();
}
void YieldExpression::generate_bytecode(Bytecode::Generator& generator) const
{
VERIFY(generator.is_in_generator_function());
if (m_is_yield_from)
TODO();
if (m_argument)
m_argument->generate_bytecode(generator);
auto& continuation_block = generator.make_block();
generator.emit<Bytecode::Op::Yield>(Bytecode::Label { continuation_block });
generator.switch_to_basic_block(continuation_block);
}
void IfStatement::generate_bytecode(Bytecode::Generator& generator) const
{
// test
// jump if_true (true) true (false) false
// true
// jump always (true) end
// false
// jump always (true) end
// end
auto& true_block = generator.make_block();
auto& false_block = generator.make_block();
m_predicate->generate_bytecode(generator);
generator.emit<Bytecode::Op::JumpConditional>().set_targets(
Bytecode::Label { true_block },
Bytecode::Label { false_block });
Bytecode::Op::Jump* true_block_jump { nullptr };
generator.switch_to_basic_block(true_block);
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
m_consequent->generate_bytecode(generator);
if (!generator.is_current_block_terminated())
true_block_jump = &generator.emit<Bytecode::Op::Jump>();
generator.switch_to_basic_block(false_block);
auto& end_block = generator.make_block();
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
if (m_alternate)
m_alternate->generate_bytecode(generator);
if (!generator.is_current_block_terminated())
generator.emit<Bytecode::Op::Jump>().set_targets(Bytecode::Label { end_block }, {});
if (true_block_jump)
true_block_jump->set_targets(Bytecode::Label { end_block }, {});
generator.switch_to_basic_block(end_block);
}
void ContinueStatement::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::Jump>().set_targets(
generator.nearest_continuable_scope(),
{});
}
void DebuggerStatement::generate_bytecode(Bytecode::Generator&) const
{
}
void ConditionalExpression::generate_bytecode(Bytecode::Generator& generator) const
{
// test
// jump if_true (true) true (false) false
// true
// jump always (true) end
// false
// jump always (true) end
// end
auto& true_block = generator.make_block();
auto& false_block = generator.make_block();
auto& end_block = generator.make_block();
m_test->generate_bytecode(generator);
generator.emit<Bytecode::Op::JumpConditional>().set_targets(
Bytecode::Label { true_block },
Bytecode::Label { false_block });
generator.switch_to_basic_block(true_block);
m_consequent->generate_bytecode(generator);
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { end_block },
{});
generator.switch_to_basic_block(false_block);
m_alternate->generate_bytecode(generator);
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { end_block },
{});
generator.switch_to_basic_block(end_block);
}
void SequenceExpression::generate_bytecode(Bytecode::Generator& generator) const
{
for (auto& expression : m_expressions)
expression.generate_bytecode(generator);
}
void TemplateLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
auto string_reg = generator.allocate_register();
for (size_t i = 0; i < m_expressions.size(); i++) {
m_expressions[i].generate_bytecode(generator);
if (i == 0) {
generator.emit<Bytecode::Op::Store>(string_reg);
} else {
generator.emit<Bytecode::Op::ConcatString>(string_reg);
}
}
generator.emit<Bytecode::Op::Load>(string_reg);
}
void TaggedTemplateLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
m_tag->generate_bytecode(generator);
auto tag_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(tag_reg);
Vector<Bytecode::Register> string_regs;
auto& expressions = m_template_literal->expressions();
for (size_t i = 0; i < expressions.size(); ++i) {
if (i % 2 != 0)
continue;
expressions[i].generate_bytecode(generator);
auto string_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(string_reg);
string_regs.append(string_reg);
}
generator.emit_with_extra_register_slots<Bytecode::Op::NewArray>(string_regs.size(), string_regs);
auto strings_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(strings_reg);
Vector<Bytecode::Register> argument_regs;
argument_regs.append(strings_reg);
for (size_t i = 0; i < expressions.size(); ++i) {
if (i % 2 == 0)
continue;
expressions[i].generate_bytecode(generator);
auto string_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(string_reg);
argument_regs.append(string_reg);
}
Vector<Bytecode::Register> raw_string_regs;
for (auto& raw_string : m_template_literal->raw_strings()) {
raw_string.generate_bytecode(generator);
auto raw_string_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(raw_string_reg);
raw_string_regs.append(raw_string_reg);
}
generator.emit_with_extra_register_slots<Bytecode::Op::NewArray>(raw_string_regs.size(), raw_string_regs);
auto raw_strings_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(raw_strings_reg);
generator.emit<Bytecode::Op::Load>(strings_reg);
generator.emit<Bytecode::Op::PutById>(raw_strings_reg, generator.intern_string("raw"));
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
auto this_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(this_reg);
generator.emit_with_extra_register_slots<Bytecode::Op::Call>(argument_regs.size(), Bytecode::Op::Call::CallType::Call, tag_reg, this_reg, move(argument_regs));
}
void UpdateExpression::generate_bytecode(Bytecode::Generator& generator) const
{
if (is<Identifier>(*m_argument)) {
auto& identifier = static_cast<Identifier const&>(*m_argument);
generator.emit<Bytecode::Op::GetVariable>(generator.intern_string(identifier.string()));
Optional<Bytecode::Register> previous_value_for_postfix_reg;
if (!m_prefixed) {
previous_value_for_postfix_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(*previous_value_for_postfix_reg);
}
if (m_op == UpdateOp::Increment)
generator.emit<Bytecode::Op::Increment>();
else
generator.emit<Bytecode::Op::Decrement>();
generator.emit<Bytecode::Op::SetVariable>(generator.intern_string(identifier.string()));
if (!m_prefixed)
generator.emit<Bytecode::Op::Load>(*previous_value_for_postfix_reg);
return;
}
TODO();
}
void ThrowStatement::generate_bytecode(Bytecode::Generator& generator) const
{
m_argument->generate_bytecode(generator);
generator.emit<Bytecode::Op::Throw>();
}
void BreakStatement::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::Jump>().set_targets(
generator.nearest_breakable_scope(),
{});
}
void TryStatement::generate_bytecode(Bytecode::Generator& generator) const
{
auto& saved_block = generator.current_block();
Optional<Bytecode::Label> handler_target;
Optional<Bytecode::Label> finalizer_target;
Bytecode::BasicBlock* next_block { nullptr };
if (m_finalizer) {
auto& finalizer_block = generator.make_block();
generator.switch_to_basic_block(finalizer_block);
m_finalizer->generate_bytecode(generator);
if (!generator.is_current_block_terminated()) {
next_block = &generator.make_block();
auto next_target = Bytecode::Label { *next_block };
generator.emit<Bytecode::Op::ContinuePendingUnwind>(next_target);
}
finalizer_target = Bytecode::Label { finalizer_block };
}
if (m_handler) {
auto& handler_block = generator.make_block();
generator.switch_to_basic_block(handler_block);
if (!m_finalizer)
generator.emit<Bytecode::Op::LeaveUnwindContext>();
m_handler->parameter().visit(
[&](FlyString const& parameter) {
if (parameter.is_empty()) {
// FIXME: We need a separate DeclarativeEnvironment here
generator.emit<Bytecode::Op::SetVariable>(generator.intern_string(parameter));
}
},
[&](NonnullRefPtr<BindingPattern> const&) {
// FIXME: Implement this path when the above DeclrativeEnvironment issue is dealt with.
TODO();
});
m_handler->body().generate_bytecode(generator);
handler_target = Bytecode::Label { handler_block };
if (!generator.is_current_block_terminated()) {
if (m_finalizer) {
generator.emit<Bytecode::Op::LeaveUnwindContext>();
generator.emit<Bytecode::Op::Jump>(finalizer_target);
} else {
VERIFY(!next_block);
next_block = &generator.make_block();
auto next_target = Bytecode::Label { *next_block };
generator.emit<Bytecode::Op::Jump>(next_target);
}
}
}
auto& target_block = generator.make_block();
generator.switch_to_basic_block(saved_block);
generator.emit<Bytecode::Op::EnterUnwindContext>(Bytecode::Label { target_block }, handler_target, finalizer_target);
generator.switch_to_basic_block(target_block);
m_block->generate_bytecode(generator);
if (m_finalizer && !generator.is_current_block_terminated())
generator.emit<Bytecode::Op::Jump>(finalizer_target);
generator.switch_to_basic_block(next_block ? *next_block : saved_block);
}
void SwitchStatement::generate_bytecode(Bytecode::Generator& generator) const
{
auto discriminant_reg = generator.allocate_register();
m_discriminant->generate_bytecode(generator);
generator.emit<Bytecode::Op::Store>(discriminant_reg);
Vector<Bytecode::BasicBlock&> case_blocks;
Bytecode::BasicBlock* default_block { nullptr };
Bytecode::BasicBlock* next_test_block = &generator.make_block();
generator.emit<Bytecode::Op::Jump>().set_targets(Bytecode::Label { *next_test_block }, {});
for (auto& switch_case : m_cases) {
auto& case_block = generator.make_block();
if (switch_case.test()) {
generator.switch_to_basic_block(*next_test_block);
switch_case.test()->generate_bytecode(generator);
generator.emit<Bytecode::Op::StrictlyEquals>(discriminant_reg);
next_test_block = &generator.make_block();
generator.emit<Bytecode::Op::JumpConditional>().set_targets(Bytecode::Label { case_block }, Bytecode::Label { *next_test_block });
} else {
default_block = &case_block;
}
case_blocks.append(case_block);
}
generator.switch_to_basic_block(*next_test_block);
auto& end_block = generator.make_block();
if (default_block != nullptr) {
generator.emit<Bytecode::Op::Jump>().set_targets(Bytecode::Label { *default_block }, {});
} else {
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
generator.emit<Bytecode::Op::Jump>().set_targets(Bytecode::Label { end_block }, {});
}
auto current_block = case_blocks.begin();
generator.begin_breakable_scope(Bytecode::Label { end_block });
for (auto& switch_case : m_cases) {
generator.switch_to_basic_block(*current_block);
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
for (auto& statement : switch_case.children()) {
statement.generate_bytecode(generator);
}
if (!generator.is_current_block_terminated()) {
auto next_block = current_block;
next_block++;
if (next_block.is_end()) {
generator.emit<Bytecode::Op::Jump>().set_targets(Bytecode::Label { end_block }, {});
} else {
generator.emit<Bytecode::Op::Jump>().set_targets(Bytecode::Label { *next_block }, {});
}
}
current_block++;
}
generator.end_breakable_scope();
generator.switch_to_basic_block(end_block);
}
void ClassDeclaration::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::NewClass>(m_class_expression);
generator.emit<Bytecode::Op::SetVariable>(generator.intern_string(m_class_expression.ptr()->name()));
}
}
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