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ladybird/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
Luke Wilde 5bc3371226 LibJS: Perform received abrupt generator completions in the generator 
Previously, throw and return completions would not be executed inside
the generator. This is incorrect, as throw and return need to perform
unwinds which can potentially execute more code inside the generator,
such as finally blocks.

This is done by also passing the completion type alongside the passed
in value. The continuation block will immediately extract and type and
value and perform the appropriate operation for the given type.

For normal completions, this is continuing as normal.
For throw completions, it will perform `throw <value>`.
For return completions, it will perform `return <value>`, which is a
`Yield return` in this case due to being inside a generator.

This also refactors GeneratorObject to properly send across the
completion type and value to the generator inside of trying to operate
on the completions itself.

This is a prerequisite for yield*, as it performs special iterator
operations when receiving a throw/return completion and does not
complete the generator like the regular yield would.

There's still more work to be done to make GeneratorObject::execute
be closer to the spec. It's mostly a restructuring of the existing
GeneratorObject::next_impl.
2022-11-26 12:55:59 +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/Find.h>
#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 {
Bytecode::CodeGenerationErrorOr<void> ASTNode::generate_bytecode(Bytecode::Generator&) const
{
return Bytecode::CodeGenerationError {
this,
"Missing generate_bytecode()"sv,
};
}
Bytecode::CodeGenerationErrorOr<void> ScopeNode::generate_bytecode(Bytecode::Generator& generator) const
{
Optional<Bytecode::CodeGenerationError> maybe_error;
size_t pushed_scope_count = 0;
auto const failing_completion = Completion(Completion::Type::Throw, {}, {});
// Note: SwitchStatement has its own codegen, but still calls into this function to handle the scoping of the switch body.
auto is_switch_statement = is<SwitchStatement>(*this);
if (is<BlockStatement>(*this) || is_switch_statement) {
// Perform the steps of BlockDeclarationInstantiation.
if (has_lexical_declarations()) {
generator.begin_variable_scope(Bytecode::Generator::BindingMode::Lexical, Bytecode::Generator::SurroundingScopeKind::Block);
pushed_scope_count++;
}
(void)for_each_lexically_scoped_declaration([&](Declaration const& declaration) -> ThrowCompletionOr<void> {
auto is_constant_declaration = declaration.is_constant_declaration();
declaration.for_each_bound_name([&](auto const& name) {
auto index = generator.intern_identifier(name);
// NOTE: BlockDeclarationInstantiation takes as input the new lexical environment that was created and checks if there is a binding for the current name only in this new scope.
// For example: `{ let a = 1; { let a = 2; } }`. The second `a` will shadow the first `a` instead of re-initializing or setting it.
if (is_constant_declaration || !generator.has_binding_in_current_scope(index)) {
generator.register_binding(index);
generator.emit<Bytecode::Op::CreateVariable>(index, Bytecode::Op::EnvironmentMode::Lexical, is_constant_declaration);
}
});
if (is<FunctionDeclaration>(declaration)) {
auto& function_declaration = static_cast<FunctionDeclaration const&>(declaration);
auto const& name = function_declaration.name();
auto index = generator.intern_identifier(name);
generator.emit<Bytecode::Op::NewFunction>(function_declaration);
generator.emit<Bytecode::Op::SetVariable>(index, Bytecode::Op::SetVariable::InitializationMode::InitializeOrSet);
}
return {};
});
if (is_switch_statement)
return {};
} else if (is<Program>(*this)) {
// Perform the steps of GlobalDeclarationInstantiation.
generator.begin_variable_scope(Bytecode::Generator::BindingMode::Global, Bytecode::Generator::SurroundingScopeKind::Global);
pushed_scope_count++;
// 1. Let lexNames be the LexicallyDeclaredNames of script.
// 2. Let varNames be the VarDeclaredNames of script.
// 3. For each element name of lexNames, do
(void)for_each_lexically_declared_name([&](auto const& name) -> ThrowCompletionOr<void> {
auto identifier = generator.intern_identifier(name);
// a. If env.HasVarDeclaration(name) is true, throw a SyntaxError exception.
// b. If env.HasLexicalDeclaration(name) is true, throw a SyntaxError exception.
if (generator.has_binding(identifier)) {
// FIXME: Throw an actual SyntaxError instance.
generator.emit<Bytecode::Op::NewString>(generator.intern_string(String::formatted("SyntaxError: toplevel variable already declared: {}", name)));
generator.emit<Bytecode::Op::Throw>();
return {};
}
// FIXME: c. If hasRestrictedGlobalProperty is true, throw a SyntaxError exception.
// d. If hasRestrictedGlobal is true, throw a SyntaxError exception.
return {};
});
// 4. For each element name of varNames, do
(void)for_each_var_declared_name([&](auto const& name) -> ThrowCompletionOr<void> {
auto identifier = generator.intern_identifier(name);
// a. If env.HasLexicalDeclaration(name) is true, throw a SyntaxError exception.
if (generator.has_binding(identifier)) {
// FIXME: Throw an actual SyntaxError instance.
generator.emit<Bytecode::Op::NewString>(generator.intern_string(String::formatted("SyntaxError: toplevel variable already declared: {}", name)));
generator.emit<Bytecode::Op::Throw>();
}
return {};
});
// 5. Let varDeclarations be the VarScopedDeclarations of script.
// 6. Let functionsToInitialize be a new empty List.
Vector<FunctionDeclaration const&> functions_to_initialize;
// 7. Let declaredFunctionNames be a new empty List.
HashTable<FlyString> declared_function_names;
// 8. For each element d of varDeclarations, in reverse List order, do
(void)for_each_var_function_declaration_in_reverse_order([&](FunctionDeclaration const& function) -> ThrowCompletionOr<void> {
// a. If d is neither a VariableDeclaration nor a ForBinding nor a BindingIdentifier, then
// i. Assert: d is either a FunctionDeclaration, a GeneratorDeclaration, an AsyncFunctionDeclaration, or an AsyncGeneratorDeclaration.
// Note: This is checked in for_each_var_function_declaration_in_reverse_order.
// ii. NOTE: If there are multiple function declarations for the same name, the last declaration is used.
// iii. Let fn be the sole element of the BoundNames of d.
// iv. If fn is not an element of declaredFunctionNames, then
if (declared_function_names.set(function.name()) != AK::HashSetResult::InsertedNewEntry)
return {};
// FIXME: 1. Let fnDefinable be ? env.CanDeclareGlobalFunction(fn).
// FIXME: 2. If fnDefinable is false, throw a TypeError exception.
// 3. Append fn to declaredFunctionNames.
// Note: Already done in step iv. above.
// 4. Insert d as the first element of functionsToInitialize.
functions_to_initialize.prepend(function);
return {};
});
// 9. Let declaredVarNames be a new empty List.
HashTable<FlyString> declared_var_names;
// 10. For each element d of varDeclarations, do
(void)for_each_var_scoped_variable_declaration([&](Declaration const& declaration) {
// a. If d is a VariableDeclaration, a ForBinding, or a BindingIdentifier, then
// Note: This is done in for_each_var_scoped_variable_declaration.
// i. For each String vn of the BoundNames of d, do
return declaration.for_each_bound_name([&](auto const& name) -> ThrowCompletionOr<void> {
// 1. If vn is not an element of declaredFunctionNames, then
if (declared_function_names.contains(name))
return {};
// FIXME: a. Let vnDefinable be ? env.CanDeclareGlobalVar(vn).
// FIXME: b. If vnDefinable is false, throw a TypeError exception.
// c. If vn is not an element of declaredVarNames, then
// i. Append vn to declaredVarNames.
declared_var_names.set(name);
return {};
});
});
// 11. NOTE: No abnormal terminations occur after this algorithm step if the global object is an ordinary object. However, if the global object is a Proxy exotic object it may exhibit behaviours that cause abnormal terminations in some of the following steps.
// 12. NOTE: Annex B.3.2.2 adds additional steps at this point.
// 12. Let strict be IsStrict of script.
// 13. If strict is false, then
if (!verify_cast<Program>(*this).is_strict_mode()) {
// a. Let declaredFunctionOrVarNames be the list-concatenation of declaredFunctionNames and declaredVarNames.
// b. For each FunctionDeclaration f that is directly contained in the StatementList of a Block, CaseClause, or DefaultClause Contained within script, do
(void)for_each_function_hoistable_with_annexB_extension([&](FunctionDeclaration& function_declaration) {
// i. Let F be StringValue of the BindingIdentifier of f.
auto& function_name = function_declaration.name();
// ii. If replacing the FunctionDeclaration f with a VariableStatement that has F as a BindingIdentifier would not produce any Early Errors for script, then
// Note: This step is already performed during parsing and for_each_function_hoistable_with_annexB_extension so this always passes here.
// 1. If env.HasLexicalDeclaration(F) is false, then
auto index = generator.intern_identifier(function_name);
if (generator.has_binding(index, Bytecode::Generator::BindingMode::Lexical))
return;
// FIXME: a. Let fnDefinable be ? env.CanDeclareGlobalVar(F).
// b. If fnDefinable is true, then
// i. NOTE: A var binding for F is only instantiated here if it is neither a VarDeclaredName nor the name of another FunctionDeclaration.
// ii. If declaredFunctionOrVarNames does not contain F, then
if (!declared_function_names.contains(function_name) && !declared_var_names.contains(function_name)) {
// i. Perform ? env.CreateGlobalVarBinding(F, false).
generator.emit<Bytecode::Op::CreateVariable>(index, Bytecode::Op::EnvironmentMode::Var, false, true);
// ii. Append F to declaredFunctionOrVarNames.
declared_function_names.set(function_name);
}
// iii. When the FunctionDeclaration f is evaluated, perform the following steps in place of the FunctionDeclaration Evaluation algorithm provided in 15.2.6:
// i. Let genv be the running execution context's VariableEnvironment.
// ii. Let benv be the running execution context's LexicalEnvironment.
// iii. Let fobj be ! benv.GetBindingValue(F, false).
// iv. Perform ? genv.SetMutableBinding(F, fobj, false).
// v. Return unused.
function_declaration.set_should_do_additional_annexB_steps();
});
}
// 15. For each element d of lexDeclarations, do
(void)for_each_lexically_scoped_declaration([&](Declaration const& declaration) -> ThrowCompletionOr<void> {
// a. NOTE: Lexically declared names are only instantiated here but not initialized.
// b. For each element dn of the BoundNames of d, do
return declaration.for_each_bound_name([&](auto const& name) -> ThrowCompletionOr<void> {
auto identifier = generator.intern_identifier(name);
// i. If IsConstantDeclaration of d is true, then
generator.register_binding(identifier);
if (declaration.is_constant_declaration()) {
// 1. Perform ? env.CreateImmutableBinding(dn, true).
generator.emit<Bytecode::Op::CreateVariable>(identifier, Bytecode::Op::EnvironmentMode::Lexical, true);
} else {
// ii. Else,
// 1. Perform ? env.CreateMutableBinding(dn, false).
generator.emit<Bytecode::Op::CreateVariable>(identifier, Bytecode::Op::EnvironmentMode::Lexical, false);
}
return {};
});
});
// 16. For each Parse Node f of functionsToInitialize, do
for (auto& function_declaration : functions_to_initialize) {
// FIXME: Do this more correctly.
// a. Let fn be the sole element of the BoundNames of f.
// b. Let fo be InstantiateFunctionObject of f with arguments env and privateEnv.
generator.emit<Bytecode::Op::NewFunction>(function_declaration);
// c. Perform ? env.CreateGlobalFunctionBinding(fn, fo, false).
auto const& name = function_declaration.name();
auto index = generator.intern_identifier(name);
if (!generator.has_binding(index)) {
generator.register_binding(index, Bytecode::Generator::BindingMode::Var);
generator.emit<Bytecode::Op::CreateVariable>(index, Bytecode::Op::EnvironmentMode::Lexical, false);
}
generator.emit<Bytecode::Op::SetVariable>(index, Bytecode::Op::SetVariable::InitializationMode::Initialize);
}
// 17. For each String vn of declaredVarNames, do
for (auto& var_name : declared_var_names) {
// a. Perform ? env.CreateGlobalVarBinding(vn, false).
auto index = generator.intern_identifier(var_name);
generator.register_binding(index, Bytecode::Generator::BindingMode::Var);
generator.emit<Bytecode::Op::CreateVariable>(index, Bytecode::Op::EnvironmentMode::Var, false, true);
}
} else {
// Perform the steps of FunctionDeclarationInstantiation.
generator.begin_variable_scope(Bytecode::Generator::BindingMode::Var, Bytecode::Generator::SurroundingScopeKind::Function);
pushed_scope_count++;
if (has_lexical_declarations()) {
generator.begin_variable_scope(Bytecode::Generator::BindingMode::Lexical, Bytecode::Generator::SurroundingScopeKind::Function);
pushed_scope_count++;
}
// FIXME: Implement this boi correctly.
(void)for_each_lexically_scoped_declaration([&](Declaration const& declaration) -> ThrowCompletionOr<void> {
auto is_constant_declaration = declaration.is_constant_declaration();
declaration.for_each_bound_name([&](auto const& name) {
auto index = generator.intern_identifier(name);
if (is_constant_declaration || !generator.has_binding(index)) {
generator.register_binding(index);
generator.emit<Bytecode::Op::CreateVariable>(index, Bytecode::Op::EnvironmentMode::Lexical, is_constant_declaration);
}
});
if (is<FunctionDeclaration>(declaration)) {
auto& function_declaration = static_cast<FunctionDeclaration const&>(declaration);
if (auto result = function_declaration.generate_bytecode(generator); result.is_error()) {
maybe_error = result.release_error();
// To make `for_each_lexically_scoped_declaration` happy.
return failing_completion;
}
auto const& name = function_declaration.name();
auto index = generator.intern_identifier(name);
if (!generator.has_binding(index)) {
generator.register_binding(index);
generator.emit<Bytecode::Op::CreateVariable>(index, Bytecode::Op::EnvironmentMode::Lexical, false);
}
generator.emit<Bytecode::Op::SetVariable>(index, Bytecode::Op::SetVariable::InitializationMode::InitializeOrSet);
}
return {};
});
}
if (maybe_error.has_value())
return maybe_error.release_value();
for (auto& child : children()) {
TRY(child.generate_bytecode(generator));
if (generator.is_current_block_terminated())
break;
}
for (size_t i = 0; i < pushed_scope_count; ++i)
generator.end_variable_scope();
return {};
}
Bytecode::CodeGenerationErrorOr<void> EmptyStatement::generate_bytecode(Bytecode::Generator&) const
{
return {};
}
Bytecode::CodeGenerationErrorOr<void> ExpressionStatement::generate_bytecode(Bytecode::Generator& generator) const
{
return m_expression->generate_bytecode(generator);
}
Bytecode::CodeGenerationErrorOr<void> BinaryExpression::generate_bytecode(Bytecode::Generator& generator) const
{
TRY(m_lhs->generate_bytecode(generator));
auto lhs_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(lhs_reg);
TRY(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();
}
return {};
}
Bytecode::CodeGenerationErrorOr<void> LogicalExpression::generate_bytecode(Bytecode::Generator& generator) const
{
TRY(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);
TRY(m_rhs->generate_bytecode(generator));
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { end_block },
{});
generator.switch_to_basic_block(end_block);
return {};
}
Bytecode::CodeGenerationErrorOr<void> UnaryExpression::generate_bytecode(Bytecode::Generator& generator) const
{
if (m_op == UnaryOp::Delete)
return generator.emit_delete_reference(m_lhs);
// Typeof needs some special handling for when the LHS is an Identifier. Namely, it shouldn't throw on unresolvable references, but instead return "undefined".
if (m_op != UnaryOp::Typeof)
TRY(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:
if (is<Identifier>(*m_lhs)) {
auto& identifier = static_cast<Identifier const&>(*m_lhs);
generator.emit<Bytecode::Op::TypeofVariable>(generator.intern_identifier(identifier.string()));
break;
}
TRY(m_lhs->generate_bytecode(generator));
generator.emit<Bytecode::Op::Typeof>();
break;
case UnaryOp::Void:
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
break;
case UnaryOp::Delete: // Delete is implemented above.
default:
VERIFY_NOT_REACHED();
}
return {};
}
Bytecode::CodeGenerationErrorOr<void> NumericLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::LoadImmediate>(m_value);
return {};
}
Bytecode::CodeGenerationErrorOr<void> BooleanLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::LoadImmediate>(Value(m_value));
return {};
}
Bytecode::CodeGenerationErrorOr<void> NullLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::LoadImmediate>(js_null());
return {};
}
Bytecode::CodeGenerationErrorOr<void> BigIntLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
// 1. Return the NumericValue of NumericLiteral as defined in 12.8.3.
auto integer = [&] {
if (m_value[0] == '0' && m_value.length() >= 3)
if (m_value[1] == 'x' || m_value[1] == 'X')
return Crypto::SignedBigInteger::from_base(16, m_value.substring(2, m_value.length() - 3));
if (m_value[1] == 'o' || m_value[1] == 'O')
return Crypto::SignedBigInteger::from_base(8, m_value.substring(2, m_value.length() - 3));
if (m_value[1] == 'b' || m_value[1] == 'B')
return Crypto::SignedBigInteger::from_base(2, m_value.substring(2, m_value.length() - 3));
return Crypto::SignedBigInteger::from_base(10, m_value.substring(0, m_value.length() - 1));
}();
generator.emit<Bytecode::Op::NewBigInt>(integer);
return {};
}
Bytecode::CodeGenerationErrorOr<void> StringLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::NewString>(generator.intern_string(m_value));
return {};
}
Bytecode::CodeGenerationErrorOr<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);
return {};
}
Bytecode::CodeGenerationErrorOr<void> Identifier::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::GetVariable>(generator.intern_identifier(m_string));
return {};
}
static Bytecode::CodeGenerationErrorOr<void> arguments_to_array_for_call(Bytecode::Generator& generator, Span<CallExpression::Argument const> arguments)
{
if (arguments.is_empty()) {
generator.emit<Bytecode::Op::NewArray>();
return {};
}
auto first_spread = find_if(arguments.begin(), arguments.end(), [](auto el) { return el.is_spread; });
Bytecode::Register args_start_reg { 0 };
for (auto it = arguments.begin(); it != first_spread; ++it) {
auto reg = generator.allocate_register();
if (args_start_reg.index() == 0)
args_start_reg = reg;
}
u32 i = 0;
for (auto it = arguments.begin(); it != first_spread; ++it, ++i) {
VERIFY(it->is_spread == false);
Bytecode::Register reg { args_start_reg.index() + i };
TRY(it->value->generate_bytecode(generator));
generator.emit<Bytecode::Op::Store>(reg);
}
if (first_spread.index() != 0)
generator.emit_with_extra_register_slots<Bytecode::Op::NewArray>(2u, AK::Array { args_start_reg, Bytecode::Register { args_start_reg.index() + static_cast<u32>(first_spread.index() - 1) } });
else
generator.emit<Bytecode::Op::NewArray>();
if (first_spread != arguments.end()) {
auto array_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(array_reg);
for (auto it = first_spread; it != arguments.end(); ++it) {
TRY(it->value->generate_bytecode(generator));
generator.emit<Bytecode::Op::Append>(array_reg, it->is_spread);
}
generator.emit<Bytecode::Op::Load>(array_reg);
}
return {};
}
Bytecode::CodeGenerationErrorOr<void> SuperCall::generate_bytecode(Bytecode::Generator& generator) const
{
if (m_is_synthetic == IsPartOfSyntheticConstructor::Yes) {
// NOTE: This is the case where we have a fake constructor(...args) { super(...args); } which
// shouldn't call @@iterator of %Array.prototype%.
VERIFY(m_arguments.size() == 1);
VERIFY(m_arguments[0].is_spread);
auto const& argument = m_arguments[0];
// This generates a single argument, which will be implicitly passed in accumulator
MUST(argument.value->generate_bytecode(generator));
} else {
TRY(arguments_to_array_for_call(generator, m_arguments));
}
generator.emit<Bytecode::Op::SuperCall>(m_is_synthetic == IsPartOfSyntheticConstructor::Yes);
return {};
}
static Bytecode::CodeGenerationErrorOr<void> generate_binding_pattern_bytecode(Bytecode::Generator& generator, BindingPattern const& pattern, Bytecode::Op::SetVariable::InitializationMode, Bytecode::Register const& value_reg);
Bytecode::CodeGenerationErrorOr<void> AssignmentExpression::generate_bytecode(Bytecode::Generator& generator) const
{
if (m_op == AssignmentOp::Assignment) {
// AssignmentExpression : LeftHandSideExpression = AssignmentExpression
return m_lhs.visit(
// 1. If LeftHandSideExpression is neither an ObjectLiteral nor an ArrayLiteral, then
[&](NonnullRefPtr<Expression> const& lhs) -> Bytecode::CodeGenerationErrorOr<void> {
// a. Let lref be the result of evaluating LeftHandSideExpression.
// b. ReturnIfAbrupt(lref).
Optional<Bytecode::Register> base_object_register;
Optional<Bytecode::Register> computed_property_register;
if (is<MemberExpression>(*lhs)) {
auto& expression = static_cast<MemberExpression const&>(*lhs);
TRY(expression.object().generate_bytecode(generator));
base_object_register = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(*base_object_register);
if (expression.is_computed()) {
TRY(expression.property().generate_bytecode(generator));
computed_property_register = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(*computed_property_register);
// To be continued later with PutByValue.
} else if (expression.property().is_identifier()) {
// Do nothing, this will be handled by PutById later.
} else {
return Bytecode::CodeGenerationError {
&expression,
"Unimplemented non-computed member expression"sv
};
}
} else if (is<Identifier>(*lhs)) {
// NOTE: For Identifiers, we cannot perform GetVariable and then write into the reference it retrieves, only SetVariable can do this.
// FIXME: However, this breaks spec as we are doing variable lookup after evaluating the RHS. This is observable in an object environment, where we visibly perform HasOwnProperty and Get(@@unscopables) on the binded object.
} else {
TRY(lhs->generate_bytecode(generator));
}
// FIXME: c. If IsAnonymousFunctionDefinition(AssignmentExpression) and IsIdentifierRef of LeftHandSideExpression are both true, then
// i. Let rval be ? NamedEvaluation of AssignmentExpression with argument lref.[[ReferencedName]].
// d. Else,
// i. Let rref be the result of evaluating AssignmentExpression.
// ii. Let rval be ? GetValue(rref).
TRY(m_rhs->generate_bytecode(generator));
// e. Perform ? PutValue(lref, rval).
if (is<Identifier>(*lhs)) {
auto& identifier = static_cast<Identifier const&>(*lhs);
generator.emit<Bytecode::Op::SetVariable>(generator.intern_identifier(identifier.string()));
} else if (is<MemberExpression>(*lhs)) {
auto& expression = static_cast<MemberExpression const&>(*lhs);
if (expression.is_computed()) {
generator.emit<Bytecode::Op::PutByValue>(*base_object_register, *computed_property_register);
} else if (expression.property().is_identifier()) {
auto identifier_table_ref = generator.intern_identifier(verify_cast<Identifier>(expression.property()).string());
generator.emit<Bytecode::Op::PutById>(*base_object_register, identifier_table_ref);
} else {
return Bytecode::CodeGenerationError {
&expression,
"Unimplemented non-computed member expression"sv
};
}
} else {
return Bytecode::CodeGenerationError {
lhs,
"Unimplemented/invalid node used a reference"sv
};
}
// f. Return rval.
// NOTE: This is already in the accumulator.
return {};
},
// 2. Let assignmentPattern be the AssignmentPattern that is covered by LeftHandSideExpression.
[&](NonnullRefPtr<BindingPattern> const& pattern) -> Bytecode::CodeGenerationErrorOr<void> {
// 3. Let rref be the result of evaluating AssignmentExpression.
// 4. Let rval be ? GetValue(rref).
TRY(m_rhs->generate_bytecode(generator));
auto value_register = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(value_register);
// 5. Perform ? DestructuringAssignmentEvaluation of assignmentPattern with argument rval.
TRY(generate_binding_pattern_bytecode(generator, pattern, Bytecode::Op::SetVariable::InitializationMode::Set, value_register));
// 6. Return rval.
generator.emit<Bytecode::Op::Load>(value_register);
return {};
});
}
VERIFY(m_lhs.has<NonnullRefPtr<Expression>>());
auto& lhs = m_lhs.get<NonnullRefPtr<Expression>>();
TRY(generator.emit_load_from_reference(lhs));
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);
TRY(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:
return Bytecode::CodeGenerationError {
this,
"Unimplemented operation"sv,
};
}
TRY(generator.emit_store_to_reference(lhs));
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 {};
}
// 14.13.3 Runtime Semantics: Evaluation, https://tc39.es/ecma262/#sec-labelled-statements-runtime-semantics-evaluation
// LabelledStatement : LabelIdentifier : LabelledItem
Bytecode::CodeGenerationErrorOr<void> LabelledStatement::generate_bytecode(Bytecode::Generator& generator) const
{
// Return ? LabelledEvaluation of this LabelledStatement with argument « ».
return generate_labelled_evaluation(generator, {});
}
// 14.13.4 Runtime Semantics: LabelledEvaluation, https://tc39.es/ecma262/#sec-runtime-semantics-labelledevaluation
// LabelledStatement : LabelIdentifier : LabelledItem
Bytecode::CodeGenerationErrorOr<void> LabelledStatement::generate_labelled_evaluation(Bytecode::Generator& generator, Vector<FlyString> const& label_set) const
{
// Convert the m_labelled_item NNRP to a reference early so we don't have to do it every single time we want to use it.
auto const& labelled_item = *m_labelled_item;
// 1. Let label be the StringValue of LabelIdentifier.
// NOTE: Not necessary, this is m_label.
// 2. Let newLabelSet be the list-concatenation of labelSet and « label ».
// FIXME: Avoid copy here.
auto new_label_set = label_set;
new_label_set.append(m_label);
// 3. Let stmtResult be LabelledEvaluation of LabelledItem with argument newLabelSet.
// NOTE: stmtResult will be in the accumulator after running the generated bytecode.
if (is<IterationStatement>(labelled_item)) {
auto const& iteration_statement = static_cast<IterationStatement const&>(labelled_item);
TRY(iteration_statement.generate_labelled_evaluation(generator, new_label_set));
} else if (is<SwitchStatement>(labelled_item)) {
auto const& switch_statement = static_cast<SwitchStatement const&>(labelled_item);
TRY(switch_statement.generate_labelled_evaluation(generator, new_label_set));
} else if (is<LabelledStatement>(labelled_item)) {
auto const& labelled_statement = static_cast<LabelledStatement const&>(labelled_item);
TRY(labelled_statement.generate_labelled_evaluation(generator, new_label_set));
} else {
auto& labelled_break_block = generator.make_block();
// NOTE: We do not need a continuable scope as `continue;` is not allowed outside of iteration statements, throwing a SyntaxError in the parser.
generator.begin_breakable_scope(Bytecode::Label { labelled_break_block }, new_label_set);
TRY(labelled_item.generate_bytecode(generator));
generator.end_breakable_scope();
if (!generator.is_current_block_terminated()) {
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { labelled_break_block },
{});
}
generator.switch_to_basic_block(labelled_break_block);
}
// 4. If stmtResult.[[Type]] is break and SameValue(stmtResult.[[Target]], label) is true, then
// a. Set stmtResult to NormalCompletion(stmtResult.[[Value]]).
// NOTE: These steps are performed by making labelled break jump straight to the appropriate break block, which preserves the statement result's value in the accumulator.
// 5. Return Completion(stmtResult).
// NOTE: This is in the accumulator.
return {};
}
Bytecode::CodeGenerationErrorOr<void> IterationStatement::generate_labelled_evaluation(Bytecode::Generator&, Vector<FlyString> const&) const
{
return Bytecode::CodeGenerationError {
this,
"Missing generate_labelled_evaluation()"sv,
};
}
Bytecode::CodeGenerationErrorOr<void> WhileStatement::generate_bytecode(Bytecode::Generator& generator) const
{
return generate_labelled_evaluation(generator, {});
}
Bytecode::CodeGenerationErrorOr<void> WhileStatement::generate_labelled_evaluation(Bytecode::Generator& generator, Vector<FlyString> const& label_set) 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);
TRY(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 }, label_set);
generator.begin_breakable_scope(Bytecode::Label { end_block }, label_set);
TRY(m_body->generate_bytecode(generator));
generator.end_breakable_scope();
generator.end_continuable_scope();
if (!generator.is_current_block_terminated()) {
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { test_block },
{});
}
generator.switch_to_basic_block(end_block);
generator.emit<Bytecode::Op::Load>(result_reg);
return {};
}
Bytecode::CodeGenerationErrorOr<void> DoWhileStatement::generate_bytecode(Bytecode::Generator& generator) const
{
return generate_labelled_evaluation(generator, {});
}
Bytecode::CodeGenerationErrorOr<void> DoWhileStatement::generate_labelled_evaluation(Bytecode::Generator& generator, Vector<FlyString> const& label_set) 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);
TRY(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 }, label_set);
generator.begin_breakable_scope(Bytecode::Label { end_block }, label_set);
TRY(m_body->generate_bytecode(generator));
generator.end_breakable_scope();
generator.end_continuable_scope();
if (!generator.is_current_block_terminated()) {
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { test_block },
{});
}
generator.switch_to_basic_block(end_block);
generator.emit<Bytecode::Op::Load>(result_reg);
return {};
}
Bytecode::CodeGenerationErrorOr<void> ForStatement::generate_bytecode(Bytecode::Generator& generator) const
{
return generate_labelled_evaluation(generator, {});
}
Bytecode::CodeGenerationErrorOr<void> ForStatement::generate_labelled_evaluation(Bytecode::Generator& generator, Vector<FlyString> const& label_set) 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();
bool has_lexical_environment = false;
if (m_init) {
if (m_init->is_variable_declaration()) {
auto& variable_declaration = verify_cast<VariableDeclaration>(*m_init);
if (variable_declaration.is_lexical_declaration()) {
has_lexical_environment = true;
// FIXME: Is Block correct?
generator.begin_variable_scope(Bytecode::Generator::BindingMode::Lexical, Bytecode::Generator::SurroundingScopeKind::Block);
bool is_const = variable_declaration.is_constant_declaration();
variable_declaration.for_each_bound_name([&](auto const& name) {
auto index = generator.intern_identifier(name);
generator.register_binding(index);
generator.emit<Bytecode::Op::CreateVariable>(index, Bytecode::Op::EnvironmentMode::Lexical, is_const);
});
}
}
TRY(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);
TRY(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 }, label_set);
generator.begin_breakable_scope(Bytecode::Label { end_block }, label_set);
TRY(m_body->generate_bytecode(generator));
generator.end_breakable_scope();
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);
TRY(m_update->generate_bytecode(generator));
}
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { *test_block_ptr },
{});
}
generator.switch_to_basic_block(end_block);
generator.emit<Bytecode::Op::Load>(result_reg);
if (has_lexical_environment)
generator.end_variable_scope();
return {};
}
Bytecode::CodeGenerationErrorOr<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) {
Bytecode::Op::PropertyKind property_kind;
switch (property.type()) {
case ObjectProperty::Type::KeyValue:
property_kind = Bytecode::Op::PropertyKind::KeyValue;
break;
case ObjectProperty::Type::Getter:
property_kind = Bytecode::Op::PropertyKind::Getter;
break;
case ObjectProperty::Type::Setter:
property_kind = Bytecode::Op::PropertyKind::Setter;
break;
case ObjectProperty::Type::Spread:
property_kind = Bytecode::Op::PropertyKind::Spread;
break;
case ObjectProperty::Type::ProtoSetter:
property_kind = Bytecode::Op::PropertyKind::ProtoSetter;
break;
}
if (is<StringLiteral>(property.key())) {
auto& string_literal = static_cast<StringLiteral const&>(property.key());
Bytecode::IdentifierTableIndex key_name = generator.intern_identifier(string_literal.value());
if (property_kind != Bytecode::Op::PropertyKind::Spread)
TRY(property.value().generate_bytecode(generator));
generator.emit<Bytecode::Op::PutById>(object_reg, key_name, property_kind);
} else {
TRY(property.key().generate_bytecode(generator));
auto property_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(property_reg);
if (property_kind != Bytecode::Op::PropertyKind::Spread)
TRY(property.value().generate_bytecode(generator));
generator.emit<Bytecode::Op::PutByValue>(object_reg, property_reg, property_kind);
}
}
generator.emit<Bytecode::Op::Load>(object_reg);
return {};
}
Bytecode::CodeGenerationErrorOr<void> ArrayExpression::generate_bytecode(Bytecode::Generator& generator) const
{
if (m_elements.is_empty()) {
generator.emit<Bytecode::Op::NewArray>();
return {};
}
auto first_spread = find_if(m_elements.begin(), m_elements.end(), [](auto el) { return el && is<SpreadExpression>(*el); });
Bytecode::Register args_start_reg { 0 };
for (auto it = m_elements.begin(); it != first_spread; ++it) {
auto reg = generator.allocate_register();
if (args_start_reg.index() == 0)
args_start_reg = reg;
}
u32 i = 0;
for (auto it = m_elements.begin(); it != first_spread; ++it, ++i) {
Bytecode::Register reg { args_start_reg.index() + i };
if (!*it)
generator.emit<Bytecode::Op::LoadImmediate>(Value {});
else {
TRY((*it)->generate_bytecode(generator));
}
generator.emit<Bytecode::Op::Store>(reg);
}
if (first_spread.index() != 0)
generator.emit_with_extra_register_slots<Bytecode::Op::NewArray>(2u, AK::Array { args_start_reg, Bytecode::Register { args_start_reg.index() + static_cast<u32>(first_spread.index() - 1) } });
else
generator.emit<Bytecode::Op::NewArray>();
if (first_spread != m_elements.end()) {
auto array_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(array_reg);
for (auto it = first_spread; it != m_elements.end(); ++it) {
if (!*it) {
generator.emit<Bytecode::Op::LoadImmediate>(Value {});
generator.emit<Bytecode::Op::Append>(array_reg, false);
} else {
TRY((*it)->generate_bytecode(generator));
generator.emit<Bytecode::Op::Append>(array_reg, *it && is<SpreadExpression>(**it));
}
}
generator.emit<Bytecode::Op::Load>(array_reg);
}
return {};
}
Bytecode::CodeGenerationErrorOr<void> MemberExpression::generate_bytecode(Bytecode::Generator& generator) const
{
return generator.emit_load_from_reference(*this);
}
Bytecode::CodeGenerationErrorOr<void> FunctionDeclaration::generate_bytecode(Bytecode::Generator& generator) const
{
if (m_is_hoisted) {
auto index = generator.intern_identifier(name());
generator.emit<Bytecode::Op::GetVariable>(index);
generator.emit<Bytecode::Op::SetVariable>(index, Bytecode::Op::SetVariable::InitializationMode::Set, Bytecode::Op::EnvironmentMode::Var);
}
return {};
}
Bytecode::CodeGenerationErrorOr<void> FunctionExpression::generate_bytecode(Bytecode::Generator& generator) const
{
bool has_name = !name().is_empty();
Optional<Bytecode::IdentifierTableIndex> name_identifier;
if (has_name) {
generator.begin_variable_scope(Bytecode::Generator::BindingMode::Lexical);
name_identifier = generator.intern_identifier(name());
generator.emit<Bytecode::Op::CreateVariable>(*name_identifier, Bytecode::Op::EnvironmentMode::Lexical, true);
}
generator.emit<Bytecode::Op::NewFunction>(*this);
if (has_name) {
generator.emit<Bytecode::Op::SetVariable>(*name_identifier, Bytecode::Op::SetVariable::InitializationMode::Initialize, Bytecode::Op::EnvironmentMode::Lexical);
generator.end_variable_scope();
}
return {};
}
static Bytecode::CodeGenerationErrorOr<void> generate_object_binding_pattern_bytecode(Bytecode::Generator& generator, BindingPattern const& pattern, Bytecode::Op::SetVariable::InitializationMode initialization_mode, 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_identifier(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, initialization_mode);
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>(generator.intern_identifier(identifier));
} else {
auto expression = name.get<NonnullRefPtr<Expression>>();
TRY(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);
TRY(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);
TRY(generate_binding_pattern_bytecode(generator, binding_pattern, initialization_mode, 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
return Bytecode::CodeGenerationError {
name.get<NonnullRefPtr<Expression>>().ptr(),
"Unimplemented name/alias pair: Empty/Expression"sv,
};
}
auto& identifier = name.get<NonnullRefPtr<Identifier>>()->string();
generator.emit<Bytecode::Op::SetVariable>(generator.intern_identifier(identifier), initialization_mode);
} else {
auto& identifier = alias.get<NonnullRefPtr<Identifier>>()->string();
generator.emit<Bytecode::Op::SetVariable>(generator.intern_identifier(identifier), initialization_mode);
}
}
return {};
}
static Bytecode::CodeGenerationErrorOr<void> generate_array_binding_pattern_bytecode(Bytecode::Generator& generator, BindingPattern const& pattern, Bytecode::Op::SetVariable::InitializationMode initialization_mode, 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) {
return alias.visit(
[&](Empty) -> Bytecode::CodeGenerationErrorOr<void> {
// This element is an elision
return {};
},
[&](NonnullRefPtr<Identifier> const& identifier) -> Bytecode::CodeGenerationErrorOr<void> {
auto interned_index = generator.intern_identifier(identifier->string());
generator.emit<Bytecode::Op::SetVariable>(interned_index, initialization_mode);
return {};
},
[&](NonnullRefPtr<BindingPattern> const& pattern) -> Bytecode::CodeGenerationErrorOr<void> {
// Store the accumulator value in a permanent register
auto target_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(target_reg);
return generate_binding_pattern_bytecode(generator, pattern, initialization_mode, target_reg);
},
[&](NonnullRefPtr<MemberExpression> const& expr) -> Bytecode::CodeGenerationErrorOr<void> {
return generator.emit_store_to_reference(*expr);
});
};
for (auto& [name, alias, initializer, is_rest] : pattern.entries) {
VERIFY(name.has<Empty>());
if (is_rest) {
VERIFY(!initializer);
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);
}
return assign_accumulator_to_alias(alias);
}
// 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);
if (initializer) {
auto& value_is_undefined_block = generator.make_block();
auto& value_is_not_undefined_block = generator.make_block();
generator.emit<Bytecode::Op::JumpUndefined>().set_targets(
Bytecode::Label { value_is_undefined_block },
Bytecode::Label { value_is_not_undefined_block });
generator.switch_to_basic_block(value_is_undefined_block);
TRY(initializer->generate_bytecode(generator));
generator.emit<Bytecode::Op::Jump>(Bytecode::Label { value_is_not_undefined_block });
generator.switch_to_basic_block(value_is_not_undefined_block);
}
TRY(assign_accumulator_to_alias(alias));
first = false;
}
return {};
}
static Bytecode::CodeGenerationErrorOr<void> generate_binding_pattern_bytecode(Bytecode::Generator& generator, BindingPattern const& pattern, Bytecode::Op::SetVariable::InitializationMode initialization_mode, Bytecode::Register const& value_reg)
{
if (pattern.kind == BindingPattern::Kind::Object)
return generate_object_binding_pattern_bytecode(generator, pattern, initialization_mode, value_reg);
return generate_array_binding_pattern_bytecode(generator, pattern, initialization_mode, value_reg);
}
static Bytecode::CodeGenerationErrorOr<void> assign_accumulator_to_variable_declarator(Bytecode::Generator& generator, VariableDeclarator const& declarator, VariableDeclaration const& declaration)
{
auto initialization_mode = declaration.is_lexical_declaration() ? Bytecode::Op::SetVariable::InitializationMode::Initialize : Bytecode::Op::SetVariable::InitializationMode::Set;
auto environment_mode = declaration.is_lexical_declaration() ? Bytecode::Op::EnvironmentMode::Lexical : Bytecode::Op::EnvironmentMode::Var;
return declarator.target().visit(
[&](NonnullRefPtr<Identifier> const& id) -> Bytecode::CodeGenerationErrorOr<void> {
generator.emit<Bytecode::Op::SetVariable>(generator.intern_identifier(id->string()), initialization_mode, environment_mode);
return {};
},
[&](NonnullRefPtr<BindingPattern> const& pattern) -> Bytecode::CodeGenerationErrorOr<void> {
auto value_register = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(value_register);
return generate_binding_pattern_bytecode(generator, pattern, initialization_mode, value_register);
});
}
Bytecode::CodeGenerationErrorOr<void> VariableDeclaration::generate_bytecode(Bytecode::Generator& generator) const
{
for (auto& declarator : m_declarations) {
if (declarator.init())
TRY(declarator.init()->generate_bytecode(generator));
else
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
TRY(assign_accumulator_to_variable_declarator(generator, declarator, *this));
}
return {};
}
Bytecode::CodeGenerationErrorOr<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)) {
TRY(m_callee->generate_bytecode(generator));
generator.emit<Bytecode::Op::Store>(callee_reg);
} else if (is<SuperExpression>(*m_callee)) {
return Bytecode::CodeGenerationError {
this,
"Unimplemented callee kind: SuperExpression"sv,
};
} else if (is<MemberExpression>(*m_callee)) {
auto& member_expression = static_cast<MemberExpression const&>(*m_callee);
if (is<SuperExpression>(member_expression.object())) {
return Bytecode::CodeGenerationError {
this,
"Unimplemented callee kind: MemberExpression on SuperExpression"sv,
};
}
TRY(member_expression.object().generate_bytecode(generator));
generator.emit<Bytecode::Op::Store>(this_reg);
if (member_expression.is_computed()) {
TRY(member_expression.property().generate_bytecode(generator));
generator.emit<Bytecode::Op::GetByValue>(this_reg);
} else {
auto identifier_table_ref = generator.intern_identifier(verify_cast<Identifier>(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.
TRY(m_callee->generate_bytecode(generator));
generator.emit<Bytecode::Op::Store>(callee_reg);
}
TRY(arguments_to_array_for_call(generator, m_arguments));
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;
}
Optional<Bytecode::StringTableIndex> expression_string_index;
if (auto expression_string = this->expression_string(); expression_string.has_value())
expression_string_index = generator.intern_string(expression_string.release_value());
generator.emit<Bytecode::Op::Call>(call_type, callee_reg, this_reg, expression_string_index);
return {};
}
Bytecode::CodeGenerationErrorOr<void> ReturnStatement::generate_bytecode(Bytecode::Generator& generator) const
{
if (m_argument)
TRY(m_argument->generate_bytecode(generator));
else
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
if (generator.is_in_generator_or_async_function()) {
generator.perform_needed_unwinds<Bytecode::Op::Yield>();
generator.emit<Bytecode::Op::Yield>(nullptr);
} else {
generator.perform_needed_unwinds<Bytecode::Op::Return>();
generator.emit<Bytecode::Op::Return>();
}
return {};
}
Bytecode::CodeGenerationErrorOr<void> YieldExpression::generate_bytecode(Bytecode::Generator& generator) const
{
VERIFY(generator.is_in_generator_function());
auto received_completion_register = generator.allocate_register();
auto received_completion_type_register = generator.allocate_register();
auto received_completion_value_register = generator.allocate_register();
auto type_identifier = generator.intern_identifier("type");
auto value_identifier = generator.intern_identifier("value");
auto get_received_completion_type_and_value = [&]() {
// The accumulator is set to an object, for example: { "type": 1 (normal), value: 1337 }
generator.emit<Bytecode::Op::Store>(received_completion_register);
generator.emit<Bytecode::Op::GetById>(type_identifier);
generator.emit<Bytecode::Op::Store>(received_completion_type_register);
generator.emit<Bytecode::Op::Load>(received_completion_register);
generator.emit<Bytecode::Op::GetById>(value_identifier);
generator.emit<Bytecode::Op::Store>(received_completion_value_register);
};
if (m_is_yield_from) {
return Bytecode::CodeGenerationError {
this,
"Unimplemented form: `yield*`"sv,
};
}
if (m_argument)
TRY(m_argument->generate_bytecode(generator));
else
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
auto& continuation_block = generator.make_block();
generator.emit<Bytecode::Op::Yield>(Bytecode::Label { continuation_block });
generator.switch_to_basic_block(continuation_block);
get_received_completion_type_and_value();
auto& normal_completion_continuation_block = generator.make_block();
auto& throw_completion_continuation_block = generator.make_block();
generator.emit<Bytecode::Op::LoadImmediate>(Value(to_underlying(Completion::Type::Normal)));
generator.emit<Bytecode::Op::StrictlyEquals>(received_completion_type_register);
generator.emit<Bytecode::Op::JumpConditional>(
Bytecode::Label { normal_completion_continuation_block },
Bytecode::Label { throw_completion_continuation_block });
auto& throw_value_block = generator.make_block();
auto& return_value_block = generator.make_block();
generator.switch_to_basic_block(throw_completion_continuation_block);
generator.emit<Bytecode::Op::LoadImmediate>(Value(to_underlying(Completion::Type::Throw)));
generator.emit<Bytecode::Op::StrictlyEquals>(received_completion_type_register);
// If type is not equal to "throw" or "normal", assume it's "return".
generator.emit<Bytecode::Op::JumpConditional>(
Bytecode::Label { throw_value_block },
Bytecode::Label { return_value_block });
generator.switch_to_basic_block(throw_value_block);
generator.emit<Bytecode::Op::Load>(received_completion_value_register);
generator.perform_needed_unwinds<Bytecode::Op::Throw>();
generator.emit<Bytecode::Op::Throw>();
generator.switch_to_basic_block(return_value_block);
generator.emit<Bytecode::Op::Load>(received_completion_value_register);
generator.perform_needed_unwinds<Bytecode::Op::Yield>();
generator.emit<Bytecode::Op::Yield>(nullptr);
generator.switch_to_basic_block(normal_completion_continuation_block);
generator.emit<Bytecode::Op::Load>(received_completion_value_register);
return {};
}
Bytecode::CodeGenerationErrorOr<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();
TRY(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());
TRY(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)
TRY(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);
return {};
}
Bytecode::CodeGenerationErrorOr<void> ContinueStatement::generate_bytecode(Bytecode::Generator& generator) const
{
if (m_target_label.is_null()) {
generator.perform_needed_unwinds<Bytecode::Op::Jump>();
generator.emit<Bytecode::Op::Jump>().set_targets(
generator.nearest_continuable_scope(),
{});
return {};
}
auto target_to_jump_to = generator.perform_needed_unwinds_for_labelled_continue_and_return_target_block(m_target_label);
generator.emit<Bytecode::Op::Jump>().set_targets(
target_to_jump_to,
{});
return {};
}
Bytecode::CodeGenerationErrorOr<void> DebuggerStatement::generate_bytecode(Bytecode::Generator&) const
{
return {};
}
Bytecode::CodeGenerationErrorOr<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();
TRY(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);
TRY(m_consequent->generate_bytecode(generator));
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { end_block },
{});
generator.switch_to_basic_block(false_block);
TRY(m_alternate->generate_bytecode(generator));
generator.emit<Bytecode::Op::Jump>().set_targets(
Bytecode::Label { end_block },
{});
generator.switch_to_basic_block(end_block);
return {};
}
Bytecode::CodeGenerationErrorOr<void> SequenceExpression::generate_bytecode(Bytecode::Generator& generator) const
{
for (auto& expression : m_expressions)
TRY(expression.generate_bytecode(generator));
return {};
}
Bytecode::CodeGenerationErrorOr<void> TemplateLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
auto string_reg = generator.allocate_register();
for (size_t i = 0; i < m_expressions.size(); i++) {
TRY(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);
return {};
}
Bytecode::CodeGenerationErrorOr<void> TaggedTemplateLiteral::generate_bytecode(Bytecode::Generator& generator) const
{
TRY(m_tag->generate_bytecode(generator));
auto tag_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(tag_reg);
// FIXME: We only need to record the first and last register,
// due to packing everything in an array, same goes for argument_regs
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;
string_regs.append(generator.allocate_register());
}
size_t reg_index = 0;
for (size_t i = 0; i < expressions.size(); ++i) {
if (i % 2 != 0)
continue;
TRY(expressions[i].generate_bytecode(generator));
auto string_reg = string_regs[reg_index++];
generator.emit<Bytecode::Op::Store>(string_reg);
}
if (string_regs.is_empty()) {
generator.emit<Bytecode::Op::NewArray>();
} else {
generator.emit_with_extra_register_slots<Bytecode::Op::NewArray>(2u, AK::Array { string_regs.first(), string_regs.last() });
}
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 = 1; i < expressions.size(); i += 2)
argument_regs.append(generator.allocate_register());
for (size_t i = 1; i < expressions.size(); i += 2) {
auto string_reg = argument_regs[1 + i / 2];
TRY(expressions[i].generate_bytecode(generator));
generator.emit<Bytecode::Op::Store>(string_reg);
}
Vector<Bytecode::Register> raw_string_regs;
for ([[maybe_unused]] auto& raw_string : m_template_literal->raw_strings())
string_regs.append(generator.allocate_register());
reg_index = 0;
for (auto& raw_string : m_template_literal->raw_strings()) {
TRY(raw_string.generate_bytecode(generator));
auto raw_string_reg = string_regs[reg_index++];
generator.emit<Bytecode::Op::Store>(raw_string_reg);
raw_string_regs.append(raw_string_reg);
}
if (raw_string_regs.is_empty()) {
generator.emit<Bytecode::Op::NewArray>();
} else {
generator.emit_with_extra_register_slots<Bytecode::Op::NewArray>(2u, AK::Array { raw_string_regs.first(), raw_string_regs.last() });
}
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_identifier("raw"));
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
auto this_reg = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(this_reg);
if (!argument_regs.is_empty())
generator.emit_with_extra_register_slots<Bytecode::Op::NewArray>(2, AK::Array { argument_regs.first(), argument_regs.last() });
else
generator.emit<Bytecode::Op::NewArray>();
generator.emit<Bytecode::Op::Call>(Bytecode::Op::Call::CallType::Call, tag_reg, this_reg);
return {};
}
Bytecode::CodeGenerationErrorOr<void> UpdateExpression::generate_bytecode(Bytecode::Generator& generator) const
{
TRY(generator.emit_load_from_reference(*m_argument));
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>();
TRY(generator.emit_store_to_reference(*m_argument));
if (!m_prefixed)
generator.emit<Bytecode::Op::Load>(*previous_value_for_postfix_reg);
return {};
}
Bytecode::CodeGenerationErrorOr<void> ThrowStatement::generate_bytecode(Bytecode::Generator& generator) const
{
TRY(m_argument->generate_bytecode(generator));
generator.perform_needed_unwinds<Bytecode::Op::Throw>();
generator.emit<Bytecode::Op::Throw>();
return {};
}
Bytecode::CodeGenerationErrorOr<void> BreakStatement::generate_bytecode(Bytecode::Generator& generator) const
{
if (m_target_label.is_null()) {
generator.perform_needed_unwinds<Bytecode::Op::Jump>(true);
generator.emit<Bytecode::Op::Jump>().set_targets(
generator.nearest_breakable_scope(),
{});
return {};
}
auto target_to_jump_to = generator.perform_needed_unwinds_for_labelled_break_and_return_target_block(m_target_label);
generator.emit<Bytecode::Op::Jump>().set_targets(
target_to_jump_to,
{});
return {};
}
Bytecode::CodeGenerationErrorOr<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);
TRY(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);
generator.begin_variable_scope(Bytecode::Generator::BindingMode::Lexical, Bytecode::Generator::SurroundingScopeKind::Block);
TRY(m_handler->parameter().visit(
[&](FlyString const& parameter) -> Bytecode::CodeGenerationErrorOr<void> {
if (!parameter.is_empty()) {
auto parameter_identifier = generator.intern_identifier(parameter);
generator.register_binding(parameter_identifier);
generator.emit<Bytecode::Op::CreateVariable>(parameter_identifier, Bytecode::Op::EnvironmentMode::Lexical, false);
generator.emit<Bytecode::Op::SetVariable>(parameter_identifier, Bytecode::Op::SetVariable::InitializationMode::Initialize);
}
return {};
},
[&](NonnullRefPtr<BindingPattern> const&) -> Bytecode::CodeGenerationErrorOr<void> {
// FIXME: Implement this path when the above DeclarativeEnvironment issue is dealt with.
return Bytecode::CodeGenerationError {
this,
"Unimplemented catch argument: BindingPattern"sv,
};
}));
TRY(m_handler->body().generate_bytecode(generator));
handler_target = Bytecode::Label { handler_block };
generator.end_variable_scope();
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.start_boundary(Bytecode::Generator::BlockBoundaryType::Unwind);
generator.switch_to_basic_block(target_block);
TRY(m_block->generate_bytecode(generator));
if (!generator.is_current_block_terminated()) {
if (m_finalizer) {
generator.emit<Bytecode::Op::Jump>(finalizer_target);
} else {
auto& block = generator.make_block();
generator.emit<Bytecode::Op::FinishUnwind>(Bytecode::Label { block });
next_block = &block;
}
}
generator.end_boundary(Bytecode::Generator::BlockBoundaryType::Unwind);
generator.switch_to_basic_block(next_block ? *next_block : saved_block);
return {};
}
Bytecode::CodeGenerationErrorOr<void> SwitchStatement::generate_bytecode(Bytecode::Generator& generator) const
{
return generate_labelled_evaluation(generator, {});
}
Bytecode::CodeGenerationErrorOr<void> SwitchStatement::generate_labelled_evaluation(Bytecode::Generator& generator, Vector<FlyString> const& label_set) const
{
auto discriminant_reg = generator.allocate_register();
TRY(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();
auto has_lexical_block = has_lexical_declarations();
// Note: This call ends up calling begin_variable_scope() if has_lexical_block is true, so we need to clean up after it at the end.
TRY(ScopeNode::generate_bytecode(generator));
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);
TRY(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 }, label_set);
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()) {
TRY(statement.generate_bytecode(generator));
if (generator.is_current_block_terminated())
break;
}
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();
if (has_lexical_block)
generator.end_variable_scope();
generator.switch_to_basic_block(end_block);
return {};
}
Bytecode::CodeGenerationErrorOr<void> ClassDeclaration::generate_bytecode(Bytecode::Generator& generator) const
{
TRY(m_class_expression->generate_bytecode(generator));
generator.emit<Bytecode::Op::SetVariable>(generator.intern_identifier(m_class_expression.ptr()->name()), Bytecode::Op::SetVariable::InitializationMode::Initialize);
return {};
}
Bytecode::CodeGenerationErrorOr<void> ClassExpression::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::NewClass>(*this);
return {};
}
Bytecode::CodeGenerationErrorOr<void> SpreadExpression::generate_bytecode(Bytecode::Generator& generator) const
{
// NOTE: All users of this should handle the behaviour of this on their own,
// assuming it returns an Array-like object
return m_target->generate_bytecode(generator);
}
Bytecode::CodeGenerationErrorOr<void> ThisExpression::generate_bytecode(Bytecode::Generator& generator) const
{
generator.emit<Bytecode::Op::ResolveThisBinding>();
return {};
}
Bytecode::CodeGenerationErrorOr<void> AwaitExpression::generate_bytecode(Bytecode::Generator& generator) const
{
VERIFY(generator.is_in_async_function());
// Transform `await expr` to `yield expr`
TRY(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);
return {};
}
Bytecode::CodeGenerationErrorOr<void> WithStatement::generate_bytecode(Bytecode::Generator& generator) const
{
TRY(m_object->generate_bytecode(generator));
generator.emit<Bytecode::Op::EnterObjectEnvironment>();
// EnterObjectEnvironment sets the running execution context's lexical_environment to a new Object Environment.
generator.start_boundary(Bytecode::Generator::BlockBoundaryType::LeaveLexicalEnvironment);
TRY(m_body->generate_bytecode(generator));
generator.end_boundary(Bytecode::Generator::BlockBoundaryType::LeaveLexicalEnvironment);
if (!generator.is_current_block_terminated())
generator.emit<Bytecode::Op::LeaveEnvironment>(Bytecode::Op::EnvironmentMode::Lexical);
return {};
}
enum class LHSKind {
Assignment,
VarBinding,
LexicalBinding,
};
enum class IterationKind {
Enumerate,
Iterate,
AsyncIterate,
};
// 14.7.5.6 ForIn/OfHeadEvaluation ( uninitializedBoundNames, expr, iterationKind ), https://tc39.es/ecma262/#sec-runtime-semantics-forinofheadevaluation
struct ForInOfHeadEvaluationResult {
bool is_destructuring { false };
LHSKind lhs_kind { LHSKind::Assignment };
};
static Bytecode::CodeGenerationErrorOr<ForInOfHeadEvaluationResult> for_in_of_head_evaluation(Bytecode::Generator& generator, IterationKind iteration_kind, Variant<NonnullRefPtr<ASTNode>, NonnullRefPtr<BindingPattern>> const& lhs, NonnullRefPtr<ASTNode> const& rhs)
{
ForInOfHeadEvaluationResult result {};
bool entered_lexical_scope = false;
if (auto* ast_ptr = lhs.get_pointer<NonnullRefPtr<ASTNode>>(); ast_ptr && is<VariableDeclaration>(**ast_ptr)) {
// Runtime Semantics: ForInOfLoopEvaluation, for any of:
// ForInOfStatement : for ( var ForBinding in Expression ) Statement
// ForInOfStatement : for ( ForDeclaration in Expression ) Statement
// ForInOfStatement : for ( var ForBinding of AssignmentExpression ) Statement
// ForInOfStatement : for ( ForDeclaration of AssignmentExpression ) Statement
auto& variable_declaration = static_cast<VariableDeclaration const&>(**ast_ptr);
result.is_destructuring = variable_declaration.declarations().first().target().has<NonnullRefPtr<BindingPattern>>();
result.lhs_kind = variable_declaration.is_lexical_declaration() ? LHSKind::LexicalBinding : LHSKind::VarBinding;
// 1. Let oldEnv be the running execution context's LexicalEnvironment.
// NOTE: 'uninitializedBoundNames' refers to the lexical bindings (i.e. Const/Let) present in the second and last form.
// 2. If uninitializedBoundNames is not an empty List, then
if (variable_declaration.declaration_kind() != DeclarationKind::Var) {
entered_lexical_scope = true;
// a. Assert: uninitializedBoundNames has no duplicate entries.
// b. Let newEnv be NewDeclarativeEnvironment(oldEnv).
generator.begin_variable_scope();
// c. For each String name of uninitializedBoundNames, do
variable_declaration.for_each_bound_name([&](auto const& name) {
// i. Perform ! newEnv.CreateMutableBinding(name, false).
auto identifier = generator.intern_identifier(name);
generator.register_binding(identifier);
generator.emit<Bytecode::Op::CreateVariable>(identifier, Bytecode::Op::EnvironmentMode::Lexical, false);
});
// d. Set the running execution context's LexicalEnvironment to newEnv.
// NOTE: Done by CreateEnvironment.
}
} else {
// Runtime Semantics: ForInOfLoopEvaluation, for any of:
// ForInOfStatement : for ( LeftHandSideExpression in Expression ) Statement
// ForInOfStatement : for ( LeftHandSideExpression of AssignmentExpression ) Statement
result.lhs_kind = LHSKind::Assignment;
}
// 3. Let exprRef be the result of evaluating expr.
TRY(rhs->generate_bytecode(generator));
// 4. Set the running execution context's LexicalEnvironment to oldEnv.
if (entered_lexical_scope)
generator.end_variable_scope();
// 5. Let exprValue be ? GetValue(exprRef).
// NOTE: No need to store this anywhere.
// 6. If iterationKind is enumerate, then
if (iteration_kind == IterationKind::Enumerate) {
// a. If exprValue is undefined or null, then
auto& nullish_block = generator.make_block();
auto& continuation_block = generator.make_block();
auto& jump = generator.emit<Bytecode::Op::JumpNullish>();
jump.set_targets(Bytecode::Label { nullish_block }, Bytecode::Label { continuation_block });
// i. Return Completion Record { [[Type]]: break, [[Value]]: empty, [[Target]]: empty }.
generator.switch_to_basic_block(nullish_block);
generator.perform_needed_unwinds<Bytecode::Op::Jump>(true);
generator.emit<Bytecode::Op::Jump>().set_targets(generator.nearest_breakable_scope(), {});
generator.switch_to_basic_block(continuation_block);
// b. Let obj be ! ToObject(exprValue).
// NOTE: GetObjectPropertyIterator does this.
// c. Let iterator be EnumerateObjectProperties(obj).
// d. Let nextMethod be ! GetV(iterator, "next").
// e. Return the Iterator Record { [[Iterator]]: iterator, [[NextMethod]]: nextMethod, [[Done]]: false }.
generator.emit<Bytecode::Op::GetObjectPropertyIterator>();
}
// 7. Else,
else {
// a. Assert: iterationKind is iterate or async-iterate.
// b. If iterationKind is async-iterate, let iteratorHint be async.
if (iteration_kind == IterationKind::AsyncIterate) {
return Bytecode::CodeGenerationError {
rhs.ptr(),
"Unimplemented iteration mode: AsyncIterate"sv,
};
}
// c. Else, let iteratorHint be sync.
// d. Return ? GetIterator(exprValue, iteratorHint).
generator.emit<Bytecode::Op::GetIterator>();
}
return result;
}
// 14.7.5.7 ForIn/OfBodyEvaluation ( lhs, stmt, iteratorRecord, iterationKind, lhsKind, labelSet [ , iteratorKind ] ), https://tc39.es/ecma262/#sec-runtime-semantics-forin-div-ofbodyevaluation-lhs-stmt-iterator-lhskind-labelset
static Bytecode::CodeGenerationErrorOr<void> for_in_of_body_evaluation(Bytecode::Generator& generator, ASTNode const& node, Variant<NonnullRefPtr<ASTNode>, NonnullRefPtr<BindingPattern>> const& lhs, ASTNode const& body, ForInOfHeadEvaluationResult const& head_result, Vector<FlyString> const& label_set, Bytecode::BasicBlock& loop_end, Bytecode::BasicBlock& loop_update)
{
auto iterator_register = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(iterator_register);
// FIXME: Implement this
// 1. If iteratorKind is not present, set iteratorKind to sync.
// 2. Let oldEnv be the running execution context's LexicalEnvironment.
bool has_lexical_binding = false;
// 3. Let V be undefined.
// NOTE: We don't need 'V' as the resulting value will naturally flow through via the accumulator register.
// 4. Let destructuring be IsDestructuring of lhs.
auto destructuring = head_result.is_destructuring;
// 5. If destructuring is true and if lhsKind is assignment, then
if (destructuring) {
// a. Assert: lhs is a LeftHandSideExpression.
// b. Let assignmentPattern be the AssignmentPattern that is covered by lhs.
// FIXME: Implement this.
return Bytecode::CodeGenerationError {
&node,
"Unimplemented: destructuring in for-in/of"sv,
};
}
// 6. Repeat,
generator.emit<Bytecode::Op::Jump>(Bytecode::Label { loop_update });
generator.switch_to_basic_block(loop_update);
generator.begin_continuable_scope(Bytecode::Label { loop_update }, label_set);
// a. Let nextResult be ? Call(iteratorRecord.[[NextMethod]], iteratorRecord.[[Iterator]]).
generator.emit<Bytecode::Op::Load>(iterator_register);
generator.emit<Bytecode::Op::IteratorNext>();
// FIXME: Implement this:
// b. If iteratorKind is async, set nextResult to ? Await(nextResult).
// c. If Type(nextResult) is not Object, throw a TypeError exception.
// NOTE: IteratorComplete already does this.
// d. Let done be ? IteratorComplete(nextResult).
auto iterator_result_register = generator.allocate_register();
generator.emit<Bytecode::Op::Store>(iterator_result_register);
generator.emit<Bytecode::Op::IteratorResultDone>();
// e. If done is true, return V.
auto& loop_continue = generator.make_block();
generator.emit<Bytecode::Op::JumpConditional>().set_targets(Bytecode::Label { loop_end }, Bytecode::Label { loop_continue });
generator.switch_to_basic_block(loop_continue);
// f. Let nextValue be ? IteratorValue(nextResult).
generator.emit<Bytecode::Op::Load>(iterator_result_register);
generator.emit<Bytecode::Op::IteratorResultValue>();
// g. If lhsKind is either assignment or varBinding, then
if (head_result.lhs_kind != LHSKind::LexicalBinding) {
// i. If destructuring is false, then
if (!destructuring) {
// 1. Let lhsRef be the result of evaluating lhs. (It may be evaluated repeatedly.)
// NOTE: We're skipping all the completion stuff that the spec does, as the unwinding mechanism will take case of doing that.
if (head_result.lhs_kind == LHSKind::VarBinding) {
auto& declaration = static_cast<VariableDeclaration const&>(*lhs.get<NonnullRefPtr<ASTNode>>());
VERIFY(declaration.declarations().size() == 1);
TRY(assign_accumulator_to_variable_declarator(generator, declaration.declarations().first(), declaration));
} else {
if (auto ptr = lhs.get_pointer<NonnullRefPtr<ASTNode>>()) {
TRY(generator.emit_store_to_reference(**ptr));
} else {
auto& binding_pattern = lhs.get<NonnullRefPtr<BindingPattern>>();
TRY(generate_binding_pattern_bytecode(generator, *binding_pattern, Bytecode::Op::SetVariable::InitializationMode::Set, Bytecode::Register::accumulator()));
}
}
}
}
// h. Else,
else {
// i. Assert: lhsKind is lexicalBinding.
// ii. Assert: lhs is a ForDeclaration.
// iii. Let iterationEnv be NewDeclarativeEnvironment(oldEnv).
// iv. Perform ForDeclarationBindingInstantiation of lhs with argument iterationEnv.
// v. Set the running execution context's LexicalEnvironment to iterationEnv.
generator.begin_variable_scope(Bytecode::Generator::BindingMode::Lexical);
has_lexical_binding = true;
// 14.7.5.4 Runtime Semantics: ForDeclarationBindingInstantiation, https://tc39.es/ecma262/#sec-runtime-semantics-fordeclarationbindinginstantiation
// 1. Assert: environment is a declarative Environment Record.
// NOTE: We just made it.
auto& variable_declaration = static_cast<VariableDeclaration const&>(*lhs.get<NonnullRefPtr<ASTNode>>());
// 2. For each element name of the BoundNames of ForBinding, do
variable_declaration.for_each_bound_name([&](auto const& name) {
auto identifier = generator.intern_identifier(name);
generator.register_binding(identifier, Bytecode::Generator::BindingMode::Lexical);
// a. If IsConstantDeclaration of LetOrConst is true, then
if (variable_declaration.is_constant_declaration()) {
// i. Perform ! environment.CreateImmutableBinding(name, true).
generator.emit<Bytecode::Op::CreateVariable>(identifier, Bytecode::Op::EnvironmentMode::Lexical, true);
}
// b. Else,
else {
// i. Perform ! environment.CreateMutableBinding(name, false).
generator.emit<Bytecode::Op::CreateVariable>(identifier, Bytecode::Op::EnvironmentMode::Lexical, false);
}
});
// 3. Return unused.
// NOTE: No need to do that as we've inlined this.
// vi. If destructuring is false, then
if (!destructuring) {
// 1. Assert: lhs binds a single name.
// 2. Let lhsName be the sole element of BoundNames of lhs.
auto lhs_name = variable_declaration.declarations().first().target().get<NonnullRefPtr<Identifier>>()->string();
// 3. Let lhsRef be ! ResolveBinding(lhsName).
// NOTE: We're skipping all the completion stuff that the spec does, as the unwinding mechanism will take case of doing that.
auto identifier = generator.intern_identifier(lhs_name);
generator.emit<Bytecode::Op::SetVariable>(identifier, Bytecode::Op::SetVariable::InitializationMode::Initialize, Bytecode::Op::EnvironmentMode::Lexical);
}
}
// i. If destructuring is false, then
if (!destructuring) {
// i. If lhsRef is an abrupt completion, then
// 1. Let status be lhsRef.
// ii. Else if lhsKind is lexicalBinding, then
// 1. Let status be Completion(InitializeReferencedBinding(lhsRef, nextValue)).
// iii. Else,
// 1. Let status be Completion(PutValue(lhsRef, nextValue)).
// NOTE: This is performed above.
}
// j. Else,
else {
// FIXME: Implement destructuring
// i. If lhsKind is assignment, then
// 1. Let status be Completion(DestructuringAssignmentEvaluation of assignmentPattern with argument nextValue).
// ii. Else if lhsKind is varBinding, then
// 1. Assert: lhs is a ForBinding.
// 2. Let status be Completion(BindingInitialization of lhs with arguments nextValue and undefined).
// iii. Else,
// 1. Assert: lhsKind is lexicalBinding.
// 2. Assert: lhs is a ForDeclaration.
// 3. Let status be Completion(ForDeclarationBindingInitialization of lhs with arguments nextValue and iterationEnv).
return Bytecode::CodeGenerationError {
&node,
"Unimplemented: destructuring in for-in/of"sv,
};
}
// FIXME: Implement iteration closure.
// k. If status is an abrupt completion, then
// i. Set the running execution context's LexicalEnvironment to oldEnv.
// ii. If iteratorKind is async, return ? AsyncIteratorClose(iteratorRecord, status).
// iii. If iterationKind is enumerate, then
// 1. Return ? status.
// iv. Else,
// 1. Assert: iterationKind is iterate.
// 2. Return ? IteratorClose(iteratorRecord, status).
// l. Let result be the result of evaluating stmt.
TRY(body.generate_bytecode(generator));
// m. Set the running execution context's LexicalEnvironment to oldEnv.
if (has_lexical_binding)
generator.end_variable_scope();
generator.end_continuable_scope();
generator.end_breakable_scope();
// NOTE: If we're here, then the loop definitely continues.
// n. If LoopContinues(result, labelSet) is false, then
// i. If iterationKind is enumerate, then
// 1. Return ? UpdateEmpty(result, V).
// ii. Else,
// 1. Assert: iterationKind is iterate.
// 2. Set status to Completion(UpdateEmpty(result, V)).
// 3. If iteratorKind is async, return ? AsyncIteratorClose(iteratorRecord, status).
// 4. Return ? IteratorClose(iteratorRecord, status).
// o. If result.[[Value]] is not empty, set V to result.[[Value]].
// The body can contain an unconditional block terminator (e.g. return, throw), so we have to check for that before generating the Jump.
if (!generator.is_current_block_terminated())
generator.emit<Bytecode::Op::Jump>().set_targets(Bytecode::Label { loop_update }, {});
generator.switch_to_basic_block(loop_end);
return {};
}
Bytecode::CodeGenerationErrorOr<void> ForInStatement::generate_bytecode(Bytecode::Generator& generator) const
{
return generate_labelled_evaluation(generator, {});
}
// 14.7.5.5 Runtime Semantics: ForInOfLoopEvaluation, https://tc39.es/ecma262/#sec-runtime-semantics-forinofloopevaluation
Bytecode::CodeGenerationErrorOr<void> ForInStatement::generate_labelled_evaluation(Bytecode::Generator& generator, Vector<FlyString> const& label_set) const
{
auto& loop_end = generator.make_block();
auto& loop_update = generator.make_block();
generator.begin_breakable_scope(Bytecode::Label { loop_end }, label_set);
auto head_result = TRY(for_in_of_head_evaluation(generator, IterationKind::Enumerate, m_lhs, m_rhs));
// Now perform the rest of ForInOfLoopEvaluation, given that the accumulator holds the iterator we're supposed to iterate over.
return for_in_of_body_evaluation(generator, *this, m_lhs, body(), head_result, label_set, loop_end, loop_update);
}
Bytecode::CodeGenerationErrorOr<void> ForOfStatement::generate_bytecode(Bytecode::Generator& generator) const
{
return generate_labelled_evaluation(generator, {});
}
Bytecode::CodeGenerationErrorOr<void> ForOfStatement::generate_labelled_evaluation(Bytecode::Generator& generator, Vector<FlyString> const& label_set) const
{
auto& loop_end = generator.make_block();
auto& loop_update = generator.make_block();
generator.begin_breakable_scope(Bytecode::Label { loop_end }, label_set);
auto head_result = TRY(for_in_of_head_evaluation(generator, IterationKind::Iterate, m_lhs, m_rhs));
// Now perform the rest of ForInOfLoopEvaluation, given that the accumulator holds the iterator we're supposed to iterate over.
return for_in_of_body_evaluation(generator, *this, m_lhs, body(), head_result, label_set, loop_end, loop_update);
}
// 13.3.12.1 Runtime Semantics: Evaluation, https://tc39.es/ecma262/#sec-meta-properties-runtime-semantics-evaluation
Bytecode::CodeGenerationErrorOr<void> MetaProperty::generate_bytecode(Bytecode::Generator& generator) const
{
// NewTarget : new . target
if (m_type == MetaProperty::Type::NewTarget) {
// 1. Return GetNewTarget().
generator.emit<Bytecode::Op::GetNewTarget>();
return {};
}
// ImportMeta : import . meta
if (m_type == MetaProperty::Type::ImportMeta) {
return Bytecode::CodeGenerationError {
this,
"Unimplemented meta property: import.meta"sv,
};
}
VERIFY_NOT_REACHED();
}
}
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