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LibJS/Bytecode: Extract code to generate a super reference to a helper

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This code is already repeated twice, and would be repeated a third time
for the `delete` operator.
This commit is contained in:
Timothy Flynn 2023-07-06 17:02:06 -04:00 committed by Andreas Kling
parent d5ca51b461
commit 0d50e5eeee
Notes: sideshowbarker 2024-07-17 09:49:33 +09:00 
Author: https://github.com/trflynn89
Commit: https://github.com/SerenityOS/serenity/commit/0d50e5eeee
Pull-request: https://github.com/SerenityOS/serenity/pull/19857
2 changed files with 56 additions and 61 deletions
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110
Userland/Libraries/LibJS/Bytecode/Generator.cpp
View file

@ -137,6 +137,46 @@ void Generator::end_breakable_scope()
end_boundary(BlockBoundaryType::Break);
}
CodeGenerationErrorOr<Generator::ReferenceRegisters> Generator::emit_super_reference(MemberExpression const& expression)
{
VERIFY(is<SuperExpression>(expression.object()));
// https://tc39.es/ecma262/#sec-super-keyword-runtime-semantics-evaluation
// 1. Let env be GetThisEnvironment().
// 2. Let actualThis be ? env.GetThisBinding().
auto actual_this_register = allocate_register();
emit<Bytecode::Op::ResolveThisBinding>();
emit<Bytecode::Op::Store>(actual_this_register);
Optional<Bytecode::Register> computed_property_value_register;
if (expression.is_computed()) {
// SuperProperty : super [ Expression ]
// 3. Let propertyNameReference be ? Evaluation of Expression.
// 4. Let propertyNameValue be ? GetValue(propertyNameReference).
TRY(expression.property().generate_bytecode(*this));
computed_property_value_register = allocate_register();
emit<Bytecode::Op::Store>(*computed_property_value_register);
}
// 5/7. Return ? MakeSuperPropertyReference(actualThis, propertyKey, strict).
// https://tc39.es/ecma262/#sec-makesuperpropertyreference
// 1. Let env be GetThisEnvironment().
// 2. Assert: env.HasSuperBinding() is true.
// 3. Let baseValue be ? env.GetSuperBase().
auto super_base_register = allocate_register();
emit<Bytecode::Op::ResolveSuperBase>();
emit<Bytecode::Op::Store>(super_base_register);
// 4. Return the Reference Record { [[Base]]: baseValue, [[ReferencedName]]: propertyKey, [[Strict]]: strict, [[ThisValue]]: actualThis }.
return ReferenceRegisters {
.base = super_base_register,
.referenced_name = move(computed_property_value_register),
.this_value = actual_this_register,
};
}
CodeGenerationErrorOr<void> Generator::emit_load_from_reference(JS::ASTNode const& node)
{
if (is<Identifier>(node)) {
@ -149,43 +189,17 @@ CodeGenerationErrorOr<void> Generator::emit_load_from_reference(JS::ASTNode cons
// https://tc39.es/ecma262/#sec-super-keyword-runtime-semantics-evaluation
if (is<SuperExpression>(expression.object())) {
// 1. Let env be GetThisEnvironment().
// 2. Let actualThis be ? env.GetThisBinding().
auto this_register = allocate_register();
emit<Bytecode::Op::ResolveThisBinding>();
emit<Bytecode::Op::Store>(this_register);
auto super_reference = TRY(emit_super_reference(expression));
Optional<Bytecode::Register> computed_property_value_register;
if (expression.is_computed()) {
// SuperProperty : super [ Expression ]
// 3. Let propertyNameReference be ? Evaluation of Expression.
// 4. Let propertyNameValue be ? GetValue(propertyNameReference).
TRY(expression.property().generate_bytecode(*this));
computed_property_value_register = allocate_register();
emit<Bytecode::Op::Store>(*computed_property_value_register);
}
// 5/7. Return ? MakeSuperPropertyReference(actualThis, propertyKey, strict).
// https://tc39.es/ecma262/#sec-makesuperpropertyreference
// 1. Let env be GetThisEnvironment().
// 2. Assert: env.HasSuperBinding() is true.
// 3. Let baseValue be ? env.GetSuperBase().
emit<Bytecode::Op::ResolveSuperBase>();
// 4. Return the Reference Record { [[Base]]: baseValue, [[ReferencedName]]: propertyKey, [[Strict]]: strict, [[ThisValue]]: actualThis }.
if (computed_property_value_register.has_value()) {
if (super_reference.referenced_name.has_value()) {
// 5. Let propertyKey be ? ToPropertyKey(propertyNameValue).
// FIXME: This does ToPropertyKey out of order, which is observable by Symbol.toPrimitive!
auto super_base_register = allocate_register();
emit<Bytecode::Op::Store>(super_base_register);
emit<Bytecode::Op::Load>(*computed_property_value_register);
emit<Bytecode::Op::GetByValueWithThis>(super_base_register, this_register);
emit<Bytecode::Op::Load>(*super_reference.referenced_name);
emit<Bytecode::Op::GetByValueWithThis>(super_reference.base, super_reference.this_value);
} else {
// 3. Let propertyKey be StringValue of IdentifierName.
auto identifier_table_ref = intern_identifier(verify_cast<Identifier>(expression.property()).string());
emit<Bytecode::Op::GetByIdWithThis>(identifier_table_ref, this_register);
emit<Bytecode::Op::GetByIdWithThis>(identifier_table_ref, super_reference.this_value);
}
} else {
TRY(expression.object().generate_bytecode(*this));
@ -230,44 +244,18 @@ CodeGenerationErrorOr<void> Generator::emit_store_to_reference(JS::ASTNode const
// https://tc39.es/ecma262/#sec-super-keyword-runtime-semantics-evaluation
if (is<SuperExpression>(expression.object())) {
// 1. Let env be GetThisEnvironment().
// 2. Let actualThis be ? env.GetThisBinding().
auto this_register = allocate_register();
emit<Bytecode::Op::ResolveThisBinding>();
emit<Bytecode::Op::Store>(this_register);
Optional<Bytecode::Register> computed_property_value_register;
if (expression.is_computed()) {
// SuperProperty : super [ Expression ]
// 3. Let propertyNameReference be ? Evaluation of Expression.
// 4. Let propertyNameValue be ? GetValue(propertyNameReference).
TRY(expression.property().generate_bytecode(*this));
computed_property_value_register = allocate_register();
emit<Bytecode::Op::Store>(*computed_property_value_register);
}
// 5/7. Return ? MakeSuperPropertyReference(actualThis, propertyKey, strict).
// https://tc39.es/ecma262/#sec-makesuperpropertyreference
// 1. Let env be GetThisEnvironment().
// 2. Assert: env.HasSuperBinding() is true.
// 3. Let baseValue be ? env.GetSuperBase().
auto super_base_register = allocate_register();
emit<Bytecode::Op::ResolveSuperBase>();
emit<Bytecode::Op::Store>(super_base_register);
auto super_reference = TRY(emit_super_reference(expression));
emit<Bytecode::Op::Load>(value_reg);
// 4. Return the Reference Record { [[Base]]: baseValue, [[ReferencedName]]: propertyKey, [[Strict]]: strict, [[ThisValue]]: actualThis }.
if (computed_property_value_register.has_value()) {
if (super_reference.referenced_name.has_value()) {
// 5. Let propertyKey be ? ToPropertyKey(propertyNameValue).
// FIXME: This does ToPropertyKey out of order, which is observable by Symbol.toPrimitive!
emit<Bytecode::Op::PutByValueWithThis>(super_base_register, *computed_property_value_register, this_register);
emit<Bytecode::Op::PutByValueWithThis>(super_reference.base, *super_reference.referenced_name, super_reference.this_value);
} else {
// 3. Let propertyKey be StringValue of IdentifierName.
auto identifier_table_ref = intern_identifier(verify_cast<Identifier>(expression.property()).string());
emit<Bytecode::Op::PutByIdWithThis>(super_base_register, this_register, identifier_table_ref);
emit<Bytecode::Op::PutByIdWithThis>(super_reference.base, super_reference.this_value, identifier_table_ref);
}
} else {
TRY(expression.object().generate_bytecode(*this));

7
Userland/Libraries/LibJS/Bytecode/Generator.h
View file

@ -83,6 +83,13 @@ public:
CodeGenerationErrorOr<void> emit_store_to_reference(JS::ASTNode const&);
CodeGenerationErrorOr<void> emit_delete_reference(JS::ASTNode const&);
struct ReferenceRegisters {
Register base; // [[Base]]
Optional<Bytecode::Register> referenced_name; // [[ReferencedName]]
Register this_value; // [[ThisValue]]
};
CodeGenerationErrorOr<ReferenceRegisters> emit_super_reference(MemberExpression const&);
void emit_set_variable(JS::Identifier const& identifier, Bytecode::Op::SetVariable::InitializationMode initialization_mode = Bytecode::Op::SetVariable::InitializationMode::Set, Bytecode::Op::EnvironmentMode mode = Bytecode::Op::EnvironmentMode::Lexical);
void push_home_object(Register);