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LibJS: Generate unwind chains for continue in Bytecode

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This works similar to `break`
The `try-finally-continue` still do not pass with this, likely because
of binding issues.
This commit is contained in:
Hendiadyoin1 2022-11-25 16:35:39 +01:00 committed by Linus Groh
parent f5376cb282
commit d65488b80c
Notes: sideshowbarker 2024-07-16 23:52:22 +09:00 
Author: https://github.com/Hendiadyoin1
Commit: https://github.com/SerenityOS/serenity/commit/d65488b80c
Pull-request: https://github.com/SerenityOS/serenity/pull/16184
Issue: https://github.com/SerenityOS/serenity/issues/16393
Reviewed-by: https://github.com/alimpfard ✅
Reviewed-by: https://github.com/kleinesfilmroellchen
4 changed files with 55 additions and 19 deletions
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10
Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
View file

@ -1972,17 +1972,11 @@ Bytecode::CodeGenerationErrorOr<void> ContinueStatement::generate_bytecode(Bytec
// We need to execute the finally block, but tell it to resume
// execution at the designated block
if (m_target_label.is_null()) {
generator.perform_needed_unwinds<Bytecode::Op::Jump>();
generator.emit<Bytecode::Op::Jump>().set_targets(
generator.nearest_continuable_scope(),
{});
generator.generate_continue();
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,
{});
generator.generate_continue(m_target_label);
return {};
}

59
Userland/Libraries/LibJS/Bytecode/Generator.cpp
View file

@ -335,23 +335,62 @@ void Generator::generate_break(DeprecatedFlyString const& break_label)
VERIFY_NOT_REACHED();
}
Label Generator::perform_needed_unwinds_for_labelled_continue_and_return_target_block(DeprecatedFlyString const& continue_label)
void Generator::generate_continue()
{
bool last_was_finally = false;
// FIXME: Reduce code duplication
for (size_t i = m_boundaries.size(); i > 0; --i) {
auto boundary = m_boundaries[i - 1];
using enum BlockBoundaryType;
switch (boundary) {
case Continue:
emit<Op::Jump>().set_targets(nearest_continuable_scope(), {});
return;
case Unwind:
if (!last_was_finally)
emit<Bytecode::Op::LeaveUnwindContext>();
last_was_finally = false;
break;
case LeaveLexicalEnvironment:
emit<Bytecode::Op::LeaveEnvironment>(Bytecode::Op::EnvironmentMode::Lexical);
break;
case LeaveVariableEnvironment:
emit<Bytecode::Op::LeaveEnvironment>(Bytecode::Op::EnvironmentMode::Var);
break;
case Break:
break;
case ReturnToFinally: {
auto& block = make_block(DeprecatedString::formatted("{}.continue", current_block().name()));
emit<Op::ScheduleJump>(Label { block });
switch_to_basic_block(block);
last_was_finally = true;
break;
};
}
}
VERIFY_NOT_REACHED();
}
void Generator::generate_continue(DeprecatedFlyString const& continue_label)
{
size_t current_boundary = m_boundaries.size();
for (auto& continuable_scope : m_continuable_scopes.in_reverse()) {
bool last_was_finally = false;
for (auto const& continuable_scope : m_continuable_scopes.in_reverse()) {
for (; current_boundary > 0; --current_boundary) {
auto boundary = m_boundaries[current_boundary - 1];
// FIXME: Handle ReturnToFinally in a graceful manner
// We need to execute the finally block, but tell it to resume
// execution at the designated label
if (boundary == BlockBoundaryType::Unwind) {
emit<Bytecode::Op::LeaveUnwindContext>();
if (!last_was_finally)
emit<Bytecode::Op::LeaveUnwindContext>();
last_was_finally = false;
} else if (boundary == BlockBoundaryType::LeaveLexicalEnvironment) {
emit<Bytecode::Op::LeaveEnvironment>(Bytecode::Op::EnvironmentMode::Lexical);
} else if (boundary == BlockBoundaryType::LeaveVariableEnvironment) {
emit<Bytecode::Op::LeaveEnvironment>(Bytecode::Op::EnvironmentMode::Var);
} else if (boundary == BlockBoundaryType::ReturnToFinally) {
// FIXME: We need to enter the `finally`, while still scheduling the continue to happen
auto& block = make_block(DeprecatedString::formatted("{}.continue", current_block().name()));
emit<Op::ScheduleJump>(Label { block });
switch_to_basic_block(block);
last_was_finally = true;
} else if (boundary == BlockBoundaryType::Continue) {
// Make sure we don't process this boundary twice if the current continuable scope doesn't contain the target label.
--current_boundary;
@ -359,8 +398,10 @@ Label Generator::perform_needed_unwinds_for_labelled_continue_and_return_target_
}
}
if (continuable_scope.language_label_set.contains_slow(continue_label))
return continuable_scope.bytecode_target;
if (continuable_scope.language_label_set.contains_slow(continue_label)) {
emit<Op::Jump>().set_targets(continuable_scope.bytecode_target, {});
return;
}
}
// We must have a continuable scope available that contains the label, as this should be enforced by the parser.

3
Userland/Libraries/LibJS/Bytecode/Generator.h
View file

@ -216,7 +216,8 @@ public:
void generate_break();
void generate_break(DeprecatedFlyString const& break_label);
Label perform_needed_unwinds_for_labelled_continue_and_return_target_block(DeprecatedFlyString const& continue_label);
void generate_continue();
void generate_continue(DeprecatedFlyString const& continue_label);
void start_boundary(BlockBoundaryType type) { m_boundaries.append(type); }
void end_boundary(BlockBoundaryType type)

2
Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
View file

@ -45,7 +45,7 @@ Interpreter::ValueAndFrame Interpreter::run_and_return_frame(Executable const& e
TemporaryChange restore_executable { m_current_executable, &executable };
TemporaryChange restore_saved_jump { m_scheduled_jump, static_cast<BasicBlock const*>(nullptr) };
VERIFY(m_saved_exception.is_null());
TemporaryChange restore_saved_exception { m_saved_exception, {} };
bool pushed_execution_context = false;
ExecutionContext execution_context(vm().heap());