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LibJS: Leave the unwind context on break/continue/return in bytecode

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Otherwise we'd keep the old unwind context, and end up never invoking
the other handlers up the stack.
This commit is contained in:
Ali Mohammad Pur 2022-03-13 11:51:02 +03:30 • committed by Andreas Kling
parent 41184c960d
commit ba9c4959d6
3 changed files with 44 additions and 2 deletions
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11
Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
View file

@ -1207,10 +1207,13 @@ Bytecode::CodeGenerationErrorOr<void> ReturnStatement::generate_bytecode(Bytecod
if (m_argument)
TRY(m_argument->generate_bytecode(generator));
if (generator.is_in_generator_or_async_function())
if (generator.is_in_generator_or_async_function()) {
generator.perform_needed_unwinds<Bytecode::Op::Yield>();
generator.emit<Bytecode::Op::Yield>(nullptr);
else
} else {
generator.perform_needed_unwinds<Bytecode::Op::Return>();
generator.emit<Bytecode::Op::Return>();
}
return {};
}
@ -1279,6 +1282,7 @@ Bytecode::CodeGenerationErrorOr<void> IfStatement::generate_bytecode(Bytecode::G
Bytecode::CodeGenerationErrorOr<void> ContinueStatement::generate_bytecode(Bytecode::Generator& generator) const
{
generator.perform_needed_unwinds<Bytecode::Op::Jump>();
generator.emit<Bytecode::Op::Jump>().set_targets(
generator.nearest_continuable_scope(),
{});
@ -1438,6 +1442,7 @@ Bytecode::CodeGenerationErrorOr<void> ThrowStatement::generate_bytecode(Bytecode
Bytecode::CodeGenerationErrorOr<void> BreakStatement::generate_bytecode(Bytecode::Generator& generator) const
{
generator.perform_needed_unwinds<Bytecode::Op::Jump>(true);
generator.emit<Bytecode::Op::Jump>().set_targets(
generator.nearest_breakable_scope(),
{});
@ -1502,6 +1507,7 @@ Bytecode::CodeGenerationErrorOr<void> TryStatement::generate_bytecode(Bytecode::
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));
@ -1514,6 +1520,7 @@ Bytecode::CodeGenerationErrorOr<void> TryStatement::generate_bytecode(Bytecode::
next_block = &block;
}
}
generator.end_boundary(Bytecode::Generator::BlockBoundaryType::Unwind);
generator.switch_to_basic_block(next_block ? *next_block : saved_block);
return {};

4
Userland/Libraries/LibJS/Bytecode/Generator.cpp
View file

@ -79,11 +79,13 @@ Label Generator::nearest_continuable_scope() const
void Generator::begin_continuable_scope(Label continue_target)
{
m_continuable_scopes.append(continue_target);
start_boundary(BlockBoundaryType::Continue);
}
void Generator::end_continuable_scope()
{
m_continuable_scopes.take_last();
end_boundary(BlockBoundaryType::Continue);
}
Label Generator::nearest_breakable_scope() const
{
@ -92,11 +94,13 @@ Label Generator::nearest_breakable_scope() const
void Generator::begin_breakable_scope(Label breakable_target)
{
m_breakable_scopes.append(breakable_target);
start_boundary(BlockBoundaryType::Break);
}
void Generator::end_breakable_scope()
{
m_breakable_scopes.take_last();
end_boundary(BlockBoundaryType::Break);
}
CodeGenerationErrorOr<void> Generator::emit_load_from_reference(JS::ASTNode const& node)

31
Userland/Libraries/LibJS/Bytecode/Generator.h
View file

@ -171,6 +171,36 @@ public:
}
}
enum class BlockBoundaryType {
Break,
Continue,
Unwind,
};
template<typename OpType>
void perform_needed_unwinds(bool is_break_node = false) requires(OpType::IsTerminator)
{
Optional<BlockBoundaryType> boundary_to_stop_at;
if constexpr (IsSame<OpType, Bytecode::Op::Return> || IsSame<OpType, Bytecode::Op::Yield>)
VERIFY(!is_break_node);
else
boundary_to_stop_at = is_break_node ? BlockBoundaryType::Break : BlockBoundaryType::Continue;
for (size_t i = m_boundaries.size(); i > 0; --i) {
auto boundary = m_boundaries[i - 1];
if (boundary_to_stop_at.has_value() && boundary == *boundary_to_stop_at)
break;
if (boundary == BlockBoundaryType::Unwind)
emit<Bytecode::Op::LeaveUnwindContext>();
}
}
void start_boundary(BlockBoundaryType type) { m_boundaries.append(type); }
void end_boundary(BlockBoundaryType type)
{
VERIFY(m_boundaries.last() == type);
m_boundaries.take_last();
}
private:
Generator();
~Generator();
@ -189,6 +219,7 @@ private:
Vector<Label> m_continuable_scopes;
Vector<Label> m_breakable_scopes;
Vector<LexicalScope> m_variable_scopes;
Vector<BlockBoundaryType> m_boundaries;
};
}