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LibJS: Intercept returns through finally blocks in Bytecode

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This is still not perfect, as we now actually crash in the
`try-finally-continue` tests, while we now succeed all
`try-catch-finally-*` tests.

Note that we do not yet go through the finally block when exiting the
unwind context through a break or continue.
This commit is contained in:
Hendiadyoin1 2022-11-13 20:56:53 +01:00 • committed by Ali Mohammad Pur
parent c2108489a5
commit fcc3348bc8
5 changed files with 81 additions and 9 deletions
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19
Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
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@ -1707,6 +1707,9 @@ Bytecode::CodeGenerationErrorOr<void> IfStatement::generate_bytecode(Bytecode::G
Bytecode::CodeGenerationErrorOr<void> ContinueStatement::generate_bytecode(Bytecode::Generator& generator) const
{
// FIXME: Handle finally blocks in a graceful manner
// 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(
@ -1900,6 +1903,9 @@ Bytecode::CodeGenerationErrorOr<void> ThrowStatement::generate_bytecode(Bytecode
Bytecode::CodeGenerationErrorOr<void> BreakStatement::generate_bytecode(Bytecode::Generator& generator) const
{
// FIXME: Handle finally blocks in a graceful manner
// 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>(true);
generator.emit<Bytecode::Op::Jump>().set_targets(
@ -1937,9 +1943,15 @@ Bytecode::CodeGenerationErrorOr<void> TryStatement::generate_bytecode(Bytecode::
finalizer_target = Bytecode::Label { finalizer_block };
}
if (m_finalizer)
generator.start_boundary(Bytecode::Generator::BlockBoundaryType::ReturnToFinally);
if (m_handler) {
auto& handler_block = generator.make_block();
generator.switch_to_basic_block(handler_block);
if (!m_finalizer)
generator.emit<Bytecode::Op::LeaveUnwindContext>();
generator.begin_variable_scope(Bytecode::Generator::BindingMode::Lexical, Bytecode::Generator::SurroundingScopeKind::Block);
TRY(m_handler->parameter().visit(
[&](FlyString const& parameter) -> Bytecode::CodeGenerationErrorOr<void> {
@ -1974,11 +1986,15 @@ Bytecode::CodeGenerationErrorOr<void> TryStatement::generate_bytecode(Bytecode::
}
}
}
if (m_finalizer)
generator.end_boundary(Bytecode::Generator::BlockBoundaryType::ReturnToFinally);
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);
if (m_finalizer)
generator.start_boundary(Bytecode::Generator::BlockBoundaryType::ReturnToFinally);
generator.switch_to_basic_block(target_block);
TRY(m_block->generate_bytecode(generator));
@ -1992,6 +2008,9 @@ Bytecode::CodeGenerationErrorOr<void> TryStatement::generate_bytecode(Bytecode::
next_block = &block;
}
}
if (m_finalizer)
generator.end_boundary(Bytecode::Generator::BlockBoundaryType::ReturnToFinally);
generator.end_boundary(Bytecode::Generator::BlockBoundaryType::Unwind);
generator.switch_to_basic_block(next_block ? *next_block : saved_block);