mirrors/ladybird
0
0
Fork 0
mirror of https://github.com/LadybirdBrowser/ladybird.git synced 2025-06-19 08:41:53 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 10

LibJS: Avoid emptying the return value register in try/finally

Browse source 
This works because at the end of the finally chunk, a
ContinuePendingUnwind is generated which copies the saved return value
register into the return value register. In cases where
ContinuePendingUnwind is not generated such as when there is a break
statement in the finally block, the fonction will return undefined which
is consistent with V8 and SpiderMonkey.
This commit is contained in:
Lucien Fiorini 2025-03-27 12:02:14 +01:00 • committed by Jelle Raaijmakers
parent fbdabace8e
commit 6b6e13e28c
Notes: github-actions[bot] 2025-03-27 12:19:55 +00:00
3 changed files with 14 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

4
Libraries/LibJS/Bytecode/Generator.h
View file

@ -274,8 +274,6 @@ public:
void emit_return(ScopedOperand value) void emit_return(ScopedOperand value)
requires(IsOneOf<OpType, Op::Return, Op::Yield>) requires(IsOneOf<OpType, Op::Return, Op::Yield>)
{ {
// FIXME: Tell the call sites about the `saved_return_value` destination
// And take that into account in the movs below.
perform_needed_unwinds<OpType>(); perform_needed_unwinds<OpType>();
if (must_enter_finalizer()) { if (must_enter_finalizer()) {
VERIFY(m_current_basic_block->finalizer() != nullptr); VERIFY(m_current_basic_block->finalizer() != nullptr);
@ -289,8 +287,6 @@ public:
else else
emit<Bytecode::Op::Mov>(Operand(Register::saved_return_value()), value); emit<Bytecode::Op::Mov>(Operand(Register::saved_return_value()), value);
emit<Bytecode::Op::Mov>(Operand(Register::exception()), add_constant(Value {})); emit<Bytecode::Op::Mov>(Operand(Register::exception()), add_constant(Value {}));
// FIXME: Do we really need to clear the return value register here?
emit<Bytecode::Op::Mov>(Operand(Register::return_value()), add_constant(Value {}));
emit<Bytecode::Op::Jump>(Label { *m_current_basic_block->finalizer() }); emit<Bytecode::Op::Jump>(Label { *m_current_basic_block->finalizer() });
return; return;
} }

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

@ -778,8 +778,6 @@ Interpreter::ResultAndReturnRegister Interpreter::run_executable(Executable& exe
auto return_value = js_undefined(); auto return_value = js_undefined();
if (!reg(Register::return_value()).is_empty()) if (!reg(Register::return_value()).is_empty())
return_value = reg(Register::return_value()); return_value = reg(Register::return_value());
else if (!reg(Register::saved_return_value()).is_empty())
return_value = reg(Register::saved_return_value());
auto exception = reg(Register::exception()); auto exception = reg(Register::exception());
vm().run_queued_promise_jobs(); vm().run_queued_promise_jobs();

14
Libraries/LibJS/Tests/try-finally-break.js
View file

@ -490,3 +490,17 @@ test("Break with nested mixed try-catch/finally", () => {
expect(executionOrder).toEqual([1, 2]); expect(executionOrder).toEqual([1, 2]);
}); });
test("Break in finally return in try", () => {
function foo() {
do {
try {
return "bar";
} finally {
break;
}
} while (expect.fail("Continued after do-while loop"));
}
expect(foo()).toEqual(undefined);
});