Bug 113907 – Closure caching causes crash in exception handling

• Status: NEW
• Component: JavaScriptCore

[Oliver Hunt]

This piece of code crashes, as far as i can tell it appears to be due to CodeBlock::bytecodeOffset(CallFrame, ReturnAddressPtr) returning the  bytecodeOffset from a ClosureCallStubRoutine that isn't in the target code block:
var value = 0;
function f(x) {
    var result = 0;
    function g(a) {
        function throwEventually() {
            if (value++ > 10000)
                throw new Error;
            return 5;
        }
        return a * throwEventually();
    }
    for (var i = 0; i < 3; i++)
        i += g(x);
    return i;
}

while (true)
    f(5)

[Filip Pizlo]

(In reply to comment #0)
> This piece of code crashes, as far as i can tell it appears to be due to CodeBlock::bytecodeOffset(CallFrame, ReturnAddressPtr) returning the  bytecodeOffset from a ClosureCallStubRoutine that isn't in the target code block:
> var value = 0;
> function f(x) {
>     var result = 0;
>     function g(a) {
>         function throwEventually() {
>             if (value++ > 10000)
>                 throw new Error;
>             return 5;
>         }
>         return a * throwEventually();
>     }
>     for (var i = 0; i < 3; i++)
>         i += g(x);
>     return i;
> }
> 
> while (true)
>     f(5)

What happens if the closure call cache is cleared while one of the closure calls is still on the stack?

Maybe that's what's going on?

[Oliver Hunt]

(In reply to comment #1)
> (In reply to comment #0)
> > This piece of code crashes, as far as i can tell it appears to be due to CodeBlock::bytecodeOffset(CallFrame, ReturnAddressPtr) returning the  bytecodeOffset from a ClosureCallStubRoutine that isn't in the target code block:
> > var value = 0;
> > function f(x) {
> >     var result = 0;
> >     function g(a) {
> >         function throwEventually() {
> >             if (value++ > 10000)
> >                 throw new Error;
> >             return 5;
> >         }
> >         return a * throwEventually();
> >     }
> >     for (var i = 0; i < 3; i++)
> >         i += g(x);
> >     return i;
> > }
> > 
> > while (true)
> >     f(5)
> 
> What happens if the closure call cache is cleared while one of the closure calls is still on the stack?
> 
> Maybe that's what's going on?

Alas the crash i'm getting isn't in the above test case, i had an incorrect tree in my change.