Re: Conservative GC isn't safe

[Eli Zaretskii]

> From: Stefan Monnier <address@hidden>
> Date: Mon, 28 Nov 2016 12:49:28 -0500
> 
> >> >> res = Fvector (ito - ifrom, aref_addr (string, ifrom));
> >> > But 'string' still references the contents array of the vector, so GC
> >> > will mark it when it comes to 'string'.
> >> But after computing "aref_addr (string, ifrom)", it may very well be
> >> that `string` is dead and the compiler may then decide not to write
> >> it into the stack.
> > It will still be there in the caller.
> 
> Only if the caller still needs it after the call.
> That's usually the case, but it's not a given.

If it is not needed after the call, it will be clobbered after the
call, but not during the call.