On 12.06.2013 02:08, Adam D. Ruppe wrote:
I'm catching up on the dconf videos tonight and just watched the precise
garbage collector one, where he said there's no info for closures. Would
it work if the closure's void* went to something along these lines?
struct Closure {
// magic a magic number to help identify this block
size_t number_of_variables_captured;
TypeInfo[number_of_vars_captured] capturedVarTypes;
// whatever else is needed
ubyte[xx] capturedVars;
}
The gc could read this and it might be useful for debugging too.
But I'm mostly just wondering if you guys thought any more about how to
(or if you want to) tackle this at the conference.
I was considering a struct that has the exact memory layout of the
allocated closure. When allocating it the type info of this struct can
be passes to the GC.
Example:
auto fun()
{
int x = 3;
int *y = &x;
return () { return x + *y };
}
auto dg = fun();
Assuming it is not optimized away, the allocated closure would be
identical to
struct fun_anonymous_closure
{
int x;
int* y;
}
and typeid(fun_anonymous_closure) can be passed to the GC to describe
the allocated memory.
The debug info for the struct would probably immediately work for
watching "x" and "y" in a debugger as the context pointer is usually
called "this" inside the delegate.
