compiler support added for precise GC

[Andrei Alexandrescu]

On 4/16/12 1:02 PM, Sean Kelly wrote:
> As for pointer maps, I think it's reasonable to establish a format
> that these will be made available to the GC, and for them to come
> from elsewhere in the runtime.  I realize that different GC
> implementations may prefer different formats, but hopefully we can
> settle on one that's pretty generally usable and efficient.  I'd
> really rather avoid expecting GC writers to know how to meta-process
> D types to statically generate this themselves.  Moving this into the
> GC would also eliminate the possibility of having the GC chosen at
> link-time, which is something that's currently still an option.

I know you didn't mean it that way, but this gets close enough to a 
dogma to warrant a protest. "We don't need no steenkin' templates in 
<sacred area X>" is, I think, an attitude we need to just rid ourselves 
of. There's the same harm in using templates too much or too little.

The scheme Walter proposed has a lot of flexibility - it plants one 
pointer to function per type. This is very flexible because that pointer 
could point to the same function and use a bitmap-based scheme, or (as 
Walter proposed) point to different instances of a template that does 
scanning in a type-specific manner.


Andrei