More radical ideas about gc and reference counting

[via Digitalmars-d]

On Monday, 12 May 2014 at 21:22:09 UTC, Steven Schveighoffer 
wrote:
> On Mon, 12 May 2014 14:14:28 -0400, Ola Fosheim Grøstad 
> <ola.fosheim.grostad+dlang at gmail.com> wrote:
>
>> On Monday, 12 May 2014 at 17:52:18 UTC, Walter Bright wrote:
>>> On 5/12/2014 7:46 AM, Steven Schveighoffer wrote:
>>>> pointing at it is roughly 1/256. This problem is just about 
>>>> eliminated with
>>>> 64-bit pointers.
>>
>> Not generally true. This presumes that the heap is not in the 
>> lower region of the address space and that you don't use 64 
>> bit ints on the stack.
>
> I was thinking in terms of purely a random number happening to 
> point at heap data. Practically speaking, I don't know the true 
> likelihood based on the heap address scheme of 64-bit OSes, but

Wicked topic. In AMD64 mode hi-mem is usually reserved for kernel 
etc. Traditionally the unixy heap grew from low towards high 
addresses:

http://en.wikipedia.org/wiki/Sbrk

But that is legacy. I think mmap is it… :-P And layout is 
randomized to reduce the effect of buffer overflow etc.

:-(

> I know that we always have a complainer who will try and do an 
> array-append test on 32-bit code, and end up exhausting memory 
> unexpectedly.

Uhuh. Not focusing on precise collection gets ugly.