Re: Fat references

Jon Harrop <jon@ffconsultancy.com>
Wed, 30 Dec 2009 21:05:37 +0000

          From comp.compilers

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[23 later articles]
| List of all articles for this month |

From: Jon Harrop <jon@ffconsultancy.com>
Newsgroups: comp.compilers
Date: Wed, 30 Dec 2009 21:05:37 +0000
Organization: Flying Frog Consultancy Ltd.
References: 09-12-045 09-12-048
Keywords: storage, GC

Paul Biggar wrote:
> One difference might be that in the PHP implementation, a pointer to
> the struct is passed around. I get the impression your "fat
> references" are passed by copy instead, but I'm not sure?


That is correct, yes.


> If you did, and found that was faster due to less indirection, that would
> be interesting.


From the benchmarks I have done, it seems to have had little adverse effect
on performance. The main effect has been to slow down stack operations but
that is largely because I'm using a naive shadow stack.


Memory consumption must be higher because pointers are all 4x larger. Some
operations should be faster, like computing the sum of the lengths of the
subarrays in an array of arrays because the locality of those lengths is
better.


I also have an unusual GC design that works well in concert with these fat
pointers.


--
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
http://www.ffconsultancy.com/?u



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