On Sunday, 1 November 2015 at 22:36:46 UTC, Andrei Alexandrescu
wrote:
On 11/01/2015 03:51 PM, Martin Nowak wrote:
On 10/27/2015 01:27 PM, Andrei Alexandrescu wrote:
Unrelated, and a foreshadowing of the discussion on the
lifetime mailing
list: the compiler has ample opportunity to fuse incs/decs
together, so
the signatures of these functions is:
void opInc(uint delta);
void opDec(uint delta);
Any hint/numbers showing that this is actually useful?
Would be great to collect some, and generally get rigorous
about the whole approach.
Implementing such a cross statement optimization is quite some
work. If
this occurs often enough (in particular for shared classes
with atomic
ref counting) it might be worth the effort.
Most reference counting techniques revolve around reducing
mutation of the reference count. See e.g.
https://users.cecs.anu.edu.au/~steveb/downloads/pdf/rc-ismm-2012.pdf.
So we need to show that many refcount updates take it from 1 to
larger than 1 and back. According to
https://users.cecs.anu.edu.au/~steveb/downloads/pdf/rc-ismm-2012.pdf, many objects have a reference count of just one; the "eclipse" benchmark has 31.8% objects with a refcount greater than 1.
Andrei
That paper is assuming that you take Java(a language that does
*not* have allocation patterns like D such as favoring data on
the stack, tightly packed arrays of data, and immutability) rip
out its GC, and replace it with a RC-based GC with no concept of
unique ownership - no?
