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
