[Bug c++/55135] Segfault of gcc on a big file

[steven at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55135

--- Comment #28 from Steven Bosscher <steven at gcc dot gnu.org> 2013-03-06 12:18:01 UTC ---
(In reply to comment #22)
> Posted for discussion here:
> http://gcc.gnu.org/ml/gcc-patches/2013-03/msg00193.html

OT: Another trivial speed-up for bitmaps used as regsets (and probably
in general) is to look at head->first if head->current is not the element
containing the sought bit, and *not* update head->current if head->first
is the right element.  This speeds up regsets because a common access
pattern is to look at sets containing both pseudos and hardregs, and on
most targets all hardregs are in head->first.  Not updating head->current
preserves a pointer to the latest accessed pseudos.

I'll implement this idea and come back with some timings.