On Mon, 2006-03-20 at 18:55 -0500, Andrew Pinski wrote: > On Mar 20, 2006, at 5:18 PM, Andrew MacLeod wrote: > > > I'm not sure when this happened, but I noticed on the weekend that > > there > > has been an explosion in the time spent during the alias analysis > > phase. > > using cplusplus-grammer.ii, it use to compile on my machine in about 55 > > seconds, and its now up to about 150 seconds. > > > > A quick gprof indicated about 60% of compile time is being spent in > > bitmap_bit_p, called from compute_may_aliases. > > > > someone made it WAY slow :-) > > Could it be that 2 more passes of may_alias was added?
I don't think so. I would expect that to double or triple the time spent in alias analysis, not the entire compile time. This is a 200% increase in compiler time... going from 50 seconds to 150 is pretty significant. And since its almost all in bitmap_bit_p, it sounds algorithmic to me... btw, this was on a 3.0 Ghz P4 running linux with a checkout from mainline this morning built with no checking... Doing a quick check back, on 01/23 shows similar time (71% of compiler time spent in alias analysis, 97 seconds out of 135). The previous compiler to that which I have laying around is 10/30/05, and it shows a much more sensible 6.32 seconds in alias analysis. It looks like sometime between 10/30 and 01/23 alias analysis got out of hand. Odd it hasn't been noted before. Andrew
