On Wed, Apr 13, 2011 at 8:43 PM, Nathan Froyd <froy...@codesourcery.com> wrote: > On Wed, Apr 13, 2011 at 11:07:15AM +0200, Richard Guenther wrote: >> On Tue, Apr 12, 2011 at 5:09 PM, Nathan Froyd <froy...@codesourcery.com> >> wrote: >> > Granted, but that fact should still be recorded. The situation we have >> > today, for something like: >> > >> > func1: statistic for "statx" was 0 >> > - nothing is recorded in the statistics table >> > func2: statistic for "statx" was 0 >> > - nothing is recorded in the statistics table >> > func3: statistic for "statx" was 0 >> > - nothing is recorded in the statistics table >> > ... >> > >> > and so forth, is that at the end of the day, the dump file won't even >> > include any information about "statx". If you had some func7387 where >> > "statx" was non-zero, you could infer that nothing else happened in the >> > previous 7386 functions. For the case where a pass is truly useless on >> > a TU, it's hard to figure out from the statistics dump alone. And I'd >> > argue that it's useful to see explicitly that the pass only helped in 1 >> > out of 7387 functions, rather than trying to infer it from missing data. >> >> I always use statistics-stats (thus, overall stats, not per function). The >> per function ones omit zero counts during dumping on purpose >> (to make the dump smaller). > > I didn't know about statistics-stats (or didn't realize that's what the > code was trying to do), that's useful. And it looks like all the > statistics dumping things omit zero counts on purpose, not just the > per-function ones. > > But that has no bearing on the point above: zero counts are not even > *recorded* today. E.g. if you apply the patch upthread, grab a random C > file, compile it with -O2/3 -fdump-statistics/-stats, and examine the > dump file, you might not even know that new statistics counters have > been added. Taking out the checks to avoid printing zero counts doesn't > help either, because the data simply doesn't get recorded. This > infrastructure makes it somewhat difficult to figure out, in an > automated way from the dump file alone, whether passes are actually > doing anything.
Oh, ok - now I understand what you are saying. Yes, that's by design and hard to fix - counters are "registered" on their first bump. > Enough grousing. I'm assuming turning on accumulation and dumping of > zero counts always would be frowned upon; would it be acceptable to turn > accumulation and dumping of zero counts if -details is given? Well, you'd have to fix the registration problem ... But I don't see zero counts as very important, if not to verify that the statistics code is placed at a good spot. Richard. > -Nathan >