On Tue, Dec 11, 2012 at 10:12 AM, Jan Hubicka <hubi...@ucw.cz> wrote: >> On 2012.12.11 at 09:13 -0800, Teresa Johnson wrote: >> > Ping. >> > Teresa >> > >> > On Mon, Nov 19, 2012 at 4:58 PM, Teresa Johnson <tejohn...@google.com> >> > wrote: >> > > This patch was proposed awhile back, and the new working set program >> > > summary was split out and committed separately. I would like to >> > > see if the loop unroller part of the patch can now go in. For the >> > > previous versions of the patch and related discussion, see: >> > > >> > > http://gcc.gnu.org/ml/gcc-patches/2012-06/msg00437.html >> > > and >> > > http://gcc.gnu.org/ml/gcc-patches/2012-07/msg01373.html >> > > >> > > Use the new working set information in the FDO program summary for >> > > codesize based unroll and peel decisions, to prevent those >> > > optimizations from increasing code size too much when the >> > > program may be sensitive to icache effects. >> > > >> > > As part of this, cache additional loop analysis results in the niter_desc >> > > auxiliary information hanging off the loop structure to reduce >> > > redundant analyses during unrolling. >> > > >> > > Bootstrapped and tested on x86_64-unknown-linux-gnu. Ok for trunk? >> >> I guess this is the missing piece that would fix the Firefox lto/pgo >> code-size issue: >> >> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45375#c144 > > It won't help in this case - the problem is that too much of code is > identified as hot, > similar as for spec2k GCC benchmark. Teresa - do you have any ideas what to > do here > short of re-adding the BB ratio parameter and combining both heuristics for > 4.8?
Right, I doubt this patch would help. I looked through the bugzilla log and it is most likely inlining increases. What was the size of the gcc lto/pgo binary before the change to use the histogram? Was it close to the gcc 4.7 lto/pgo size? In that case that is a very large increase, ~25%. Markus, could you attach to the bug one of the gcda files so that I can see the program summary and figure out how far off the old hot bb threshold is from the new histogram-based one? Also, it would be good to see the -fdump-ipa-inline dumps before and after the regression (if necessary, the before one could be from 4_7). I'll update the bug with the same, so that we can track the discussion there. Thanks, Teresa > > Honza >> >> -- >> Markus -- Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
