On Wed, 25 Apr 2018, Richard Biener wrote: > > The following patch improves bootstrap times in general, without > resorting to file splitting. The observation that stage2 build > of gimple-match.c improves by 50% when using -fno-checking > suggests that we avoid doing redundant checking when bootstrapping > and simply disable that when using the slow stage1 compiler > (or building stage2 target libs - maybe that should include stage1 > target libs as well). Given we in the end compare stage2 and stage3 > this will "only" delay checking failures plus also check whether > the IL checking affects code generation (hah). I've resorted to > leave STAGE4 alone. > > For a release checking build the overall win should be slightly > lower given the patch ends up enabling -fchecking for all target > libaries built in the final stage rather than just for those > built by the stage1 compiler (the stage1 compiler has checking > enabled for release builds as well unless manually specified). > > Bootstrap with all languages enabled running on x86_64-unknown-linux-gnu. > > I'll provide timings before/after the patch when they are gathered.
On a i7-8700 with --enable-languages=c,c++ and -j12 unpatched trunk bootstraps in 17196.62user 313.77system 37:40.82elapsed 774%CPU (0avgtext+0avgdata 734572maxresident)k 152inputs+27472376outputs (0major+161848104minor)pagefaults 0swaps and with an adjusted patch to also do STAGE1_TFLAGS += -fno-checking we can get that down to 12683.57user 310.63system 29:35.19elapsed 731%CPU (0avgtext+0avgdata 734572maxresident)k 176inputs+27461016outputs (0major+161926483minor)pagefaults 0swaps that's a 25% reduction in user/system time and a 22% reduction in wall-clock time. As you can see I'm not lucky and parallellism is reduced (if I can trust %CPU). Forcefully setting STAGE3_[CT]FLAGS doesn't have any effect on a checking enabled build but it will disrupt profiledbootstrap on a release build by training with -fchecking. Suggestions welcome - not sure whether adjusting STAGE3_[CT]FLAGS after setting STAGEtrain_[CT]FLAGS will have the desired effect of leaving the latter alone. Richard. > Any comments? Any suggested changes (STAGE1_TFLAGS?) > > Thanks, > Richard. > > 2018-04-25 Richard Biener <rguent...@suse.de> > > * Makefile.tpl (STAGE2_CFLAGS): Add -fno-checking. > (STAGE2_TFLAGS): Likewise. > (STAGE3_CFLAGS): Add -fchecking. > (STAGE3_TFLAGS): Likewise. > * Makefile.in: Re-generate. > > Index: Makefile.tpl > =================================================================== > --- Makefile.tpl (revision 259638) > +++ Makefile.tpl (working copy) > @@ -452,6 +452,15 @@ STAGE1_CONFIGURE_FLAGS = --disable-inter > --disable-coverage --enable-languages="$(STAGE1_LANGUAGES)" \ > --disable-build-format-warnings > > +# When using the slow stage1 compiler disable IL verification and forcefully > +# enable it when using the stage2 compiler instead. As we later compare > +# stage2 and stage3 we are merely avoid doing redundant work, plus we apply > +# checking when building all target libraries for release builds. > +STAGE2_CFLAGS += -fno-checking > +STAGE2_TFLAGS += -fno-checking > +STAGE3_CFLAGS += -fchecking > +STAGE3_TFLAGS += -fchecking > + > STAGEprofile_CFLAGS = $(STAGE2_CFLAGS) -fprofile-generate > STAGEprofile_TFLAGS = $(STAGE2_TFLAGS) > > Index: Makefile.in > =================================================================== > --- Makefile.in (revision 259638) > +++ Makefile.in (working copy) > @@ -529,6 +529,15 @@ STAGE1_CONFIGURE_FLAGS = --disable-inter > --disable-coverage --enable-languages="$(STAGE1_LANGUAGES)" \ > --disable-build-format-warnings > > +# When using the slow stage1 compiler disable IL verification and forcefully > +# enable it when using the stage2 compiler instead. As we later compare > +# stage2 and stage3 we are merely avoid doing redundant work, plus we apply > +# checking when building all target libraries for release builds. > +STAGE2_CFLAGS += -fno-checking > +STAGE2_TFLAGS += -fno-checking > +STAGE3_CFLAGS += -fchecking > +STAGE3_TFLAGS += -fchecking > + > STAGEprofile_CFLAGS = $(STAGE2_CFLAGS) -fprofile-generate > STAGEprofile_TFLAGS = $(STAGE2_TFLAGS) > > -- Richard Biener <rguent...@suse.de> SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)
