On Sat, Nov 11, 2017 at 1:15 AM, Alexandre Oliva <aol...@redhat.com> wrote: > On Oct 30, 2017, Jeff Law <l...@redhat.com> wrote: > >> I'd support either or both. Your call. > > Thanks. I think I'll go with both, then. > > Ok to install as follows? (edited the comments and added a ChangeLog)
Ok. > > Use compare-debug for bootstrap-debug-lean to ignore != DW_AT_producer > > Unlike bootstrap-debug, bootstrap-debug-lean used to pass compare using > the traditional compare command, because it compiled both stage2 and > stage3 with options that used to generate identical output > (-fcompare-debug= in stage2 vs -fcompare-debug in stage3). > > Since we started adding relevant command-line flags to DW_AT_producer, > this is no longer the case, and stages 2 and 3 object files that differ > in nothing but the DW_AT_producer strings. > > > -fcompare-debug is short for -fcompare-debug=-gtoggle, so stage3 > compiles twice, once with the normal options, once with toggled -g, to > then compare the temporary final dumps. When enabled, both compilations > get from the driver an additional -frandom-seed flag (if none is given > explicitly). > > -fcompare-debug= is short for -fno-compare-debug, disabling the second > compilation. > > > The difference between the DW_AT_producer lines are the different > -fcompare-debug flags, and the presence of the -frandom-seed flag in the > stage3 compilation. > > It is easy and sensible enough to filter the -fcompare-debug flags out > of the DW_AT_producer string. This option should never affect the > compilation output, it just determines whether or not to perform an > additional compilation that should produce the same executable output. > > However, dropping -frandom-seed is not quite correct, in that it might > have other consequences on the compilation. So, it makes little sense > to make the effort to drop it when it's implicit; for those comparing > compiler output differences, it might even hint at what causes, and > could fix, difficult to explain differences, namely, explicitly > supplying -frandom-seed options. > > They don't seem to matter for compiler bootstraps, though, at least > for now, so we can safely refrain from issuing -frandom-seed (or maybe > we already issue it where needed :-), and then, for > bootstrap-debug-lean, use the compare-debug script, that strips out > debug information before comparing the object files. > > > for config/ChangeLog > > * bootstrap-debug-lean.mk (do-compare): Use the > contrib/compare-debug script. > > for gcc/ChangeLog > > * dwarf2out.c (gen_producer_string): Discard > OPT_fcompare_debug. > > --- > config/bootstrap-debug-lean.mk | 1 + > gcc/dwarf2out.c | 1 + > 2 files changed, 2 insertions(+) > > diff --git a/config/bootstrap-debug-lean.mk b/config/bootstrap-debug-lean.mk > index e215280b09f3..5f2db80687fa 100644 > --- a/config/bootstrap-debug-lean.mk > +++ b/config/bootstrap-debug-lean.mk > @@ -9,3 +9,4 @@ > > STAGE2_CFLAGS += -fcompare-debug= > STAGE3_CFLAGS += -fcompare-debug > +do-compare = $(SHELL) $(srcdir)/contrib/compare-debug $$f1 $$f2 > diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c > index b8f4e4888f1b..01d90808fd3b 100644 > --- a/gcc/dwarf2out.c > +++ b/gcc/dwarf2out.c > @@ -23403,6 +23403,7 @@ gen_producer_string (void) > case OPT_fltrans_output_list_: > case OPT_fresolution_: > case OPT_fdebug_prefix_map_: > + case OPT_fcompare_debug: > /* Ignore these. */ > continue; > default: > > > -- > Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/ > You must be the change you wish to see in the world. -- Gandhi > Be Free! -- http://FSFLA.org/ FSF Latin America board member > Free Software Evangelist|Red Hat Brasil GNU Toolchain Engineer
