Re: testsuite requires LTO?

[Steve Kargl <sgk@troutmask.apl.washington.edu>]

On Tue, Apr 12, 2022 at 09:26:58AM +0200, Richard Biener wrote:
> On Tue, Apr 12, 2022 at 9:07 AM Richard Biener
> <richard.guenther@gmail.com> wrote:
> >
> > On Tue, Apr 12, 2022 at 1:53 AM Steve Kargl via Gcc <gcc@gcc.gnu.org> wrote:
> > >
> > > If I configure gcc with the following
> > >
> > > ../gccx/configure --prefix=$HOME/work/x --enable-languages=c,c++,fortran \
> > >   --enable-bootstrap --disable-nls --enable-checking --disable-multilib \
> > >   --disable-libsanitizer --disable-lto.
> > >
> > > then bootstrap gcc, why do I see 1000s of failures with
> > >
> > > % cd gcc
> > > % gmake -j7 check-c
> > > ...
> > > FAIL: gcc.dg/torture/pr64365.c   -O2 -flto  (test for excess errors)
> > > FAIL: gcc.dg/torture/pr61786.c   -O2 -flto  (test for excess errors)
> > > FAIL: gcc.dg/torture/pr63380-2.c   -O2 -flto  (test for excess errors)
> > > FAIL: gcc.dg/torture/pr65270-2.c   -O2 -flto  (test for excess errors)
> > >
> > > Should the testsuite recognize that gcc is built without LTO support?
> >
> > Yes, it does, in testsuite/lib/gcc-dg.exp
> >
> > if [info exists TORTURE_OPTIONS] {
> >     set DG_TORTURE_OPTIONS $TORTURE_OPTIONS
> > } else {
> >     # It is theoretically beneficial to group all of the O2/O3 options together,
> >     # as in many cases the compiler will generate identical executables for
> >     # all of them--and the c-torture testsuite will skip testing identical
> >     # executables multiple times.
> >     # Also note that -finline-functions is explicitly included in one of the
> >     # items below, even though -O3 is also specified, because some ports may
> >     # choose to disable inlining functions by default, even when optimizing.
> >     set DG_TORTURE_OPTIONS [list \
> >         { -O0 } \
> >         { -O1 } \
> >         { -O2 } \
> >         { -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops
> > -ftracer -finline-functions } \
> >         { -O3 -g } \
> >         { -Os } ]
> >
> >     if [check_effective_target_lto] {
> >         # When having plugin test both slim and fat LTO and plugin/nonplugin
> >         # path.
> >         if [check_linker_plugin_available] {
> >            set LTO_TORTURE_OPTIONS [list \
> >               { -O2 -flto -fno-use-linker-plugin -flto-partition=none } \
> >               { -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects }
> >            ]
> >         } else {
> >            set LTO_TORTURE_OPTIONS [list \
> >               { -O2 -flto -flto-partition=none } \
> >               { -O2 -flto }
> >            ]
> >         }
> >
> > so either TORTURE_OPTIONS is set or check_effective_target_lto doesn't work.
> > The check does simply
> >
> >     return [check_no_compiler_messages lto object {
> >         void foo (void) { }
> >     } "-flto"]
> >
> > so I wonder what your excess errors are?  The check above should also
> > leave traces
> > in the testsuite log.  It might be that --disable-lto doesn't disable
> > gcc -c -flto but just
> > disables lto1 building though.
> 
> I checked and it works fine for me, --disable-lto disables LTO support
> and  there's
> no extra FAILs in dg-torture.exp.  The testsuite log has
> 
> Executing on host: /tmp/obj/gcc/xgcc -B/tmp/obj/gcc/
> -fdiagnostics-plain-output  -flto -c -o lto10207.o lto10207.c
> (timeout = 300)
> spawn -ignore SIGHUP /tmp/obj/gcc/xgcc -B/tmp/obj/gcc/
> -fdiagnostics-plain-output -flto -c -o lto10207.o lto10207.c^M
> cc1: error: LTO support has not been enabled in this configuration^M
> compiler exited with status 1
> 
> which causes no -flto to be used.
> 

Well, I determined what the problem is.  On FreeBSD,
GNU make is gmake.  make(1) on FreeBSD is BSD make.

% gmake -j7 check-c

Does not pass down the name of the invoking command 
to sub-make jobs.  4000+ FAILs had the form

make[2]: illegal argument to -j -- must be positive integer!
FAIL ...

Well, that's an error message from BSD make.  If I do 

% setenv MAKE gmake
% gmake -j7 check-c

4000+ FAILS disappear, so it's good that he environmental
variable MAKE is honored.  I know in the past I did not
need to sete MAKE.

With LTO disabled and MAKE set, I see

                === gcc Summary ===

# of expected passes            175408
# of unexpected failures        1078
# of unexpected successes       20
# of expected failures          1459
# of unresolved testcases       10
# of unsupported tests          3248
/usr/home/sgk/gcc/objx/gcc/xgcc  version 12.0.1 20220411 (experimental) (GCC) 

-- 
Steve