On Tue, Apr 12, 2022 at 9:07 AM Richard Biener
<richard.guent...@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.
Richard.
>
> >
> > --
> > Steve
