* [PATCH] Remove fno-unit-at-a-time make variable @ 2022-03-30 5:07 Fangrui Song 2022-03-30 12:46 ` Adhemerval Zanella 0 siblings, 1 reply; 20+ messages in thread From: Fangrui Song @ 2022-03-30 5:07 UTC (permalink / raw) To: libc-alpha, Adhemerval Zanella 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder is a rough replacement for this legacy option (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). The reordering requirement does not seem to be needed any longer. --- config.make.in | 1 - configure | 32 -------------------------------- configure.ac | 19 ------------------- stdio-common/Makefile | 2 -- 4 files changed, 54 deletions(-) diff --git a/config.make.in b/config.make.in index 6d43e691f7..ecde84a7da 100644 --- a/config.make.in +++ b/config.make.in @@ -69,7 +69,6 @@ have-selinux = @have_selinux@ have-libaudit = @have_libaudit@ have-libcap = @have_libcap@ have-cc-with-libunwind = @libc_cv_cc_with_libunwind@ -fno-unit-at-a-time = @fno_unit_at_a_time@ bind-now = @bindnow@ have-hash-style = @libc_cv_hashstyle@ use-default-link = @use_default_link@ diff --git a/configure b/configure index 2a3cb49b0b..f836874a58 100755 --- a/configure +++ b/configure @@ -620,7 +620,6 @@ libc_cv_cc_loop_to_function libc_cv_cc_submachine libc_cv_cc_nofma libc_cv_mtls_dialect_gnu2 -fno_unit_at_a_time libc_cv_has_glob_dat libc_cv_hashstyle libc_cv_fpie @@ -6319,37 +6318,6 @@ fi $as_echo "$libc_cv_has_glob_dat" >&6; } -{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for -fno-toplevel-reorder -fno-section-anchors" >&5 -$as_echo_n "checking for -fno-toplevel-reorder -fno-section-anchors... " >&6; } -if ${libc_cv_fno_toplevel_reorder+:} false; then : - $as_echo_n "(cached) " >&6 -else - cat > conftest.c <<EOF -int foo; -EOF -if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -S -fno-toplevel-reorder -fno-section-anchors - conftest.c 1>&5' - { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 - (eval $ac_try) 2>&5 - ac_status=$? - $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 - test $ac_status = 0; }; } -then - libc_cv_fno_toplevel_reorder=yes -else - libc_cv_fno_toplevel_reorder=no -fi -rm -f conftest* -fi -{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_fno_toplevel_reorder" >&5 -$as_echo "$libc_cv_fno_toplevel_reorder" >&6; } -if test $libc_cv_fno_toplevel_reorder = yes; then - fno_unit_at_a_time="-fno-toplevel-reorder -fno-section-anchors" -else - fno_unit_at_a_time=-fno-unit-at-a-time -fi - - { $as_echo "$as_me:${as_lineno-$LINENO}: checking for -mtls-dialect=gnu2" >&5 $as_echo_n "checking for -mtls-dialect=gnu2... " >&6; } if ${libc_cv_mtls_dialect_gnu2+:} false; then : diff --git a/configure.ac b/configure.ac index fa7d3c025b..ec1db36d46 100644 --- a/configure.ac +++ b/configure.ac @@ -1478,25 +1478,6 @@ fi rm -f conftest*]) AC_SUBST(libc_cv_has_glob_dat) -AC_CACHE_CHECK(for -fno-toplevel-reorder -fno-section-anchors, libc_cv_fno_toplevel_reorder, [dnl -cat > conftest.c <<EOF -int foo; -EOF -if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -S -fno-toplevel-reorder -fno-section-anchors - conftest.c 1>&AS_MESSAGE_LOG_FD]) -then - libc_cv_fno_toplevel_reorder=yes -else - libc_cv_fno_toplevel_reorder=no -fi -rm -f conftest*]) -if test $libc_cv_fno_toplevel_reorder = yes; then - fno_unit_at_a_time="-fno-toplevel-reorder -fno-section-anchors" -else - fno_unit_at_a_time=-fno-unit-at-a-time -fi -AC_SUBST(fno_unit_at_a_time) - AC_CACHE_CHECK([for -mtls-dialect=gnu2], libc_cv_mtls_dialect_gnu2, [dnl cat > conftest.c <<EOF diff --git a/stdio-common/Makefile b/stdio-common/Makefile index 435cd8904f..dbaecbd76e 100644 --- a/stdio-common/Makefile +++ b/stdio-common/Makefile @@ -333,8 +333,6 @@ CFLAGS-isoc99_vfscanf.c += -fexceptions CFLAGS-isoc99_vscanf.c += -fexceptions CFLAGS-isoc99_fscanf.c += -fexceptions CFLAGS-isoc99_scanf.c += -fexceptions -CFLAGS-errlist.c += $(fno-unit-at-a-time) -CFLAGS-siglist.c += $(fno-unit-at-a-time) # scanf14a.c and scanf16a.c test a deprecated extension which is no # longer visible under most conformance levels; see the source files -- 2.35.1.1021.g381101b075-goog ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-03-30 5:07 [PATCH] Remove fno-unit-at-a-time make variable Fangrui Song @ 2022-03-30 12:46 ` Adhemerval Zanella 2022-03-30 16:23 ` Fangrui Song 0 siblings, 1 reply; 20+ messages in thread From: Adhemerval Zanella @ 2022-03-30 12:46 UTC (permalink / raw) To: Fangrui Song, libc-alpha On 30/03/2022 02:07, Fangrui Song wrote: > 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and > siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder > is a rough replacement for this legacy option > (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). > > The reordering requirement does not seem to be needed any longer. We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c does not create _sys_errlist and _sys_siglist with expected sizes defined by glibc ABI. I am trying to fix without resorting to compiler options. > --- > config.make.in | 1 - > configure | 32 -------------------------------- > configure.ac | 19 ------------------- > stdio-common/Makefile | 2 -- > 4 files changed, 54 deletions(-) > > diff --git a/config.make.in b/config.make.in > index 6d43e691f7..ecde84a7da 100644 > --- a/config.make.in > +++ b/config.make.in > @@ -69,7 +69,6 @@ have-selinux = @have_selinux@ > have-libaudit = @have_libaudit@ > have-libcap = @have_libcap@ > have-cc-with-libunwind = @libc_cv_cc_with_libunwind@ > -fno-unit-at-a-time = @fno_unit_at_a_time@ > bind-now = @bindnow@ > have-hash-style = @libc_cv_hashstyle@ > use-default-link = @use_default_link@ > diff --git a/configure b/configure > index 2a3cb49b0b..f836874a58 100755 > --- a/configure > +++ b/configure > @@ -620,7 +620,6 @@ libc_cv_cc_loop_to_function > libc_cv_cc_submachine > libc_cv_cc_nofma > libc_cv_mtls_dialect_gnu2 > -fno_unit_at_a_time > libc_cv_has_glob_dat > libc_cv_hashstyle > libc_cv_fpie > @@ -6319,37 +6318,6 @@ fi > $as_echo "$libc_cv_has_glob_dat" >&6; } > > > -{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for -fno-toplevel-reorder -fno-section-anchors" >&5 > -$as_echo_n "checking for -fno-toplevel-reorder -fno-section-anchors... " >&6; } > -if ${libc_cv_fno_toplevel_reorder+:} false; then : > - $as_echo_n "(cached) " >&6 > -else > - cat > conftest.c <<EOF > -int foo; > -EOF > -if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -S -fno-toplevel-reorder -fno-section-anchors > - conftest.c 1>&5' > - { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > - (eval $ac_try) 2>&5 > - ac_status=$? > - $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > - test $ac_status = 0; }; } > -then > - libc_cv_fno_toplevel_reorder=yes > -else > - libc_cv_fno_toplevel_reorder=no > -fi > -rm -f conftest* > -fi > -{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_fno_toplevel_reorder" >&5 > -$as_echo "$libc_cv_fno_toplevel_reorder" >&6; } > -if test $libc_cv_fno_toplevel_reorder = yes; then > - fno_unit_at_a_time="-fno-toplevel-reorder -fno-section-anchors" > -else > - fno_unit_at_a_time=-fno-unit-at-a-time > -fi > - > - > { $as_echo "$as_me:${as_lineno-$LINENO}: checking for -mtls-dialect=gnu2" >&5 > $as_echo_n "checking for -mtls-dialect=gnu2... " >&6; } > if ${libc_cv_mtls_dialect_gnu2+:} false; then : > diff --git a/configure.ac b/configure.ac > index fa7d3c025b..ec1db36d46 100644 > --- a/configure.ac > +++ b/configure.ac > @@ -1478,25 +1478,6 @@ fi > rm -f conftest*]) > AC_SUBST(libc_cv_has_glob_dat) > > -AC_CACHE_CHECK(for -fno-toplevel-reorder -fno-section-anchors, libc_cv_fno_toplevel_reorder, [dnl > -cat > conftest.c <<EOF > -int foo; > -EOF > -if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -S -fno-toplevel-reorder -fno-section-anchors > - conftest.c 1>&AS_MESSAGE_LOG_FD]) > -then > - libc_cv_fno_toplevel_reorder=yes > -else > - libc_cv_fno_toplevel_reorder=no > -fi > -rm -f conftest*]) > -if test $libc_cv_fno_toplevel_reorder = yes; then > - fno_unit_at_a_time="-fno-toplevel-reorder -fno-section-anchors" > -else > - fno_unit_at_a_time=-fno-unit-at-a-time > -fi > -AC_SUBST(fno_unit_at_a_time) > - > AC_CACHE_CHECK([for -mtls-dialect=gnu2], libc_cv_mtls_dialect_gnu2, > [dnl > cat > conftest.c <<EOF > diff --git a/stdio-common/Makefile b/stdio-common/Makefile > index 435cd8904f..dbaecbd76e 100644 > --- a/stdio-common/Makefile > +++ b/stdio-common/Makefile > @@ -333,8 +333,6 @@ CFLAGS-isoc99_vfscanf.c += -fexceptions > CFLAGS-isoc99_vscanf.c += -fexceptions > CFLAGS-isoc99_fscanf.c += -fexceptions > CFLAGS-isoc99_scanf.c += -fexceptions > -CFLAGS-errlist.c += $(fno-unit-at-a-time) > -CFLAGS-siglist.c += $(fno-unit-at-a-time) > > # scanf14a.c and scanf16a.c test a deprecated extension which is no > # longer visible under most conformance levels; see the source files ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-03-30 12:46 ` Adhemerval Zanella @ 2022-03-30 16:23 ` Fangrui Song 2022-03-30 16:28 ` Adhemerval Zanella 0 siblings, 1 reply; 20+ messages in thread From: Fangrui Song @ 2022-03-30 16:23 UTC (permalink / raw) To: Adhemerval Zanella; +Cc: libc-alpha On 2022-03-30, Adhemerval Zanella wrote: > > >On 30/03/2022 02:07, Fangrui Song wrote: >> 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and >> siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder >> is a rough replacement for this legacy option >> (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). >> >> The reordering requirement does not seem to be needed any longer. > >We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c >does not create _sys_errlist and _sys_siglist with expected sizes defined by >glibc ABI. > >I am trying to fix without resorting to compiler options. DEFINE_COMPAT_ERRLIST does not expand to code/data, just reordeable directives: .globl __GLIBC_2_1_sys_errlist .set __GLIBC_2_1_sys_errlist, _sys_errlist_internal .type __GLIBC_2_1_sys_errlist,@object .size __GLIBC_2_1_sys_errlist, 1000 .globl __GLIBC_2_1__sys_errlist .set __GLIBC_2_1__sys_errlist, _sys_errlist_internal .type __GLIBC_2_1__sys_errlist,@object .size __GLIBC_2_1__sys_errlist, 1000 .symver __GLIBC_2_1_sys_nerr, sys_nerr@GLIBC_2.2.5 .symver __GLIBC_2_1__sys_nerr, _sys_nerr@GLIBC_2.2.5 .symver __GLIBC_2_1_sys_errlist, sys_errlist@GLIBC_2.2.5 .symver __GLIBC_2_1__sys_errlist, _sys_errlist@GLIBC_2.2.5 .globl __GLIBC_2_3_sys_errlist .set __GLIBC_2_3_sys_errlist, _sys_errlist_internal .type __GLIBC_2_3_sys_errlist,@object .size __GLIBC_2_3_sys_errlist, 1008 .globl __GLIBC_2_3__sys_errlist .set __GLIBC_2_3__sys_errlist, _sys_errlist_internal .type __GLIBC_2_3__sys_errlist,@object .size __GLIBC_2_3__sys_errlist, 1008 .symver __GLIBC_2_3_sys_nerr, sys_nerr@GLIBC_2.3 .symver __GLIBC_2_3__sys_nerr, _sys_nerr@GLIBC_2.3 .symver __GLIBC_2_3_sys_errlist, sys_errlist@GLIBC_2.3 .symver __GLIBC_2_3__sys_errlist, _sys_errlist@GLIBC_2.3 .globl __GLIBC_2_4_sys_errlist I do not know whether GCC would reorder these macros. Even yes, that'd just change the .symtab entries in the relocatable object file. The linker behavior remains the same with reordering. >> --- >> config.make.in | 1 - >> configure | 32 -------------------------------- >> configure.ac | 19 ------------------- >> stdio-common/Makefile | 2 -- >> 4 files changed, 54 deletions(-) >> >> diff --git a/config.make.in b/config.make.in >> index 6d43e691f7..ecde84a7da 100644 >> --- a/config.make.in >> +++ b/config.make.in >> @@ -69,7 +69,6 @@ have-selinux = @have_selinux@ >> have-libaudit = @have_libaudit@ >> have-libcap = @have_libcap@ >> have-cc-with-libunwind = @libc_cv_cc_with_libunwind@ >> -fno-unit-at-a-time = @fno_unit_at_a_time@ >> bind-now = @bindnow@ >> have-hash-style = @libc_cv_hashstyle@ >> use-default-link = @use_default_link@ >> diff --git a/configure b/configure >> index 2a3cb49b0b..f836874a58 100755 >> --- a/configure >> +++ b/configure >> @@ -620,7 +620,6 @@ libc_cv_cc_loop_to_function >> libc_cv_cc_submachine >> libc_cv_cc_nofma >> libc_cv_mtls_dialect_gnu2 >> -fno_unit_at_a_time >> libc_cv_has_glob_dat >> libc_cv_hashstyle >> libc_cv_fpie >> @@ -6319,37 +6318,6 @@ fi >> $as_echo "$libc_cv_has_glob_dat" >&6; } >> >> >> -{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for -fno-toplevel-reorder -fno-section-anchors" >&5 >> -$as_echo_n "checking for -fno-toplevel-reorder -fno-section-anchors... " >&6; } >> -if ${libc_cv_fno_toplevel_reorder+:} false; then : >> - $as_echo_n "(cached) " >&6 >> -else >> - cat > conftest.c <<EOF >> -int foo; >> -EOF >> -if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -S -fno-toplevel-reorder -fno-section-anchors >> - conftest.c 1>&5' >> - { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> - (eval $ac_try) 2>&5 >> - ac_status=$? >> - $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> - test $ac_status = 0; }; } >> -then >> - libc_cv_fno_toplevel_reorder=yes >> -else >> - libc_cv_fno_toplevel_reorder=no >> -fi >> -rm -f conftest* >> -fi >> -{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_fno_toplevel_reorder" >&5 >> -$as_echo "$libc_cv_fno_toplevel_reorder" >&6; } >> -if test $libc_cv_fno_toplevel_reorder = yes; then >> - fno_unit_at_a_time="-fno-toplevel-reorder -fno-section-anchors" >> -else >> - fno_unit_at_a_time=-fno-unit-at-a-time >> -fi >> - >> - >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for -mtls-dialect=gnu2" >&5 >> $as_echo_n "checking for -mtls-dialect=gnu2... " >&6; } >> if ${libc_cv_mtls_dialect_gnu2+:} false; then : >> diff --git a/configure.ac b/configure.ac >> index fa7d3c025b..ec1db36d46 100644 >> --- a/configure.ac >> +++ b/configure.ac >> @@ -1478,25 +1478,6 @@ fi >> rm -f conftest*]) >> AC_SUBST(libc_cv_has_glob_dat) >> >> -AC_CACHE_CHECK(for -fno-toplevel-reorder -fno-section-anchors, libc_cv_fno_toplevel_reorder, [dnl >> -cat > conftest.c <<EOF >> -int foo; >> -EOF >> -if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -S -fno-toplevel-reorder -fno-section-anchors >> - conftest.c 1>&AS_MESSAGE_LOG_FD]) >> -then >> - libc_cv_fno_toplevel_reorder=yes >> -else >> - libc_cv_fno_toplevel_reorder=no >> -fi >> -rm -f conftest*]) >> -if test $libc_cv_fno_toplevel_reorder = yes; then >> - fno_unit_at_a_time="-fno-toplevel-reorder -fno-section-anchors" >> -else >> - fno_unit_at_a_time=-fno-unit-at-a-time >> -fi >> -AC_SUBST(fno_unit_at_a_time) >> - >> AC_CACHE_CHECK([for -mtls-dialect=gnu2], libc_cv_mtls_dialect_gnu2, >> [dnl >> cat > conftest.c <<EOF >> diff --git a/stdio-common/Makefile b/stdio-common/Makefile >> index 435cd8904f..dbaecbd76e 100644 >> --- a/stdio-common/Makefile >> +++ b/stdio-common/Makefile >> @@ -333,8 +333,6 @@ CFLAGS-isoc99_vfscanf.c += -fexceptions >> CFLAGS-isoc99_vscanf.c += -fexceptions >> CFLAGS-isoc99_fscanf.c += -fexceptions >> CFLAGS-isoc99_scanf.c += -fexceptions >> -CFLAGS-errlist.c += $(fno-unit-at-a-time) >> -CFLAGS-siglist.c += $(fno-unit-at-a-time) >> >> # scanf14a.c and scanf16a.c test a deprecated extension which is no >> # longer visible under most conformance levels; see the source files ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-03-30 16:23 ` Fangrui Song @ 2022-03-30 16:28 ` Adhemerval Zanella 2022-03-31 3:43 ` Fangrui Song 0 siblings, 1 reply; 20+ messages in thread From: Adhemerval Zanella @ 2022-03-30 16:28 UTC (permalink / raw) To: Fangrui Song; +Cc: libc-alpha On 30/03/2022 13:23, Fangrui Song wrote: > On 2022-03-30, Adhemerval Zanella wrote: >> >> >> On 30/03/2022 02:07, Fangrui Song wrote: >>> 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and >>> siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder >>> is a rough replacement for this legacy option >>> (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). >>> >>> The reordering requirement does not seem to be needed any longer. >> >> We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c >> does not create _sys_errlist and _sys_siglist with expected sizes defined by >> glibc ABI. >> >> I am trying to fix without resorting to compiler options. > > DEFINE_COMPAT_ERRLIST does not expand to code/data, just reordeable directives: > > > .globl __GLIBC_2_1_sys_errlist > .set __GLIBC_2_1_sys_errlist, _sys_errlist_internal > .type __GLIBC_2_1_sys_errlist,@object > .size __GLIBC_2_1_sys_errlist, 1000 > .globl __GLIBC_2_1__sys_errlist > .set __GLIBC_2_1__sys_errlist, _sys_errlist_internal > .type __GLIBC_2_1__sys_errlist,@object > .size __GLIBC_2_1__sys_errlist, 1000 > .symver __GLIBC_2_1_sys_nerr, sys_nerr@GLIBC_2.2.5 > .symver __GLIBC_2_1__sys_nerr, _sys_nerr@GLIBC_2.2.5 > .symver __GLIBC_2_1_sys_errlist, sys_errlist@GLIBC_2.2.5 > .symver __GLIBC_2_1__sys_errlist, _sys_errlist@GLIBC_2.2.5 > .globl __GLIBC_2_3_sys_errlist > .set __GLIBC_2_3_sys_errlist, _sys_errlist_internal > .type __GLIBC_2_3_sys_errlist,@object > .size __GLIBC_2_3_sys_errlist, 1008 > .globl __GLIBC_2_3__sys_errlist > .set __GLIBC_2_3__sys_errlist, _sys_errlist_internal > .type __GLIBC_2_3__sys_errlist,@object > .size __GLIBC_2_3__sys_errlist, 1008 > .symver __GLIBC_2_3_sys_nerr, sys_nerr@GLIBC_2.3 > .symver __GLIBC_2_3__sys_nerr, _sys_nerr@GLIBC_2.3 > .symver __GLIBC_2_3_sys_errlist, sys_errlist@GLIBC_2.3 > .symver __GLIBC_2_3__sys_errlist, _sys_errlist@GLIBC_2.3 > .globl __GLIBC_2_4_sys_errlist > > I do not know whether GCC would reorder these macros. Even yes, > that'd just change the .symtab entries in the relocatable object file. > The linker behavior remains the same with reordering. It does not seem to, just remove the -fno-unit-at-a-time and issue make check-abi and you will see that object size for the compat symbols reference to _sys_err_internal instead of the define compat ones. ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-03-30 16:28 ` Adhemerval Zanella @ 2022-03-31 3:43 ` Fangrui Song 2022-03-31 11:33 ` Adhemerval Zanella 0 siblings, 1 reply; 20+ messages in thread From: Fangrui Song @ 2022-03-31 3:43 UTC (permalink / raw) To: Adhemerval Zanella; +Cc: libc-alpha On 2022-03-30, Adhemerval Zanella wrote: > > >On 30/03/2022 13:23, Fangrui Song wrote: >> On 2022-03-30, Adhemerval Zanella wrote: >>> >>> >>> On 30/03/2022 02:07, Fangrui Song wrote: >>>> 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and >>>> siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder >>>> is a rough replacement for this legacy option >>>> (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). >>>> >>>> The reordering requirement does not seem to be needed any longer. >>> >>> We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c >>> does not create _sys_errlist and _sys_siglist with expected sizes defined by >>> glibc ABI. >>> >>> I am trying to fix without resorting to compiler options. >> >> DEFINE_COMPAT_ERRLIST does not expand to code/data, just reordeable directives: >> >> >> .globl __GLIBC_2_1_sys_errlist >> .set __GLIBC_2_1_sys_errlist, _sys_errlist_internal >> .type __GLIBC_2_1_sys_errlist,@object >> .size __GLIBC_2_1_sys_errlist, 1000 >> .globl __GLIBC_2_1__sys_errlist >> .set __GLIBC_2_1__sys_errlist, _sys_errlist_internal >> .type __GLIBC_2_1__sys_errlist,@object >> .size __GLIBC_2_1__sys_errlist, 1000 >> .symver __GLIBC_2_1_sys_nerr, sys_nerr@GLIBC_2.2.5 >> .symver __GLIBC_2_1__sys_nerr, _sys_nerr@GLIBC_2.2.5 >> .symver __GLIBC_2_1_sys_errlist, sys_errlist@GLIBC_2.2.5 >> .symver __GLIBC_2_1__sys_errlist, _sys_errlist@GLIBC_2.2.5 >> .globl __GLIBC_2_3_sys_errlist >> .set __GLIBC_2_3_sys_errlist, _sys_errlist_internal >> .type __GLIBC_2_3_sys_errlist,@object >> .size __GLIBC_2_3_sys_errlist, 1008 >> .globl __GLIBC_2_3__sys_errlist >> .set __GLIBC_2_3__sys_errlist, _sys_errlist_internal >> .type __GLIBC_2_3__sys_errlist,@object >> .size __GLIBC_2_3__sys_errlist, 1008 >> .symver __GLIBC_2_3_sys_nerr, sys_nerr@GLIBC_2.3 >> .symver __GLIBC_2_3__sys_nerr, _sys_nerr@GLIBC_2.3 >> .symver __GLIBC_2_3_sys_errlist, sys_errlist@GLIBC_2.3 >> .symver __GLIBC_2_3__sys_errlist, _sys_errlist@GLIBC_2.3 >> .globl __GLIBC_2_4_sys_errlist >> >> I do not know whether GCC would reorder these macros. Even yes, >> that'd just change the .symtab entries in the relocatable object file. >> The linker behavior remains the same with reordering. > >It does not seem to, just remove the -fno-unit-at-a-time and issue make >check-abi and you will see that object size for the compat symbols >reference to _sys_err_internal instead of the define compat ones. I see. I think this is a brittle behavior in GNU assembler. Filed https://sourceware.org/bugzilla/show_bug.cgi?id=29012 with detailed information. I have created a patch but I know that will not solve glibc's problem :( ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-03-31 3:43 ` Fangrui Song @ 2022-03-31 11:33 ` Adhemerval Zanella 2022-04-04 15:57 ` Fangrui Song 0 siblings, 1 reply; 20+ messages in thread From: Adhemerval Zanella @ 2022-03-31 11:33 UTC (permalink / raw) To: Fangrui Song; +Cc: libc-alpha On 31/03/2022 00:43, Fangrui Song wrote: > On 2022-03-30, Adhemerval Zanella wrote: >> >> >> On 30/03/2022 13:23, Fangrui Song wrote: >>> On 2022-03-30, Adhemerval Zanella wrote: >>>> >>>> >>>> On 30/03/2022 02:07, Fangrui Song wrote: >>>>> 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and >>>>> siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder >>>>> is a rough replacement for this legacy option >>>>> (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). >>>>> >>>>> The reordering requirement does not seem to be needed any longer. >>>> >>>> We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c >>>> does not create _sys_errlist and _sys_siglist with expected sizes defined by >>>> glibc ABI. >>>> >>>> I am trying to fix without resorting to compiler options. >>> >>> DEFINE_COMPAT_ERRLIST does not expand to code/data, just reordeable directives: >>> >>> >>> .globl __GLIBC_2_1_sys_errlist >>> .set __GLIBC_2_1_sys_errlist, _sys_errlist_internal >>> .type __GLIBC_2_1_sys_errlist,@object >>> .size __GLIBC_2_1_sys_errlist, 1000 >>> .globl __GLIBC_2_1__sys_errlist >>> .set __GLIBC_2_1__sys_errlist, _sys_errlist_internal >>> .type __GLIBC_2_1__sys_errlist,@object >>> .size __GLIBC_2_1__sys_errlist, 1000 >>> .symver __GLIBC_2_1_sys_nerr, sys_nerr@GLIBC_2.2.5 >>> .symver __GLIBC_2_1__sys_nerr, _sys_nerr@GLIBC_2.2.5 >>> .symver __GLIBC_2_1_sys_errlist, sys_errlist@GLIBC_2.2.5 >>> .symver __GLIBC_2_1__sys_errlist, _sys_errlist@GLIBC_2.2.5 >>> .globl __GLIBC_2_3_sys_errlist >>> .set __GLIBC_2_3_sys_errlist, _sys_errlist_internal >>> .type __GLIBC_2_3_sys_errlist,@object >>> .size __GLIBC_2_3_sys_errlist, 1008 >>> .globl __GLIBC_2_3__sys_errlist >>> .set __GLIBC_2_3__sys_errlist, _sys_errlist_internal >>> .type __GLIBC_2_3__sys_errlist,@object >>> .size __GLIBC_2_3__sys_errlist, 1008 >>> .symver __GLIBC_2_3_sys_nerr, sys_nerr@GLIBC_2.3 >>> .symver __GLIBC_2_3__sys_nerr, _sys_nerr@GLIBC_2.3 >>> .symver __GLIBC_2_3_sys_errlist, sys_errlist@GLIBC_2.3 >>> .symver __GLIBC_2_3__sys_errlist, _sys_errlist@GLIBC_2.3 >>> .globl __GLIBC_2_4_sys_errlist >>> >>> I do not know whether GCC would reorder these macros. Even yes, >>> that'd just change the .symtab entries in the relocatable object file. >>> The linker behavior remains the same with reordering. >> >> It does not seem to, just remove the -fno-unit-at-a-time and issue make >> check-abi and you will see that object size for the compat symbols >> reference to _sys_err_internal instead of the define compat ones. > > I see. I think this is a brittle behavior in GNU assembler. Filed > https://sourceware.org/bugzilla/show_bug.cgi?id=29012 with detailed > information. I have created a patch but I know that will not solve > glibc's problem :( It would be good to have this fixes, but unfortunately we need a way to handle this on older binutils. I am kind worried that the only possible way to actually fix this without resorting to any compiler flags is coding the array definitions in assembly direct... ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-03-31 11:33 ` Adhemerval Zanella @ 2022-04-04 15:57 ` Fangrui Song 2022-04-05 14:35 ` Adhemerval Zanella 0 siblings, 1 reply; 20+ messages in thread From: Fangrui Song @ 2022-04-04 15:57 UTC (permalink / raw) To: Adhemerval Zanella; +Cc: libc-alpha On 2022-03-31, Adhemerval Zanella wrote: > > >On 31/03/2022 00:43, Fangrui Song wrote: >> On 2022-03-30, Adhemerval Zanella wrote: >>> >>> >>> On 30/03/2022 13:23, Fangrui Song wrote: >>>> On 2022-03-30, Adhemerval Zanella wrote: >>>>> >>>>> >>>>> On 30/03/2022 02:07, Fangrui Song wrote: >>>>>> 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and >>>>>> siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder >>>>>> is a rough replacement for this legacy option >>>>>> (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). >>>>>> >>>>>> The reordering requirement does not seem to be needed any longer. >>>>> >>>>> We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c >>>>> does not create _sys_errlist and _sys_siglist with expected sizes defined by >>>>> glibc ABI. >>>>> >>>>> I am trying to fix without resorting to compiler options. >>>> >>>> DEFINE_COMPAT_ERRLIST does not expand to code/data, just reordeable directives: >>>> >>>> >>>> .globl __GLIBC_2_1_sys_errlist >>>> .set __GLIBC_2_1_sys_errlist, _sys_errlist_internal >>>> .type __GLIBC_2_1_sys_errlist,@object >>>> .size __GLIBC_2_1_sys_errlist, 1000 >>>> .globl __GLIBC_2_1__sys_errlist >>>> .set __GLIBC_2_1__sys_errlist, _sys_errlist_internal >>>> .type __GLIBC_2_1__sys_errlist,@object >>>> .size __GLIBC_2_1__sys_errlist, 1000 >>>> .symver __GLIBC_2_1_sys_nerr, sys_nerr@GLIBC_2.2.5 >>>> .symver __GLIBC_2_1__sys_nerr, _sys_nerr@GLIBC_2.2.5 >>>> .symver __GLIBC_2_1_sys_errlist, sys_errlist@GLIBC_2.2.5 >>>> .symver __GLIBC_2_1__sys_errlist, _sys_errlist@GLIBC_2.2.5 >>>> .globl __GLIBC_2_3_sys_errlist >>>> .set __GLIBC_2_3_sys_errlist, _sys_errlist_internal >>>> .type __GLIBC_2_3_sys_errlist,@object >>>> .size __GLIBC_2_3_sys_errlist, 1008 >>>> .globl __GLIBC_2_3__sys_errlist >>>> .set __GLIBC_2_3__sys_errlist, _sys_errlist_internal >>>> .type __GLIBC_2_3__sys_errlist,@object >>>> .size __GLIBC_2_3__sys_errlist, 1008 >>>> .symver __GLIBC_2_3_sys_nerr, sys_nerr@GLIBC_2.3 >>>> .symver __GLIBC_2_3__sys_nerr, _sys_nerr@GLIBC_2.3 >>>> .symver __GLIBC_2_3_sys_errlist, sys_errlist@GLIBC_2.3 >>>> .symver __GLIBC_2_3__sys_errlist, _sys_errlist@GLIBC_2.3 >>>> .globl __GLIBC_2_4_sys_errlist >>>> >>>> I do not know whether GCC would reorder these macros. Even yes, >>>> that'd just change the .symtab entries in the relocatable object file. >>>> The linker behavior remains the same with reordering. >>> >>> It does not seem to, just remove the -fno-unit-at-a-time and issue make >>> check-abi and you will see that object size for the compat symbols >>> reference to _sys_err_internal instead of the define compat ones. >> >> I see. I think this is a brittle behavior in GNU assembler. Filed >> https://sourceware.org/bugzilla/show_bug.cgi?id=29012 with detailed >> information. I have created a patch but I know that will not solve >> glibc's problem :( > >It would be good to have this fixes, but unfortunately we need a way >to handle this on older binutils. I am kind worried that the only >possible way to actually fix this without resorting to any compiler >flags is coding the array definitions in assembly direct... The GNU assembler issue has been fixed https://sourceware.org/bugzilla/show_bug.cgi?id=29012 (milestone 2.39, way larger than the current required version: 2.25) Switching to assembly output doesn't seem bad :-) If you keep the compiler driver option but need to refactor the nearby code, you may drop -fno-unit-at-a-time. It was added in 2006 (somewhere between GCC 4.1 and 4.4), while glibc requires GCC>=6.2. ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-04 15:57 ` Fangrui Song @ 2022-04-05 14:35 ` Adhemerval Zanella 2022-04-05 16:22 ` Fāng-ruì Sòng 0 siblings, 1 reply; 20+ messages in thread From: Adhemerval Zanella @ 2022-04-05 14:35 UTC (permalink / raw) To: Fangrui Song; +Cc: libc-alpha On 04/04/2022 12:57, Fangrui Song wrote: > > On 2022-03-31, Adhemerval Zanella wrote: >> >> >> On 31/03/2022 00:43, Fangrui Song wrote: >>> On 2022-03-30, Adhemerval Zanella wrote: >>>> >>>> >>>> On 30/03/2022 13:23, Fangrui Song wrote: >>>>> On 2022-03-30, Adhemerval Zanella wrote: >>>>>> >>>>>> >>>>>> On 30/03/2022 02:07, Fangrui Song wrote: >>>>>>> 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and >>>>>>> siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder >>>>>>> is a rough replacement for this legacy option >>>>>>> (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). >>>>>>> >>>>>>> The reordering requirement does not seem to be needed any longer. >>>>>> >>>>>> We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c >>>>>> does not create _sys_errlist and _sys_siglist with expected sizes defined by >>>>>> glibc ABI. >>>>>> >>>>>> I am trying to fix without resorting to compiler options. >>>>> >>>>> DEFINE_COMPAT_ERRLIST does not expand to code/data, just reordeable directives: >>>>> >>>>> >>>>> .globl __GLIBC_2_1_sys_errlist >>>>> .set __GLIBC_2_1_sys_errlist, _sys_errlist_internal >>>>> .type __GLIBC_2_1_sys_errlist,@object >>>>> .size __GLIBC_2_1_sys_errlist, 1000 >>>>> .globl __GLIBC_2_1__sys_errlist >>>>> .set __GLIBC_2_1__sys_errlist, _sys_errlist_internal >>>>> .type __GLIBC_2_1__sys_errlist,@object >>>>> .size __GLIBC_2_1__sys_errlist, 1000 >>>>> .symver __GLIBC_2_1_sys_nerr, sys_nerr@GLIBC_2.2.5 >>>>> .symver __GLIBC_2_1__sys_nerr, _sys_nerr@GLIBC_2.2.5 >>>>> .symver __GLIBC_2_1_sys_errlist, sys_errlist@GLIBC_2.2.5 >>>>> .symver __GLIBC_2_1__sys_errlist, _sys_errlist@GLIBC_2.2.5 >>>>> .globl __GLIBC_2_3_sys_errlist >>>>> .set __GLIBC_2_3_sys_errlist, _sys_errlist_internal >>>>> .type __GLIBC_2_3_sys_errlist,@object >>>>> .size __GLIBC_2_3_sys_errlist, 1008 >>>>> .globl __GLIBC_2_3__sys_errlist >>>>> .set __GLIBC_2_3__sys_errlist, _sys_errlist_internal >>>>> .type __GLIBC_2_3__sys_errlist,@object >>>>> .size __GLIBC_2_3__sys_errlist, 1008 >>>>> .symver __GLIBC_2_3_sys_nerr, sys_nerr@GLIBC_2.3 >>>>> .symver __GLIBC_2_3__sys_nerr, _sys_nerr@GLIBC_2.3 >>>>> .symver __GLIBC_2_3_sys_errlist, sys_errlist@GLIBC_2.3 >>>>> .symver __GLIBC_2_3__sys_errlist, _sys_errlist@GLIBC_2.3 >>>>> .globl __GLIBC_2_4_sys_errlist >>>>> >>>>> I do not know whether GCC would reorder these macros. Even yes, >>>>> that'd just change the .symtab entries in the relocatable object file. >>>>> The linker behavior remains the same with reordering. >>>> >>>> It does not seem to, just remove the -fno-unit-at-a-time and issue make >>>> check-abi and you will see that object size for the compat symbols >>>> reference to _sys_err_internal instead of the define compat ones. >>> >>> I see. I think this is a brittle behavior in GNU assembler. Filed >>> https://sourceware.org/bugzilla/show_bug.cgi?id=29012 with detailed >>> information. I have created a patch but I know that will not solve >>> glibc's problem :( >> >> It would be good to have this fixes, but unfortunately we need a way >> to handle this on older binutils. I am kind worried that the only >> possible way to actually fix this without resorting to any compiler >> flags is coding the array definitions in assembly direct... > > The GNU assembler issue has been fixed https://sourceware.org/bugzilla/show_bug.cgi?id=29012 > (milestone 2.39, way larger than the current required version: 2.25) > > Switching to assembly output doesn't seem bad :-) > > If you keep the compiler driver option but need to refactor the nearby > code, you may drop -fno-unit-at-a-time. It was added in 2006 (somewhere > between GCC 4.1 and 4.4), while glibc requires GCC>=6.2. Good to know we won't need to rely on compiler flags to get the expected correct asm directives. I am still struggling to get a fix without resorting to compiler flags, but without much success. Trying to move it to assembly might be tricky, I am not sure if the data directives would be architecture agnostic. ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-05 14:35 ` Adhemerval Zanella @ 2022-04-05 16:22 ` Fāng-ruì Sòng 2022-04-05 16:40 ` Adhemerval Zanella 0 siblings, 1 reply; 20+ messages in thread From: Fāng-ruì Sòng @ 2022-04-05 16:22 UTC (permalink / raw) To: Adhemerval Zanella; +Cc: libc-alpha On Tue, Apr 5, 2022 at 8:35 AM Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote: > > > > On 04/04/2022 12:57, Fangrui Song wrote: > > > > On 2022-03-31, Adhemerval Zanella wrote: > >> > >> > >> On 31/03/2022 00:43, Fangrui Song wrote: > >>> On 2022-03-30, Adhemerval Zanella wrote: > >>>> > >>>> > >>>> On 30/03/2022 13:23, Fangrui Song wrote: > >>>>> On 2022-03-30, Adhemerval Zanella wrote: > >>>>>> > >>>>>> > >>>>>> On 30/03/2022 02:07, Fangrui Song wrote: > >>>>>>> 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and > >>>>>>> siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder > >>>>>>> is a rough replacement for this legacy option > >>>>>>> (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). > >>>>>>> > >>>>>>> The reordering requirement does not seem to be needed any longer. > >>>>>> > >>>>>> We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c > >>>>>> does not create _sys_errlist and _sys_siglist with expected sizes defined by > >>>>>> glibc ABI. > >>>>>> > >>>>>> I am trying to fix without resorting to compiler options. > >>>>> > >>>>> DEFINE_COMPAT_ERRLIST does not expand to code/data, just reordeable directives: > >>>>> > >>>>> > >>>>> .globl __GLIBC_2_1_sys_errlist > >>>>> .set __GLIBC_2_1_sys_errlist, _sys_errlist_internal > >>>>> .type __GLIBC_2_1_sys_errlist,@object > >>>>> .size __GLIBC_2_1_sys_errlist, 1000 > >>>>> .globl __GLIBC_2_1__sys_errlist > >>>>> .set __GLIBC_2_1__sys_errlist, _sys_errlist_internal > >>>>> .type __GLIBC_2_1__sys_errlist,@object > >>>>> .size __GLIBC_2_1__sys_errlist, 1000 > >>>>> .symver __GLIBC_2_1_sys_nerr, sys_nerr@GLIBC_2.2.5 > >>>>> .symver __GLIBC_2_1__sys_nerr, _sys_nerr@GLIBC_2.2.5 > >>>>> .symver __GLIBC_2_1_sys_errlist, sys_errlist@GLIBC_2.2.5 > >>>>> .symver __GLIBC_2_1__sys_errlist, _sys_errlist@GLIBC_2.2.5 > >>>>> .globl __GLIBC_2_3_sys_errlist > >>>>> .set __GLIBC_2_3_sys_errlist, _sys_errlist_internal > >>>>> .type __GLIBC_2_3_sys_errlist,@object > >>>>> .size __GLIBC_2_3_sys_errlist, 1008 > >>>>> .globl __GLIBC_2_3__sys_errlist > >>>>> .set __GLIBC_2_3__sys_errlist, _sys_errlist_internal > >>>>> .type __GLIBC_2_3__sys_errlist,@object > >>>>> .size __GLIBC_2_3__sys_errlist, 1008 > >>>>> .symver __GLIBC_2_3_sys_nerr, sys_nerr@GLIBC_2.3 > >>>>> .symver __GLIBC_2_3__sys_nerr, _sys_nerr@GLIBC_2.3 > >>>>> .symver __GLIBC_2_3_sys_errlist, sys_errlist@GLIBC_2.3 > >>>>> .symver __GLIBC_2_3__sys_errlist, _sys_errlist@GLIBC_2.3 > >>>>> .globl __GLIBC_2_4_sys_errlist > >>>>> > >>>>> I do not know whether GCC would reorder these macros. Even yes, > >>>>> that'd just change the .symtab entries in the relocatable object file. > >>>>> The linker behavior remains the same with reordering. > >>>> > >>>> It does not seem to, just remove the -fno-unit-at-a-time and issue make > >>>> check-abi and you will see that object size for the compat symbols > >>>> reference to _sys_err_internal instead of the define compat ones. > >>> > >>> I see. I think this is a brittle behavior in GNU assembler. Filed > >>> https://sourceware.org/bugzilla/show_bug.cgi?id=29012 with detailed > >>> information. I have created a patch but I know that will not solve > >>> glibc's problem :( > >> > >> It would be good to have this fixes, but unfortunately we need a way > >> to handle this on older binutils. I am kind worried that the only > >> possible way to actually fix this without resorting to any compiler > >> flags is coding the array definitions in assembly direct... > > > > The GNU assembler issue has been fixed https://sourceware.org/bugzilla/show_bug.cgi?id=29012 > > (milestone 2.39, way larger than the current required version: 2.25) > > > > Switching to assembly output doesn't seem bad :-) > > > > If you keep the compiler driver option but need to refactor the nearby > > code, you may drop -fno-unit-at-a-time. It was added in 2006 (somewhere > > between GCC 4.1 and 4.4), while glibc requires GCC>=6.2. > > Good to know we won't need to rely on compiler flags to get the expected > correct asm directives. I am still struggling to get a fix without resorting > to compiler flags, but without much success. Trying to move it to assembly > might be tricky, I am not sure if the data directives would be architecture > agnostic. Many directives are architecture-independent: https://sourceware.org/binutils/docs/as/Pseudo-Ops.html#Pseudo-Ops binutils-gdb/gas/read.c:346 The `portable[]` array. To support Clang, no refactoring is probably needed: just change fno_unit_at_a_time to only specify -fno-toplevel-reorder (and rename it), not th legacy -fno-unit-at-a-time. ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-05 16:22 ` Fāng-ruì Sòng @ 2022-04-05 16:40 ` Adhemerval Zanella 2022-04-05 16:44 ` Fāng-ruì Sòng 0 siblings, 1 reply; 20+ messages in thread From: Adhemerval Zanella @ 2022-04-05 16:40 UTC (permalink / raw) To: Fāng-ruì Sòng; +Cc: libc-alpha On 05/04/2022 13:22, Fāng-ruì Sòng wrote: > On Tue, Apr 5, 2022 at 8:35 AM Adhemerval Zanella > <adhemerval.zanella@linaro.org> wrote: >> >> >> >> On 04/04/2022 12:57, Fangrui Song wrote: >>> >>> On 2022-03-31, Adhemerval Zanella wrote: >>>> >>>> >>>> On 31/03/2022 00:43, Fangrui Song wrote: >>>>> On 2022-03-30, Adhemerval Zanella wrote: >>>>>> >>>>>> >>>>>> On 30/03/2022 13:23, Fangrui Song wrote: >>>>>>> On 2022-03-30, Adhemerval Zanella wrote: >>>>>>>> >>>>>>>> >>>>>>>> On 30/03/2022 02:07, Fangrui Song wrote: >>>>>>>>> 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and >>>>>>>>> siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder >>>>>>>>> is a rough replacement for this legacy option >>>>>>>>> (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). >>>>>>>>> >>>>>>>>> The reordering requirement does not seem to be needed any longer. >>>>>>>> >>>>>>>> We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c >>>>>>>> does not create _sys_errlist and _sys_siglist with expected sizes defined by >>>>>>>> glibc ABI. >>>>>>>> >>>>>>>> I am trying to fix without resorting to compiler options. >>>>>>> >>>>>>> DEFINE_COMPAT_ERRLIST does not expand to code/data, just reordeable directives: >>>>>>> >>>>>>> >>>>>>> .globl __GLIBC_2_1_sys_errlist >>>>>>> .set __GLIBC_2_1_sys_errlist, _sys_errlist_internal >>>>>>> .type __GLIBC_2_1_sys_errlist,@object >>>>>>> .size __GLIBC_2_1_sys_errlist, 1000 >>>>>>> .globl __GLIBC_2_1__sys_errlist >>>>>>> .set __GLIBC_2_1__sys_errlist, _sys_errlist_internal >>>>>>> .type __GLIBC_2_1__sys_errlist,@object >>>>>>> .size __GLIBC_2_1__sys_errlist, 1000 >>>>>>> .symver __GLIBC_2_1_sys_nerr, sys_nerr@GLIBC_2.2.5 >>>>>>> .symver __GLIBC_2_1__sys_nerr, _sys_nerr@GLIBC_2.2.5 >>>>>>> .symver __GLIBC_2_1_sys_errlist, sys_errlist@GLIBC_2.2.5 >>>>>>> .symver __GLIBC_2_1__sys_errlist, _sys_errlist@GLIBC_2.2.5 >>>>>>> .globl __GLIBC_2_3_sys_errlist >>>>>>> .set __GLIBC_2_3_sys_errlist, _sys_errlist_internal >>>>>>> .type __GLIBC_2_3_sys_errlist,@object >>>>>>> .size __GLIBC_2_3_sys_errlist, 1008 >>>>>>> .globl __GLIBC_2_3__sys_errlist >>>>>>> .set __GLIBC_2_3__sys_errlist, _sys_errlist_internal >>>>>>> .type __GLIBC_2_3__sys_errlist,@object >>>>>>> .size __GLIBC_2_3__sys_errlist, 1008 >>>>>>> .symver __GLIBC_2_3_sys_nerr, sys_nerr@GLIBC_2.3 >>>>>>> .symver __GLIBC_2_3__sys_nerr, _sys_nerr@GLIBC_2.3 >>>>>>> .symver __GLIBC_2_3_sys_errlist, sys_errlist@GLIBC_2.3 >>>>>>> .symver __GLIBC_2_3__sys_errlist, _sys_errlist@GLIBC_2.3 >>>>>>> .globl __GLIBC_2_4_sys_errlist >>>>>>> >>>>>>> I do not know whether GCC would reorder these macros. Even yes, >>>>>>> that'd just change the .symtab entries in the relocatable object file. >>>>>>> The linker behavior remains the same with reordering. >>>>>> >>>>>> It does not seem to, just remove the -fno-unit-at-a-time and issue make >>>>>> check-abi and you will see that object size for the compat symbols >>>>>> reference to _sys_err_internal instead of the define compat ones. >>>>> >>>>> I see. I think this is a brittle behavior in GNU assembler. Filed >>>>> https://sourceware.org/bugzilla/show_bug.cgi?id=29012 with detailed >>>>> information. I have created a patch but I know that will not solve >>>>> glibc's problem :( >>>> >>>> It would be good to have this fixes, but unfortunately we need a way >>>> to handle this on older binutils. I am kind worried that the only >>>> possible way to actually fix this without resorting to any compiler >>>> flags is coding the array definitions in assembly direct... >>> >>> The GNU assembler issue has been fixed https://sourceware.org/bugzilla/show_bug.cgi?id=29012 >>> (milestone 2.39, way larger than the current required version: 2.25) >>> >>> Switching to assembly output doesn't seem bad :-) >>> >>> If you keep the compiler driver option but need to refactor the nearby >>> code, you may drop -fno-unit-at-a-time. It was added in 2006 (somewhere >>> between GCC 4.1 and 4.4), while glibc requires GCC>=6.2. >> >> Good to know we won't need to rely on compiler flags to get the expected >> correct asm directives. I am still struggling to get a fix without resorting >> to compiler flags, but without much success. Trying to move it to assembly >> might be tricky, I am not sure if the data directives would be architecture >> agnostic. > > Many directives are architecture-independent: > https://sourceware.org/binutils/docs/as/Pseudo-Ops.html#Pseudo-Ops > binutils-gdb/gas/read.c:346 The `portable[]` array. I think we can make it work with asciz directive. > > To support Clang, no refactoring is probably needed: just change > fno_unit_at_a_time to only specify -fno-toplevel-reorder (and rename > it), not th legacy -fno-unit-at-a-time. Afaik llvm does not support -fno-toplevel-reorder ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-05 16:40 ` Adhemerval Zanella @ 2022-04-05 16:44 ` Fāng-ruì Sòng 2022-04-05 16:49 ` Adhemerval Zanella 0 siblings, 1 reply; 20+ messages in thread From: Fāng-ruì Sòng @ 2022-04-05 16:44 UTC (permalink / raw) To: Adhemerval Zanella; +Cc: libc-alpha On Tue, Apr 5, 2022 at 10:40 AM Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote: > > > > On 05/04/2022 13:22, Fāng-ruì Sòng wrote: > > On Tue, Apr 5, 2022 at 8:35 AM Adhemerval Zanella > > <adhemerval.zanella@linaro.org> wrote: > >> > >> > >> > >> On 04/04/2022 12:57, Fangrui Song wrote: > >>> > >>> On 2022-03-31, Adhemerval Zanella wrote: > >>>> > >>>> > >>>> On 31/03/2022 00:43, Fangrui Song wrote: > >>>>> On 2022-03-30, Adhemerval Zanella wrote: > >>>>>> > >>>>>> > >>>>>> On 30/03/2022 13:23, Fangrui Song wrote: > >>>>>>> On 2022-03-30, Adhemerval Zanella wrote: > >>>>>>>> > >>>>>>>> > >>>>>>>> On 30/03/2022 02:07, Fangrui Song wrote: > >>>>>>>>> 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and > >>>>>>>>> siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder > >>>>>>>>> is a rough replacement for this legacy option > >>>>>>>>> (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). > >>>>>>>>> > >>>>>>>>> The reordering requirement does not seem to be needed any longer. > >>>>>>>> > >>>>>>>> We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c > >>>>>>>> does not create _sys_errlist and _sys_siglist with expected sizes defined by > >>>>>>>> glibc ABI. > >>>>>>>> > >>>>>>>> I am trying to fix without resorting to compiler options. > >>>>>>> > >>>>>>> DEFINE_COMPAT_ERRLIST does not expand to code/data, just reordeable directives: > >>>>>>> > >>>>>>> > >>>>>>> .globl __GLIBC_2_1_sys_errlist > >>>>>>> .set __GLIBC_2_1_sys_errlist, _sys_errlist_internal > >>>>>>> .type __GLIBC_2_1_sys_errlist,@object > >>>>>>> .size __GLIBC_2_1_sys_errlist, 1000 > >>>>>>> .globl __GLIBC_2_1__sys_errlist > >>>>>>> .set __GLIBC_2_1__sys_errlist, _sys_errlist_internal > >>>>>>> .type __GLIBC_2_1__sys_errlist,@object > >>>>>>> .size __GLIBC_2_1__sys_errlist, 1000 > >>>>>>> .symver __GLIBC_2_1_sys_nerr, sys_nerr@GLIBC_2.2.5 > >>>>>>> .symver __GLIBC_2_1__sys_nerr, _sys_nerr@GLIBC_2.2.5 > >>>>>>> .symver __GLIBC_2_1_sys_errlist, sys_errlist@GLIBC_2.2.5 > >>>>>>> .symver __GLIBC_2_1__sys_errlist, _sys_errlist@GLIBC_2.2.5 > >>>>>>> .globl __GLIBC_2_3_sys_errlist > >>>>>>> .set __GLIBC_2_3_sys_errlist, _sys_errlist_internal > >>>>>>> .type __GLIBC_2_3_sys_errlist,@object > >>>>>>> .size __GLIBC_2_3_sys_errlist, 1008 > >>>>>>> .globl __GLIBC_2_3__sys_errlist > >>>>>>> .set __GLIBC_2_3__sys_errlist, _sys_errlist_internal > >>>>>>> .type __GLIBC_2_3__sys_errlist,@object > >>>>>>> .size __GLIBC_2_3__sys_errlist, 1008 > >>>>>>> .symver __GLIBC_2_3_sys_nerr, sys_nerr@GLIBC_2.3 > >>>>>>> .symver __GLIBC_2_3__sys_nerr, _sys_nerr@GLIBC_2.3 > >>>>>>> .symver __GLIBC_2_3_sys_errlist, sys_errlist@GLIBC_2.3 > >>>>>>> .symver __GLIBC_2_3__sys_errlist, _sys_errlist@GLIBC_2.3 > >>>>>>> .globl __GLIBC_2_4_sys_errlist > >>>>>>> > >>>>>>> I do not know whether GCC would reorder these macros. Even yes, > >>>>>>> that'd just change the .symtab entries in the relocatable object file. > >>>>>>> The linker behavior remains the same with reordering. > >>>>>> > >>>>>> It does not seem to, just remove the -fno-unit-at-a-time and issue make > >>>>>> check-abi and you will see that object size for the compat symbols > >>>>>> reference to _sys_err_internal instead of the define compat ones. > >>>>> > >>>>> I see. I think this is a brittle behavior in GNU assembler. Filed > >>>>> https://sourceware.org/bugzilla/show_bug.cgi?id=29012 with detailed > >>>>> information. I have created a patch but I know that will not solve > >>>>> glibc's problem :( > >>>> > >>>> It would be good to have this fixes, but unfortunately we need a way > >>>> to handle this on older binutils. I am kind worried that the only > >>>> possible way to actually fix this without resorting to any compiler > >>>> flags is coding the array definitions in assembly direct... > >>> > >>> The GNU assembler issue has been fixed https://sourceware.org/bugzilla/show_bug.cgi?id=29012 > >>> (milestone 2.39, way larger than the current required version: 2.25) > >>> > >>> Switching to assembly output doesn't seem bad :-) > >>> > >>> If you keep the compiler driver option but need to refactor the nearby > >>> code, you may drop -fno-unit-at-a-time. It was added in 2006 (somewhere > >>> between GCC 4.1 and 4.4), while glibc requires GCC>=6.2. > >> > >> Good to know we won't need to rely on compiler flags to get the expected > >> correct asm directives. I am still struggling to get a fix without resorting > >> to compiler flags, but without much success. Trying to move it to assembly > >> might be tricky, I am not sure if the data directives would be architecture > >> agnostic. > > > > Many directives are architecture-independent: > > https://sourceware.org/binutils/docs/as/Pseudo-Ops.html#Pseudo-Ops > > binutils-gdb/gas/read.c:346 The `portable[]` array. > > I think we can make it work with asciz directive. > > > > > To support Clang, no refactoring is probably needed: just change > > fno_unit_at_a_time to only specify -fno-toplevel-reorder (and rename > > it), not th legacy -fno-unit-at-a-time. > > Afaik llvm does not support -fno-toplevel-reorder It doesn't, but its integrated assembler does not need the option to have the desired semantics. I have a note that the new GNU as behavior is quite similar to LLVM's integrated assembler since 2014-03: https://sourceware.org/bugzilla/show_bug.cgi?id=29012#c1 ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-05 16:44 ` Fāng-ruì Sòng @ 2022-04-05 16:49 ` Adhemerval Zanella 2022-04-05 17:53 ` Florian Weimer 2022-04-07 7:02 ` Fāng-ruì Sòng 0 siblings, 2 replies; 20+ messages in thread From: Adhemerval Zanella @ 2022-04-05 16:49 UTC (permalink / raw) To: Fāng-ruì Sòng; +Cc: libc-alpha On 05/04/2022 13:44, Fāng-ruì Sòng wrote: > On Tue, Apr 5, 2022 at 10:40 AM Adhemerval Zanella > <adhemerval.zanella@linaro.org> wrote: >> >> >> >> On 05/04/2022 13:22, Fāng-ruì Sòng wrote: >>> On Tue, Apr 5, 2022 at 8:35 AM Adhemerval Zanella >>> <adhemerval.zanella@linaro.org> wrote: >>>> >>>> >>>> >>>> On 04/04/2022 12:57, Fangrui Song wrote: >>>>> >>>>> On 2022-03-31, Adhemerval Zanella wrote: >>>>>> >>>>>> >>>>>> On 31/03/2022 00:43, Fangrui Song wrote: >>>>>>> On 2022-03-30, Adhemerval Zanella wrote: >>>>>>>> >>>>>>>> >>>>>>>> On 30/03/2022 13:23, Fangrui Song wrote: >>>>>>>>> On 2022-03-30, Adhemerval Zanella wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On 30/03/2022 02:07, Fangrui Song wrote: >>>>>>>>>>> 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and >>>>>>>>>>> siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder >>>>>>>>>>> is a rough replacement for this legacy option >>>>>>>>>>> (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). >>>>>>>>>>> >>>>>>>>>>> The reordering requirement does not seem to be needed any longer. >>>>>>>>>> >>>>>>>>>> We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c >>>>>>>>>> does not create _sys_errlist and _sys_siglist with expected sizes defined by >>>>>>>>>> glibc ABI. >>>>>>>>>> >>>>>>>>>> I am trying to fix without resorting to compiler options. >>>>>>>>> >>>>>>>>> DEFINE_COMPAT_ERRLIST does not expand to code/data, just reordeable directives: >>>>>>>>> >>>>>>>>> >>>>>>>>> .globl __GLIBC_2_1_sys_errlist >>>>>>>>> .set __GLIBC_2_1_sys_errlist, _sys_errlist_internal >>>>>>>>> .type __GLIBC_2_1_sys_errlist,@object >>>>>>>>> .size __GLIBC_2_1_sys_errlist, 1000 >>>>>>>>> .globl __GLIBC_2_1__sys_errlist >>>>>>>>> .set __GLIBC_2_1__sys_errlist, _sys_errlist_internal >>>>>>>>> .type __GLIBC_2_1__sys_errlist,@object >>>>>>>>> .size __GLIBC_2_1__sys_errlist, 1000 >>>>>>>>> .symver __GLIBC_2_1_sys_nerr, sys_nerr@GLIBC_2.2.5 >>>>>>>>> .symver __GLIBC_2_1__sys_nerr, _sys_nerr@GLIBC_2.2.5 >>>>>>>>> .symver __GLIBC_2_1_sys_errlist, sys_errlist@GLIBC_2.2.5 >>>>>>>>> .symver __GLIBC_2_1__sys_errlist, _sys_errlist@GLIBC_2.2.5 >>>>>>>>> .globl __GLIBC_2_3_sys_errlist >>>>>>>>> .set __GLIBC_2_3_sys_errlist, _sys_errlist_internal >>>>>>>>> .type __GLIBC_2_3_sys_errlist,@object >>>>>>>>> .size __GLIBC_2_3_sys_errlist, 1008 >>>>>>>>> .globl __GLIBC_2_3__sys_errlist >>>>>>>>> .set __GLIBC_2_3__sys_errlist, _sys_errlist_internal >>>>>>>>> .type __GLIBC_2_3__sys_errlist,@object >>>>>>>>> .size __GLIBC_2_3__sys_errlist, 1008 >>>>>>>>> .symver __GLIBC_2_3_sys_nerr, sys_nerr@GLIBC_2.3 >>>>>>>>> .symver __GLIBC_2_3__sys_nerr, _sys_nerr@GLIBC_2.3 >>>>>>>>> .symver __GLIBC_2_3_sys_errlist, sys_errlist@GLIBC_2.3 >>>>>>>>> .symver __GLIBC_2_3__sys_errlist, _sys_errlist@GLIBC_2.3 >>>>>>>>> .globl __GLIBC_2_4_sys_errlist >>>>>>>>> >>>>>>>>> I do not know whether GCC would reorder these macros. Even yes, >>>>>>>>> that'd just change the .symtab entries in the relocatable object file. >>>>>>>>> The linker behavior remains the same with reordering. >>>>>>>> >>>>>>>> It does not seem to, just remove the -fno-unit-at-a-time and issue make >>>>>>>> check-abi and you will see that object size for the compat symbols >>>>>>>> reference to _sys_err_internal instead of the define compat ones. >>>>>>> >>>>>>> I see. I think this is a brittle behavior in GNU assembler. Filed >>>>>>> https://sourceware.org/bugzilla/show_bug.cgi?id=29012 with detailed >>>>>>> information. I have created a patch but I know that will not solve >>>>>>> glibc's problem :( >>>>>> >>>>>> It would be good to have this fixes, but unfortunately we need a way >>>>>> to handle this on older binutils. I am kind worried that the only >>>>>> possible way to actually fix this without resorting to any compiler >>>>>> flags is coding the array definitions in assembly direct... >>>>> >>>>> The GNU assembler issue has been fixed https://sourceware.org/bugzilla/show_bug.cgi?id=29012 >>>>> (milestone 2.39, way larger than the current required version: 2.25) >>>>> >>>>> Switching to assembly output doesn't seem bad :-) >>>>> >>>>> If you keep the compiler driver option but need to refactor the nearby >>>>> code, you may drop -fno-unit-at-a-time. It was added in 2006 (somewhere >>>>> between GCC 4.1 and 4.4), while glibc requires GCC>=6.2. >>>> >>>> Good to know we won't need to rely on compiler flags to get the expected >>>> correct asm directives. I am still struggling to get a fix without resorting >>>> to compiler flags, but without much success. Trying to move it to assembly >>>> might be tricky, I am not sure if the data directives would be architecture >>>> agnostic. >>> >>> Many directives are architecture-independent: >>> https://sourceware.org/binutils/docs/as/Pseudo-Ops.html#Pseudo-Ops >>> binutils-gdb/gas/read.c:346 The `portable[]` array. >> >> I think we can make it work with asciz directive. >> >>> >>> To support Clang, no refactoring is probably needed: just change >>> fno_unit_at_a_time to only specify -fno-toplevel-reorder (and rename >>> it), not th legacy -fno-unit-at-a-time. >> >> Afaik llvm does not support -fno-toplevel-reorder > > It doesn't, but its integrated assembler does not need the option to > have the desired semantics. I have a note that the new GNU as behavior > is quite similar to LLVM's integrated assembler since 2014-03: > https://sourceware.org/bugzilla/show_bug.cgi?id=29012#c1 This is not what I am seeing on my clang branch, where clang with integrated moves the global asm directives to the top of the file. And it makes check-abi fail due the _sys_errlist/sys_errlist being with wrong value. ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-05 16:49 ` Adhemerval Zanella @ 2022-04-05 17:53 ` Florian Weimer 2022-04-05 20:01 ` Adhemerval Zanella 2022-04-07 7:02 ` Fāng-ruì Sòng 1 sibling, 1 reply; 20+ messages in thread From: Florian Weimer @ 2022-04-05 17:53 UTC (permalink / raw) To: Adhemerval Zanella via Libc-alpha * Adhemerval Zanella via Libc-alpha: > This is not what I am seeing on my clang branch, where clang with integrated > moves the global asm directives to the top of the file. And it makes > check-abi fail due the _sys_errlist/sys_errlist being with wrong value. You can move the directives to the bottom of the file by creating a temporary .s file and #include that from a wrapper .S file that #includes the .s file. Or perhaps generate the assembler file directly, as in elf/dl-debug-symbols.S, which solves the same problem. Linux <errno.h> should be includable directly from assembler, hopefully that's true for the Hurd version as well. Thanks, Florian ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-05 17:53 ` Florian Weimer @ 2022-04-05 20:01 ` Adhemerval Zanella 2022-04-05 20:26 ` Florian Weimer 0 siblings, 1 reply; 20+ messages in thread From: Adhemerval Zanella @ 2022-04-05 20:01 UTC (permalink / raw) To: Florian Weimer, Adhemerval Zanella via Libc-alpha On 05/04/2022 14:53, Florian Weimer wrote: > * Adhemerval Zanella via Libc-alpha: > >> This is not what I am seeing on my clang branch, where clang with integrated >> moves the global asm directives to the top of the file. And it makes >> check-abi fail due the _sys_errlist/sys_errlist being with wrong value. > > You can move the directives to the bottom of the file by creating a > temporary .s file and #include that from a wrapper .S file that > #includes the .s file. Not sure I am following your suggestion here, do you mean get the -S output file from compiler? > > Or perhaps generate the assembler file directly, as in > elf/dl-debug-symbols.S, which solves the same problem. Linux <errno.h> > should be includable directly from assembler, hopefully that's true for > the Hurd version as well. Making an assembly file is really tricky here because _sys_errlist_internal contains internal gap (the errno values are not strictly sequential). The compiler handles by adding '.zero' commands, which is not easily. I think we might generate it though a script. ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-05 20:01 ` Adhemerval Zanella @ 2022-04-05 20:26 ` Florian Weimer 2022-04-05 20:30 ` Adhemerval Zanella 0 siblings, 1 reply; 20+ messages in thread From: Florian Weimer @ 2022-04-05 20:26 UTC (permalink / raw) To: Adhemerval Zanella Cc: Adhemerval Zanella via Libc-alpha, Fāng-ruì Sòng * Adhemerval Zanella: > On 05/04/2022 14:53, Florian Weimer wrote: >> * Adhemerval Zanella via Libc-alpha: >> >>> This is not what I am seeing on my clang branch, where clang with integrated >>> moves the global asm directives to the top of the file. And it makes >>> check-abi fail due the _sys_errlist/sys_errlist being with wrong value. >> >> You can move the directives to the bottom of the file by creating a >> temporary .s file and #include that from a wrapper .S file that >> #includes the .s file. > > Not sure I am following your suggestion here, do you mean get the -S > output file from compiler? Yes, H.J. did that in earlier patches. But I didn't like it back then. 8-p > Making an assembly file is really tricky here because _sys_errlist_internal > contains internal gap (the errno values are not strictly sequential). The > compiler handles by adding '.zero' commands, which is not easily. I think > we might generate it though a script. I think the input file is already generated by a script. Thanks, Florian ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-05 20:26 ` Florian Weimer @ 2022-04-05 20:30 ` Adhemerval Zanella 2022-04-05 20:40 ` Florian Weimer 0 siblings, 1 reply; 20+ messages in thread From: Adhemerval Zanella @ 2022-04-05 20:30 UTC (permalink / raw) To: Florian Weimer Cc: Adhemerval Zanella via Libc-alpha, Fāng-ruì Sòng On 05/04/2022 17:26, Florian Weimer wrote: > * Adhemerval Zanella: > >> On 05/04/2022 14:53, Florian Weimer wrote: >>> * Adhemerval Zanella via Libc-alpha: >>> >>>> This is not what I am seeing on my clang branch, where clang with integrated >>>> moves the global asm directives to the top of the file. And it makes >>>> check-abi fail due the _sys_errlist/sys_errlist being with wrong value. >>> >>> You can move the directives to the bottom of the file by creating a >>> temporary .s file and #include that from a wrapper .S file that >>> #includes the .s file. >> >> Not sure I am following your suggestion here, do you mean get the -S >> output file from compiler? > > Yes, H.J. did that in earlier patches. But I didn't like it back then. 8-p For dl-debug-symbols.S? I might take it as an example. > >> Making an assembly file is really tricky here because _sys_errlist_internal >> contains internal gap (the errno values are not strictly sequential). The >> compiler handles by adding '.zero' commands, which is not easily. I think >> we might generate it though a script. > > I think the input file is already generated by a script. No, what is scripted is the tst-errno-manual (which checks the errlist.h against manual/errno.texi). ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-05 20:30 ` Adhemerval Zanella @ 2022-04-05 20:40 ` Florian Weimer 2022-04-05 21:15 ` Adhemerval Zanella 0 siblings, 1 reply; 20+ messages in thread From: Florian Weimer @ 2022-04-05 20:40 UTC (permalink / raw) To: Adhemerval Zanella Cc: Adhemerval Zanella via Libc-alpha, Fāng-ruì Sòng * Adhemerval Zanella: > On 05/04/2022 17:26, Florian Weimer wrote: >> * Adhemerval Zanella: >> >>> On 05/04/2022 14:53, Florian Weimer wrote: >>>> * Adhemerval Zanella via Libc-alpha: >>>> >>>>> This is not what I am seeing on my clang branch, where clang with integrated >>>>> moves the global asm directives to the top of the file. And it makes >>>>> check-abi fail due the _sys_errlist/sys_errlist being with wrong value. >>>> >>>> You can move the directives to the bottom of the file by creating a >>>> temporary .s file and #include that from a wrapper .S file that >>>> #includes the .s file. >>> >>> Not sure I am following your suggestion here, do you mean get the -S >>> output file from compiler? >> >> Yes, H.J. did that in earlier patches. But I didn't like it back then. 8-p > > For dl-debug-symbols.S? I might take it as an example. Yes, here's a link to one of the earlier patches: [PATCH] Extend struct r_debug to support multiple namespaces <https://sourceware.org/pipermail/libc-alpha/2021-August/130149.html> In the end, I think it was easier to use a manually written assembler file in that case, with the constants filled in via the .sym expander. Thanks, Florian ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-05 20:40 ` Florian Weimer @ 2022-04-05 21:15 ` Adhemerval Zanella 2022-04-06 15:35 ` Adhemerval Zanella 0 siblings, 1 reply; 20+ messages in thread From: Adhemerval Zanella @ 2022-04-05 21:15 UTC (permalink / raw) To: Florian Weimer Cc: Adhemerval Zanella via Libc-alpha, Fāng-ruì Sòng On 05/04/2022 17:40, Florian Weimer wrote: > * Adhemerval Zanella: > >> On 05/04/2022 17:26, Florian Weimer wrote: >>> * Adhemerval Zanella: >>> >>>> On 05/04/2022 14:53, Florian Weimer wrote: >>>>> * Adhemerval Zanella via Libc-alpha: >>>>> >>>>>> This is not what I am seeing on my clang branch, where clang with integrated >>>>>> moves the global asm directives to the top of the file. And it makes >>>>>> check-abi fail due the _sys_errlist/sys_errlist being with wrong value. >>>>> >>>>> You can move the directives to the bottom of the file by creating a >>>>> temporary .s file and #include that from a wrapper .S file that >>>>> #includes the .s file. >>>> >>>> Not sure I am following your suggestion here, do you mean get the -S >>>> output file from compiler? >>> >>> Yes, H.J. did that in earlier patches. But I didn't like it back then. 8-p >> >> For dl-debug-symbols.S? I might take it as an example. > > Yes, here's a link to one of the earlier patches: > > [PATCH] Extend struct r_debug to support multiple namespaces > <https://sourceware.org/pipermail/libc-alpha/2021-August/130149.html> Thanks, I found it on the my local inbox history. > > In the end, I think it was easier to use a manually written assembler > file in that case, with the constants filled in via the .sym expander. I think for this case, it would be simpler to use H.J strategy, I really don't want to re-implement what compiler might do to lay out a C array to assembler. ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-05 21:15 ` Adhemerval Zanella @ 2022-04-06 15:35 ` Adhemerval Zanella 0 siblings, 0 replies; 20+ messages in thread From: Adhemerval Zanella @ 2022-04-06 15:35 UTC (permalink / raw) To: Florian Weimer Cc: Adhemerval Zanella via Libc-alpha, Fāng-ruì Sòng On 05/04/2022 18:15, Adhemerval Zanella wrote: > > > On 05/04/2022 17:40, Florian Weimer wrote: >> * Adhemerval Zanella: >> >>> On 05/04/2022 17:26, Florian Weimer wrote: >>>> * Adhemerval Zanella: >>>> >>>>> On 05/04/2022 14:53, Florian Weimer wrote: >>>>>> * Adhemerval Zanella via Libc-alpha: >>>>>> >>>>>>> This is not what I am seeing on my clang branch, where clang with integrated >>>>>>> moves the global asm directives to the top of the file. And it makes >>>>>>> check-abi fail due the _sys_errlist/sys_errlist being with wrong value. >>>>>> >>>>>> You can move the directives to the bottom of the file by creating a >>>>>> temporary .s file and #include that from a wrapper .S file that >>>>>> #includes the .s file. >>>>> >>>>> Not sure I am following your suggestion here, do you mean get the -S >>>>> output file from compiler? >>>> >>>> Yes, H.J. did that in earlier patches. But I didn't like it back then. 8-p >>> >>> For dl-debug-symbols.S? I might take it as an example. >> >> Yes, here's a link to one of the earlier patches: >> >> [PATCH] Extend struct r_debug to support multiple namespaces >> <https://sourceware.org/pipermail/libc-alpha/2021-August/130149.html> > > Thanks, I found it on the my local inbox history. > >> >> In the end, I think it was easier to use a manually written assembler >> file in that case, with the constants filled in via the .sym expander. > > I think for this case, it would be simpler to use H.J strategy, I really > don't want to re-implement what compiler might do to lay out a C array > to assembler. And so it seems it does not really help clang, the integrated assembler still reorganizes the global asm directives which breaks the required ABI size directives. ^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH] Remove fno-unit-at-a-time make variable 2022-04-05 16:49 ` Adhemerval Zanella 2022-04-05 17:53 ` Florian Weimer @ 2022-04-07 7:02 ` Fāng-ruì Sòng 1 sibling, 0 replies; 20+ messages in thread From: Fāng-ruì Sòng @ 2022-04-07 7:02 UTC (permalink / raw) To: Adhemerval Zanella; +Cc: libc-alpha On 2022-04-05, Adhemerval Zanella wrote: > > >On 05/04/2022 13:44, Fāng-ruì Sòng wrote: >> On Tue, Apr 5, 2022 at 10:40 AM Adhemerval Zanella >> <adhemerval.zanella@linaro.org> wrote: >>> >>> >>> >>> On 05/04/2022 13:22, Fāng-ruì Sòng wrote: >>>> On Tue, Apr 5, 2022 at 8:35 AM Adhemerval Zanella >>>> <adhemerval.zanella@linaro.org> wrote: >>>>> >>>>> >>>>> >>>>> On 04/04/2022 12:57, Fangrui Song wrote: >>>>>> >>>>>> On 2022-03-31, Adhemerval Zanella wrote: >>>>>>> >>>>>>> >>>>>>> On 31/03/2022 00:43, Fangrui Song wrote: >>>>>>>> On 2022-03-30, Adhemerval Zanella wrote: >>>>>>>>> >>>>>>>>> >>>>>>>>> On 30/03/2022 13:23, Fangrui Song wrote: >>>>>>>>>> On 2022-03-30, Adhemerval Zanella wrote: >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> On 30/03/2022 02:07, Fangrui Song wrote: >>>>>>>>>>>> 795985e4e751 in 2003 added -fno-unit-at-a-time to errlist.c and >>>>>>>>>>>> siglist.c to "avoid reordering assembler output". -fno-toplevel-reorder >>>>>>>>>>>> is a rough replacement for this legacy option >>>>>>>>>>>> (https://sourceware.org/pipermail/gcc-patches/2006-January/186801.html). >>>>>>>>>>>> >>>>>>>>>>>> The reordering requirement does not seem to be needed any longer. >>>>>>>>>>> >>>>>>>>>>> We still need them for otherwise DEFINE_COMPAT_ERRLIST used on errlist-compat.c >>>>>>>>>>> does not create _sys_errlist and _sys_siglist with expected sizes defined by >>>>>>>>>>> glibc ABI. >>>>>>>>>>> >>>>>>>>>>> I am trying to fix without resorting to compiler options. >>>>>>>>>> >>>>>>>>>> DEFINE_COMPAT_ERRLIST does not expand to code/data, just reordeable directives: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> .globl __GLIBC_2_1_sys_errlist >>>>>>>>>> .set __GLIBC_2_1_sys_errlist, _sys_errlist_internal >>>>>>>>>> .type __GLIBC_2_1_sys_errlist,@object >>>>>>>>>> .size __GLIBC_2_1_sys_errlist, 1000 >>>>>>>>>> .globl __GLIBC_2_1__sys_errlist >>>>>>>>>> .set __GLIBC_2_1__sys_errlist, _sys_errlist_internal >>>>>>>>>> .type __GLIBC_2_1__sys_errlist,@object >>>>>>>>>> .size __GLIBC_2_1__sys_errlist, 1000 >>>>>>>>>> .symver __GLIBC_2_1_sys_nerr, sys_nerr@GLIBC_2.2.5 >>>>>>>>>> .symver __GLIBC_2_1__sys_nerr, _sys_nerr@GLIBC_2.2.5 >>>>>>>>>> .symver __GLIBC_2_1_sys_errlist, sys_errlist@GLIBC_2.2.5 >>>>>>>>>> .symver __GLIBC_2_1__sys_errlist, _sys_errlist@GLIBC_2.2.5 >>>>>>>>>> .globl __GLIBC_2_3_sys_errlist >>>>>>>>>> .set __GLIBC_2_3_sys_errlist, _sys_errlist_internal >>>>>>>>>> .type __GLIBC_2_3_sys_errlist,@object >>>>>>>>>> .size __GLIBC_2_3_sys_errlist, 1008 >>>>>>>>>> .globl __GLIBC_2_3__sys_errlist >>>>>>>>>> .set __GLIBC_2_3__sys_errlist, _sys_errlist_internal >>>>>>>>>> .type __GLIBC_2_3__sys_errlist,@object >>>>>>>>>> .size __GLIBC_2_3__sys_errlist, 1008 >>>>>>>>>> .symver __GLIBC_2_3_sys_nerr, sys_nerr@GLIBC_2.3 >>>>>>>>>> .symver __GLIBC_2_3__sys_nerr, _sys_nerr@GLIBC_2.3 >>>>>>>>>> .symver __GLIBC_2_3_sys_errlist, sys_errlist@GLIBC_2.3 >>>>>>>>>> .symver __GLIBC_2_3__sys_errlist, _sys_errlist@GLIBC_2.3 >>>>>>>>>> .globl __GLIBC_2_4_sys_errlist >>>>>>>>>> >>>>>>>>>> I do not know whether GCC would reorder these macros. Even yes, >>>>>>>>>> that'd just change the .symtab entries in the relocatable object file. >>>>>>>>>> The linker behavior remains the same with reordering. >>>>>>>>> >>>>>>>>> It does not seem to, just remove the -fno-unit-at-a-time and issue make >>>>>>>>> check-abi and you will see that object size for the compat symbols >>>>>>>>> reference to _sys_err_internal instead of the define compat ones. >>>>>>>> >>>>>>>> I see. I think this is a brittle behavior in GNU assembler. Filed >>>>>>>> https://sourceware.org/bugzilla/show_bug.cgi?id=29012 with detailed >>>>>>>> information. I have created a patch but I know that will not solve >>>>>>>> glibc's problem :( >>>>>>> >>>>>>> It would be good to have this fixes, but unfortunately we need a way >>>>>>> to handle this on older binutils. I am kind worried that the only >>>>>>> possible way to actually fix this without resorting to any compiler >>>>>>> flags is coding the array definitions in assembly direct... >>>>>> >>>>>> The GNU assembler issue has been fixed https://sourceware.org/bugzilla/show_bug.cgi?id=29012 >>>>>> (milestone 2.39, way larger than the current required version: 2.25) >>>>>> >>>>>> Switching to assembly output doesn't seem bad :-) >>>>>> >>>>>> If you keep the compiler driver option but need to refactor the nearby >>>>>> code, you may drop -fno-unit-at-a-time. It was added in 2006 (somewhere >>>>>> between GCC 4.1 and 4.4), while glibc requires GCC>=6.2. >>>>> >>>>> Good to know we won't need to rely on compiler flags to get the expected >>>>> correct asm directives. I am still struggling to get a fix without resorting >>>>> to compiler flags, but without much success. Trying to move it to assembly >>>>> might be tricky, I am not sure if the data directives would be architecture >>>>> agnostic. >>>> >>>> Many directives are architecture-independent: >>>> https://sourceware.org/binutils/docs/as/Pseudo-Ops.html#Pseudo-Ops >>>> binutils-gdb/gas/read.c:346 The `portable[]` array. >>> >>> I think we can make it work with asciz directive. >>> >>>> >>>> To support Clang, no refactoring is probably needed: just change >>>> fno_unit_at_a_time to only specify -fno-toplevel-reorder (and rename >>>> it), not th legacy -fno-unit-at-a-time. >>> >>> Afaik llvm does not support -fno-toplevel-reorder >> >> It doesn't, but its integrated assembler does not need the option to >> have the desired semantics. I have a note that the new GNU as behavior >> is quite similar to LLVM's integrated assembler since 2014-03: >> https://sourceware.org/bugzilla/show_bug.cgi?id=29012#c1 > >This is not what I am seeing on my clang branch, where clang with integrated >moves the global asm directives to the top of the file. And it makes >check-abi fail due the _sys_errlist/sys_errlist being with wrong value. I see. For gas/testsuite/gas/elf/size.s, LLVM integrated assembler's behavior matches GNU as. The glibc errlist.os example is more complex due to a symbol assignment implied by .symver . https://reviews.llvm.org/D123283 should fix it. It isn't a perfect fix but works with most cases. I can request a backport to LLVM 14.0.1 if it lands. ^ permalink raw reply [flat|nested] 20+ messages in thread
end of thread, other threads:[~2022-04-07 7:02 UTC | newest] Thread overview: 20+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-03-30 5:07 [PATCH] Remove fno-unit-at-a-time make variable Fangrui Song 2022-03-30 12:46 ` Adhemerval Zanella 2022-03-30 16:23 ` Fangrui Song 2022-03-30 16:28 ` Adhemerval Zanella 2022-03-31 3:43 ` Fangrui Song 2022-03-31 11:33 ` Adhemerval Zanella 2022-04-04 15:57 ` Fangrui Song 2022-04-05 14:35 ` Adhemerval Zanella 2022-04-05 16:22 ` Fāng-ruì Sòng 2022-04-05 16:40 ` Adhemerval Zanella 2022-04-05 16:44 ` Fāng-ruì Sòng 2022-04-05 16:49 ` Adhemerval Zanella 2022-04-05 17:53 ` Florian Weimer 2022-04-05 20:01 ` Adhemerval Zanella 2022-04-05 20:26 ` Florian Weimer 2022-04-05 20:30 ` Adhemerval Zanella 2022-04-05 20:40 ` Florian Weimer 2022-04-05 21:15 ` Adhemerval Zanella 2022-04-06 15:35 ` Adhemerval Zanella 2022-04-07 7:02 ` Fāng-ruì Sòng
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