Message ID | 20210929191430.884057-1-adhemerval.zanella@linaro.org |
---|---|
State | New |
Headers | show |
Series | arm: Enable USE_ATOMIC_COMPILER_BUILTINS (BZ #24774) | expand |
Ping. On 29/09/2021 16:14, Adhemerval Zanella wrote: > As per other architectures. I have checked on a armv8 hardware with > the following configurations: > > arm-linux-gnueabihf (gcc built with --with-float=hard --with-cpu=arm926ej-s) > armv5-linux-gnueabihf (-march=armv5te -mfpu=vfpv3) > armv7-linux-gnueabihf (-march=armv7-a -mfpu=vfpv3) > armv7-thumb-linux-gnueabihf (-march=armv7-a -mfpu=vfpv3 -mthumb) > armv7-neon-linux-gnueabihf (-march=armv7-a -mfpu=neon) > armv7-neonhard-linux-gnueabihf (-march=armv7-a -mfpu=neon -mfloat-abi=hard) > > Without any regression. > > I haven't dig into the code, but since Linux atomic-machine.h handle > pre-ARMv6 and ARMv6 I expect the compiler might have some small room > to optimize. > > The code size also improves is most of the configurations: > > * master > > text data bss dec hex filename > 1727801 9720 37928 1775449 1b1759 arm-linux-gnueabihf/libc.so > 1691729 9720 37928 1739377 1a8a71 arm-linux-gnueabihf-armv7-disable-multi-arch/libc.so > 1725509 9720 37928 1773157 1b0e65 armv5-linux-gnueabihf/libc.so > 1700757 9720 37928 1748405 1aadb5 armv6-linux-gnueabihf/libc.so > 1698973 9720 37928 1746621 1aa6bd armv6t2-linux-gnueabihf/libc.so > 1695481 9752 37928 1743161 1a9939 armv7-linux-gnueabihf/libc.so > 1692917 9744 37928 1740589 1a8f2d armv7-neonhard-linux-gnueabihf/libc.so > 1692917 9744 37928 1740589 1a8f2d armv7-neon-linux-gnueabihf/libc.so > 1225353 9752 37928 1273033 136cc9 armv7-thumb-linux-gnueabihf/libc.so > > * patched > > text data bss dec hex filename > 1726805 9720 37928 1774453 1b1375 arm-linux-gnueabihf/libc.so > 1689321 9720 37928 1736969 1a8109 arm-linux-gnueabihf-armv7-disable-multi-arch/libc.so > 1724433 9720 37928 1772081 1b0a31 armv5-linux-gnueabihf/libc.so > 1698301 9720 37928 1745949 1aa41d armv6-linux-gnueabihf/libc.so > 1696525 9720 37928 1744173 1a9d2d armv6t2-linux-gnueabihf/libc.so > 1693009 9752 37928 1740689 1a8f91 armv7-linux-gnueabihf/libc.so > 1690493 9744 37928 1738165 1a85b5 armv7-neonhard-linux-gnueabihf/libc.so > 1690493 9744 37928 1738165 1a85b5 armv7-neon-linux-gnueabihf/libc.so > 1223837 9752 37928 1271517 1366dd armv7-thumb-linux-gnueabihf/libc.so > > The idea is eventually move all architectures to use compiler builtins. > --- > sysdeps/arm/atomic-machine.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/sysdeps/arm/atomic-machine.h b/sysdeps/arm/atomic-machine.h > index 7928ff29d8..0275fcd2f7 100644 > --- a/sysdeps/arm/atomic-machine.h > +++ b/sysdeps/arm/atomic-machine.h > @@ -34,7 +34,7 @@ typedef intmax_t atomic_max_t; > typedef uintmax_t uatomic_max_t; > > #define __HAVE_64B_ATOMICS 0 > -#define USE_ATOMIC_COMPILER_BUILTINS 0 > +#define USE_ATOMIC_COMPILER_BUILTINS 1 > #define ATOMIC_EXCHANGE_USES_CAS 1 > > void __arm_link_error (void);
On 2021-09-29 16:14, Adhemerval Zanella via Libc-alpha wrote: > As per other architectures. I have checked on a armv8 hardware with > the following configurations: > > arm-linux-gnueabihf (gcc built with --with-float=hard --with-cpu=arm926ej-s) > armv5-linux-gnueabihf (-march=armv5te -mfpu=vfpv3) > armv7-linux-gnueabihf (-march=armv7-a -mfpu=vfpv3) > armv7-thumb-linux-gnueabihf (-march=armv7-a -mfpu=vfpv3 -mthumb) > armv7-neon-linux-gnueabihf (-march=armv7-a -mfpu=neon) > armv7-neonhard-linux-gnueabihf (-march=armv7-a -mfpu=neon -mfloat-abi=hard) > > Without any regression. > > I haven't dig into the code, but since Linux atomic-machine.h handle > pre-ARMv6 and ARMv6 I expect the compiler might have some small room > to optimize. > > The code size also improves is most of the configurations: > > * master > > text data bss dec hex filename > 1727801 9720 37928 1775449 1b1759 arm-linux-gnueabihf/libc.so > 1691729 9720 37928 1739377 1a8a71 arm-linux-gnueabihf-armv7-disable-multi-arch/libc.so > 1725509 9720 37928 1773157 1b0e65 armv5-linux-gnueabihf/libc.so > 1700757 9720 37928 1748405 1aadb5 armv6-linux-gnueabihf/libc.so > 1698973 9720 37928 1746621 1aa6bd armv6t2-linux-gnueabihf/libc.so > 1695481 9752 37928 1743161 1a9939 armv7-linux-gnueabihf/libc.so > 1692917 9744 37928 1740589 1a8f2d armv7-neonhard-linux-gnueabihf/libc.so > 1692917 9744 37928 1740589 1a8f2d armv7-neon-linux-gnueabihf/libc.so > 1225353 9752 37928 1273033 136cc9 armv7-thumb-linux-gnueabihf/libc.so > > * patched > > text data bss dec hex filename > 1726805 9720 37928 1774453 1b1375 arm-linux-gnueabihf/libc.so > 1689321 9720 37928 1736969 1a8109 arm-linux-gnueabihf-armv7-disable-multi-arch/libc.so > 1724433 9720 37928 1772081 1b0a31 armv5-linux-gnueabihf/libc.so > 1698301 9720 37928 1745949 1aa41d armv6-linux-gnueabihf/libc.so > 1696525 9720 37928 1744173 1a9d2d armv6t2-linux-gnueabihf/libc.so > 1693009 9752 37928 1740689 1a8f91 armv7-linux-gnueabihf/libc.so > 1690493 9744 37928 1738165 1a85b5 armv7-neonhard-linux-gnueabihf/libc.so > 1690493 9744 37928 1738165 1a85b5 armv7-neon-linux-gnueabihf/libc.so > 1223837 9752 37928 1271517 1366dd armv7-thumb-linux-gnueabihf/libc.so > > The idea is eventually move all architectures to use compiler builtins. > --- > sysdeps/arm/atomic-machine.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/sysdeps/arm/atomic-machine.h b/sysdeps/arm/atomic-machine.h > index 7928ff29d8..0275fcd2f7 100644 > --- a/sysdeps/arm/atomic-machine.h > +++ b/sysdeps/arm/atomic-machine.h > @@ -34,7 +34,7 @@ typedef intmax_t atomic_max_t; > typedef uintmax_t uatomic_max_t; > > #define __HAVE_64B_ATOMICS 0 > -#define USE_ATOMIC_COMPILER_BUILTINS 0 > +#define USE_ATOMIC_COMPILER_BUILTINS 1 > #define ATOMIC_EXCHANGE_USES_CAS 1 > > void __arm_link_error (void); > -- I have just found your patch after I stumbled on BZ #24774. I confirm it fixes this bug and also the flaky nptl/tst-rwlock9 test on arm. I did not find any regression on the testsuite on Debian armel (armv5-linux-gnueabi) and Debian armhf (armv7-linux-gnueabihf), using GCC 11. Reviewed-by: Aurelien Jarno <aurelien@aurel32.net> Tested-by: Aurelien Jarno <aurelien@aurel32.net>
diff --git a/sysdeps/arm/atomic-machine.h b/sysdeps/arm/atomic-machine.h index 7928ff29d8..0275fcd2f7 100644 --- a/sysdeps/arm/atomic-machine.h +++ b/sysdeps/arm/atomic-machine.h @@ -34,7 +34,7 @@ typedef intmax_t atomic_max_t; typedef uintmax_t uatomic_max_t; #define __HAVE_64B_ATOMICS 0 -#define USE_ATOMIC_COMPILER_BUILTINS 0 +#define USE_ATOMIC_COMPILER_BUILTINS 1 #define ATOMIC_EXCHANGE_USES_CAS 1 void __arm_link_error (void);