glibc/sysdeps/arm
Stefan Liebler 12d2dd7060 Optimize generic spinlock code and use C11 like atomic macros.
This patch optimizes the generic spinlock code.

The type pthread_spinlock_t is a typedef to volatile int on all archs.
Passing a volatile pointer to the atomic macros which are not mapped to the
C11 atomic builtins can lead to extra stores and loads to stack if such
a macro creates a temporary variable by using "__typeof (*(mem)) tmp;".
Thus, those macros which are used by spinlock code - atomic_exchange_acquire,
atomic_load_relaxed, atomic_compare_exchange_weak - have to be adjusted.
According to the comment from  Szabolcs Nagy, the type of a cast expression is
unqualified (see http://www.open-std.org/jtc1/sc22/wg14/www/docs/dr_423.htm):
__typeof ((__typeof (*(mem)) *(mem)) tmp;
Thus from spinlock perspective the variable tmp is of type int instead of
type volatile int.  This patch adjusts those macros in include/atomic.h.
With this construct GCC >= 5 omits the extra stores and loads.

The atomic macros are replaced by the C11 like atomic macros and thus
the code is aligned to it.  The pthread_spin_unlock implementation is now
using release memory order instead of sequentially consistent memory order.
The issue with passed volatile int pointers applies to the C11 like atomic
macros as well as the ones used before.

I've added a glibc_likely hint to the first atomic exchange in
pthread_spin_lock in order to return immediately to the caller if the lock is
free.  Without the hint, there is an additional jump if the lock is free.

I've added the atomic_spin_nop macro within the loop of plain reads.
The plain reads are also realized by C11 like atomic_load_relaxed macro.

The new define ATOMIC_EXCHANGE_USES_CAS determines if the first try to acquire
the spinlock in pthread_spin_lock or pthread_spin_trylock is an exchange
or a CAS.  This is defined in atomic-machine.h for all architectures.

The define SPIN_LOCK_READS_BETWEEN_CMPXCHG is now removed.
There is no technical reason for throwing in a CAS every now and then,
and so far we have no evidence that it can improve performance.
If that would be the case, we have to adjust other spin-waiting loops
elsewhere, too!  Using a CAS loop without plain reads is not a good idea
on many targets and wasn't used by one.  Thus there is now no option to
do so.

Architectures are now using the generic spinlock automatically if they
do not provide an own implementation.  Thus the pthread_spin_lock.c files
in sysdeps folder are deleted.

ChangeLog:

	* NEWS: Mention new spinlock implementation.
	* include/atomic.h:
	(__atomic_val_bysize): Cast type to omit volatile qualifier.
	(atomic_exchange_acq): Likewise.
	(atomic_load_relaxed): Likewise.
	(ATOMIC_EXCHANGE_USES_CAS): Check definition.
	* nptl/pthread_spin_init.c (pthread_spin_init):
	Use atomic_store_relaxed.
	* nptl/pthread_spin_lock.c (pthread_spin_lock):
	Use C11-like atomic macros.
	* nptl/pthread_spin_trylock.c (pthread_spin_trylock):
	Likewise.
	* nptl/pthread_spin_unlock.c (pthread_spin_unlock):
	Use atomic_store_release.
	* sysdeps/aarch64/nptl/pthread_spin_lock.c: Delete File.
	* sysdeps/arm/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/hppa/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/m68k/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/microblaze/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/mips/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/nios2/nptl/pthread_spin_lock.c: Likewise.
	* sysdeps/aarch64/atomic-machine.h (ATOMIC_EXCHANGE_USES_CAS): Define.
	* sysdeps/alpha/atomic-machine.h: Likewise.
	* sysdeps/arm/atomic-machine.h: Likewise.
	* sysdeps/i386/atomic-machine.h: Likewise.
	* sysdeps/ia64/atomic-machine.h: Likewise.
	* sysdeps/m68k/coldfire/atomic-machine.h: Likewise.
	* sysdeps/m68k/m680x0/m68020/atomic-machine.h: Likewise.
	* sysdeps/microblaze/atomic-machine.h: Likewise.
	* sysdeps/mips/atomic-machine.h: Likewise.
	* sysdeps/powerpc/powerpc32/atomic-machine.h: Likewise.
	* sysdeps/powerpc/powerpc64/atomic-machine.h: Likewise.
	* sysdeps/s390/atomic-machine.h: Likewise.
	* sysdeps/sparc/sparc32/atomic-machine.h: Likewise.
	* sysdeps/sparc/sparc32/sparcv9/atomic-machine.h: Likewise.
	* sysdeps/sparc/sparc64/atomic-machine.h: Likewise.
	* sysdeps/tile/tilegx/atomic-machine.h: Likewise.
	* sysdeps/tile/tilepro/atomic-machine.h: Likewise.
	* sysdeps/unix/sysv/linux/hppa/atomic-machine.h: Likewise.
	* sysdeps/unix/sysv/linux/m68k/coldfire/atomic-machine.h: Likewise.
	* sysdeps/unix/sysv/linux/nios2/atomic-machine.h: Likewise.
	* sysdeps/unix/sysv/linux/sh/atomic-machine.h: Likewise.
	* sysdeps/x86_64/atomic-machine.h: Likewise.
2017-06-06 09:41:56 +02:00
..
armv6 Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
armv6t2 Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
armv7 Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
bits Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
include/bits Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
nptl Optimize generic spinlock code and use C11 like atomic macros. 2017-06-06 09:41:56 +02:00
sys Fix more namespace issues in sys/ucontext.h (bug 21457). 2017-06-01 14:07:40 +00:00
__longjmp.S Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
abi-note.S Fix whitespace in ARM files to allow move. 2014-02-08 01:52:38 +00:00
add_n.S Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
addmul_1.S Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
aeabi_assert.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aeabi_atexit.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aeabi_errno_addr.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aeabi_lcsts.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aeabi_localeconv.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aeabi_math.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aeabi_mb_cur_max.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aeabi_memclr.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aeabi_memcpy.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aeabi_memmove.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aeabi_memset.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aeabi_sighandlers.S Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aeabi_unwind_cpp_pr1.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
arm-features.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
arm-mcount.S Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
arm-unwind-resume.S Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
atomic-machine.h Optimize generic spinlock code and use C11 like atomic macros. 2017-06-06 09:41:56 +02:00
backtrace.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
bsd-_setjmp.S Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
bsd-setjmp.S Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
configure Remove configure test for ARM TLS descriptors support. 2015-10-27 23:56:50 +00:00
configure.ac Remove configure test for ARM TLS descriptors support. 2015-10-27 23:56:50 +00:00
crti.S Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
crtn.S Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
dl-irel.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
dl-lookupcfg.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
dl-machine.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
dl-sysdep.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
dl-tls.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
dl-tlsdesc.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
dl-tlsdesc.S Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
dl-trampoline.S Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
e_sqrt.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
e_sqrtf.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fclrexcpt.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fedisblxcpt.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
feenablxcpt.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fegetenv.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fegetexcept.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fegetmode.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fegetround.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
feholdexcpt.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fenv_private.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fesetenv.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fesetexcept.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fesetmode.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fesetround.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
feupdateenv.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fgetexcptflg.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
find_exidx.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fix-fp-int-convert-overflow.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fpu_control.h Fix ARM fpu_control.h for assemblers requiring VFP insn names (bug 21047). 2017-01-19 00:05:34 +00:00
fraiseexcpt.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
frame.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
framestate.c Move arm from ports to libc. 2014-02-08 01:49:39 +00:00
fsetexcptflg.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
ftestexcept.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
gcc-compat.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
gccframe.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
get-rounding-mode.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
gmp-mparam.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
Implies Remove sysdeps/arm/soft-fp directory. 2014-10-16 09:54:45 -07:00
jmpbuf-unwind.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
ldsodefs.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
libc-aeabi_read_tp.S ARM: Move more aeabi routine magic out of Linux-specific directories 2014-06-26 15:08:29 -07:00
libc-tls.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
libm-test-ulps Update arm, mips, powerpc-nofpu libm-test-ulps. 2017-02-17 23:10:01 +00:00
libm-test-ulps-name Do not hardcode platform names in manual/libm-err-tab.pl (bug 14139). 2016-11-04 16:49:06 +00:00
linkmap.h Rename bits/linkmap.h to linkmap.h (bug 14912). 2015-09-04 19:44:27 +00:00
machine-gmon.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
Makefile Remove configure test for ARM TLS descriptors support. 2015-10-27 23:56:50 +00:00
math_private.h math: add LDBL_CLASSIFY_COMPAT support 2015-12-03 13:00:46 -05:00
math-tests.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
memcpy.S Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
memmove.S Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
memset.S Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
memusage.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
nptl-aeabi_unwind_cpp_pr1.c ARM: Move more aeabi routine magic out of Linux-specific directories 2014-06-26 15:08:29 -07:00
preconfigure arm: drop EABI check 2014-11-22 19:34:49 -05:00
preconfigure.ac arm: drop EABI check 2014-11-22 19:34:49 -05:00
pt-arm-unwind-resume.S ARM: Consolidate with generic unwinder wrapper code 2015-01-05 15:42:16 -08:00
rt-aeabi_unwind_cpp_pr1.c ARM: Move more aeabi routine magic out of Linux-specific directories 2014-06-26 15:08:29 -07:00
rt-arm-unwind-resume.S ARM: Consolidate with generic unwinder wrapper code 2015-01-05 15:42:16 -08:00
rtld-global-offsets.sym Move arm from ports to libc. 2014-02-08 01:49:39 +00:00
s_fma.c Move arm from ports to libc. 2014-02-08 01:49:39 +00:00
s_fmaf.c Move arm from ports to libc. 2014-02-08 01:49:39 +00:00
setfpucw.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
setjmp.S Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
sfp-machine.h Remove sysdeps/arm/soft-fp directory. 2014-10-16 09:54:45 -07:00
sotruss-lib.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
stackinfo.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
start.S Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
static-stubs.c Move arm from ports to libc. 2014-02-08 01:49:39 +00:00
strlen.S Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
sub_n.S Move arm from ports to libc. 2014-02-08 01:49:39 +00:00
submul_1.S Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
sysdep.h Remove sfi_* annotations from ARM assembly files. 2017-05-20 08:12:11 -04:00
test-fpucw.c Move arm from ports to libc. 2014-02-08 01:49:39 +00:00
tls-macros.h ARM: Rewrite sysdeps/arm/tls-macros.h 2015-03-13 10:10:09 -07:00
tlsdesc.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
tlsdesc.sym Move arm from ports to libc. 2014-02-08 01:49:39 +00:00
tst-armtlsdescextlazy.c [BZ #17075] ARM: Fix immediate calculation of R_ARM_TLS_DESC 2014-06-20 20:22:42 +01:00
tst-armtlsdescextlazymod.c [BZ #17075] ARM: Fix immediate calculation of R_ARM_TLS_DESC 2014-06-20 20:22:42 +01:00
tst-armtlsdescextnow.c [BZ #17075] ARM: Fix immediate calculation of R_ARM_TLS_DESC 2014-06-20 20:22:42 +01:00
tst-armtlsdescextnowmod.c [BZ #17075] ARM: Fix immediate calculation of R_ARM_TLS_DESC 2014-06-20 20:22:42 +01:00
tst-armtlsdescloc.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
tst-armtlsdesclocmod.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
tst-audit.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
unwind-dw2-fde-glibc.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
unwind-pe.c Move arm from ports to libc. 2014-02-08 01:49:39 +00:00
unwind-resume.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
unwind.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
Versions Use -Werror=undef for assembly code. 2015-02-12 13:57:32 -08:00