diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/x86_64/pthread_barrier_wait.S')
| -rw-r--r-- | sysdeps/unix/sysv/linux/x86_64/pthread_barrier_wait.S | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/x86_64/pthread_barrier_wait.S b/sysdeps/unix/sysv/linux/x86_64/pthread_barrier_wait.S new file mode 100644 index 0000000000..eec17f226f --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86_64/pthread_barrier_wait.S @@ -0,0 +1,160 @@ +/* Copyright (C) 2002-2014 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include <sysdep.h> +#include <lowlevellock.h> +#include <lowlevelbarrier.h> + + + .text + + .globl pthread_barrier_wait + .type pthread_barrier_wait,@function + .align 16 +pthread_barrier_wait: + /* Get the mutex. */ + xorl %eax, %eax + movl $1, %esi + LOCK + cmpxchgl %esi, MUTEX(%rdi) + jnz 1f + + /* One less waiter. If this was the last one needed wake + everybody. */ +2: decl LEFT(%rdi) + je 3f + + /* There are more threads to come. */ +#if CURR_EVENT == 0 + movl (%rdi), %edx +#else + movl CURR_EVENT(%rdi), %edx +#endif + + /* Release the mutex. */ + LOCK + decl MUTEX(%rdi) + jne 6f + + /* Wait for the remaining threads. The call will return immediately + if the CURR_EVENT memory has meanwhile been changed. */ +7: +#if FUTEX_WAIT == 0 + movl PRIVATE(%rdi), %esi +#else + movl $FUTEX_WAIT, %esi + orl PRIVATE(%rdi), %esi +#endif + xorq %r10, %r10 +8: movl $SYS_futex, %eax + syscall + + /* Don't return on spurious wakeups. The syscall does not change + any register except %eax so there is no need to reload any of + them. */ +#if CURR_EVENT == 0 + cmpl %edx, (%rdi) +#else + cmpl %edx, CURR_EVENT(%rdi) +#endif + je 8b + + /* Increment LEFT. If this brings the count back to the + initial count unlock the object. */ + movl $1, %edx + movl INIT_COUNT(%rdi), %eax + LOCK + xaddl %edx, LEFT(%rdi) + subl $1, %eax + cmpl %eax, %edx + jne,pt 10f + + /* Release the mutex. We cannot release the lock before + waking the waiting threads since otherwise a new thread might + arrive and gets waken up, too. */ + LOCK + decl MUTEX(%rdi) + jne 9f + +10: xorl %eax, %eax /* != PTHREAD_BARRIER_SERIAL_THREAD */ + + retq + + /* The necessary number of threads arrived. */ +3: +#if CURR_EVENT == 0 + incl (%rdi) +#else + incl CURR_EVENT(%rdi) +#endif + + /* Wake up all waiters. The count is a signed number in the kernel + so 0x7fffffff is the highest value. */ + movl $0x7fffffff, %edx + movl $FUTEX_WAKE, %esi + orl PRIVATE(%rdi), %esi + movl $SYS_futex, %eax + syscall + + /* Increment LEFT. If this brings the count back to the + initial count unlock the object. */ + movl $1, %edx + movl INIT_COUNT(%rdi), %eax + LOCK + xaddl %edx, LEFT(%rdi) + subl $1, %eax + cmpl %eax, %edx + jne,pt 5f + + /* Release the mutex. We cannot release the lock before + waking the waiting threads since otherwise a new thread might + arrive and gets waken up, too. */ + LOCK + decl MUTEX(%rdi) + jne 4f + +5: orl $-1, %eax /* == PTHREAD_BARRIER_SERIAL_THREAD */ + + retq + +1: movl PRIVATE(%rdi), %esi + addq $MUTEX, %rdi + xorl $LLL_SHARED, %esi + callq __lll_lock_wait + subq $MUTEX, %rdi + jmp 2b + +4: movl PRIVATE(%rdi), %esi + addq $MUTEX, %rdi + xorl $LLL_SHARED, %esi + callq __lll_unlock_wake + jmp 5b + +6: movl PRIVATE(%rdi), %esi + addq $MUTEX, %rdi + xorl $LLL_SHARED, %esi + callq __lll_unlock_wake + subq $MUTEX, %rdi + jmp 7b + +9: movl PRIVATE(%rdi), %esi + addq $MUTEX, %rdi + xorl $LLL_SHARED, %esi + callq __lll_unlock_wake + jmp 10b + .size pthread_barrier_wait,.-pthread_barrier_wait |