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Optimize x86-64 sem_wait for uncontested semaphore.

This commit is contained in:
Ulrich Drepper 2009-07-17 15:50:23 -07:00
parent c3c2f3cf56
commit 0adae46817
2 changed files with 30 additions and 24 deletions
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3
nptl/ChangeLog
View File

@ -1,5 +1,8 @@
2009-07-17 Ulrich Drepper <drepper@redhat.com>
* sysdeps/unix/sysv/linux/x86_64/sem_wait.S (sem_wait): Optimize
handling of uncontested semaphore.
* sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S
(__condvar_cleanup): Rewrite to use cfi directives instead of
hand-coded unwind tables.

51
nptl/sysdeps/unix/sysv/linux/x86_64/sem_wait.S
View File

@ -40,18 +40,11 @@ sem_wait:
cfi_personality(DW_EH_PE_udata4, __gcc_personality_v0)
cfi_lsda(DW_EH_PE_udata4, .LexceptSTART)
#endif
pushq %r12
cfi_adjust_cfa_offset(8)
cfi_rel_offset(%r12, 0)
pushq %r13
cfi_adjust_cfa_offset(8)
cfi_rel_offset(%r13, 0)
movq %rdi, %r13
#if VALUE == 0
movl (%r13), %eax
movl (%rdi), %eax
#else
movl VALUE(%r13), %eax
movl VALUE(%rdi), %eax
#endif
2: testl %eax, %eax
je 1f
@ -59,27 +52,24 @@ sem_wait:
leal -1(%rax), %edx
LOCK
#if VALUE == 0
cmpxchgl %edx, (%r13)
cmpxchgl %edx, (%rdi)
#else
cmpxchgl %edx, VALUE(%r13)
cmpxchgl %edx, VALUE(%rdi)
#endif
jne 2b
7: xorl %eax, %eax
9: popq %r13
cfi_adjust_cfa_offset(-8)
cfi_restore(%r13)
popq %r12
cfi_adjust_cfa_offset(-8)
cfi_restore(%r12)
xorl %eax, %eax
retq
cfi_adjust_cfa_offset(2 * 8)
cfi_rel_offset(%r12, 8)
1: pushq %r12
cfi_adjust_cfa_offset(8)
cfi_rel_offset(%r12, 0)
pushq %r13
cfi_adjust_cfa_offset(8)
cfi_rel_offset(%r13, 0)
1: LOCK
movq %rdi, %r13
LOCK
addq $1, NWAITERS(%r13)
.LcleanupSTART:
@ -128,8 +118,21 @@ sem_wait:
LOCK
subq $1, NWAITERS(%r13)
jmp 7b
xorl %eax, %eax
9: popq %r13
cfi_adjust_cfa_offset(-8)
cfi_restore(%r13)
popq %r12
cfi_adjust_cfa_offset(-8)
cfi_restore(%r12)
retq
cfi_adjust_cfa_offset(2 * 8)
cfi_rel_offset(%r12, 8)
cfi_rel_offset(%r13, 0)
4: negq %r12
#if USE___THREAD
movq errno@gottpoff(%rip), %rdx