GNU C Library master sources branch master updated. glibc-2.25-4-gdf3a4e1

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- Log -----------------------------------------------------------------
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=df3a4e104fb63f96f05b29931dd83e272c2b7936

commit df3a4e104fb63f96f05b29931dd83e272c2b7936
Author: Stefan Liebler <stli@linux.vnet.ibm.com>
Date:   Mon Feb 6 13:44:23 2017 +0100

    Add __glibc_unlikely hint in lll_trylock, lll_cond_trylock.
    
    The macros lll_trylock, lll_cond_trylock are extended by an __glibc_unlikely
    hint.  Now the trylock macros are based on the same assumption about a
    free/busy lock as lll_lock.
    With the hint gcc emits code in e.g. pthread_mutex_trylock which does
    not use jumps if the lock is free.  Without the hint it had to jump away
    if the lock is free.
    
    Tested on s390x, ppc.
    
    ChangeLog:
    
    	* sysdeps/nptl/lowlevellock.h (lll_trylock, lll_cond_trylock):
    	Add __glibc_unlikely hint.

diff --git a/ChangeLog b/ChangeLog
index dd0a0b5..e4885cf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2017-02-06  Stefan Liebler  <stli@linux.vnet.ibm.com>
+
+	* sysdeps/nptl/lowlevellock.h (lll_trylock, lll_cond_trylock):
+	Add __glibc_unlikely hint.
+
 2017-02-06  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
 	[BZ #16640]
diff --git a/sysdeps/nptl/lowlevellock.h b/sysdeps/nptl/lowlevellock.h
index 42d9658..54e3c28 100644
--- a/sysdeps/nptl/lowlevellock.h
+++ b/sysdeps/nptl/lowlevellock.h
@@ -64,13 +64,13 @@
    0.  Otherwise leave lock unchanged and return non-zero to indicate that the
    lock was not acquired.  */
 #define lll_trylock(lock)	\
-  atomic_compare_and_exchange_bool_acq (&(lock), 1, 0)
+  __glibc_unlikely (atomic_compare_and_exchange_bool_acq (&(lock), 1, 0))
 
 /* If LOCK is 0 (not acquired), set to 2 (acquired, possibly with waiters) and
    return 0.  Otherwise leave lock unchanged and return non-zero to indicate
    that the lock was not acquired.  */
 #define lll_cond_trylock(lock)	\
-  atomic_compare_and_exchange_bool_acq (&(lock), 2, 0)
+  __glibc_unlikely (atomic_compare_and_exchange_bool_acq (&(lock), 2, 0))
 
 extern void __lll_lock_wait_private (int *futex) attribute_hidden;
 extern void __lll_lock_wait (int *futex, int private) attribute_hidden;

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                   |    5 +++++
 sysdeps/nptl/lowlevellock.h |    4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)


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