powerpc: Add the lock elision using HTM

This patch adds support for lock elision using ISA 2.07 hardware
transactional memory instructions for pthread_mutex primitives.
Similar to s390 version, the for elision logic defined in
'force-elision.h' is only enabled if ENABLE_LOCK_ELISION is defined.

Also, the lock elision code should be able to be built even with
a compiler that does not provide HTM support with builtins.
However I have noted the performance is sub-optimal due scheduling
pressures.

1 files changed, 11 insertions, 5 deletions

diff --git a/sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h b/sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h
index 298b0f26b6..0f971cdf21 100644
--- a/sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h
+++ b/sysdeps/unix/sysv/linux/powerpc/bits/pthreadtypes.h
@@ -90,14 +90,23 @@ typedef union
        binary compatibility.  */
     int __kind;
 #if __WORDSIZE == 64
-    int __spins;
+    short __spins;
+    short __elision;
     __pthread_list_t __list;
 # define __PTHREAD_MUTEX_HAVE_PREV	1
+# define __PTHREAD_SPINS             0, 0
 #else
     unsigned int __nusers;
     __extension__ union
     {
-      int __spins;
+      struct
+      {
+	short __espins;
+	short __elision;
+# define __spins __elision_data.__espins
+# define __elision __elision_data.__elision
+# define __PTHREAD_SPINS         { 0, 0 }
+      } __elision_data;
       __pthread_slist_t __list;
     };
 #endif
@@ -106,9 +115,6 @@ typedef union
   long int __align;
 } pthread_mutex_t;
 
-/* Mutex __spins initializer used by PTHREAD_MUTEX_INITIALIZER.  */
-#define __PTHREAD_SPINS 0
-
 typedef union
 {
   char __size[__SIZEOF_PTHREAD_MUTEXATTR_T];