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, 48 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/powerpc/lowlevellock.h b/sysdeps/unix/sysv/linux/powerpc/lowlevellock.h
new file mode 100644
index 0000000..36c8ade
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/powerpc/lowlevellock.h
@@ -0,0 +1,48 @@
+/* PowerPC specific lock definitions.
+   Copyright (C) 2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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/>.  */
+
+#ifndef _POWERPC_LOWLEVELLOCK_H
+#define _POWERPC_LOWLEVELLOCK_H 1
+
+#include <sysdeps/nptl/lowlevellock.h>
+
+/* Transactional lock elision definitions.  */
+extern int __lll_timedlock_elision
+  (int *futex, short *adapt_count, const struct timespec *timeout, int private)
+  attribute_hidden;
+
+#define lll_timedlock_elision(futex, adapt_count, timeout, private)	      \
+  __lll_timedlock_elision(&(futex), &(adapt_count), timeout, private)
+
+extern int __lll_lock_elision (int *futex, short *adapt_count, int private)
+  attribute_hidden;
+
+extern int __lll_unlock_elision(int *lock, int private)
+  attribute_hidden;
+
+extern int __lll_trylock_elision(int *lock, short *adapt_count)
+  attribute_hidden;
+
+#define lll_lock_elision(futex, adapt_count, private) \
+  __lll_lock_elision (&(futex), &(adapt_count), private)
+#define lll_unlock_elision(futex, private) \
+  __lll_unlock_elision (&(futex), private)
+#define lll_trylock_elision(futex, adapt_count) \
+  __lll_trylock_elision (&(futex), &(adapt_count))
+
+#endif