Prepare for radical source tree reorganization. zack/build-layout-experiment

All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).

1 files changed, 69 insertions, 0 deletions

diff --git a/REORG.TODO/sysdeps/unix/sysv/linux/powerpc/elision-trylock.c b/REORG.TODO/sysdeps/unix/sysv/linux/powerpc/elision-trylock.c
new file mode 100644
index 0000000000..ed244d3f12
--- /dev/null
+++ b/REORG.TODO/sysdeps/unix/sysv/linux/powerpc/elision-trylock.c
@@ -0,0 +1,69 @@
+/* elision-trylock.c: Lock eliding trylock for pthreads.
+   Copyright (C) 2015-2017 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/>.  */
+
+#include <pthread.h>
+#include <pthreadP.h>
+#include <lowlevellock.h>
+#include <elision-conf.h>
+#include "htm.h"
+
+#define aconf __elision_aconf
+
+/* Try to elide a futex trylock.  FUTEX is the futex variable.  ADAPT_COUNT is
+   the adaptation counter in the mutex.  */
+
+int
+__lll_trylock_elision (int *futex, short *adapt_count)
+{
+  /* Implement POSIX semantics by forbiding nesting elided trylocks.  */
+  __libc_tabort (_ABORT_NESTED_TRYLOCK);
+
+  /* Only try a transaction if it's worth it.  */
+  if (atomic_load_relaxed (adapt_count) > 0)
+    {
+      goto use_lock;
+    }
+
+  if (__libc_tbegin (0))
+    {
+      if (*futex == 0)
+	return 0;
+
+      /* Lock was busy.  This is never a nested transaction.
+         End it, and set the adapt count.  */
+      __libc_tend (0);
+
+      if (aconf.skip_lock_busy > 0)
+	atomic_store_relaxed (adapt_count, aconf.skip_lock_busy);
+    }
+  else
+    {
+      if (_TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ()))
+	{
+	  /* A persistent failure indicates that a retry will probably
+	     result in another failure.  Use normal locking now and
+	     for the next couple of calls.  */
+	  if (aconf.skip_trylock_internal_abort > 0)
+	    atomic_store_relaxed (adapt_count,
+				aconf.skip_trylock_internal_abort);
+	}
+    }
+
+use_lock:
+  return lll_trylock (*futex);
+}