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authorFlorian Weimer <fweimer@redhat.com>2021-02-23 14:59:34 +0100
committerFlorian Weimer <fweimer@redhat.com>2021-02-23 14:59:34 +0100
commit5a664d7ae8e42d641a7b4b436987ff67ab483b08 (patch)
treed2530831e3613ab86b5f536341304ac8cc98f452 /sysdeps/pthread/elision-conf.h
parent597d0267b5c4a925f0175837ec09df9f77e0a250 (diff)
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nptl: Move elision implementations into libc
The elision interfaces are closely aligned between the targets that
implement them, so declare them in the generic <lowlevellock.h>
file.

Empty .c stubs are provided, so that fewer makefile updates
under sysdeps are needed.  Also simplify initialization via
__libc_early_init.

The symbols __lll_clocklock_elision, __lll_lock_elision,
__lll_trylock_elision, __lll_unlock_elision, __pthread_force_elision
move into libc.  For the time being, non-hidden references are used
from libpthread to access them, but once that part of libpthread
is moved into libc, hidden symbols will be used again.  (Hidden
references seem desirable to reduce the likelihood of transactions
aborts.)
Diffstat (limited to 'sysdeps/pthread/elision-conf.h')
-rw-r--r--sysdeps/pthread/elision-conf.h29
1 files changed, 29 insertions, 0 deletions
diff --git a/sysdeps/pthread/elision-conf.h b/sysdeps/pthread/elision-conf.h
new file mode 100644
index 0000000000..946f2c43b1
--- /dev/null
+++ b/sysdeps/pthread/elision-conf.h
@@ -0,0 +1,29 @@
+/* elision-conf.h: Lock elision  configuration.  Stub version.
+   Copyright (C) 2021 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
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _ELISION_CONF_H
+#define _ELISION_CONF_H 1
+
+/* No elision support by default.  */
+#define ENABLE_ELISION_SUPPORT 0
+
+/* Whether __lll_unlock_elision expects a pointer argument to the
+   adaptive counter.  Here, an unused arbitrary value.  */
+#define ELISION_UNLOCK_NEEDS_ADAPT_COUNT 0
+
+#endif