Hello!
No functional change.
2011-12-27 Uros Bizjak <ubiz...@gmail.com>
PR libgcj/49193
* sysdep/alpha/locks.h (compare_and_swap): Call
__sync_bool_compare_and_swap.
(release_set): Call __sync_synchronize.
Tested on alphaeev68-pc-linux-gnu, committed to mainline SVN.
Uros.
Index: sysdep/alpha/locks.h
===================================================================
--- sysdep/alpha/locks.h (revision 182691)
+++ sysdep/alpha/locks.h (working copy)
@@ -1,6 +1,6 @@
// locks.h - Thread synchronization primitives. Alpha implementation.
-/* Copyright (C) 2002 Free Software Foundation
+/* Copyright (C) 2002, 2011 Free Software Foundation
This file is part of libgcj.
@@ -11,41 +11,38 @@
#ifndef __SYSDEP_LOCKS_H__
#define __SYSDEP_LOCKS_H__
-typedef size_t obj_addr_t; /* Integer type big enough for object */
- /* address. */
+/* Integer type big enough for object address. */
+typedef size_t obj_addr_t;
+// Atomically replace *addr by new_val if it was initially equal to old.
+// Return true if the comparison succeeded.
+// Assumed to have acquire semantics, i.e. later memory operations
+// cannot execute before the compare_and_swap finishes.
inline static bool
compare_and_swap(volatile obj_addr_t *addr,
- obj_addr_t old,
- obj_addr_t new_val)
+ obj_addr_t old,
+ obj_addr_t new_val)
{
- unsigned long oldval;
- char result;
- __asm__ __volatile__(
- "1:ldq_l %0, %1\n\t" \
- "cmpeq %0, %5, %2\n\t" \
- "beq %2, 2f\n\t" \
- "mov %3, %0\n\t" \
- "stq_c %0, %1\n\t" \
- "bne %0, 2f\n\t" \
- "br 1b\n\t" \
- "2:mb"
- : "=&r"(oldval), "=m"(*addr), "=&r"(result)
- : "r" (new_val), "m"(*addr), "r"(old) : "memory");
- return (bool) result;
+ return __sync_bool_compare_and_swap(addr, old, new_val);
}
+// Set *addr to new_val with release semantics, i.e. making sure
+// that prior loads and stores complete before this
+// assignment.
inline static void
release_set(volatile obj_addr_t *addr, obj_addr_t new_val)
{
- __asm__ __volatile__("mb" : : : "memory");
+ __sync_synchronize();
*(addr) = new_val;
}
+// Compare_and_swap with release semantics instead of acquire semantics.
+// On many architecture, the operation makes both guarantees, so the
+// implementation can be the same.
inline static bool
compare_and_swap_release(volatile obj_addr_t *addr,
- obj_addr_t old,
- obj_addr_t new_val)
+ obj_addr_t old,
+ obj_addr_t new_val)
{
return compare_and_swap(addr, old, new_val);
}
