diff --git a/libjava/sysdep/alpha/locks.h b/libjava/sysdep/alpha/locks.h
new file mode 100644
index 0000000000000000000000000000000000000000..1c20249cce393aea1cadc02dfee08f35739e4c77
--- /dev/null
+++ b/libjava/sysdep/alpha/locks.h
@@ -0,0 +1,53 @@
+// locks.h - Thread synchronization primitives. Alpha implementation.
+
+/* Copyright (C) 2002 Free Software Foundation
+
+ This file is part of libgcj.
+
+This software is copyrighted work licensed under the terms of the
+Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
+details. */
+
+#ifndef __SYSDEP_LOCKS_H__
+#define __SYSDEP_LOCKS_H__
+
+typedef size_t obj_addr_t; /* Integer type big enough for object */
+ /* address. */
+
+inline static bool
+compare_and_swap(volatile obj_addr_t *addr,
+ 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;
+}
+
+inline static void
+release_set(volatile obj_addr_t *addr, obj_addr_t new_val)
+{
+ __asm__ __volatile__("mb" : : : "memory");
+ *(addr) = new_val;
+}
+
+inline static bool
+compare_and_swap_release(volatile obj_addr_t *addr,
+ obj_addr_t old,
+ obj_addr_t new_val)
+{
+ return compare_and_swap(addr, old, new_val);
+}
+
+#endif
diff --git a/libjava/sysdep/generic/locks.h b/libjava/sysdep/generic/locks.h
new file mode 100644
index 0000000000000000000000000000000000000000..fce6c71669ebc8505a82a6f134c6d48661a993c8
--- /dev/null
+++ b/libjava/sysdep/generic/locks.h
@@ -0,0 +1,11 @@
+// locks.h - Thread synchronization primitives. Generic implementation.
+
+/* Copyright (C) 2002 Free Software Foundation
+
+ This file is part of libgcj.
+
+This software is copyrighted work licensed under the terms of the
+Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
+details. */
+
+#error Thread synchronization primitives not implemented for this platform.
diff --git a/libjava/sysdep/i386/locks.h b/libjava/sysdep/i386/locks.h
new file mode 100644
index 0000000000000000000000000000000000000000..0c029ac939aa9c457ee2caa7323e8c1fd2e5373e
--- /dev/null
+++ b/libjava/sysdep/i386/locks.h
@@ -0,0 +1,65 @@
+// locks.h - Thread synchronization primitives. X86 implementation.
+
+/* Copyright (C) 2002 Free Software Foundation
+
+ This file is part of libgcj.
+
+This software is copyrighted work licensed under the terms of the
+Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
+details. */
+
+#ifndef __SYSDEP_LOCKS_H__
+#define __SYSDEP_LOCKS_H__
+
+typedef size_t obj_addr_t; /* Integer type big enough for object */
+ /* address. */
+
+// 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)
+{
+ char result;
+ __asm__ __volatile__("lock; cmpxchgl %2, %0; setz %1"
+ : "+m"(*(addr)), "=q"(result)
+ : "r" (new_val), "a"(old)
+ : "memory");
+ return (bool) result;
+}
+
+// Set *addr to new_val with release semantics, i.e. making sure
+// that prior loads and stores complete before this
+// assignment.
+// On X86, the hardware shouldn't reorder reads and writes,
+// so we just have to convince gcc not to do it either.
+inline static void
+release_set(volatile obj_addr_t *addr, obj_addr_t new_val)
+{
+ __asm__ __volatile__(" " : : : "memory");
+ *(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)
+{
+ return compare_and_swap(addr, old, new_val);
+}
+
+// Ensure that subsequent instructions do not execute on stale
+// data that was loaded from memory before the barrier.
+// On X86, the hardware ensures that reads are properly ordered.
+inline static void
+read_barrier()
+{
+}
+
+#endif
diff --git a/libjava/sysdep/ia64/locks.h b/libjava/sysdep/ia64/locks.h
new file mode 100644
index 0000000000000000000000000000000000000000..6edee83ea99a41294a706522054f64e94b8029ae
--- /dev/null
+++ b/libjava/sysdep/ia64/locks.h
@@ -0,0 +1,50 @@
+// locks.h - Thread synchronization primitives. IA64 implementation.
+
+/* Copyright (C) 2002 Free Software Foundation
+
+ This file is part of libgcj.
+
+This software is copyrighted work licensed under the terms of the
+Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
+details. */
+
+#ifndef __SYSDEP_LOCKS_H__
+#define __SYSDEP_LOCKS_H__
+
+typedef size_t obj_addr_t; /* Integer type big enough for object */
+ /* address. */
+
+inline static bool
+compare_and_swap(volatile obj_addr_t *addr,
+ obj_addr_t old,
+ obj_addr_t new_val)
+{
+ unsigned long oldval;
+ __asm__ __volatile__("mov ar.ccv=%4 ;; cmpxchg8.acq %0=%1,%2,ar.ccv"
+ : "=r"(oldval), "=m"(*addr)
+ : "r"(new_val), "1"(*addr), "r"(old) : "memory");
+ return (oldval == old);
+}
+
+// The fact that *addr is volatile should cause the compiler to
+// automatically generate an st8.rel.
+inline static void
+release_set(volatile obj_addr_t *addr, obj_addr_t new_val)
+{
+ __asm__ __volatile__(" " : : : "memory");
+ *(addr) = new_val;
+}
+
+inline static bool
+compare_and_swap_release(volatile obj_addr_t *addr,
+ obj_addr_t old,
+ obj_addr_t new_val)
+{
+ unsigned long oldval;
+ __asm__ __volatile__("mov ar.ccv=%4 ;; cmpxchg8.rel %0=%1,%2,ar.ccv"
+ : "=r"(oldval), "=m"(*addr)
+ : "r"(new_val), "1"(*addr), "r"(old) : "memory");
+ return (oldval == old);
+}
+
+#endif
diff --git a/libjava/sysdep/powerpc/locks.h b/libjava/sysdep/powerpc/locks.h
new file mode 100644
index 0000000000000000000000000000000000000000..414b5dcb7f8699f4adce83d4fe3361f805e29185
--- /dev/null
+++ b/libjava/sysdep/powerpc/locks.h
@@ -0,0 +1,78 @@
+// locks.h - Thread synchronization primitives. PowerPC implementation.
+
+/* Copyright (C) 2002 Free Software Foundation
+
+ This file is part of libgcj.
+
+This software is copyrighted work licensed under the terms of the
+Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
+details. */
+
+#ifndef __SYSDEP_LOCKS_H__
+#define __SYSDEP_LOCKS_H__
+
+typedef size_t obj_addr_t; /* Integer type big enough for object */
+ /* address. */
+
+inline static bool
+compare_and_swap(volatile obj_addr_t *addr,
+ obj_addr_t old,
+ obj_addr_t new_val)
+{
+ int ret;
+
+ __asm__ __volatile__ (
+ "0: lwarx %0,0,%1 ;"
+ " xor. %0,%3,%0;"
+ " bne 1f;"
+ " stwcx. %2,0,%1;"
+ " bne- 0b;"
+ "1: "
+ : "=&r"(ret)
+ : "r"(addr), "r"(new_val), "r"(old)
+ : "cr0", "memory");
+ /* This version of __compare_and_swap is to be used when acquiring
+ a lock, so we don't need to worry about whether other memory
+ operations have completed, but we do need to be sure that any loads
+ after this point really occur after we have acquired the lock. */
+ __asm__ __volatile__ ("isync" : : : "memory");
+ return ret == 0;
+}
+
+inline static void
+release_set(volatile obj_addr_t *addr, obj_addr_t new_val)
+{
+ __asm__ __volatile__ ("sync" : : : "memory");
+ *(addr) = new_val;
+}
+
+inline static bool
+compare_and_swap_release(volatile obj_addr_t *addr,
+ obj_addr_t old,
+ obj_addr_t new_val)
+{
+ int ret;
+
+ __asm__ __volatile__ ("sync" : : : "memory");
+ __asm__ __volatile__ (
+ "0: lwarx %0,0,%1 ;"
+ " xor. %0,%3,%0;"
+ " bne 1f;"
+ " stwcx. %2,0,%1;"
+ " bne- 0b;"
+ "1: "
+ : "=&r"(ret)
+ : "r"(addr), "r"(new_val), "r"(old)
+ : "cr0", "memory");
+ return ret == 0;
+}
+
+// Ensure that subsequent instructions do not execute on stale
+// data that was loaded from memory before the barrier.
+inline static void
+read_barrier()
+{
+ __asm__ __volatile__ ("isync" : : : "memory");
+}
+
+#endif