gcc/

2012-06-18  Mikael Pettersson  <mikpe@it.uu.se>

	* config/m68k/linux-atomic.c: Update description and attribution.
	Remove ARM and little-endian specific code.
	(__kernel_cmpxchg): Replace with clone of libjava/sysdep/m68k/locks.h (compare_and_swap),
	negate return value to match different calling convention.
	(__kernel_dmb): Replace with clone of libjava/sysdep/m68k/locks.h (write_barrier).

--- gcc-4.6.3/gcc/config/m68k/linux-atomic.c.~1~	2012-06-18 22:12:40.000000000 +0200
+++ gcc-4.6.3/gcc/config/m68k/linux-atomic.c	2012-06-18 22:34:08.000000000 +0200
@@ -1,6 +1,7 @@
-/* Linux-specific atomic operations for ARM EABI.
+/* Linux-specific atomic operations for M68K Linux.
    Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc.
-   Contributed by CodeSourcery.
+   Based on code contributed by CodeSourcery for ARM EABI Linux.
+   Modifications for M68K Linux by Mikael Pettersson <mikpe@it.uu.se>
 
 This file is part of GCC.
 
@@ -23,13 +24,38 @@ a copy of the GCC Runtime Library Except
 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 <http://www.gnu.org/licenses/>.  */
 
-/* Kernel helper for compare-and-exchange.  */
-typedef int (__kernel_cmpxchg_t) (int oldval, int newval, int *ptr);
-#define __kernel_cmpxchg (*(__kernel_cmpxchg_t *) 0xffff0fc0)
-
-/* Kernel helper for memory barrier.  */
-typedef void (__kernel_dmb_t) (void);
-#define __kernel_dmb (*(__kernel_dmb_t *) 0xffff0fa0)
+#if (defined(__mc68020__) || defined(__mc68030__) \
+     || defined(__mc68040__) || defined(__mc68060__)) \
+    && !defined(__mcpu32__)
+
+/* The target has CAS.  */
+
+static inline int
+__kernel_cmpxchg (int oldval, int newval, int *ptr)
+{
+    char success;
+
+    __asm__ __volatile__ (
+	"cas.l %2,%3,%0\n\t"
+	"seq %1"
+	: "+m" (*ptr), "=d" (success), "+d" (oldval)
+	: "d" (newval)
+	: "memory", "cc");
+    return !success;	/* Callers expect failure return, not success.  */
+}
+
+static inline void
+__kernel_dmb (void)
+{
+    /* M68K does not reorder writes.  Ensure that gcc also does not.  */
+    __asm__ __volatile__("" : : : "memory");
+}
+
+#else	/* !mc680[2346] */
+
+#error "NYI: use kernel helpers for non-mc680[2346]0 ISAs"
+
+#endif	/* !mc680[2346] */
 
 /* Note: we implement byte, short and int versions of atomic operations using
    the above kernel helpers, but there is no support for "long long" (64-bit)
@@ -37,13 +63,9 @@ typedef void (__kernel_dmb_t) (void);
 
 #define HIDDEN __attribute__ ((visibility ("hidden")))
 
-#ifdef __ARMEL__
-#define INVERT_MASK_1 0
-#define INVERT_MASK_2 0
-#else
+/* Big endian masks  */
 #define INVERT_MASK_1 24
 #define INVERT_MASK_2 16
-#endif
 
 #define MASK_1 0xffu
 #define MASK_2 0xffffu