1 files changed, 17 insertions, 4 deletions

diff --git a/arch/mn10300/include/asm/div64.h b/arch/mn10300/include/asm/div64.h
index 34dcb8e68309..503efab2a516 100644
--- a/arch/mn10300/include/asm/div64.h
+++ b/arch/mn10300/include/asm/div64.h
@@ -16,6 +16,19 @@
 extern void ____unhandled_size_in_do_div___(void);
 
 /*
+ * Beginning with gcc 4.6, the MDR register is represented explicitly.  We
+ * must, therefore, at least explicitly clobber the register when we make
+ * changes to it.  The following assembly fragments *could* be rearranged in
+ * order to leave the moves to/from the MDR register to the compiler, but the
+ * gains would be minimal at best.
+ */
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
+# define CLOBBER_MDR_CC         "mdr", "cc"
+#else
+# define CLOBBER_MDR_CC         "cc"
+#endif
+
+/*
  * divide n by base, leaving the result in n and returning the remainder
  * - we can do this quite efficiently on the MN10300 by cascading the divides
  *   through the MDR register
@@ -29,7 +42,7 @@ extern void ____unhandled_size_in_do_div___(void);
                     "mov        mdr,%1  \n"                             \
                     : "+r"(n), "=d"(__rem)                              \
                     : "r"(base), "1"(__rem)                             \
-                    : "cc"                                              \
+                    : CLOBBER_MDR_CC                                    \
                     );                                                  \
         } else if (sizeof(n) <= 8) {                                    \
                 union {                                                 \
@@ -48,7 +61,7 @@ extern void ____unhandled_size_in_do_div___(void);
                     : "=d"(__rem), "=r"(__quot.w[1]), "=r"(__quot.w[0]) \
                     : "r"(base), "0"(__rem), "1"(__quot.w[1]),          \
                       "2"(__quot.w[0])                                  \
-                    : "cc"                                              \
+                    : CLOBBER_MDR_CC                                    \
                     );                                                  \
                 n = __quot.l;                                           \
         } else {                                                        \
@@ -72,7 +85,7 @@ unsigned __muldiv64u(unsigned val, unsigned mult, unsigned div)
                                          * MDR = MDR:val%div */
             : "=r"(result)
             : "0"(val), "ir"(mult), "r"(div)
-            : "cc"
+            : CLOBBER_MDR_CC
             );
 
         return result;
@@ -93,7 +106,7 @@ signed __muldiv64s(signed val, signed mult, signed div)
                                          * MDR = MDR:val%div */
             : "=r"(result)
             : "0"(val), "ir"(mult), "r"(div)
-            : "cc"
+            : CLOBBER_MDR_CC
             );
 
         return result;