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-rw-r--r--arch/mn10300/include/asm/div64.h21
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;