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Subject[PATCH] MIPS: Make BUG() __noreturn.
MIPS: Make BUG() __noreturn.

Often we do things like put BUG() in the default clause of a case
statement. Since it was not declared __noreturn, this could sometimes
lead to bogus compiler warnings that variables were used
uninitialized.

There is a small problem in that we have to put a magic while(1); loop to
fool GCC into really thinking it is noreturn. This makes the new
BUG() function 3 instructions long instead of just 1, but I think it
is worth it as it is now unnecessary to do extra work to silence the
'used uninitialized' warnings.

I also re-wrote BUG_ON so that if it is given a constant condition, it
just does BUG() instead of loading a constant value in to a register
and testing it.


Signed-off-by: David Daney <ddaney@caviumnetworks.com>
---
arch/mips/include/asm/bug.h | 29 ++++++++++++++++++++---------
1 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/arch/mips/include/asm/bug.h b/arch/mips/include/asm/bug.h
index 7eb63de..08ea468 100644
--- a/arch/mips/include/asm/bug.h
+++ b/arch/mips/include/asm/bug.h
@@ -7,20 +7,31 @@

#include <asm/break.h>

-#define BUG() \
-do { \
- __asm__ __volatile__("break %0" : : "i" (BRK_BUG)); \
-} while (0)
+static inline void __noreturn BUG(void)
+{
+ __asm__ __volatile__("break %0" : : "i" (BRK_BUG));
+ /* Fool GCC into thinking the function doesn't return. */
+ while (1)
+ ;
+}

#define HAVE_ARCH_BUG

#if (_MIPS_ISA > _MIPS_ISA_MIPS1)

-#define BUG_ON(condition) \
-do { \
- __asm__ __volatile__("tne $0, %0, %1" \
- : : "r" (condition), "i" (BRK_BUG)); \
-} while (0)
+static inline void __BUG_ON(unsigned long condition)
+{
+ if (__builtin_constant_p(condition)) {
+ if (condition)
+ BUG();
+ else
+ return;
+ }
+ __asm__ __volatile__("tne $0, %0, %1"
+ : : "r" (condition), "i" (BRK_BUG));
+}
+
+#define BUG_ON(C) __BUG_ON((unsigned long)(C))

#define HAVE_ARCH_BUG_ON


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