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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>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
David Daney 2008-11-20 17:26:36 -08:00 committed by Ralf Baechle
parent ed313489ba
commit 8ec2e24356
1 changed files with 20 additions and 9 deletions
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29
arch/mips/include/asm/bug.h
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@ -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