[PATCH][PPC32] Reduce WARN_ON(0) to nothing

[Paul Mackerras]

The last patch I sent means that we have WARN_ON(0) in a couple of
places when CONFIG_PREEMPT=n.  This patch makes that reduce to
nothing (rather than a conditional trap on a 0 value), and also makes
BUG_ON(0) reduce to nothing for completeness.

Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>

diff -urN linux-2.5/include/asm-ppc/bug.h pmac-2.5/include/asm-ppc/bug.h
--- linux-2.5/include/asm-ppc/bug.h	2003-06-08 08:08:29.000000000 +1000
+++ pmac-2.5/include/asm-ppc/bug.h	2004-06-03 21:35:42.385963144 +1000
@@ -23,26 +23,30 @@
 		: : "i" (__LINE__), "i" (__FILE__), "i" (__FUNCTION__)); \
 } while (0)
 
-#define BUG_ON(x) do {						\
-	__asm__ __volatile__(					\
-		"1:	twnei %0,0\n"				\
-		".section __bug_table,\"a\"\n\t"		\
-		"	.long 1b,%1,%2,%3\n"			\
-		".previous"					\
-		: : "r" (x), "i" (__LINE__), "i" (__FILE__),	\
-		    "i" (__FUNCTION__));			\
+#define BUG_ON(x) do {							\
+	if (!__builtin_constant_p(x) || (x)) {				\
+		__asm__ __volatile__(					\
+			"1:	twnei %0,0\n"				\
+			".section __bug_table,\"a\"\n\t"		\
+			"	.long 1b,%1,%2,%3\n"			\
+			".previous"					\
+			: : "r" (x), "i" (__LINE__), "i" (__FILE__),	\
+			    "i" (__FUNCTION__));			\
+	}								\
 } while (0)
 
-#define PAGE_BUG(page) do { BUG(); } while (0)
+#define PAGE_BUG(page)	BUG()
 
-#define WARN_ON(x) do {						\
-	__asm__ __volatile__(					\
-		"1:	twnei %0,0\n"				\
-		".section __bug_table,\"a\"\n\t"		\
-		"	.long 1b,%1,%2,%3\n"			\
-		".previous"					\
-		: : "r" (x), "i" (__LINE__ + BUG_WARNING_TRAP),	\
-		    "i" (__FILE__), "i" (__FUNCTION__));	\
+#define WARN_ON(x) do {							\
+	if (!__builtin_constant_p(x) || (x)) {				\
+		__asm__ __volatile__(					\
+			"1:	twnei %0,0\n"				\
+			".section __bug_table,\"a\"\n\t"		\
+			"	.long 1b,%1,%2,%3\n"			\
+			".previous"					\
+			: : "r" (x), "i" (__LINE__ + BUG_WARNING_TRAP),	\
+			    "i" (__FILE__), "i" (__FUNCTION__));	\
+	}								\
 } while (0)
 
 #endif
-
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