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authorMichael Ellerman <michael@ellerman.id.au>2006-03-23 23:32:24 +1100
committerPaul Mackerras <paulus@samba.org>2006-03-27 14:48:10 +1100
commite3f94b85f98a346c5eb0ac0d9539b71cb7057143 (patch)
tree69cc1fcb75d5af9e89c6a28264547bfc5deadd1b
parentaf308377e204e25f1f58627d05fe0f483703b514 (diff)
downloadblackbird-op-linux-e3f94b85f98a346c5eb0ac0d9539b71cb7057143.tar.gz
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[PATCH] powerpc: Make BUG_ON & WARN_ON play nice with compile-time optimisations
Change BUG_ON and WARN_ON to give the compiler a chance to perform compile-time optimsations. Depending on the complexity of the condition, the compiler may not do this very well, so if it's important check the object code. Current GCC's (4.x) produce good code as long as the condition does not include a function call, including a static inline. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Paul Mackerras <paulus@samba.org>
-rw-r--r--include/asm-powerpc/bug.h30
1 files changed, 28 insertions, 2 deletions
diff --git a/include/asm-powerpc/bug.h b/include/asm-powerpc/bug.h
index 99817a802ca4..8003997ddc73 100644
--- a/include/asm-powerpc/bug.h
+++ b/include/asm-powerpc/bug.h
@@ -30,6 +30,12 @@ struct bug_entry *find_bug(unsigned long bugaddr);
#ifdef CONFIG_BUG
+/*
+ * BUG_ON() and WARN_ON() do their best to cooperate with compile-time
+ * optimisations. However depending on the complexity of the condition
+ * some compiler versions may not produce optimal results.
+ */
+
#define BUG() do { \
__asm__ __volatile__( \
"1: twi 31,0,0\n" \
@@ -40,17 +46,36 @@ struct bug_entry *find_bug(unsigned long bugaddr);
} while (0)
#define BUG_ON(x) do { \
- __asm__ __volatile__( \
+ if (__builtin_constant_p(x)) { \
+ if (x) \
+ BUG(); \
+ } else { \
+ __asm__ __volatile__( \
"1: "PPC_TLNEI" %0,0\n" \
".section __bug_table,\"a\"\n" \
"\t"PPC_LONG" 1b,%1,%2,%3\n" \
".previous" \
: : "r" ((long)(x)), "i" (__LINE__), \
"i" (__FILE__), "i" (__FUNCTION__)); \
+ } \
} while (0)
-#define WARN_ON(x) do { \
+#define WARN() do { \
__asm__ __volatile__( \
+ "1: twi 31,0,0\n" \
+ ".section __bug_table,\"a\"\n" \
+ "\t"PPC_LONG" 1b,%0,%1,%2\n" \
+ ".previous" \
+ : : "i" (__LINE__ + BUG_WARNING_TRAP), \
+ "i" (__FILE__), "i" (__FUNCTION__)); \
+} while (0)
+
+#define WARN_ON(x) do { \
+ if (__builtin_constant_p(x)) { \
+ if (x) \
+ WARN(); \
+ } else { \
+ __asm__ __volatile__( \
"1: "PPC_TLNEI" %0,0\n" \
".section __bug_table,\"a\"\n" \
"\t"PPC_LONG" 1b,%1,%2,%3\n" \
@@ -58,6 +83,7 @@ struct bug_entry *find_bug(unsigned long bugaddr);
: : "r" ((long)(x)), \
"i" (__LINE__ + BUG_WARNING_TRAP), \
"i" (__FILE__), "i" (__FUNCTION__)); \
+ } \
} while (0)
#define HAVE_ARCH_BUG
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