x86 & generic: change to __builtin_prefetch()

gcc 3.2+ supports __builtin_prefetch, so it's possible to use it on all
architectures. Change the generic fallback in linux/prefetch.h to use it
instead of noping it out. gcc should do the right thing when the
architecture doesn't support prefetching

Undefine the x86-64 inline assembler version and use the fallback.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 2 insertions, 7 deletions

diff --git a/include/linux/prefetch.h b/include/linux/prefetch.h
index 1adfe668d031..af7c36a5a521 100644
--- a/include/linux/prefetch.h
+++ b/include/linux/prefetch.h
@@ -34,17 +34,12 @@
         
 */
 
-/*
- *      These cannot be do{}while(0) macros. See the mental gymnastics in
- *      the loop macro.
- */
- 
 #ifndef ARCH_HAS_PREFETCH
-static inline void prefetch(const void *x) {;}
+#define prefetch(x) __builtin_prefetch(x)
 #endif
 
 #ifndef ARCH_HAS_PREFETCHW
-static inline void prefetchw(const void *x) {;}
+#define prefetchw(x) __builtin_prefetch(x,1)
 #endif
 
 #ifndef ARCH_HAS_SPINLOCK_PREFETCH