[Xen-changelog] [xen master] xen: x86 & generic: change to __builtin_prefetch()

[patchbot@xxxxxxx]

commit 630017f420f111e0c0332dbd99df30ebb8fed207
Author:     Ian Campbell <ian.campbell@xxxxxxxxxx>
AuthorDate: Wed Mar 26 13:38:36 2014 +0000
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Thu Apr 3 17:15:41 2014 +0100

    xen: x86 & generic: change to __builtin_prefetch()
    
    Quoting Andi Kleen in Linux b483570a13be from 2007:
        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.
    
    ARM wants to use the builtins.
    
    Fix a pair of spelling errors, one of which was from Lucas De Marchi in the
    Linux tree.
    
    Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Cc: Keir Fraser <keir@xxxxxxx>
    Acked-by: Tim Deegan <tim@xxxxxxx>
---
 xen/include/xen/prefetch.h |   13 +++----------
 1 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/xen/include/xen/prefetch.h b/xen/include/xen/prefetch.h
index 8d7d3ff..ba73998 100644
--- a/xen/include/xen/prefetch.h
+++ b/xen/include/xen/prefetch.h
@@ -28,24 +28,17 @@
        prefetchw(x)    - prefetches the cacheline at "x" for write
        spin_lock_prefetch(x) - prefectches the spinlock *x for taking
        
-       there is also PREFETCH_STRIDE which is the architecure-prefered 
+       there is also PREFETCH_STRIDE which is the architecture-preferred
        "lookahead" size for prefetching streamed operations.
        
 */
 
-/*
- *     These cannot be do{}while(0) macros. See the mental gymnastics in
- *     the loop macro.
- */
- 
 #ifndef ARCH_HAS_PREFETCH
-#define ARCH_HAS_PREFETCH
-static inline void prefetch(const void *x) {;}
+#define prefetch(x) __builtin_prefetch(x)
 #endif
 
 #ifndef ARCH_HAS_PREFETCHW
-#define ARCH_HAS_PREFETCHW
-static inline void prefetchw(const void *x) {;}
+#define prefetchw(x) __builtin_prefetch(x,1)
 #endif
 
 #ifndef ARCH_HAS_SPINLOCK_PREFETCH
--
generated by git-patchbot for /home/xen/git/xen.git#master

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