[Xen-devel] [PATCH 1/3] linux/x86-64: don't use explicit moves in 4- and 5-argument hypercall macros

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

.., allowing the compiler to schedule the moves earlier or even avoid
an extra move.

As usual, written and tested on 2.6.24 and made apply to the 2.6.18
tree without further testing.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

Index: head-2008-01-28/include/asm-x86_64/mach-xen/asm/hypercall.h
===================================================================
--- head-2008-01-28.orig/include/asm-x86_64/mach-xen/asm/hypercall.h    
2008-01-29 09:53:01.000000000 +0100
+++ head-2008-01-28/include/asm-x86_64/mach-xen/asm/hypercall.h 2008-01-29 
10:03:28.000000000 +0100
@@ -103,29 +103,29 @@
 #define _hypercall4(type, name, a1, a2, a3, a4)                        \
 ({                                                             \
        long __res, __ign1, __ign2, __ign3;                     \
+       register long __arg4 asm("r10") = (long)(a4);           \
        asm volatile (                                          \
-               "movq %7,%%r10; "                               \
                HYPERCALL_STR(name)                             \
                : "=a" (__res), "=D" (__ign1), "=S" (__ign2),   \
-               "=d" (__ign3)                                   \
+                 "=d" (__ign3), "+r" (__arg4)                  \
                : "1" ((long)(a1)), "2" ((long)(a2)),           \
-               "3" ((long)(a3)), "g" ((long)(a4))              \
-               : "memory", "r10" );                            \
+                 "3" ((long)(a3))                              \
+               : "memory" );                                   \
        (type)__res;                                            \
 })
 
 #define _hypercall5(type, name, a1, a2, a3, a4, a5)            \
 ({                                                             \
        long __res, __ign1, __ign2, __ign3;                     \
+       register long __arg4 asm("r10") = (long)(a4);           \
+       register long __arg5 asm("r8") = (long)(a5);            \
        asm volatile (                                          \
-               "movq %7,%%r10; movq %8,%%r8; "                 \
                HYPERCALL_STR(name)                             \
                : "=a" (__res), "=D" (__ign1), "=S" (__ign2),   \
-               "=d" (__ign3)                                   \
+                 "=d" (__ign3), "+r" (__arg4), "+r" (__arg5)   \
                : "1" ((long)(a1)), "2" ((long)(a2)),           \
-               "3" ((long)(a3)), "g" ((long)(a4)),             \
-               "g" ((long)(a5))                                \
-               : "memory", "r10", "r8" );                      \
+                 "3" ((long)(a3))                              \
+               : "memory" );                                   \
        (type)__res;                                            \
 })
 




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