[Xen-changelog] [xen master] x86/HVM: slightly improve hvm_mmio_{first, last}_byte()

[patchbot@xxxxxxx]

commit 4561569a11353688b97220be8d6a0821d53b97a6
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Apr 26 13:47:21 2016 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Apr 26 13:47:21 2016 +0200

    x86/HVM: slightly improve hvm_mmio_{first,last}_byte()
    
    EFLAGS.DF can be assumed to be usually clear, so unlikely()-annotate
    the conditionals accordingly.
    
    Also prefer latching p->size (used twice) into a local variable, at
    once making it unnecessary for the reader to be sure expressions get
    evaluated left to right (operand promotion would yield a different
    result if p->addr + p->size - 1 was evaluted right to left).
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
    Release-acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/include/asm-x86/hvm/io.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/xen/include/asm-x86/hvm/io.h b/xen/include/asm-x86/hvm/io.h
index ceefa2e..5445fce 100644
--- a/xen/include/asm-x86/hvm/io.h
+++ b/xen/include/asm-x86/hvm/io.h
@@ -44,18 +44,18 @@ struct hvm_mmio_ops {
 
 static inline paddr_t hvm_mmio_first_byte(const ioreq_t *p)
 {
-    return p->df ?
+    return unlikely(p->df) ?
            p->addr - (p->count - 1ul) * p->size :
            p->addr;
 }
 
 static inline paddr_t hvm_mmio_last_byte(const ioreq_t *p)
 {
-    unsigned long count = p->count;
+    unsigned long size = p->size;
 
-    return p->df ?
-           p->addr + p->size - 1:
-           p->addr + (count * p->size) - 1;
+    return unlikely(p->df) ?
+           p->addr + size - 1:
+           p->addr + (p->count * size) - 1;
 }
 
 typedef int (*portio_action_t)(
--
generated by git-patchbot for /home/xen/git/xen.git#master

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