[Qemu-devel] [PULL 06/29] exec.c: add a check between constants to see whether we could skip

[Paolo Bonzini]

From: Wei Yang <address@hidden>

The maximum level is defined as P_L2_LEVELS and skip is defined with 6
bits, which means if P_L2_LEVELS < (1 << 6), skip never exceeds the
boundary.

Since this check is between two constants, which leverages compiler
to optimize the code based on different configuration.

Signed-off-by: Wei Yang <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
 exec.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/exec.c b/exec.c
index d1969bb..b9511be 100644
--- a/exec.c
+++ b/exec.c
@@ -324,7 +324,8 @@ static void phys_page_compact(PhysPageEntry *lp, Node 
*nodes)
     assert(valid_ptr < P_L2_SIZE);
 
     /* Don't compress if it won't fit in the # of bits we have. */
-    if (lp->skip + p[valid_ptr].skip >= (1 << 6)) {
+    if (P_L2_LEVELS >= (1 << 6) &&
+        lp->skip + p[valid_ptr].skip >= (1 << 6)) {
         return;
     }
 
-- 
1.8.3.1