[PATCH] resource: Micro-tune resource hash computation

[Adam Jackson]

We do actually call Hash() on resource lookup, so let's not make it more
expensive than necessary.  The compiler isnmay not be smart enough to
notice that we only ever have a power of two count of buckets, so
flatten the log2 math so it doesn't have to know.

Signed-off-by: Adam Jackson <ajax at redhat.com>
---
 dix/resource.c |   14 +++++++-------
 1 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/dix/resource.c b/dix/resource.c
index 9cdddba..d2cf0e4 100644
--- a/dix/resource.c
+++ b/dix/resource.c
@@ -343,19 +343,19 @@ static int
 Hash(int client, XID id)
 {
     id &= RESOURCE_ID_MASK;
-    switch (ilog2(clientTable[client].buckets))
+    switch (clientTable[client].buckets)
     {
-	case 6:
+	case 64:
 	    return ((int)(0x03F & (id ^ (id>>6) ^ (id>>12))));
-	case 7:
+	case 128:
 	    return ((int)(0x07F & (id ^ (id>>7) ^ (id>>13))));
-	case 8:
+	case 256:
 	    return ((int)(0x0FF & (id ^ (id>>8) ^ (id>>16))));
-	case 9:
+	case 512:
 	    return ((int)(0x1FF & (id ^ (id>>9))));
-	case 10:
+	case 1024:
 	    return ((int)(0x3FF & (id ^ (id>>10))));
-	case 11:
+	case 2048:
 	    return ((int)(0x7FF & (id ^ (id>>11))));
     }
     return -1;
-- 
1.7.3.4