Add another optimization, now that 0.9[.x] is out (having fixed several

optimizer bugs in 0.9[.x], I didn't want to add more potentially-buggy
optimizations).

diff --git a/optimize.c b/optimize.c
index 5cdde19df9a8ab924a9be13713661c4e56a5b4c9..40f8d1a22d540865d23a469fba136bfd236167ea 100644 (file)
--- a/optimize.c
+++ b/optimize.c
@@ -22,7 +22,7 @@
  */
 #ifndef lint
 static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/libpcap/optimize.c,v 1.85 2005-04-04 08:42:18 guy Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/libpcap/optimize.c,v 1.86 2005-07-31 17:58:24 guy Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -905,6 +905,17 @@ opt_peep(b)
                if (b->s.k == 0xffffffff)
                        JF(b) = JT(b);
        }
+       /*
+        * If we're comparing against the index register, and the index
+        * register is a known constant, we can just compare against that
+        * constant.
+        */
+       val = b->val[X_ATOM];
+       if (vmap[val].is_const && BPF_SRC(b->s.code) == BPF_X) {
+               bpf_int32 v = vmap[val].const_val;
+               b->s.code &= ~BPF_X;
+               b->s.k = v;
+       }
        /*
         * If the accumulator is a known constant, we can compute the
         * comparison result.