Don't optimize away "sub #0" as it may be required to recognize

the code that is generated for e.g. 'icmp[0] > 0'.

diff --git a/optimize.c b/optimize.c
index 463da0cf167972f8abfc7554b36759ee62cf613f..eddc0b0cd9be0f2022b980edc5a1e92b4ab684d3 100644 (file)
--- a/optimize.c
+++ b/optimize.c
@@ -22,7 +22,7 @@
  */
 #ifndef lint
 static const char rcsid[] =
-    "@(#) $Header: /tcpdump/master/libpcap/optimize.c,v 1.68 2001-10-13 04:23:28 fenner Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/libpcap/optimize.c,v 1.69 2001-11-12 21:57:06 fenner Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -940,7 +940,10 @@ opt_stmt(s, val, alter)
                op = BPF_OP(s->code);
                if (alter) {
                        if (s->k == 0) {
-                               if (op == BPF_ADD || op == BPF_SUB ||
+                               /* don't optimize away "sub #0"
+                                * as it may be needed later to
+                                * fixup the generated math code */
+                               if (op == BPF_ADD ||
                                    op == BPF_LSH || op == BPF_RSH ||
                                    op == BPF_OR) {
                                        s->code = NOP;