Source: upstream ...
> revision 1.291
> date: 2007-10-26 00:44:56 +0000;  author: guy;  state: Exp;  lines: +13 -1
> Re-initialize the table of used registers, and the current register,
> before compiling an expression; pcap_compile() can be called more than
> once, and some registers can now be allocated and not freed in the
> process of code generation (for example, the register allocated to hold
> the length of a radiotap header, which can't be freed until we're
> finished generating all the code).

Index: gencode.c
===================================================================
RCS file: /tcpdump/master/libpcap/gencode.c,v
retrieving revision 1.290
retrieving revision 1.291
diff -c -r1.290 -r1.291
*** gencode.c	5 Oct 2007 01:40:14 -0000	1.290
--- gencode.c	26 Oct 2007 00:44:56 -0000	1.291
***************
*** 134,139 ****
--- 134,140 ----
  
  static void init_linktype(pcap_t *);
  
+ static void init_regs(void);
  static int alloc_reg(void);
  static void free_reg(int);
  
***************
*** 369,374 ****
--- 370,376 ----
  	n_errors = 0;
  	root = NULL;
  	bpf_pcap = p;
+ 	init_regs();
  	if (setjmp(top_ctx)) {
  		lex_cleanup();
  		freechunks();
***************
*** 6045,6050 ****
--- 6047,6062 ----
  static int curreg;
  
  /*
+  * Initialize the table of used registers and the current register.
+  */
+ static void
+ init_regs()
+ {
+ 	curreg = 0;
+ 	memset(regused, 0, sizeof regused);
+ }
+ 
+ /*
   * Return the next free register.
   */
  static int