diff --git a/ChangeLog b/ChangeLog
index bf0f749..913b4a3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,21 @@
+2011-07-05         John Haque      <address@hidden>
+ 
+	* awk.h (Op_sub_builtin): New opcode.
+	(GSUB, GENSUB, AFTER_ASSIGN, LITERAL): New flags for 
+	Op_sub_builtin.
+	* awkgram.y (struct tokentab): Change opcode to	Op_sub_builtin
+	for sub, gsub and gensub.
+	(snode): Update processing of sub, gsub and gensub.
+	* builtin.c (do_sub, do_gsub, do_gensub): Nuke.
+	(sub_common): Renamed to do_sub. Relocate gensub argument
+	handling code from do_gensub to here; Simplify the code a
+	little bit. 
+	* eval.c (r_interpret): Handle Op_sub_builtin. Avoid field
+	re-splitting or $0 rebuilding if (g)sub target string is
+	a field and no substitutions were done.
+	* pprint (profile.c): Add case for the new opcode.
+	* print_instruction (debug.c): Ditto.
+
 2011-06-24         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* Makefile.am (EXTRA_DIST): Add ChangeLog.0.
diff --git a/awk.h b/awk.h
index 25abf41..e224061 100644
--- a/awk.h
+++ b/awk.h
@@ -521,6 +521,7 @@ typedef enum opcodeval {
 	Op_K_nextfile,
 
 	Op_builtin,
+	Op_sub_builtin,		/* sub, gsub and gensub */
 	Op_in_array,		/* boolean test of membership in array */
 
 	/* function call instruction */
@@ -626,6 +627,16 @@ typedef struct exp_instruction {
 #define target_jmp      d.di
 #define target_break    x.xi
 
+/* Op_sub_builtin */
+#define sub_flags       d.dl
+#define GSUB            0x01	/* builtin is gsub */
+#define GENSUB          0x02	/* builtin is gensub */
+#define AFTER_ASSIGN    0x04	/* (g)sub target is a field or a special var with
+                            	 * set_XX routine.
+                            	 */
+#define LITERAL         0x08	/* target is a literal string */
+
+
 /* Op_K_exit */
 #define target_end      d.di
 #define target_atexit   x.xi	
@@ -1181,9 +1192,7 @@ extern NODE *do_cos(int nargs);
 extern NODE *do_rand(int nargs);
 extern NODE *do_srand(int nargs);
 extern NODE *do_match(int nargs);
-extern NODE *do_gsub(int nargs);
-extern NODE *do_sub(int nargs);
-extern NODE *do_gensub(int nargs);
+extern NODE *do_sub(int nargs, unsigned int flags, int *num_matches);
 extern NODE *format_tree(const char *, size_t, NODE **, long);
 extern NODE *do_lshift(int nargs);
 extern NODE *do_rshift(int nargs);
diff --git a/awkgram.c b/awkgram.c
index 4edec57..ac4ceaa 100644
--- a/awkgram.c
+++ b/awkgram.c
@@ -2065,7 +2065,7 @@ yyreduce:
     {
         case 3:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 221 "awkgram.y"
     {
 		rule = 0;
@@ -2075,7 +2075,7 @@ yyreduce:
 
   case 5:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 227 "awkgram.y"
     {
 		next_sourcefile();
@@ -2084,7 +2084,7 @@ yyreduce:
 
   case 6:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 231 "awkgram.y"
     {
 		rule = 0;
@@ -2098,7 +2098,7 @@ yyreduce:
 
   case 7:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 243 "awkgram.y"
     {
 		(void) append_rule((yyvsp[(1) - (2)]), (yyvsp[(2) - (2)]));
@@ -2107,7 +2107,7 @@ yyreduce:
 
   case 8:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 247 "awkgram.y"
     {
 		if (rule != Rule) {
@@ -2123,7 +2123,7 @@ yyreduce:
 
   case 9:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 258 "awkgram.y"
     {
 		can_return = FALSE;
@@ -2136,7 +2136,7 @@ yyreduce:
 
   case 10:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 266 "awkgram.y"
     {
 		want_source = FALSE;
@@ -2146,7 +2146,7 @@ yyreduce:
 
   case 11:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 274 "awkgram.y"
     {
 		if (include_source((yyvsp[(1) - (1)])) < 0)
@@ -2159,35 +2159,35 @@ yyreduce:
 
   case 12:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 282 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 13:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 284 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 14:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 289 "awkgram.y"
     {	(yyval) = NULL; rule = Rule; }
     break;
 
   case 15:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 291 "awkgram.y"
     {	(yyval) = (yyvsp[(1) - (1)]); rule = Rule; }
     break;
 
   case 16:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 293 "awkgram.y"
     {
 		INSTRUCTION *tp;
@@ -2218,7 +2218,7 @@ yyreduce:
 
   case 17:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 319 "awkgram.y"
     {
 		static int begin_seen = 0;
@@ -2234,7 +2234,7 @@ yyreduce:
 
   case 18:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 330 "awkgram.y"
     {
 		static int end_seen = 0;
@@ -2250,7 +2250,7 @@ yyreduce:
 
   case 19:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 341 "awkgram.y"
     {
 		(yyvsp[(1) - (1)])->in_rule = rule = BEGINFILE;
@@ -2261,7 +2261,7 @@ yyreduce:
 
   case 20:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 347 "awkgram.y"
     {
 		(yyvsp[(1) - (1)])->in_rule = rule = ENDFILE;
@@ -2272,7 +2272,7 @@ yyreduce:
 
   case 21:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 356 "awkgram.y"
     {
 		if ((yyvsp[(2) - (5)]) == NULL)
@@ -2284,21 +2284,21 @@ yyreduce:
 
   case 22:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 366 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 23:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 368 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 24:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 370 "awkgram.y"
     {
 		yyerror(_("`%s' is a built-in function, it cannot be redefined"),
@@ -2314,14 +2314,14 @@ yyreduce:
 
   case 25:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 381 "awkgram.y"
     { (yyval) = (yyvsp[(2) - (2)]); }
     break;
 
   case 28:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 391 "awkgram.y"
     {
 		param_counter = 0;
@@ -2331,7 +2331,7 @@ yyreduce:
 
   case 29:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 396 "awkgram.y"
     {
 			NODE *t;
@@ -2353,14 +2353,14 @@ yyreduce:
 
   case 30:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 420 "awkgram.y"
     { ++want_regexp; }
     break;
 
   case 31:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 422 "awkgram.y"
     {
 		  NODE *n, *exp;
@@ -2393,21 +2393,21 @@ yyreduce:
 
   case 32:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 453 "awkgram.y"
     { bcfree((yyvsp[(1) - (1)])); }
     break;
 
   case 34:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 459 "awkgram.y"
     {	(yyval) = NULL; }
     break;
 
   case 35:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 461 "awkgram.y"
     {
 		if ((yyvsp[(2) - (2)]) == NULL)
@@ -2425,28 +2425,28 @@ yyreduce:
 
   case 36:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 474 "awkgram.y"
     {	(yyval) = NULL; }
     break;
 
   case 39:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 484 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 40:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 486 "awkgram.y"
     { (yyval) = (yyvsp[(2) - (3)]); }
     break;
 
   case 41:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 488 "awkgram.y"
     {
 		if (do_profiling)
@@ -2458,7 +2458,7 @@ yyreduce:
 
   case 42:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 495 "awkgram.y"
     {
 		INSTRUCTION *dflt, *curr = NULL, *cexp, *cstmt;
@@ -2553,7 +2553,7 @@ yyreduce:
 
   case 43:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 585 "awkgram.y"
     { 
 		/*
@@ -2600,7 +2600,7 @@ yyreduce:
 
   case 44:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 627 "awkgram.y"
     {
 		/*
@@ -2647,7 +2647,7 @@ yyreduce:
 
   case 45:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 669 "awkgram.y"
     {
 		INSTRUCTION *ip;
@@ -2767,7 +2767,7 @@ regular_loop:
 
   case 46:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 784 "awkgram.y"
     {
 		(yyval) = mk_for_loop((yyvsp[(1) - (12)]), (yyvsp[(3) - (12)]), (yyvsp[(6) - (12)]), (yyvsp[(9) - (12)]), (yyvsp[(12) - (12)]));
@@ -2779,7 +2779,7 @@ regular_loop:
 
   case 47:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 791 "awkgram.y"
     {
 		(yyval) = mk_for_loop((yyvsp[(1) - (11)]), (yyvsp[(3) - (11)]), (INSTRUCTION *) NULL, (yyvsp[(8) - (11)]), (yyvsp[(11) - (11)]));
@@ -2791,7 +2791,7 @@ regular_loop:
 
   case 48:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 798 "awkgram.y"
     {
 		if (do_profiling)
@@ -2803,7 +2803,7 @@ regular_loop:
 
   case 49:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 808 "awkgram.y"
     { 
 		if (! break_allowed)
@@ -2817,7 +2817,7 @@ regular_loop:
 
   case 50:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 817 "awkgram.y"
     {
 		if (! continue_allowed)
@@ -2831,7 +2831,7 @@ regular_loop:
 
   case 51:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 826 "awkgram.y"
     {
 		/* if inside function (rule = 0), resolve context at run-time */
@@ -2845,7 +2845,7 @@ regular_loop:
 
   case 52:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 835 "awkgram.y"
     {
 		if (do_traditional)
@@ -2865,7 +2865,7 @@ regular_loop:
 
   case 53:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 850 "awkgram.y"
     {
 		/* Initialize the two possible jump targets, the actual target
@@ -2885,7 +2885,7 @@ regular_loop:
 
   case 54:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 865 "awkgram.y"
     {
 		if (! can_return)
@@ -2895,7 +2895,7 @@ regular_loop:
 
   case 55:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 868 "awkgram.y"
     {
 		if ((yyvsp[(3) - (4)]) == NULL) {
@@ -2909,14 +2909,14 @@ regular_loop:
 
   case 57:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 888 "awkgram.y"
     { in_print = TRUE; in_parens = 0; }
     break;
 
   case 58:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 889 "awkgram.y"
     {
 		/*
@@ -3016,14 +3016,14 @@ regular_loop:
 
   case 59:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 984 "awkgram.y"
     { sub_counter = 0; }
     break;
 
   case 60:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 985 "awkgram.y"
     {
 		char *arr = (yyvsp[(2) - (4)])->lextok;
@@ -3053,7 +3053,7 @@ regular_loop:
 
   case 61:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1014 "awkgram.y"
     {
 		static short warned = FALSE;
@@ -3077,35 +3077,35 @@ regular_loop:
 
   case 62:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1033 "awkgram.y"
     {	(yyval) = optimize_assignment((yyvsp[(1) - (1)])); }
     break;
 
   case 63:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1038 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 64:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1040 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 65:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1045 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 66:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1047 "awkgram.y"
     {
 		if ((yyvsp[(1) - (2)]) == NULL)
@@ -3117,14 +3117,14 @@ regular_loop:
 
   case 67:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1054 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 68:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1059 "awkgram.y"
     {
 		INSTRUCTION *casestmt = (yyvsp[(5) - (5)]);
@@ -3141,7 +3141,7 @@ regular_loop:
 
   case 69:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1071 "awkgram.y"
     {
 		INSTRUCTION *casestmt = (yyvsp[(4) - (4)]);
@@ -3157,14 +3157,14 @@ regular_loop:
 
   case 70:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1085 "awkgram.y"
     {	(yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 71:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1087 "awkgram.y"
     { 
 		(yyvsp[(2) - (2)])->memory->numbr = -(force_number((yyvsp[(2) - (2)])->memory));
@@ -3175,7 +3175,7 @@ regular_loop:
 
   case 72:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1093 "awkgram.y"
     {
 		bcfree((yyvsp[(1) - (2)]));
@@ -3185,14 +3185,14 @@ regular_loop:
 
   case 73:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1098 "awkgram.y"
     {	(yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 74:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1100 "awkgram.y"
     {
 		(yyvsp[(1) - (1)])->opcode = Op_push_re;
@@ -3202,21 +3202,21 @@ regular_loop:
 
   case 75:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1108 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 76:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1110 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 78:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1120 "awkgram.y"
     {
 		(yyval) = (yyvsp[(2) - (3)]);
@@ -3225,7 +3225,7 @@ regular_loop:
 
   case 79:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1127 "awkgram.y"
     {
 		in_print = FALSE;
@@ -3236,14 +3236,14 @@ regular_loop:
 
   case 80:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1132 "awkgram.y"
     { in_print = FALSE; in_parens = 0; }
     break;
 
   case 81:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1133 "awkgram.y"
     {
 		if ((yyvsp[(1) - (3)])->redir_type == redirect_twoway
@@ -3256,7 +3256,7 @@ regular_loop:
 
   case 82:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1144 "awkgram.y"
     {
 		(yyval) = mk_condition((yyvsp[(3) - (6)]), (yyvsp[(1) - (6)]), (yyvsp[(6) - (6)]), NULL, NULL);
@@ -3265,7 +3265,7 @@ regular_loop:
 
   case 83:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1149 "awkgram.y"
     {
 		(yyval) = mk_condition((yyvsp[(3) - (9)]), (yyvsp[(1) - (9)]), (yyvsp[(6) - (9)]), (yyvsp[(7) - (9)]), (yyvsp[(9) - (9)]));
@@ -3274,14 +3274,14 @@ regular_loop:
 
   case 88:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1166 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 89:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1168 "awkgram.y"
     {
 		bcfree((yyvsp[(1) - (2)]));
@@ -3291,7 +3291,7 @@ regular_loop:
 
   case 92:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1181 "awkgram.y"
     {
 		append_param((yyvsp[(1) - (1)])->lextok);
@@ -3302,7 +3302,7 @@ regular_loop:
 
   case 93:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1187 "awkgram.y"
     {
 		append_param((yyvsp[(3) - (3)])->lextok);
@@ -3314,63 +3314,63 @@ regular_loop:
 
   case 94:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1194 "awkgram.y"
     { /* func_params = NULL; */ }
     break;
 
   case 95:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1196 "awkgram.y"
     { /* func_params = NULL; */ }
     break;
 
   case 96:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1198 "awkgram.y"
     { /* func_params = NULL; */ }
     break;
 
   case 97:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1204 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 98:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1206 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 99:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1211 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 100:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1213 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 101:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1218 "awkgram.y"
     {	(yyval) = mk_expression_list(NULL, (yyvsp[(1) - (1)])); }
     break;
 
   case 102:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1220 "awkgram.y"
     {
 		(yyval) = mk_expression_list((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]));
@@ -3380,35 +3380,35 @@ regular_loop:
 
   case 103:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1225 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 104:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1227 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 105:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1229 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 106:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1231 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 107:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1237 "awkgram.y"
     {
 		if (do_lint && (yyvsp[(3) - (3)])->lasti->opcode == Op_match_rec)
@@ -3420,21 +3420,21 @@ regular_loop:
 
   case 108:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1244 "awkgram.y"
     {	(yyval) = mk_boolean((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 109:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1246 "awkgram.y"
     {	(yyval) = mk_boolean((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 110:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1248 "awkgram.y"
     {
 		if ((yyvsp[(1) - (3)])->lasti->opcode == Op_match_rec)
@@ -3455,7 +3455,7 @@ regular_loop:
 
   case 111:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1264 "awkgram.y"
     {
 		if (do_lint_old)
@@ -3470,7 +3470,7 @@ regular_loop:
 
   case 112:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1274 "awkgram.y"
     {
 		if (do_lint && (yyvsp[(3) - (3)])->lasti->opcode == Op_match_rec)
@@ -3482,35 +3482,35 @@ regular_loop:
 
   case 113:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1281 "awkgram.y"
     { (yyval) = mk_condition((yyvsp[(1) - (5)]), (yyvsp[(2) - (5)]), (yyvsp[(3) - (5)]), (yyvsp[(4) - (5)]), (yyvsp[(5) - (5)])); }
     break;
 
   case 114:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1283 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 115:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1288 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 116:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1290 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 117:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1292 "awkgram.y"
     {	
 		(yyvsp[(2) - (2)])->opcode = Op_assign_quotient;
@@ -3520,49 +3520,49 @@ regular_loop:
 
   case 118:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1300 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 119:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1302 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 120:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1307 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 121:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1309 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 122:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1314 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 123:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1316 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 124:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1318 "awkgram.y"
     {
 		int count = 2;
@@ -3617,49 +3617,49 @@ regular_loop:
 
   case 126:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1373 "awkgram.y"
     { (yyval) = mk_binary((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 127:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1375 "awkgram.y"
     { (yyval) = mk_binary((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 128:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1377 "awkgram.y"
     { (yyval) = mk_binary((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 129:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1379 "awkgram.y"
     { (yyval) = mk_binary((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 130:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1381 "awkgram.y"
     { (yyval) = mk_binary((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 131:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1383 "awkgram.y"
     { (yyval) = mk_binary((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 132:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1385 "awkgram.y"
     {
 		/*
@@ -3687,7 +3687,7 @@ regular_loop:
 
   case 133:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1408 "awkgram.y"
     {
 		(yyvsp[(2) - (2)])->opcode = Op_postincrement;
@@ -3697,7 +3697,7 @@ regular_loop:
 
   case 134:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1413 "awkgram.y"
     {
 		(yyvsp[(2) - (2)])->opcode = Op_postdecrement;
@@ -3707,7 +3707,7 @@ regular_loop:
 
   case 135:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1418 "awkgram.y"
     {
 		if (do_lint_old) {
@@ -3732,7 +3732,7 @@ regular_loop:
 
   case 136:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1443 "awkgram.y"
     {
 		  (yyval) = mk_getline((yyvsp[(3) - (4)]), (yyvsp[(4) - (4)]), (yyvsp[(1) - (4)]), (yyvsp[(2) - (4)])->redir_type);
@@ -3742,49 +3742,49 @@ regular_loop:
 
   case 137:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1449 "awkgram.y"
     { (yyval) = mk_binary((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 138:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1451 "awkgram.y"
     { (yyval) = mk_binary((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 139:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1453 "awkgram.y"
     { (yyval) = mk_binary((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 140:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1455 "awkgram.y"
     { (yyval) = mk_binary((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 141:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1457 "awkgram.y"
     { (yyval) = mk_binary((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 142:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1459 "awkgram.y"
     { (yyval) = mk_binary((yyvsp[(1) - (3)]), (yyvsp[(3) - (3)]), (yyvsp[(2) - (3)])); }
     break;
 
   case 143:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1464 "awkgram.y"
     {
 		(yyval) = list_create((yyvsp[(1) - (1)]));
@@ -3793,7 +3793,7 @@ regular_loop:
 
   case 144:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1468 "awkgram.y"
     {
 		if ((yyvsp[(2) - (2)])->opcode == Op_match_rec) {
@@ -3829,14 +3829,14 @@ regular_loop:
 
   case 145:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1499 "awkgram.y"
     { (yyval) = (yyvsp[(2) - (3)]); }
     break;
 
   case 146:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1501 "awkgram.y"
     {
 		(yyval) = snode((yyvsp[(3) - (4)]), (yyvsp[(1) - (4)]));
@@ -3847,7 +3847,7 @@ regular_loop:
 
   case 147:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1507 "awkgram.y"
     {
 		(yyval) = snode((yyvsp[(3) - (4)]), (yyvsp[(1) - (4)]));
@@ -3858,7 +3858,7 @@ regular_loop:
 
   case 148:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1513 "awkgram.y"
     {
 		static short warned1 = FALSE;
@@ -3876,7 +3876,7 @@ regular_loop:
 
   case 151:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1528 "awkgram.y"
     {
 		(yyvsp[(1) - (2)])->opcode = Op_preincrement;
@@ -3886,7 +3886,7 @@ regular_loop:
 
   case 152:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1533 "awkgram.y"
     {
 		(yyvsp[(1) - (2)])->opcode = Op_predecrement;
@@ -3896,7 +3896,7 @@ regular_loop:
 
   case 153:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1538 "awkgram.y"
     {
 		(yyval) = list_create((yyvsp[(1) - (1)]));
@@ -3905,7 +3905,7 @@ regular_loop:
 
   case 154:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1542 "awkgram.y"
     {
 		(yyval) = list_create((yyvsp[(1) - (1)]));
@@ -3914,7 +3914,7 @@ regular_loop:
 
   case 155:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1546 "awkgram.y"
     {
 		if ((yyvsp[(2) - (2)])->lasti->opcode == Op_push_i
@@ -3931,7 +3931,7 @@ regular_loop:
 
   case 156:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1558 "awkgram.y"
     {
 	    /*
@@ -3946,7 +3946,7 @@ regular_loop:
 
   case 157:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1571 "awkgram.y"
     {
 		func_use((yyvsp[(1) - (1)])->lasti->func_name, FUNC_USE);
@@ -3956,7 +3956,7 @@ regular_loop:
 
   case 158:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1576 "awkgram.y"
     {
 		/* indirect function call */
@@ -3994,7 +3994,7 @@ regular_loop:
 
   case 159:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1612 "awkgram.y"
     {
 		param_sanity((yyvsp[(3) - (4)]));
@@ -4013,42 +4013,42 @@ regular_loop:
 
   case 160:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1629 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 161:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1631 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 162:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1636 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 163:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1638 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (2)]); }
     break;
 
   case 164:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1643 "awkgram.y"
     {	(yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 165:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1645 "awkgram.y"
     {
 		(yyval) = list_merge((yyvsp[(1) - (2)]), (yyvsp[(2) - (2)]));
@@ -4057,7 +4057,7 @@ regular_loop:
 
   case 166:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1652 "awkgram.y"
     {
 		INSTRUCTION *ip = (yyvsp[(1) - (1)])->lasti; 
@@ -4076,7 +4076,7 @@ regular_loop:
 
   case 167:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1669 "awkgram.y"
     {
 		INSTRUCTION *t = (yyvsp[(2) - (3)]);
@@ -4095,14 +4095,14 @@ regular_loop:
 
   case 168:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1686 "awkgram.y"
     {	(yyval) = (yyvsp[(1) - (1)]); }
     break;
 
   case 169:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1688 "awkgram.y"
     {
 		(yyval) = list_merge((yyvsp[(1) - (2)]), (yyvsp[(2) - (2)]));
@@ -4111,14 +4111,14 @@ regular_loop:
 
   case 170:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1695 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (2)]); }
     break;
 
   case 171:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1700 "awkgram.y"
     {
 		char *var_name = (yyvsp[(1) - (1)])->lextok;
@@ -4131,7 +4131,7 @@ regular_loop:
 
   case 172:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1708 "awkgram.y"
     {
 		NODE *n;
@@ -4147,7 +4147,7 @@ regular_loop:
 
   case 173:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1722 "awkgram.y"
     {
 		INSTRUCTION *ip = (yyvsp[(1) - (1)])->nexti;
@@ -4165,7 +4165,7 @@ regular_loop:
 
   case 174:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1735 "awkgram.y"
     {
 		(yyval) = list_append((yyvsp[(2) - (3)]), (yyvsp[(1) - (3)]));
@@ -4176,7 +4176,7 @@ regular_loop:
 
   case 175:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1744 "awkgram.y"
     {
 		(yyvsp[(1) - (1)])->opcode = Op_postincrement;
@@ -4185,7 +4185,7 @@ regular_loop:
 
   case 176:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1748 "awkgram.y"
     {
 		(yyvsp[(1) - (1)])->opcode = Op_postdecrement;
@@ -4194,49 +4194,49 @@ regular_loop:
 
   case 177:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1751 "awkgram.y"
     { (yyval) = NULL; }
     break;
 
   case 179:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1759 "awkgram.y"
     { yyerrok; }
     break;
 
   case 180:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1763 "awkgram.y"
     { yyerrok; }
     break;
 
   case 183:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1772 "awkgram.y"
     { yyerrok; }
     break;
 
   case 184:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1776 "awkgram.y"
     { (yyval) = (yyvsp[(1) - (1)]); yyerrok; }
     break;
 
   case 185:
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 1780 "awkgram.y"
     { yyerrok; }
     break;
 
 
 
-/* Line 1806 of yacc.c  */
+/* Line 1821 of yacc.c  */
 #line 4253 "awkgram.c"
       default: break;
     }
@@ -4485,6 +4485,7 @@ struct token {
 #	define	RESX		0x0800	/* Bell Labs Research extension */
 #	define	BREAK		0x1000	/* break allowed inside */
 #	define	CONTINUE	0x2000	/* continue allowed inside */
+	
 	NODE *(*ptr)(int);	/* function that implements this keyword */
 };
 
@@ -4542,9 +4543,9 @@ static const struct token tokentab[] = {
 {"for",		Op_K_for,	 LEX_FOR,	BREAK|CONTINUE,	0},
 {"func",	Op_func, LEX_FUNCTION,	NOT_POSIX|NOT_OLD,	0},
 {"function",Op_func, LEX_FUNCTION,	NOT_OLD,	0},
-{"gensub",	Op_builtin,	 LEX_BUILTIN,	GAWKX|A(3)|A(4), do_gensub},
+{"gensub",	Op_sub_builtin,	 LEX_BUILTIN,	GAWKX|A(3)|A(4), 0},
 {"getline",	Op_K_getline_redir,	 LEX_GETLINE,	NOT_OLD,	0},
-{"gsub",	Op_builtin,	 LEX_BUILTIN,	NOT_OLD|A(2)|A(3), do_gsub},
+{"gsub",	Op_sub_builtin,	 LEX_BUILTIN,	NOT_OLD|A(2)|A(3), 0},
 {"if",		Op_K_if,	 LEX_IF,	0,		0},
 {"in",		Op_symbol,	 LEX_IN,	0,		0},
 {"include",  Op_symbol,	 LEX_INCLUDE,	GAWKX,	0},
@@ -4575,7 +4576,7 @@ static const struct token tokentab[] = {
 #endif
 {"strftime",	Op_builtin,	 LEX_BUILTIN,	GAWKX|A(0)|A(1)|A(2)|A(3), do_strftime},
 {"strtonum",	Op_builtin,    LEX_BUILTIN,	GAWKX|A(1),	do_strtonum},
-{"sub",		Op_builtin,	 LEX_BUILTIN,	NOT_OLD|A(2)|A(3), do_sub},
+{"sub",		Op_sub_builtin,	 LEX_BUILTIN,	NOT_OLD|A(2)|A(3), 0},
 {"substr",	Op_builtin,	 LEX_BUILTIN,	A(2)|A(3),	do_substr},
 {"switch",	Op_K_switch,	 LEX_SWITCH,	GAWKX|BREAK,	0},
 {"system",	Op_builtin,	 LEX_BUILTIN,	NOT_OLD|A(1),	do_system},
@@ -6286,8 +6287,6 @@ snode(INSTRUCTION *subn, INSTRUCTION *r)
 		assert(nexp > 0);
 	}		
 
-	r->builtin = tokentab[idx].ptr;
-
 	/* check against how many args. are allowed for this builtin */
 	args_allowed = tokentab[idx].flags & ARGS;
 	if (args_allowed && (args_allowed & A(nexp)) == 0) {
@@ -6296,7 +6295,85 @@ snode(INSTRUCTION *subn, INSTRUCTION *r)
 		return NULL;
 	}
 
+	/* special processing for sub, gsub and gensub */
+
+	if (tokentab[idx].value == Op_sub_builtin) {
+		const char *operator = tokentab[idx].operator;
+
+		r->sub_flags = 0;
+
+		arg = subn->nexti;		/* first arg list */
+		(void) mk_rexp(arg);
+
+		if (strcmp(operator, "gensub") != 0) {
+			/* sun and gsub */
+
+			if (strcmp(operator, "gsub") == 0)
+				r->sub_flags |= GSUB;
+
+			arg = arg->lasti->nexti;	/* 2nd arg list */
+			if (nexp == 2) {
+				INSTRUCTION *expr;
+				expr = list_create(instruction(Op_push_i));
+				expr->nexti->memory = mk_number((AWKNUM) 0.0, (PERM|NUMCUR|NUMBER));
+				(void) mk_expression_list(subn,
+						list_append(expr, instruction(Op_field_spec)));
+			}
+
+			arg = arg->lasti->nexti; 	/* third arg list */
+			ip = arg->lasti;
+			if (ip->opcode == Op_push_i) {
+				if (do_lint)
+					lintwarn(_("%s: string literal as last arg of substitute has no effect"),
+						operator);
+				r->sub_flags |=	LITERAL;
+			} else {
+				if (make_assignable(ip) == NULL)
+					yyerror(_("%s third parameter is not a changeable object"),
+						operator);
+				else
+					ip->do_reference = TRUE;
+			}
+
+			r->expr_count = count_expressions(&subn, FALSE);
+			ip = subn->lasti;
+
+			(void) list_append(subn, r);
+
+			/* add after_assign code */
+			if (ip->opcode == Op_push_lhs && ip->memory->type == Node_var && ip->memory->var_assign) {
+				(void) list_append(subn, instruction(Op_var_assign));
+				subn->lasti->memory = ip->memory;
+				subn->lasti->assign_var = ip->memory->var_assign;
+				r->sub_flags |= AFTER_ASSIGN;
+			} else if (ip->opcode == Op_field_spec_lhs) {
+				(void) list_append(subn, instruction(Op_field_assign));
+				subn->lasti->field_assign = (Func_ptr) 0;
+				ip->target_assign = subn->lasti;
+				r->sub_flags |= AFTER_ASSIGN;
+			}
+			return subn;	
+
+		} else {
+			/* gensub */
+
+			r->sub_flags |= GENSUB;
+			if (nexp == 3) {
+				ip = instruction(Op_push_i);
+				ip->memory = mk_number((AWKNUM) 0.0, (PERM|NUMCUR|NUMBER));
+				(void) mk_expression_list(subn,
+						list_append(list_create(ip), instruction(Op_field_spec)));
+			}
+
+			r->expr_count = count_expressions(&subn, FALSE);
+			return list_append(subn, r);
+		}
+	}
+
+	r->builtin = tokentab[idx].ptr;
+
 	/* special case processing for a few builtins */
+
 	if (r->builtin == do_length) {
 		if (nexp == 0) {		
 		    /* no args. Use $0 */
@@ -6338,71 +6415,6 @@ snode(INSTRUCTION *subn, INSTRUCTION *r)
 			if (/*ip == arg->nexti  && */ ip->opcode == Op_push)
 				ip->opcode = Op_push_array;
 		}
-	} else if (r->builtin == do_sub || r->builtin == do_gsub) {
-		int literal = FALSE;
-		
-		arg = subn->nexti;		/* first arg list */
-		(void) mk_rexp(arg);
-
-		arg = arg->lasti->nexti;	/* 2nd arg list */
-		if (nexp == 2) {
-			INSTRUCTION *expr;
-			expr = list_create(instruction(Op_push_i));
-			expr->nexti->memory = mk_number((AWKNUM) 0.0, (PERM|NUMCUR|NUMBER));
-			(void) mk_expression_list(subn,
-					list_append(expr, instruction(Op_field_spec)));
-		}
-
-		arg = arg->lasti->nexti; 	/* third arg list */
-		ip = arg->lasti;
-		if (ip->opcode == Op_push_i) {
-			if (do_lint)
-				lintwarn(_("%s: string literal as last arg of substitute has no effect"),
-					(r->builtin == do_sub) ? "sub" : "gsub");
-			literal = TRUE;
-		} else {
-			if (make_assignable(ip) == NULL)
-				yyerror(_("%s third parameter is not a changeable object"),
-					(r->builtin == do_sub) ? "sub" : "gsub");
-			else
-				ip->do_reference = TRUE;
-		}
-
-		/* kludge: This is one of the few cases
-		 * when we need to know the type of item on stack.
-		 * In case of string literal as the last argument,
-		 * pass 4 as # of args (See sub_common code in builtin.c).
-		 * Other cases like length(array or scalar) seem
-		 * to work out ok.
-		 */
-		
-		r->expr_count = count_expressions(&subn, FALSE) + !!literal;
-		ip = subn->lasti;
-
-		(void) list_append(subn, r);
-
-		/* add after_assign bytecode(s) */
-		if (ip->opcode == Op_push_lhs && ip->memory->type == Node_var && ip->memory->var_assign) {
-			(void) list_append(subn, instruction(Op_var_assign));
-			subn->lasti->memory = ip->memory;
-			subn->lasti->assign_var = ip->memory->var_assign;
-		} else if (ip->opcode == Op_field_spec_lhs) {
-			(void) list_append(subn, instruction(Op_field_assign));
-			subn->lasti->field_assign = (Func_ptr) 0;
-			ip->target_assign = subn->lasti;
-		}
-		return subn;	
-	} else if (r->builtin == do_gensub) {
-		if (nexp == 3) {
-			arg = subn->nexti->lasti->nexti->lasti->nexti;	/* 3rd arg list */
-			ip = instruction(Op_push_i);
-			ip->memory = mk_number((AWKNUM) 0.0, (PERM|NUMCUR|NUMBER));
-			(void) mk_expression_list(subn,
-					list_append(list_create(ip),
-						instruction(Op_field_spec)));
-		}
-		arg = subn->nexti;		/* first arg list */
-		(void) mk_rexp(arg);
 	} else if (r->builtin == do_split) {
 		arg = subn->nexti->lasti->nexti;	/* 2nd arg list */
 		ip = arg->lasti;
diff --git a/awkgram.y b/awkgram.y
index 6b28b52..4553d09 100644
--- a/awkgram.y
+++ b/awkgram.y
@@ -1795,6 +1795,7 @@ struct token {
 #	define	RESX		0x0800	/* Bell Labs Research extension */
 #	define	BREAK		0x1000	/* break allowed inside */
 #	define	CONTINUE	0x2000	/* continue allowed inside */
+	
 	NODE *(*ptr)(int);	/* function that implements this keyword */
 };
 
@@ -1852,9 +1853,9 @@ static const struct token tokentab[] = {
 {"for",		Op_K_for,	 LEX_FOR,	BREAK|CONTINUE,	0},
 {"func",	Op_func, LEX_FUNCTION,	NOT_POSIX|NOT_OLD,	0},
 {"function",Op_func, LEX_FUNCTION,	NOT_OLD,	0},
-{"gensub",	Op_builtin,	 LEX_BUILTIN,	GAWKX|A(3)|A(4), do_gensub},
+{"gensub",	Op_sub_builtin,	 LEX_BUILTIN,	GAWKX|A(3)|A(4), 0},
 {"getline",	Op_K_getline_redir,	 LEX_GETLINE,	NOT_OLD,	0},
-{"gsub",	Op_builtin,	 LEX_BUILTIN,	NOT_OLD|A(2)|A(3), do_gsub},
+{"gsub",	Op_sub_builtin,	 LEX_BUILTIN,	NOT_OLD|A(2)|A(3), 0},
 {"if",		Op_K_if,	 LEX_IF,	0,		0},
 {"in",		Op_symbol,	 LEX_IN,	0,		0},
 {"include",  Op_symbol,	 LEX_INCLUDE,	GAWKX,	0},
@@ -1885,7 +1886,7 @@ static const struct token tokentab[] = {
 #endif
 {"strftime",	Op_builtin,	 LEX_BUILTIN,	GAWKX|A(0)|A(1)|A(2)|A(3), do_strftime},
 {"strtonum",	Op_builtin,    LEX_BUILTIN,	GAWKX|A(1),	do_strtonum},
-{"sub",		Op_builtin,	 LEX_BUILTIN,	NOT_OLD|A(2)|A(3), do_sub},
+{"sub",		Op_sub_builtin,	 LEX_BUILTIN,	NOT_OLD|A(2)|A(3), 0},
 {"substr",	Op_builtin,	 LEX_BUILTIN,	A(2)|A(3),	do_substr},
 {"switch",	Op_K_switch,	 LEX_SWITCH,	GAWKX|BREAK,	0},
 {"system",	Op_builtin,	 LEX_BUILTIN,	NOT_OLD|A(1),	do_system},
@@ -3596,8 +3597,6 @@ snode(INSTRUCTION *subn, INSTRUCTION *r)
 		assert(nexp > 0);
 	}		
 
-	r->builtin = tokentab[idx].ptr;
-
 	/* check against how many args. are allowed for this builtin */
 	args_allowed = tokentab[idx].flags & ARGS;
 	if (args_allowed && (args_allowed & A(nexp)) == 0) {
@@ -3606,7 +3605,85 @@ snode(INSTRUCTION *subn, INSTRUCTION *r)
 		return NULL;
 	}
 
+	/* special processing for sub, gsub and gensub */
+
+	if (tokentab[idx].value == Op_sub_builtin) {
+		const char *operator = tokentab[idx].operator;
+
+		r->sub_flags = 0;
+
+		arg = subn->nexti;		/* first arg list */
+		(void) mk_rexp(arg);
+
+		if (strcmp(operator, "gensub") != 0) {
+			/* sun and gsub */
+
+			if (strcmp(operator, "gsub") == 0)
+				r->sub_flags |= GSUB;
+
+			arg = arg->lasti->nexti;	/* 2nd arg list */
+			if (nexp == 2) {
+				INSTRUCTION *expr;
+				expr = list_create(instruction(Op_push_i));
+				expr->nexti->memory = mk_number((AWKNUM) 0.0, (PERM|NUMCUR|NUMBER));
+				(void) mk_expression_list(subn,
+						list_append(expr, instruction(Op_field_spec)));
+			}
+
+			arg = arg->lasti->nexti; 	/* third arg list */
+			ip = arg->lasti;
+			if (ip->opcode == Op_push_i) {
+				if (do_lint)
+					lintwarn(_("%s: string literal as last arg of substitute has no effect"),
+						operator);
+				r->sub_flags |=	LITERAL;
+			} else {
+				if (make_assignable(ip) == NULL)
+					yyerror(_("%s third parameter is not a changeable object"),
+						operator);
+				else
+					ip->do_reference = TRUE;
+			}
+
+			r->expr_count = count_expressions(&subn, FALSE);
+			ip = subn->lasti;
+
+			(void) list_append(subn, r);
+
+			/* add after_assign code */
+			if (ip->opcode == Op_push_lhs && ip->memory->type == Node_var && ip->memory->var_assign) {
+				(void) list_append(subn, instruction(Op_var_assign));
+				subn->lasti->memory = ip->memory;
+				subn->lasti->assign_var = ip->memory->var_assign;
+				r->sub_flags |= AFTER_ASSIGN;
+			} else if (ip->opcode == Op_field_spec_lhs) {
+				(void) list_append(subn, instruction(Op_field_assign));
+				subn->lasti->field_assign = (Func_ptr) 0;
+				ip->target_assign = subn->lasti;
+				r->sub_flags |= AFTER_ASSIGN;
+			}
+			return subn;	
+
+		} else {
+			/* gensub */
+
+			r->sub_flags |= GENSUB;
+			if (nexp == 3) {
+				ip = instruction(Op_push_i);
+				ip->memory = mk_number((AWKNUM) 0.0, (PERM|NUMCUR|NUMBER));
+				(void) mk_expression_list(subn,
+						list_append(list_create(ip), instruction(Op_field_spec)));
+			}
+
+			r->expr_count = count_expressions(&subn, FALSE);
+			return list_append(subn, r);
+		}
+	}
+
+	r->builtin = tokentab[idx].ptr;
+
 	/* special case processing for a few builtins */
+
 	if (r->builtin == do_length) {
 		if (nexp == 0) {		
 		    /* no args. Use $0 */
@@ -3648,71 +3725,6 @@ snode(INSTRUCTION *subn, INSTRUCTION *r)
 			if (/*ip == arg->nexti  && */ ip->opcode == Op_push)
 				ip->opcode = Op_push_array;
 		}
-	} else if (r->builtin == do_sub || r->builtin == do_gsub) {
-		int literal = FALSE;
-		
-		arg = subn->nexti;		/* first arg list */
-		(void) mk_rexp(arg);
-
-		arg = arg->lasti->nexti;	/* 2nd arg list */
-		if (nexp == 2) {
-			INSTRUCTION *expr;
-			expr = list_create(instruction(Op_push_i));
-			expr->nexti->memory = mk_number((AWKNUM) 0.0, (PERM|NUMCUR|NUMBER));
-			(void) mk_expression_list(subn,
-					list_append(expr, instruction(Op_field_spec)));
-		}
-
-		arg = arg->lasti->nexti; 	/* third arg list */
-		ip = arg->lasti;
-		if (ip->opcode == Op_push_i) {
-			if (do_lint)
-				lintwarn(_("%s: string literal as last arg of substitute has no effect"),
-					(r->builtin == do_sub) ? "sub" : "gsub");
-			literal = TRUE;
-		} else {
-			if (make_assignable(ip) == NULL)
-				yyerror(_("%s third parameter is not a changeable object"),
-					(r->builtin == do_sub) ? "sub" : "gsub");
-			else
-				ip->do_reference = TRUE;
-		}
-
-		/* kludge: This is one of the few cases
-		 * when we need to know the type of item on stack.
-		 * In case of string literal as the last argument,
-		 * pass 4 as # of args (See sub_common code in builtin.c).
-		 * Other cases like length(array or scalar) seem
-		 * to work out ok.
-		 */
-		
-		r->expr_count = count_expressions(&subn, FALSE) + !!literal;
-		ip = subn->lasti;
-
-		(void) list_append(subn, r);
-
-		/* add after_assign bytecode(s) */
-		if (ip->opcode == Op_push_lhs && ip->memory->type == Node_var && ip->memory->var_assign) {
-			(void) list_append(subn, instruction(Op_var_assign));
-			subn->lasti->memory = ip->memory;
-			subn->lasti->assign_var = ip->memory->var_assign;
-		} else if (ip->opcode == Op_field_spec_lhs) {
-			(void) list_append(subn, instruction(Op_field_assign));
-			subn->lasti->field_assign = (Func_ptr) 0;
-			ip->target_assign = subn->lasti;
-		}
-		return subn;	
-	} else if (r->builtin == do_gensub) {
-		if (nexp == 3) {
-			arg = subn->nexti->lasti->nexti->lasti->nexti;	/* 3rd arg list */
-			ip = instruction(Op_push_i);
-			ip->memory = mk_number((AWKNUM) 0.0, (PERM|NUMCUR|NUMBER));
-			(void) mk_expression_list(subn,
-					list_append(list_create(ip),
-						instruction(Op_field_spec)));
-		}
-		arg = subn->nexti;		/* first arg list */
-		(void) mk_rexp(arg);
 	} else if (r->builtin == do_split) {
 		arg = subn->nexti->lasti->nexti;	/* 2nd arg list */
 		ip = arg->lasti;
diff --git a/builtin.c b/builtin.c
index 724ea6d..d554930 100644
--- a/builtin.c
+++ b/builtin.c
@@ -72,7 +72,6 @@ extern NODE **fields_arr;
 extern int output_is_tty;
 extern FILE *output_fp;
 
-static NODE *sub_common(int nargs, long how_many, int backdigs);
 
 #define POP_TWO_SCALARS(s1, s2) \
 s2 = POP_SCALAR(); \
@@ -2319,7 +2318,7 @@ do_match(int nargs)
 	return make_number((AWKNUM) rstart);
 }
 
-/* sub_common --- the common code (does the work) for sub, gsub, and gensub */
+/* do_sub --- do the work for sub, gsub, and gensub */
 
 /*
  * Gsub can be tricksy; particularly when handling the case of null strings.
@@ -2412,12 +2411,12 @@ do_match(int nargs)
  * NB: `howmany' conflicts with a SunOS 4.x macro in <sys/param.h>.
  */
 
-static NODE *
-sub_common(int nargs, long how_many, int backdigs)
+NODE *
+do_sub(int nargs, unsigned int flags, int *num_matches)
 {
 	char *scan;
 	char *bp, *cp;
-	char *buf;
+	char *buf = NULL;
 	size_t buflen;
 	char *matchend;
 	size_t len;
@@ -2434,38 +2433,77 @@ sub_common(int nargs, long how_many, int backdigs)
 	NODE *s;		/* subst. pattern */
 	NODE *t;		/* string to make sub. in; $0 if none given */
 	NODE *tmp;
-	NODE **lhs;
-	int global = (how_many == -1);
+	NODE **lhs = NULL;
+	long how_many = 1;	/* one substitution for sub, also gensub default */
+	int global;
 	long current;
 	int lastmatchnonzero;
 	char *mb_indices = NULL;
-
-	tmp = PEEK(2);	/* take care of regexp early, in case re_update is fatal */
-	rp = re_update(tmp);
 	
-	/* original string */
-	if (nargs == 4) {	/* kludge: no of items on stack is really 3,
-                         * See snode(..) in awkgram.y
-                         */ 
-		lhs = NULL;
-		t = POP_STRING();
+	if ((flags & GENSUB) != 0) {
+		double d;
+		NODE *t1;
+
+		tmp = PEEK(3);
+		rp = re_update(tmp);
+
+		t = POP_STRING();	/* original string */
+
+		t1 = POP_SCALAR();	/* value of global flag */
+		if ((t1->flags & (STRCUR|STRING)) != 0) {
+			if (t1->stlen > 0 && (t1->stptr[0] == 'g' || t1->stptr[0] == 'G'))
+				how_many = -1;
+			else {
+				d = force_number(t1);
+
+				if ((t1->flags & NUMCUR) != 0)
+					goto set_how_many;
+
+				how_many = 1;
+			}
+		} else {
+			d = force_number(t1);
+set_how_many:
+			if (d < 1)
+				how_many = 1;
+			else if (d < LONG_MAX)
+				how_many = d;
+			else
+				how_many = LONG_MAX;
+			if (d == 0)
+				warning(_("gensub: third argument of 0 treated as 1"));
+		}
+		DEREF(t1);
+
 	} else {
-		lhs = POP_ADDRESS();
-		t = force_string(*lhs);
+
+		/* take care of regexp early, in case re_update is fatal */
+
+		tmp = PEEK(2);
+		rp = re_update(tmp);
+
+		if ((flags & GSUB) != 0)
+			how_many = -1;
+
+		/* original string */
+
+		if ((flags & LITERAL) != 0)
+			t = POP_STRING();
+		else {
+			lhs = POP_ADDRESS();
+			t = force_string(*lhs);
+		}
 	}
 
+	global = (how_many == -1);
 
-	s = POP_STRING();		/* replacement text */
+	s = POP_STRING();	/* replacement text */
 	decr_sp();		/* regexp, already updated above */
 
 	/* do the search early to avoid work on non-match */
 	if (research(rp, t->stptr, 0, t->stlen, RE_NEED_START) == -1 ||
-	    RESTART(rp, t->stptr) > t->stlen) {
-		if (lhs == NULL)
-			DEREF(t);
-		DEREF(s);
-		return make_number((AWKNUM) 0.0);
-	}
+			RESTART(rp, t->stptr) > t->stlen)
+		goto done;
 
 	t->flags |= STRING;
 
@@ -2476,7 +2514,7 @@ sub_common(int nargs, long how_many, int backdigs)
 	repl = s->stptr;
 	replend = repl + s->stlen;
 	repllen = replend - repl;
-	emalloc(buf, char *, buflen + 2, "sub_common");
+	emalloc(buf, char *, buflen + 2, "do_sub");
 	buf[buflen] = '\0';
 	buf[buflen + 1] = '\0';
 	ampersands = 0;
@@ -2490,7 +2528,7 @@ sub_common(int nargs, long how_many, int backdigs)
 	 * for example.
 	 */
 	if (gawk_mb_cur_max > 1 && repllen > 0) {
-		emalloc(mb_indices, char *, repllen * sizeof(char), "sub_common");
+		emalloc(mb_indices, char *, repllen * sizeof(char), "do_sub");
 		index_multibyte_buffer(repl, mb_indices, repllen);
 	}
 
@@ -2500,7 +2538,7 @@ sub_common(int nargs, long how_many, int backdigs)
 			repllen--;
 			ampersands++;
 		} else if (*scan == '\\') {
-			if (backdigs) {	/* gensub, behave sanely */
+			if (flags & GENSUB) {	/* gensub, behave sanely */
 				if (isdigit((unsigned char) scan[1])) {
 					ampersands++;
 					scan++;
@@ -2575,7 +2613,7 @@ sub_common(int nargs, long how_many, int backdigs)
 					&& (gawk_mb_cur_max == 1
 						|| (repllen > 0 && mb_indices[scan - repl] == 1))
 				) {
-					if (backdigs) {	/* gensub, behave sanely */
+					if (flags & GENSUB) {	/* gensub, behave sanely */
 						if (isdigit((unsigned char) scan[1])) {
 							int dig = scan[1] - '0';
 							if (dig < NUMSUBPATS(rp, t->stptr) && SUBPATSTART(rp, tp->stptr, dig) != -1) {
@@ -2619,7 +2657,7 @@ sub_common(int nargs, long how_many, int backdigs)
 		textlen = text + textlen - matchend;
 		text = matchend;
 
-		if ((current >= how_many && !global)
+		if ((current >= how_many && ! global)
 		    || ((long) textlen <= 0 && matchstart == matchend)
 		    || research(rp, t->stptr, text - t->stptr, textlen, RE_NEED_START) == -1)
 			break;
@@ -2628,7 +2666,7 @@ sub_common(int nargs, long how_many, int backdigs)
 	sofar = bp - buf;
 	if (buflen - sofar - textlen - 1) {
 		buflen = sofar + textlen + 2;
-		erealloc(buf, char *, buflen, "sub_common");
+		erealloc(buf, char *, buflen, "do_sub");
 		bp = buf + sofar;
 	}
 	for (scan = matchend; scan < text + textlen; scan++)
@@ -2636,102 +2674,39 @@ sub_common(int nargs, long how_many, int backdigs)
 	*bp = '\0';
 	textlen = bp - buf;
 
-	DEREF(s);
-
-	if (lhs != NULL) {
-		if (matches > 0) {
-			unref(*lhs);
-			*lhs = make_str_node(buf, textlen, ALREADY_MALLOCED);	
-		} else
-			efree(buf);
-	} else {
-		efree(buf);
-		DEREF(t);
-	}
-
 	if (mb_indices != NULL)
 		efree(mb_indices);
 
-	return make_number((AWKNUM) matches);
-}
-
-/* do_gsub --- global substitution */
-
-NODE *
-do_gsub(int nargs)
-{
-	return sub_common(nargs, -1, FALSE);
-}
-
-/* do_sub --- single substitution */
-
-NODE *
-do_sub(int nargs)
-{
-	return sub_common(nargs, 1, FALSE);
-}
-
-/* do_gensub --- fix up the tree for sub_common for the gensub function */
-
-NODE *
-do_gensub(int nargs)
-{
-	NODE *t, *tmp, *target, *ret;
-	long how_many = 1;	/* default is one substitution */
-	double d;
-
-	tmp = POP_STRING();	/* target */
-	t = POP_SCALAR();	/* value of global flag */
-
-	/*
-	 * We make copy of the original target string, and pass that
-	 * in to sub_common() as the target to make the substitution in.
-	 * We will then return the result string as the return value of
-	 * this function.
-	 */
-
-	target = make_string(tmp->stptr, tmp->stlen);
-	DEREF(tmp);
-	PUSH_ADDRESS(& target);
-
-	if ((t->flags & (STRCUR|STRING)) != 0) {
-		if (t->stlen > 0 && (t->stptr[0] == 'g' || t->stptr[0] == 'G'))
-			how_many = -1;
-		else {
-			d = force_number(t);
+done:
+	DEREF(s);
 
-			if ((t->flags & NUMCUR) != 0)
-				goto set_how_many;
+	*num_matches = matches;
+	if ((matches == 0 || (flags & LITERAL) != 0) && buf != NULL)
+		efree(buf); 
 
-			how_many = 1;
+	if (flags & GENSUB) {
+		if (matches > 0) {
+			/* return the result string */
+			DEREF(t);
+			return make_str_node(buf, textlen, ALREADY_MALLOCED);	
 		}
-	} else {
-		d = force_number(t);
-set_how_many:
-		if (d < 1)
-			how_many = 1;
-		else if (d < LONG_MAX)
-			how_many = d;
-		else
-			how_many = LONG_MAX;
-		if (d == 0)
-			warning(_("gensub: third argument of 0 treated as 1"));
-	}
-
-	DEREF(t);
 
-	ret = sub_common(3, how_many, TRUE);
-	unref(ret);
+		/* return the original string */
+		return t;
+	}
 
-	/*
-	 * Note that we don't care what sub_common() returns, since the
-	 * easiest thing for the programmer is to return the string, even
-	 * if no substitutions were done.
-	 */
+	/* For a string literal, must not change the original string. */
+	if (flags & LITERAL)
+		DEREF(t);
+	else if (matches > 0) {
+		unref(*lhs);
+		*lhs = make_str_node(buf, textlen, ALREADY_MALLOCED);	
+	}
 
-	return target;
+	return make_number((AWKNUM) matches);
 }
 
+
 /* make_integer - Convert an integer to a number node.  */
 
 static NODE *
diff --git a/debug.c b/debug.c
index 9b9db34..404042c 100644
--- a/debug.c
+++ b/debug.c
@@ -3740,7 +3740,16 @@ print_instruction(INSTRUCTION *pc, Func_print print_func, FILE *fp, int in_dump)
 		break;
 
 	case Op_var_assign:
-		print_func(fp, "[set_%s]\n", pc->memory->vname);
+		if (pc->assign_var)
+			print_func(fp, "[set_%s()]", pc->memory->vname);
+		print_func(fp, "\n");
+		break;
+
+	case Op_field_assign:
+		if (pc->field_assign)
+			print_func(fp, "[%s]", pc->field_assign == reset_record ?
+					"reset_record()" : "invalidate_field0()");
+		print_func(fp, "\n");
 		break;
 
 	case Op_field_spec_lhs:
@@ -3830,6 +3839,27 @@ print_instruction(INSTRUCTION *pc, Func_print print_func, FILE *fp, int in_dump)
 		                pc->line_range, pc->target_jmp);
 		break;
 
+	case Op_sub_builtin:
+	{
+		const char *fname = "sub";
+		static const struct flagtab values[] = {
+                	{ GSUB, "GSUB" },
+			{ GENSUB, "GENSUB" },
+			{ AFTER_ASSIGN,	"AFTER_ASSIGN" },
+			{ LITERAL, "LITERAL" },
+			{ 0, NULL }
+		};
+
+		if (pc->sub_flags & GSUB)
+			fname = "gsub";
+		else if (pc->sub_flags & GENSUB)
+			fname = "gensub";
+		print_func(fp, "%s [arg_count = %ld] [sub_flags = %s]\n",
+				fname, pc->expr_count,
+				genflags2str(pc->sub_flags, values));
+	}
+		break;
+	
 	case Op_builtin:
 	{
 		const char *fname = getfname(pc->builtin);
diff --git a/eval.c b/eval.c
index 4132474..bdbd04b 100644
--- a/eval.c
+++ b/eval.c
@@ -348,6 +348,7 @@ static struct optypetab {
 	{ "Op_K_getline", "getline" },
 	{ "Op_K_nextfile", "nextfile" },
 	{ "Op_builtin", NULL },
+	{ "Op_sub_builtin", NULL },
 	{ "Op_in_array", " in " },
 	{ "Op_func_call", NULL },
 	{ "Op_indirect_func_call", NULL },
@@ -2114,11 +2115,13 @@ post:
 			break;
 
 		case Op_var_assign:
-			pc->assign_var();
+			if (pc->assign_var)
+				pc->assign_var();
 			break;
 
 		case Op_field_assign:
-			pc->field_assign();
+			if (pc->field_assign)
+				pc->field_assign();
 			break;
 
 		case Op_concat:
@@ -2256,7 +2259,34 @@ arrayfor:
 #endif
 				PUSH(r);
 			break;
-			
+
+		case Op_sub_builtin:
+		{
+			/* sub, gsub and gensub */
+ 
+			int matches = 0;
+
+			r = do_sub(pc->expr_count, pc->sub_flags, & matches);
+			PUSH(r);
+
+			if (matches == 0 && (pc->sub_flags & AFTER_ASSIGN) != 0) {
+
+				/* For sub and gsub, must not execute after_assign code;
+				 * If the target is a FIELD, this means no field re-splitting or
+				 * $0 reconstruction. For a special variable as target,
+				 * set_XX routine is not called. 
+				 */
+
+				ni = pc->nexti;
+				assert(ni->opcode == Op_field_assign || ni->opcode == Op_var_assign);
+				if (ni->opcode == Op_field_assign)
+					ni->field_assign = (Func_ptr) 0;
+				else
+					ni->assign_var = (Func_ptr) 0;
+			}
+		}
+			break;
+
 		case Op_K_print:
 			do_print(pc->expr_count, pc->redir_type);
 			break;
diff --git a/profile.c b/profile.c
index cba8be9..01d1e42 100644
--- a/profile.c
+++ b/profile.c
@@ -507,6 +507,20 @@ cleanup:
 		case Op_after_endfile:
 			break;
 
+		case Op_sub_builtin:
+		{
+			const char *fname = "sub";
+			if (pc->sub_flags & GSUB)
+				fname = "gsub";
+			else if (pc->sub_flags & GENSUB)
+				fname = "gensub";
+			tmp = pp_list(pc->expr_count, "()", ", ");
+			str = pp_concat(fname, tmp, "");
+			efree(tmp);
+			pp_push(Op_sub_builtin, str, CAN_FREE);
+		}
+			break;
+
 		case Op_builtin:
 		{
 			static char *ext_func = "extension_function()";