Permit opcode names as labels as long as they are followed by a colon

Permit opcode names to be used as labels if and only if they are
succeeded by a colon.  Opcode names occurring when parsing expressions
are all treated as labels; a leading colon occurred when parsing an
instruction forces a parser restart with the instruction forcibly
treated as an identifier.

3 files changed, 35 insertions, 4 deletions

diff --git a/eval.c b/eval.c
index 2be18a6e..3fc9732d 100644
--- a/eval.c
+++ b/eval.c
@@ -741,6 +741,7 @@ static expr *expr6(int critical)
     case TOKEN_NUM:
     case TOKEN_REG:
     case TOKEN_ID:
+    case TOKEN_INSN:		/* Opcodes that occur here are really labels */
     case TOKEN_HERE:
     case TOKEN_BASE:
         begintemp();
@@ -754,6 +755,7 @@ static expr *expr6(int critical)
                 hint->base = tokval->t_integer, hint->type = EAH_MAKEBASE;
             break;
         case TOKEN_ID:
+	case TOKEN_INSN:
         case TOKEN_HERE:
         case TOKEN_BASE:
             /*
@@ -764,8 +766,9 @@ static expr *expr6(int critical)
             if (!location->known) {
                 error(ERR_NONFATAL,
                       "%s not supported in preprocess-only mode",
-                      (i == TOKEN_ID ? "symbol references" :
-                       i == TOKEN_HERE ? "`$'" : "`$$'"));
+		      (i == TOKEN_HERE ? "`$'" :
+		       i == TOKEN_BASE ? "`$$'" :
+		       "symbol references"));
                 addtotemp(EXPR_UNKNOWN, 1L);
                 break;
             }
diff --git a/parser.c b/parser.c
index 9b7f6176..8011733c 100644
--- a/parser.c
+++ b/parser.c
@@ -171,7 +171,11 @@ insn *parse_line(int pass, char *buffer, insn * result,
     int critical;
     struct eval_hints hints;
     int j;
+    bool first;
+    bool insn_is_label = false;
 
+restart_parse:
+    first = true;
     result->forw_ref = false;
     error = errfunc;
 
@@ -195,7 +199,9 @@ insn *parse_line(int pass, char *buffer, insn * result,
         return result;
     }
 
-    if (i == TOKEN_ID) {        /* there's a label here */
+    if (i == TOKEN_ID || (insn_is_label && i == TOKEN_INSN)) {
+        /* there's a label here */
+	first = false;
         result->label = tokval.t_charptr;
         i = stdscan(NULL, &tokval);
         if (i == ':') {         /* skip over the optional colon */
@@ -229,6 +235,8 @@ insn *parse_line(int pass, char *buffer, insn * result,
     while (i == TOKEN_PREFIX ||
            (i == TOKEN_REG && !(REG_SREG & ~reg_flags[tokval.t_integer])))
     {
+	first = false;
+
         /*
          * Handle special case: the TIMES prefix.
          */
@@ -259,7 +267,7 @@ insn *parse_line(int pass, char *buffer, insn * result,
 	    int slot = prefix_slot(tokval.t_integer);
 	    if (result->prefixes[slot]) {
                if (result->prefixes[slot] == tokval.t_integer)
- 		    error(ERR_WARNING,
+		    error(ERR_WARNING,
 		      "instruction has redundant prefixes");
                else
 		    error(ERR_NONFATAL,
@@ -335,6 +343,11 @@ insn *parse_line(int pass, char *buffer, insn * result,
             i = stdscan(NULL, &tokval);
             if (i == 0)
                 break;
+	    else if (first && i == ':') {
+		insn_is_label = true;
+		goto restart_parse;
+	    }
+	    first = false;
             fixptr = tail;
             eop = *tail = nasm_malloc(sizeof(extop));
             tail = &eop->next;
@@ -507,6 +520,11 @@ insn *parse_line(int pass, char *buffer, insn * result,
         i = stdscan(NULL, &tokval);
         if (i == 0)
             break;              /* end of operands: get out of here */
+	else if (first && i == ':') {
+	    insn_is_label = true;
+	    goto restart_parse;
+	}
+	first = false;
         result->oprs[operand].type = 0; /* so far, no override */
         while (i == TOKEN_SPECIAL) {    /* size specifiers */
             switch ((int)tokval.t_integer) {
diff --git a/test/insnlbl.asm b/test/insnlbl.asm
new file mode 100644
index 00000000..5c163846
--- /dev/null
+++ b/test/insnlbl.asm
@@ -0,0 +1,10 @@
+;
+; Test "instruction as label" -- make opcodes legal as labels if
+; they are followed by a colon.
+;
+
+do:	jmp incbin+2
+	dw do, add, sub, incbin
+add:	jmp add-2
+sub:	jmp do+2
+incbin:	dw $-sub