asm: implement $-prefixed label references for branch instructions

asm/include/ivy/asm/lex.h

@@ -15,6 +15,7 @@ enum ivy_asm_token_type {
 	IVY_ASM_TOK_INT,
 	IVY_ASM_TOK_DOUBLE,
 	IVY_ASM_TOK_LABEL,
+	IVY_ASM_TOK_LABEL_REF,
 	IVY_ASM_TOK_IDENT,
 	IVY_ASM_TOK_STRING,
 	IVY_ASM_TOK_LINEFEED,
@@ -52,7 +53,6 @@ enum ivy_asm_symbol {
 	IVY_ASM_SYM_RIGHT_BRACE,
 	IVY_ASM_SYM_COLON,
 	IVY_ASM_SYM_SEMICOLON,
-	IVY_ASM_SYM_DOLLAR,
 	IVY_ASM_SYM_HYPHEN,
 	IVY_ASM_SYM_PLUS,
 	IVY_ASM_SYM_SQUOTE,

asm/lex.c

@@ -47,7 +47,6 @@ static struct lex_token_def symbols[] = {
 	LEX_TOKEN_DEF(IVY_ASM_SYM_RIGHT_BRACE, "}"),
 	LEX_TOKEN_DEF(IVY_ASM_SYM_COLON, ":"),
 	LEX_TOKEN_DEF(IVY_ASM_SYM_SEMICOLON, ";"),
-	LEX_TOKEN_DEF(IVY_ASM_SYM_DOLLAR, "$"),
 	LEX_TOKEN_DEF(IVY_ASM_SYM_HYPHEN, "-"),
 	LEX_TOKEN_DEF(IVY_ASM_SYM_SQUOTE, "'"),
 	LEX_TOKEN_DEF(IVY_ASM_SYM_DQUOTE, "\""),
@@ -853,6 +852,43 @@ static enum ivy_status read_keyword(struct ivy_asm_lexer *lex)
 	return push_keyword(lex, keyword);
 }
 
+static enum ivy_status read_label_ref(struct ivy_asm_lexer *lex)
+{
+	advance(lex);
+
+	b_string *str = get_temp_string(lex);
+	bool label = false;
+
+	while (true) {
+		int c = peek(lex);
+
+		if (c < 0) {
+			break;
+		}
+
+		if (c == ':' && peek_next(lex) != ':') {
+			advance(lex);
+			label = true;
+			break;
+		}
+
+		if (!isalnum(c) && c != '_') {
+			break;
+		}
+
+		char s[2] = {c, 0};
+		b_string_append_cstr(str, s);
+		advance(lex);
+	}
+
+	const char *s = b_string_ptr(str);
+
+	struct ivy_asm_token *tok = create_token(IVY_ASM_TOK_LABEL_REF);
+	tok->t_str = b_string_steal(str);
+
+	return push_token(lex, tok);
+}
+
 static enum ivy_status read_ident(struct ivy_asm_lexer *lex)
 {
 	b_string *str = get_temp_string(lex);
@@ -942,6 +978,10 @@ static enum ivy_status pump_tokens(struct ivy_asm_lexer *lex)
 		return read_symbol(lex);
 	}
 
+	if (c == '$') {
+		return read_label_ref(lex);
+	}
+
 	if (c == '@') {
 		return read_keyword(lex);
 	}
@@ -1018,6 +1058,7 @@ const char *ivy_asm_token_type_to_string(enum ivy_asm_token_type type)
 		ENUM_STR(IVY_ASM_TOK_INT);
 		ENUM_STR(IVY_ASM_TOK_DOUBLE);
 		ENUM_STR(IVY_ASM_TOK_LABEL);
+		ENUM_STR(IVY_ASM_TOK_LABEL_REF);
 		ENUM_STR(IVY_ASM_TOK_IDENT);
 		ENUM_STR(IVY_ASM_TOK_STRING);
 		ENUM_STR(IVY_ASM_TOK_LINEFEED);
@@ -1064,7 +1105,6 @@ const char *ivy_asm_symbol_to_string(enum ivy_asm_symbol sym)
 		ENUM_STR(IVY_ASM_SYM_HYPHEN);
 		ENUM_STR(IVY_ASM_SYM_COMMA);
 		ENUM_STR(IVY_ASM_SYM_SEMICOLON);
-		ENUM_STR(IVY_ASM_SYM_DOLLAR);
 		ENUM_STR(IVY_ASM_SYM_FORWARD_SLASH_ASTERISK);
 	default:
 		return "";

asm/parse/block.c

@@ -487,7 +487,7 @@ static enum ivy_status parse_ident(
 		state->s_prev_component = INSTR_OPERAND;
 
 		if (x == REG_INDEX_INVALID) {
-			return push_label_arg(state, tok, x);
+			return IVY_ERR_BAD_SYNTAX;
 		} else {
 			return push_reg_arg(state, tok, x);
 		}
@@ -510,6 +510,28 @@ static enum ivy_status parse_ident(
 	return IVY_ERR_BAD_SYNTAX;
 }
 
+static enum ivy_status parse_label_ref(
+	struct ivy_asm_parser *ctx, struct ivy_asm_token *tok)
+{
+	struct block_parser_state *state
+		= (struct block_parser_state *)asm_parser_get_state(ctx);
+
+	unsigned long long x = 0;
+
+	switch (state->s_prev_component) {
+	case INSTR_OPCODE:
+	case INSTR_OPERAND_SEPARATOR:
+		state->s_prev_component = INSTR_OPERAND;
+
+		return push_label_arg(state, tok, x);
+	default:
+		return IVY_ERR_BAD_SYNTAX;
+	}
+
+	/* not sure what this is but we aren't expecting it. */
+	return IVY_ERR_BAD_SYNTAX;
+}
+
 static enum ivy_status parse_dot(
 	struct ivy_asm_parser *ctx, struct ivy_asm_token *tok)
 {
@@ -633,6 +655,7 @@ struct parser_state_type block_parser_state_type = {
 	.n_token_parsers = {
 		TOK_PARSER(IDENT, parse_ident),
 		TOK_PARSER(LABEL, parse_label),
+		TOK_PARSER(LABEL_REF, parse_label_ref),
 		TOK_PARSER(INT, parse_int),
 		TOK_PARSER(LINEFEED, parse_linefeed),
 	},