scc

commit 7efbe8681cbdbfe860296e32fa771f8d204757c1
parent 6c203246f0b7e3fa9ac8748b14e50e4381928d1a
Author: Roberto E. Vargas Caballero <k0ga@shike2.com>
Date:   Thu, 26 Dec 2024 22:09:09 +0100

cc2: Add a reference counter to symbols

This makes easy to detect labels not used for any jump
or branch.

Diffstat:
M
src/cmd/scc-cc/cc2/cc2.h
 | 
1
+
M
src/cmd/scc-cc/cc2/parser.c
 | 
5
++++-

2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/src/cmd/scc-cc/cc2/cc2.h b/src/cmd/scc-cc/cc2/cc2.h
@@ -165,6 +165,7 @@ struct symbol {
 	Type rtype;
 	unsigned short id;
 	unsigned short numid;
+	int refcnt;
 	char *name;
 	char kind;
 	union {
diff --git a/src/cmd/scc-cc/cc2/parser.c b/src/cmd/scc-cc/cc2/parser.c
@@ -413,6 +413,7 @@ ocase(char *token, union tokenop u)
 static void
 jump(char *token, union tokenop u)
 {
+	Symbol *label;
 	Node *aux, *np = node(u.op);
 
 	eval(strtok(NULL, "\t\n"));
@@ -420,7 +421,9 @@ jump(char *token, union tokenop u)
 	if (u.op == OBRANCH || u.op == OCASE)
 		np->left = pop();
 	aux = pop();
-	np->u.sym = aux->u.sym;
+	label = aux->u.sym;
+	label->refcnt++;
+	np->u.sym = label;
 	delnode(aux);
 	push(np);
 }