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-rw-r--r--src/cmd/gc/gen.c157
1 files changed, 95 insertions, 62 deletions
diff --git a/src/cmd/gc/gen.c b/src/cmd/gc/gen.c
index 04af5a7bb..8ad6c437d 100644
--- a/src/cmd/gc/gen.c
+++ b/src/cmd/gc/gen.c
@@ -64,62 +64,83 @@ allocparams(void)
lineno = lno;
}
+void
+clearlabels(void)
+{
+ Label *l;
+
+ for(l=labellist; l!=L; l=l->link)
+ l->sym->label = L;
+
+ labellist = L;
+ lastlabel = L;
+}
+
static void
-newlab(int op, Sym *s, Node *stmt)
+newlab(int op, Node *nlab, Node *stmt)
{
Label *lab;
+ Sym *s;
+ int32 lno;
+
+ s = nlab->left->sym;
+ lno = nlab->left->lineno;
lab = mal(sizeof(*lab));
- lab->link = labellist;
- labellist = lab;
+ if(lastlabel == nil)
+ labellist = lab;
+ else
+ lastlabel->link = lab;
+ lastlabel = lab;
+ lab->lineno = lno;
lab->sym = s;
lab->op = op;
lab->label = pc;
lab->stmt = stmt;
+ if(op == OLABEL) {
+ if(s->label != L) {
+ lineno = lno;
+ yyerror("label %S already defined at %L", s, s->label->lineno);
+ } else
+ s->label = lab;
+ }
}
void
checklabels(void)
{
- Label *l, *m;
+ Label *l;
Sym *s;
+ int lno;
-// // print the label list
-// for(l=labellist; l!=L; l=l->link) {
-// print("lab %O %S\n", l->op, l->sym);
-// }
-
+ lno = lineno;
+
+ // resolve goto using syms
for(l=labellist; l!=L; l=l->link) {
- switch(l->op) {
- case OLABEL:
- // these are definitions -
+ switch(l->op) {
+ case OGOTO:
s = l->sym;
- for(m=labellist; m!=L; m=m->link) {
- if(m->sym != s)
- continue;
- switch(m->op) {
- case OLABEL:
- // these are definitions -
- // look for redefinitions
- if(l != m)
- yyerror("label %S redefined", s);
- break;
- case OGOTO:
- // these are references -
- // patch to definition
- patch(m->label, l->label);
- m->sym = S; // mark done
- break;
- }
+ if(s->label == L) {
+ lineno = l->lineno;
+ yyerror("label %S not defined", s);
+ break;
}
+ s->label->used = 1;
+ patch(l->label, s->label->label);
+ break;
}
}
-
- // diagnostic for all undefined references
- for(l=labellist; l!=L; l=l->link)
- if(l->op == OGOTO && l->sym != S)
- yyerror("label %S not defined", l->sym);
+
+ // diagnose unused labels
+ for(l=labellist; l!=L; l=l->link) {
+ if(l->op == OLABEL && !l->used) {
+ lineno = l->lineno;
+ yyerror("label %S defined and not used", l->sym);
+ }
+ }
+
+ lineno = lno;
}
/*
@@ -171,7 +192,7 @@ gen(Node *n)
// insert no-op so that
// L:; for { }
// does not treat L as a label for the loop.
- if(labellist && labellist->label == p3)
+ if(lastlabel != L && lastlabel->label == p3)
gused(N);
break;
@@ -180,26 +201,27 @@ gen(Node *n)
break;
case OLABEL:
- newlab(OLABEL, n->left->sym, n->right);
+ newlab(OLABEL, n, n->right);
break;
case OGOTO:
- newlab(OGOTO, n->left->sym, N);
+ newlab(OGOTO, n, N);
gjmp(P);
break;
case OBREAK:
if(n->left != N) {
- for(lab=labellist; lab!=L; lab=lab->link) {
- if(lab->sym == n->left->sym) {
- if(lab->breakpc == P)
- yyerror("invalid break label %S", n->left->sym);
- gjmp(lab->breakpc);
- goto donebreak;
- }
- }
- if(lab == L)
+ lab = n->left->sym->label;
+ if(lab == L) {
yyerror("break label not defined: %S", n->left->sym);
+ break;
+ }
+ lab->used = 1;
+ if(lab->breakpc == P) {
+ yyerror("invalid break label %S", n->left->sym);
+ break;
+ }
+ gjmp(lab->breakpc);
break;
}
if(breakpc == P) {
@@ -207,30 +229,28 @@ gen(Node *n)
break;
}
gjmp(breakpc);
- donebreak:
break;
case OCONTINUE:
if(n->left != N) {
- for(lab=labellist; lab!=L; lab=lab->link) {
- if(lab->sym == n->left->sym) {
- if(lab->continpc == P)
- yyerror("invalid continue label %S", n->left->sym);
- gjmp(lab->continpc);
- goto donecont;
- }
- }
- if(lab == L)
+ lab = n->left->sym->label;
+ if(lab == L) {
yyerror("continue label not defined: %S", n->left->sym);
+ break;
+ }
+ lab->used = 1;
+ if(lab->continpc == P) {
+ yyerror("invalid continue label %S", n->left->sym);
+ break;
+ }
+ gjmp(lab->continpc);
break;
}
-
if(continpc == P) {
yyerror("continue is not in a loop");
break;
}
gjmp(continpc);
- donecont:
break;
case OFOR:
@@ -241,10 +261,11 @@ gen(Node *n)
continpc = pc;
// define break and continue labels
- if((lab = labellist) != L && lab->label == p3 && lab->op == OLABEL && lab->stmt == n) {
+ if((lab = lastlabel) != L && lab->label == p3 && lab->op == OLABEL && lab->stmt == n) {
lab->breakpc = breakpc;
lab->continpc = continpc;
- }
+ } else
+ lab = L;
gen(n->nincr); // contin: incr
patch(p1, pc); // test:
@@ -254,6 +275,10 @@ gen(Node *n)
patch(breakpc, pc); // done:
continpc = scontin;
breakpc = sbreak;
+ if(lab) {
+ lab->breakpc = P;
+ lab->continpc = P;
+ }
break;
case OIF:
@@ -274,13 +299,17 @@ gen(Node *n)
breakpc = gjmp(P); // break: goto done
// define break label
- if((lab = labellist) != L && lab->label == p3 && lab->op == OLABEL && lab->stmt == n)
+ if((lab = lastlabel) != L && lab->label == p3 && lab->op == OLABEL && lab->stmt == n)
lab->breakpc = breakpc;
+ else
+ lab = L;
patch(p1, pc); // test:
genlist(n->nbody); // switch(test) body
patch(breakpc, pc); // done:
breakpc = sbreak;
+ if(lab != L)
+ lab->breakpc = P;
break;
case OSELECT:
@@ -289,13 +318,17 @@ gen(Node *n)
breakpc = gjmp(P); // break: goto done
// define break label
- if((lab = labellist) != L && lab->label == p3 && lab->op == OLABEL && lab->stmt == n)
+ if((lab = lastlabel) != L && lab->label == p3 && lab->op == OLABEL && lab->stmt == n)
lab->breakpc = breakpc;
+ else
+ lab = L;
patch(p1, pc); // test:
genlist(n->nbody); // select() body
patch(breakpc, pc); // done:
breakpc = sbreak;
+ if(lab != L)
+ lab->breakpc = P;
break;
case OASOP:
generated by cgit v1.2.3 (git 2.46.0) at 2025-10-14 00:06:07 +0000