fixed labels/break/continue/goto

R=r
OCL=14675
CL=14675

src/cmd/6g/gen.c

@@ -36,6 +36,10 @@ if(newproc == N) {
 
 	if(fn->nbody == N)
 		return;
+
+	// set up domain for labels
+	labellist = L;
+
 	lno = setlineno(fn);
 
 	curfn = fn;
@@ -60,8 +64,9 @@ if(newproc == N) {
 //	inarggen();
 
 	ginit();
-	gen(curfn->nbody);
+	gen(curfn->nbody, L);
 	gclean();
+	checklabels();
 
 //	if(curfn->type->outtuple != 0)
 //		gins(AGOK, N, N);
@@ -118,12 +123,14 @@ allocparams(void)
  * compile statements
  */
 void
-gen(Node *n)
+gen(Node *n, Label *labloop)
 {
 	int32 lno;
 	Prog *scontin, *sbreak;
 	Prog *p1, *p2, *p3;
 	Sym *s;
+	Node *l;
+	Label *lab;
 
 	lno = setlineno(n);
 
@@ -138,8 +145,24 @@ loop:
 		break;
 
 	case OLIST:
-		gen(n->left);
+		l = n->left;
+		gen(l, L);
+		if(l != N && l->op == OLABEL) {
+			// call the next statement with a label
+			l = n->right;
+			if(l != N) {
+				if(l->op != OLIST) {
+					gen(l, labellist);
+					break;
+				}
+				gen(l->left, labellist);
+				n = l->right;
+				labloop = L;
+				goto loop;
+			}
+		}
 		n = n->right;
+		labloop = L;
 		goto loop;
 
 	case OPANIC:
@@ -154,59 +177,55 @@ loop:
 		break;
 
 	case OLABEL:
-		// before declaration, s->label points at
-		// a link list of PXGOTO instructions.
-		// after declaration, s->label points
-		// at a AJMP to .+1
+		lab = mal(sizeof(*lab));
+		lab->link = labellist;
+		labellist = lab;
+		lab->sym = n->left->sym;
 
-		s = n->left->sym;
-		p1 = (Prog*)s->label;
-
-		if(p1 != P) {
-			if(p1->as == AJMP) {
-				yyerror("label redeclared: %S", s);
-				break;
-			}
-			while(p1 != P) {
-				if(p1->as != AJMPX)
-					fatal("bad label pointer: %S", s);
-				p1->as = AJMP;
-				p2 = p1->to.branch;
-				patch(p1, pc);
-				p1 = p2;
-			}
-		}
-
-		s->label = pc;
-		p1 = gbranch(AJMP, T);
-		patch(p1, pc);
+		lab->op = OLABEL;
+		lab->label = pc;
 		break;
 
 	case OGOTO:
-		s = n->left->sym;
-		p1 = (Prog*)s->label;
-		if(p1 != P && p1->as == AJMP) {
-			// already declared
-			p2 = gbranch(AJMP, T);
-			patch(p2, p1->to.branch);
-			break;
-		}
+		lab = mal(sizeof(*lab));
+		lab->link = labellist;
+		labellist = lab;
+		lab->sym = n->left->sym;
 
-		// link thru to.branch
-		p2 = gbranch(AJMPX, T);
-		p2->to.branch = p1;
-		s->label = p2;
+		lab->op = OGOTO;
+		lab->label = pc;
+		gbranch(AJMP, T);
 		break;
 
 	case OBREAK:
+		if(n->left != N) {
+			lab = findlab(n->left->sym);
+			if(lab == L || lab->breakpc == P) {
+				yyerror("break label is not defined: %S", n->left->sym);
+				break;
+			}
+			patch(gbranch(AJMP, T), lab->breakpc);
+			break;
+		}
+
 		if(breakpc == P) {
-			yyerror("gen: break is not in a loop");
+			yyerror("break is not in a loop");
 			break;
 		}
 		patch(gbranch(AJMP, T), breakpc);
 		break;
 
 	case OCONTINUE:
+		if(n->left != N) {
+			lab = findlab(n->left->sym);
+			if(lab == L || lab->continpc == P) {
+				yyerror("continue label is not defined: %S", n->left->sym);
+				break;
+			}
+			patch(gbranch(AJMP, T), lab->continpc);
+			break;
+		}
+
 		if(continpc == P) {
 			yyerror("gen: continue is not in a loop");
 			break;
@@ -215,16 +234,21 @@ loop:
 		break;
 
 	case OFOR:
-		gen(n->ninit);				// 		init
+		gen(n->ninit, L);			// 		init
 		p1 = gbranch(AJMP, T);			// 		goto test
 		sbreak = breakpc;
 		breakpc = gbranch(AJMP, T);		// break:	goto done
 		scontin = continpc;
 		continpc = pc;
-		gen(n->nincr);				// contin:	incr
+		gen(n->nincr, L);				// contin:	incr
 		patch(p1, pc);				// test:
 		bgen(n->ntest, 0, breakpc);		//		if(!test) goto break
-		gen(n->nbody);				//		body
+		if(labloop != L) {
+			labloop->op = OFOR;
+			labloop->continpc = continpc;
+			labloop->breakpc = breakpc;
+		}
+		gen(n->nbody, L);			//		body
 		patch(gbranch(AJMP, T), continpc);	//		goto contin
 		patch(breakpc, pc);			// done:
 		continpc = scontin;
@@ -232,36 +256,44 @@ loop:
 		break;
 
 	case OIF:
-		gen(n->ninit);				//		init
+		gen(n->ninit, L);			//		init
 		p1 = gbranch(AJMP, T);			//		goto test
 		p2 = gbranch(AJMP, T);			// p2:		goto else
 		patch(p1, pc);				// test:
 		bgen(n->ntest, 0, p2);			// 		if(!test) goto p2
-		gen(n->nbody);				//		then
+		gen(n->nbody, L);			//		then
 		p3 = gbranch(AJMP, T);			//		goto done
 		patch(p2, pc);				// else:
-		gen(n->nelse);				//		else
+		gen(n->nelse, L);			//		else
 		patch(p3, pc);				// done:
 		break;
 
 	case OSWITCH:
-		gen(n->ninit);				// 		init
+		gen(n->ninit, L);			// 		init
 		p1 = gbranch(AJMP, T);			// 		goto test
 		sbreak = breakpc;
 		breakpc = gbranch(AJMP, T);		// break:	goto done
 		patch(p1, pc);				// test:
+		if(labloop != L) {
+			labloop->op = OFOR;
+			labloop->breakpc = breakpc;
+		}
 		swgen(n);				//		switch(test) body
 		patch(breakpc, pc);			// done:
 		breakpc = sbreak;
 		break;
 
 	case OSELECT:
-		gen(n->ninit);
+		gen(n->ninit, L);
 		sbreak = breakpc;
 		p1 = gbranch(AJMP, T);			// 		goto test
 		breakpc = gbranch(AJMP, T);		// break:	goto done
 		patch(p1, pc);				// test:
-		gen(n->nbody);				//		select() body
+		if(labloop != L) {
+			labloop->op = OFOR;
+			labloop->breakpc = breakpc;
+		}
+		gen(n->nbody, L);			//		select() body
 		patch(breakpc, pc);			// done:
 		breakpc = sbreak;
 		break;
@@ -448,7 +480,7 @@ swgen(Node *n)
 		if(c1->op != OCASE) {
 			if(s0 == C && dflt == P)
 				yyerror("unreachable statements in a switch");
-			gen(c1);
+			gen(c1, L);
 
 			any = 1;
 			if(c1->op == OFALL)
@@ -606,7 +638,7 @@ cgen_callinter(Node *n, Node *res, int proc)
 		i = &tmpi;
 	}
 
-	gen(n->right);		// args
+	gen(n->right, L);		// args
 
 	regalloc(&nodr, types[tptr], res);
 	regalloc(&nodo, types[tptr], &nodr);
@@ -673,7 +705,7 @@ cgen_call(Node *n, int proc)
 			agen(n->left, &afun);
 	}
 
-	gen(n->right);	// assign the args
+	gen(n->right, L);	// assign the args
 	t = n->left->type;
 	if(isptr[t->etype])
 		t = t->type;
@@ -784,7 +816,7 @@ cgen_aret(Node *n, Node *res)
 void
 cgen_ret(Node *n)
 {
-	gen(n->left);	// copy out args
+	gen(n->left, L);	// copy out args
 	gins(ARET, N, N);
 }
 
@@ -1143,3 +1175,63 @@ cgen_shift(int op, Node *nl, Node *nr, Node *res)
 ret:
 	;
 }
+
+void
+checklabels(void)
+{
+	Label *l, *m;
+	Sym *s;
+
+//	// print the label list
+//	for(l=labellist; l!=L; l=l->link) {
+//		print("lab %O %S\n", l->op, l->sym);
+//	}
+
+	for(l=labellist; l!=L; l=l->link) {
+	switch(l->op) {
+		case OFOR:
+		case OLABEL:
+			// these are definitions -
+			s = l->sym;
+			for(m=labellist; m!=L; m=m->link) {
+				if(m->sym != s)
+					continue;
+				switch(m->op) {
+				case OFOR:
+				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;
+				}
+			}
+		}
+	}
+
+	// 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);
+}
+
+Label*
+findlab(Sym *s)
+{
+	Label *l;
+
+	for(l=labellist; l!=L; l=l->link) {
+		if(l->sym != s)
+			continue;
+		if(l->op != OFOR)
+			continue;
+		return l;
+	}
+	return L;
+}

src/cmd/6g/gg.h

@@ -78,6 +78,18 @@ struct	Pool
 	Pool*	link;
 };
 
+typedef	struct	Label Label;
+struct	Label
+{
+	uchar	op;		// OFOR/OGOTO/OLABEL
+	Sym*	sym;
+	Prog*	label;		// pointer to code
+	Prog*	breakpc;	// pointer to code
+	Prog*	continpc;	// pointer to code
+	Label*	link;
+};
+#define	L	((Label*)0)
+
 EXTERN	Prog*	continpc;
 EXTERN	Prog*	breakpc;
 EXTERN	Prog*	pc;
@@ -99,13 +111,15 @@ EXTERN	String	emptystring;
 extern	char*	anames[];
 EXTERN	Hist*	hist;
 EXTERN	Prog	zprog;
+EXTERN	Label*	labellist;
+EXTERN	Label*	findlab(Sym*);
 
 /*
  * gen.c
  */
 void	compile(Node*);
 void	proglist(void);
-void	gen(Node*);
+void	gen(Node*, Label*);
 void	swgen(Node*);
 void	selgen(Node*);
 Node*	lookdot(Node*, Node*, int);
@@ -125,6 +139,7 @@ void	genpanic(void);
 int	needconvert(Type*, Type*);
 void	genconv(Type*, Type*);
 void	allocparams(void);
+void	checklabels();
 
 /*
  * cgen

src/cmd/gc/go.h

@@ -205,7 +205,6 @@ struct	Sym
 	Type*	otype;		// TYPE node if a type
 	Node*	oconst;		// OLITERAL node if a const
 	Type*	forwtype;	// TPTR iff forward declared
-	void*	label;		// pointer to Prog* of label
 	vlong	offset;		// stack location if automatic
 	int32	lexical;
 	int32	vargen;		// unique variable number

src/cmd/gc/go.y

@@ -42,7 +42,7 @@
 %type	<node>		range_header range_body range_stmt select_stmt
 %type	<node>		simple_stmt osimple_stmt semi_stmt
 %type	<node>		expr uexpr pexpr expr_list oexpr oexpr_list expr_list_r
-%type	<node>		name name_name new_name new_name_list_r conexpr
+%type	<node>		name name_name onew_name new_name new_name_list_r conexpr
 %type	<node>		vardcl_list_r vardcl Avardcl Bvardcl
 %type	<node>		interfacedcl_list_r interfacedcl
 %type	<node>		structdcl_list_r structdcl
@@ -326,6 +326,14 @@ noninc_stmt:
 	{
 		$$ = nod(OAS, colas($1, $3), $3);
 	}
+|	LPRINT '(' oexpr_list ')'
+	{
+		$$ = nod(OPRINT, $3, N);
+	}
+|	LPANIC '(' oexpr_list ')'
+	{
+		$$ = nod(OPANIC, $3, N);
+	}
 
 inc_stmt:
 	expr LINC
@@ -398,11 +406,11 @@ semi_stmt:
 		// will be converted to OFALL
 		$$ = nod(OXFALL, N, N);
 	}
-|	LBREAK oexpr
+|	LBREAK onew_name
 	{
 		$$ = nod(OBREAK, $2, N);
 	}
-|	LCONTINUE oexpr
+|	LCONTINUE onew_name
 	{
 		$$ = nod(OCONTINUE, $2, N);
 	}
@@ -411,14 +419,6 @@ semi_stmt:
 		$$ = nod(OCALL, $2, $4);
 		$$ = nod(OPROC, $$, N);
 	}
-|	LPRINT '(' oexpr_list ')'
-	{
-		$$ = nod(OPRINT, $3, N);
-	}
-|	LPANIC '(' oexpr_list ')'
-	{
-		$$ = nod(OPANIC, $3, N);
-	}
 |	LGOTO new_name
 	{
 		$$ = nod(OGOTO, $2, N);
@@ -832,6 +832,12 @@ new_type:
 		$$ = newtype($1);
 	}
 
+onew_name:
+	{
+		$$ = N;
+	}
+|	new_name
+
 sym:
 	LATYPE
 |	LNAME