if take address of local, move to heap.

heuristic to not print bogus strings.
fix one error message format.

R=ken
OCL=23849
CL=23851

14 files changed, 515 insertions, 78 deletions

diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index 43497adb2..2774456c0 100644
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -48,6 +48,11 @@ cgen(Node *n, Node *res)
 		if(n->ullman > res->ullman) {
 			regalloc(&n1, n->type, res);
 			cgen(n, &n1);
+			if(n1.ullman > res->ullman) {
+				dump("n1", &n1);
+				dump("res", res);
+				fatal("loop in cgen");
+			}
 			cgen(&n1, res);
 			regfree(&n1);
 			goto ret;
@@ -198,6 +203,7 @@ cgen(Node *n, Node *res)
 	case ODOTPTR:
 	case OINDEX:
 	case OIND:
+	case ONAME:	// PHEAP var
 		igen(n, &n1, res);
 		gmove(&n1, res);
 		regfree(&n1);
@@ -517,6 +523,17 @@ agen(Node *n, Node *res)
 		regfree(&n3);
 		break;
 
+	case ONAME:
+		// should only get here for heap vars
+		if(!(n->class & PHEAP))
+			fatal("agen: bad ONAME class %#x", n->class);
+		cgen(n->heapaddr, res);
+		if(n->xoffset != 0) {
+			nodconst(&n1, types[TINT64], n->xoffset);
+			gins(optoas(OADD, types[tptr]), &n1, res);
+		}
+		break;
+
 	case OIND:
 		cgen(nl, res);
 		break;
diff --git a/src/cmd/6g/gen.c b/src/cmd/6g/gen.c
index f01f1d8b5..e6a685033 100644
--- a/src/cmd/6g/gen.c
+++ b/src/cmd/6g/gen.c
@@ -99,6 +99,7 @@ if(throwreturn == N) {
 //	inarggen();
 
 	ginit();
+	gen(curfn->enter, L);
 	gen(curfn->nbody, L);
 	gclean();
 	checklabels();
@@ -151,6 +152,8 @@ allocparams(void)
 
 		dowidth(n->type);
 		w = n->type->width;
+		if(n->class & PHEAP)
+			w = widthptr;
 		stksize += w;
 		stksize = rnd(stksize, w);
 
@@ -345,6 +348,10 @@ loop:
 		cgen_asop(n);
 		break;
 
+	case ODCL:
+		cgen_dcl(n->left);
+		break;
+
 	case OAS:
 		cgen_as(n->left, n->right);
 		break;
@@ -1115,6 +1122,26 @@ ret:
 }
 
 /*
+ * generate declaration.
+ * nothing to do for on-stack automatics,
+ * but might have to allocate heap copy
+ * for escaped variables.
+ */
+void
+cgen_dcl(Node *n)
+{
+	if(debug['g'])
+		dump("\ncgen-dcl", n);
+	if(n->op != ONAME) {
+		dump("cgen_dcl", n);
+		fatal("cgen_dcl");
+	}
+	if(!(n->class & PHEAP))
+		return;
+	cgen_as(n->heapaddr, n->alloc);
+}
+
+/*
  * generate assignment:
  *	nl = nr
  * nr == N means zero nl.
@@ -1130,6 +1157,11 @@ cgen_as(Node *nl, Node *nr)
 	if(nl == N)
 		return;
 
+	if(debug['g']) {
+		dump("cgen_as", nl);
+		dump("cgen_as = ", nr);
+	}
+
 	iszer = 0;
 	if(nr == N || isnil(nr)) {
 		if(nl->op == OLIST) {
diff --git a/src/cmd/6g/gg.h b/src/cmd/6g/gg.h
index 881a23073..602de32b4 100644
--- a/src/cmd/6g/gg.h
+++ b/src/cmd/6g/gg.h
@@ -158,6 +158,7 @@ void	cgen_callret(Node*, Node*);
 void	cgen_div(int, Node*, Node*, Node*);
 void	cgen_bmul(int, Node*, Node*, Node*);
 void	cgen_shift(int, Node*, Node*, Node*);
+void	cgen_dcl(Node*);
 void	genpanic(void);
 int	needconvert(Type*, Type*);
 void	genconv(Type*, Type*);
diff --git a/src/cmd/6g/gsubr.c b/src/cmd/6g/gsubr.c
index 86ba52c3f..cd4f6e294 100644
--- a/src/cmd/6g/gsubr.c
+++ b/src/cmd/6g/gsubr.c
@@ -547,6 +547,7 @@ gmove(Node *f, Node *t)
 				break;
 			case PAUTO:
 			case PPARAM:
+			case PPARAMOUT:
 				break;
 			}
 			break;
@@ -1046,6 +1047,15 @@ naddr(Node *n, Addr *a)
 		a->offset = n->xoffset;
 		break;
 
+	case OPARAM:
+		// n->left is PHEAP ONAME for stack parameter.
+		// compute address of actual parameter on stack.
+		a->etype = n->left->type->etype;
+		a->offset = n->xoffset;
+		a->sym = n->left->sym;
+		a->type = D_PARAM;
+		break;
+
 	case ONAME:
 		a->etype = 0;
 		if(n->type != T)
@@ -1071,6 +1081,7 @@ naddr(Node *n, Addr *a)
 			a->type = D_AUTO;
 			break;
 		case PPARAM:
+		case PPARAMOUT:
 			a->type = D_PARAM;
 			break;
 		}
@@ -1749,6 +1760,7 @@ tempname(Node *n, Type *t)
 	n->class = PAUTO;
 	n->addable = 1;
 	n->ullman = 1;
+	n->noescape = 1;
 
 	dowidth(t);
 	w = t->width;
diff --git a/src/cmd/gc/dcl.c b/src/cmd/gc/dcl.c
index edac4ca2c..2ae8fd308 100644
--- a/src/cmd/gc/dcl.c
+++ b/src/cmd/gc/dcl.c
@@ -36,6 +36,7 @@ dodclvar(Node *n, Type *t)
 
 	addvar(n, t, dclcontext);
 	autoexport(n->sym);
+	addtop = list(addtop, nod(ODCL, n, N));
 }
 
 void
@@ -434,7 +435,7 @@ funcargs(Type *ft)
 		if(t->nname != N)
 			t->nname->xoffset = t->width;
 		if(t->nname != N) {
-			addvar(t->nname, t->type, PPARAM);
+			addvar(t->nname, t->type, PPARAMOUT);
 			all |= 1;
 		} else
 			all |= 2;
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index ba2672390..1e1f4b28f 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -180,12 +180,13 @@ struct	Node
 	uchar	addable;	// type of addressability - 0 is not addressable
 	uchar	trecur;		// to detect loops
 	uchar	etype;		// op for OASOP, etype for OTYPE, exclam for export
-	uchar	class;		// PPARAM, PAUTO, PEXTERN
+	uchar	class;		// PPARAM, PAUTO, PEXTERN, etc
 	uchar	method;		// OCALLMETH name
 	uchar	iota;		// OLITERAL made from iota
 	uchar	embedded;	// ODCLFIELD embedded type
 	uchar	colas;		// OAS resulting from :=
 	uchar	diag;		// already printed error about this
+	uchar	noescape;	// ONAME never move to heap
 
 	// most nodes
 	Node*	left;
@@ -206,10 +207,17 @@ struct	Node
 
 	// func
 	Node*	nname;
+	Node*	enter;
+	Node*	exit;
 
 	// OLITERAL/OREGISTER
 	Val	val;
 
+	// ONAME func param with PHEAP
+	Node*	heapaddr;	// temp holding heap address of param
+	Node*	stackparam;	// OPARAM node referring to stack copy of param
+	Node*	alloc;	// allocation call
+
 	Sym*	osym;		// import
 	Sym*	psym;		// import
 	Sym*	sym;		// various
@@ -287,7 +295,7 @@ enum
 
 	OTYPE, OCONST, OVAR, OIMPORT,
 
-	ONAME, ONONAME,
+	ONAME, ONONAME, ODCL,
 	ODOT, ODOTPTR, ODOTMETH, ODOTINTER,
 	ODCLFUNC, ODCLFIELD, ODCLARG,
 	OLIST, OCMP, OPTR, OARRAY, ORANGE,
@@ -312,7 +320,7 @@ enum
 	OINDEX, OSLICE,
 	ONOT, OCOM, OPLUS, OMINUS, OSEND, ORECV,
 	OLITERAL, OREGISTER, OINDREG,
-	OCONV, OCOMP, OKEY,
+	OCONV, OCOMP, OKEY, OPARAM,
 	OBAD,
 
 	OEXTEND,	// 6g internal
@@ -405,6 +413,9 @@ enum
 	PEXTERN,	// declaration context
 	PAUTO,
 	PPARAM,
+	PPARAMOUT,
+
+	PHEAP = 1<<7,
 };
 
 enum
@@ -654,6 +665,7 @@ Node*	treecopy(Node*);
 int	isselect(Node*);
 void	tempname(Node*, Type*);
 int	iscomposite(Type*);
+Node*	callnew(Type*);
 
 Type**	getthis(Type*);
 Type**	getoutarg(Type*);
@@ -812,11 +824,13 @@ Node*	reorder1(Node*);
 Node*	reorder2(Node*);
 Node*	reorder3(Node*);
 Node*	reorder4(Node*);
-Node*	structlit(Node*);
+Node*	structlit(Node*, Node*);
 Node*	arraylit(Node*);
 Node*	maplit(Node*);
 Node*	selectas(Node*, Node*);
 Node*	old2new(Node*, Type*);
+void	addrescapes(Node*);
+void	heapmoves(void);
 
 /*
  *	const.c
diff --git a/src/cmd/gc/go.y b/src/cmd/gc/go.y
index d04991dc4..29c9b29d9 100644
--- a/src/cmd/gc/go.y
+++ b/src/cmd/gc/go.y
@@ -278,6 +278,7 @@ Avardcl:
 		dodclvar($$, $2);
 
 		$$ = nod(OAS, $$, N);
+		addtotop($$);
 	}
 
 Bvardcl:
@@ -287,6 +288,7 @@ Bvardcl:
 		dodclvar($$, $2);
 
 		$$ = nod(OAS, $$, N);
+		addtotop($$);
 	}
 |	new_name_list_r type '=' expr_list
 	{
@@ -478,6 +480,7 @@ complex_stmt:
 		poptodcl();
 		$$ = nod(OAS, selectas($2,$4), $4);
 		$$ = nod(OXCASE, $$, N);
+		addtotop($$);
 	}
 |	LDEFAULT ':'
 	{
diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index 6cd038412..d6fb25147 100644
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -702,6 +702,8 @@ opnames[] =
 	[OPANICN]	= "PANICN",
 	[OPRINT]	= "PRINT",
 	[OPRINTN]	= "PRINTN",
+	[OPARAM]	= "PARAM",
+	[ODCL]	= "DCL",
 	[OXXX]		= "XXX",
 };
 
@@ -877,6 +879,16 @@ Jconv(Fmt *fp)
 		strncat(buf, buf1, sizeof(buf));
 	}
 
+	if(n->class != 0) {
+		snprint(buf1, sizeof(buf1), " class(%d)", n->class);
+		strncat(buf, buf1, sizeof(buf));
+	}
+
+	if(n->colas != 0) {
+		snprint(buf1, sizeof(buf1), " colas(%d)", n->colas);
+		strncat(buf, buf1, sizeof(buf));
+	}
+
 	return fmtstrcpy(fp, buf);
 }
 
@@ -2031,6 +2043,7 @@ ullmancalc(Node *n)
 		return;
 
 	switch(n->op) {
+	case OREGISTER:
 	case OLITERAL:
 	case ONAME:
 		ul = 1;
@@ -2281,7 +2294,7 @@ Type**
 getthis(Type *t)
 {
 	if(t->etype != TFUNC)
-		fatal("getthis: not a func %N", t);
+		fatal("getthis: not a func %T", t);
 	return &t->type;
 }
 
@@ -2289,7 +2302,7 @@ Type**
 getoutarg(Type *t)
 {
 	if(t->etype != TFUNC)
-		fatal("getoutarg: not a func %N", t);
+		fatal("getoutarg: not a func %T", t);
 	return &t->type->down;
 }
 
@@ -2297,7 +2310,7 @@ Type**
 getinarg(Type *t)
 {
 	if(t->etype != TFUNC)
-		fatal("getinarg: not a func %N", t);
+		fatal("getinarg: not a func %T", t);
 	return &t->type->down->down;
 }
 
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index 780da1433..1b5ca4746 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -65,13 +65,20 @@ walk(Node *fn)
 	if(curfn->type->outtuple)
 		if(walkret(curfn->nbody))
 			yyerror("function ends without a return statement");
-	if(addtop != N)
+	if(addtop != N) {
+		dump("addtop", addtop);
 		fatal("addtop in walk");
+	}
 	walkstate(curfn->nbody);
 	if(debug['W']) {
-		snprint(s, sizeof(s), "after %S", curfn->nname->sym);
+		snprint(s, sizeof(s), "after walk %S", curfn->nname->sym);
 		dump(s, curfn->nbody);
 	}
+	heapmoves();
+	if(debug['W'] && curfn->enter != N) {
+		snprint(s, sizeof(s), "enter %S", curfn->nname->sym);
+		dump(s, curfn->enter);
+	}
 }
 
 void
@@ -125,6 +132,7 @@ loop:
 	case OCALLMETH:
 	case OCALLINTER:
 	case OCALL:
+	case ODCL:
 	case OSEND:
 	case ORECV:
 	case OPRINT:
@@ -229,6 +237,9 @@ loop:
 		fatal("walktype: switch 1 unknown op %N", n);
 		goto ret;
 
+	case ODCL:
+		goto ret;
+
 	case OLIST:
 	case OKEY:
 		walktype(n->left, top);
@@ -283,7 +294,8 @@ loop:
 	case ONAME:
 		if(top == Etop)
 			goto nottop;
-		n->addable = 1;
+		if(!(n->class & PHEAP))
+			n->addable = 1;
 		if(n->type == T) {
 			s = n->sym;
 			if(s->undef == 0) {
@@ -681,7 +693,7 @@ loop:
 
 		// structure literal
 		if(t->etype == TSTRUCT) {
-			indir(n, structlit(n));
+			indir(n, structlit(n, nil));
 			goto ret;
 		}
 
@@ -996,32 +1008,20 @@ loop:
 			//	nvar := new(*Point);
 			//	*nvar = Point{1, 2};
 			// and replace expression with nvar
+			Node *nvar, *nas;
 
-			// TODO(rsc): might do a better job (fewer copies) later
-			Node *nnew, *nvar, *nas;
-
-			t = ptrto(n->left->type);
-			walktype(n->left, Elv);
-			if(n->left == N)
-				goto ret;
-
-			nvar = nod(0, N, N);
-			tempname(nvar, t);
-
-			nnew = nod(ONEW, N, N);
-			nnew->type = n->left->type;
-			nnew = newcompat(nnew);
+			nvar = nod(OXXX, N, N);
+			tempname(nvar, ptrto(n->left->type));
 
-			nas = nod(OAS, nvar, nnew);
-			addtop = list(addtop, nas);
-
-			nas = nod(OAS, nod(OIND, nvar, N), n->left);
+			nas = nod(OAS, nvar, callnew(n->left->type));
 			addtop = list(addtop, nas);
 
+			structlit(n->left, nvar);
 			indir(n, nvar);
 			goto ret;
 		}
 		walktype(n->left, Elv);
+		addrescapes(n->left);
 		if(n->left == N)
 			goto ret;
 		t = n->left->type;
@@ -1055,7 +1055,16 @@ loop:
 	case ONEW:
 		if(top != Erv)
 			goto nottop;
-		indir(n, newcompat(n));
+		if(n->left != N) {
+			yyerror("cannot new(%T, expr)", t);
+			goto ret;
+		}
+		t = n->type;
+		if(t == T || t->etype == TFUNC) {
+			yyerror("cannot new(%T)", t);
+			goto ret;
+		}
+		indir(n, callnew(t));
 		goto ret;
 	}
 
@@ -1455,8 +1464,8 @@ void
 walkselect(Node *sel)
 {
 	Iter iter;
-	Node *n, *oc, *on, *r;
-	Node *var, *bod, *res, *def;
+	Node *n, *l, *oc, *on, *r;
+	Node *var, *bod, *nbod, *res, *def;
 	int count, op;
 	int32 lno;
 
@@ -1492,6 +1501,7 @@ walkselect(Node *sel)
 				def = n;
 			} else
 				op = n->left->op;
+			nbod = N;
 			switch(op) {
 			default:
 				yyerror("select cases must be send, recv or default");
@@ -1499,14 +1509,32 @@ walkselect(Node *sel)
 
 			case OAS:
 				// convert new syntax (a=recv(chan)) to (recv(a,chan))
-				if(n->left->right == N || n->left->right->op != ORECV) {
+				l = n->left;
+				if(l->right == N || l->right->op != ORECV) {
 					yyerror("select cases must be send, recv or default");
 					break;
 				}
-				n->left->right->right = n->left->right->left;
-				n->left->right->left = n->left->left;
-				n->left = n->left->right;
+				r = l->right;	// rcv
+				r->right = r->left;
+				r->left = l->left;
+				n->left = r;
+
+				// convert case x := foo: body
+				// to case tmp := foo: x := tmp; body.
+				// if x escapes and must be allocated
+				// on the heap, this delays the allocation
+				// until after the select has chosen this branch.
+				if(n->ninit != N && n->ninit->op == ODCL) {
+					on = nod(OXXX, N, N);
+					tempname(on, l->left->type);
+					on->sym = lookup("!tmpselect!");
+					r->left = on;
+					nbod = nod(OAS, l->left, on);
+					nbod->ninit = n->ninit;
+					n->ninit = N;
+				}
 
+				// fall through
 			case OSEND:
 			case ORECV:
 				if(oc != N) {
@@ -1516,10 +1544,8 @@ walkselect(Node *sel)
 				oc = selcase(n, var);
 				res = list(res, oc);
 				break;
-
-
 			}
-			bod = N;
+			bod = nbod;
 			count++;
 			break;
 		}
@@ -1610,6 +1636,7 @@ lookdot(Node *n, Type *t)
 			switch(op) {
 			case OADDR:
 				walktype(n->left, Elv);
+				addrescapes(n->left);
 				n->left = nod(OADDR, n->left, N);
 				n->left->type = ptrto(tt);
 				break;
@@ -1781,7 +1808,7 @@ sigtype(Type *st)
  * match a ... parameter into an
  * automatic structure.
  * then call the ... arg (interface)
- * with a pointer to the structure
+ * with a pointer to the structure.
  */
 Node*
 mkdotargs(Node *r, Node *rr, Iter *saver, Node *nn, Type *l, int fp)
@@ -1817,10 +1844,12 @@ mkdotargs(Node *r, Node *rr, Iter *saver, Node *nn, Type *l, int fp)
 
 	// make a named type for the struct
 	st = sigtype(st);
+	dowidth(st);
 
 	// now we have the size, make the struct
 	var = nod(OXXX, N, N);
 	tempname(var, st);
+	var->sym = lookup(".ddd");
 
 	// assign the fields to the struct.
 	// use addtop so that reorder1 doesn't reorder
@@ -1840,8 +1869,7 @@ mkdotargs(Node *r, Node *rr, Iter *saver, Node *nn, Type *l, int fp)
 	}
 
 	// last thing is to put assignment
-	// of a pointer to the structure to
-	// the DDD parameter
+	// of the structure to the DDD parameter
 	a = nod(OAS, nodarg(l, fp), var);
 	nn = list(convas(a), nn);
 
@@ -2081,26 +2109,17 @@ makecompat(Node *n)
 }
 
 Node*
-newcompat(Node *n)
+callnew(Type *t)
 {
 	Node *r, *on;
-	Type *t;
 
-	t = n->type;
-	if(t != T && t->etype != TFUNC) {
-		if(n->left != N)
-			yyerror("cannot new(%T, expr)", t);
-		dowidth(t);
-		on = syslook("mal", 1);
-		argtype(on, t);
-		r = nodintconst(t->width);
-		r = nod(OCALL, on, r);
-		walktype(r, Erv);
-		return r;
-	}
-
-	yyerror("cannot new(%T)", t);
-	return n;
+	dowidth(t);
+	on = syslook("mal", 1);
+	argtype(on, t);
+	r = nodintconst(t->width);
+	r = nod(OCALL, on, r);
+	walktype(r, Erv);
+	return r;
 }
 
 Node*
@@ -2648,6 +2667,7 @@ arrayop(Node *n, int top)
 		r = a;
 
 		a = nod(OADDR, n->left, N);		// old
+		addrescapes(n->left);
 		r = list(a, r);
 
 		on = syslook("arrays2d", 1);
@@ -2671,6 +2691,7 @@ arrayop(Node *n, int top)
 		r = a;
 
 		a = nod(OADDR, n->right, N);		// old
+		addrescapes(n->right);
 		r = list(a, r);
 
 		on = syslook("arrays2d", 1);
@@ -3171,6 +3192,7 @@ ary:
 		n->nbody = list(n->nbody,
 			nod(OAS, v, nod(OINDEX, m, hk)) );
 	}
+	addtotop(n);
 	goto out;
 
 map:
@@ -3457,18 +3479,20 @@ reorder4(Node *n)
 }
 
 Node*
-structlit(Node *n)
+structlit(Node *n, Node *var)
 {
 	Iter savel, saver;
 	Type *l, *t;
-	Node *var, *r, *a;
+	Node *r, *a;
 
 	t = n->type;
 	if(t->etype != TSTRUCT)
 		fatal("structlit: not struct");
 
-	var = nod(OXXX, N, N);
-	tempname(var, t);
+	if(var == N) {
+		var = nod(OXXX, N, N);
+		tempname(var, t);
+	}
 
 	l = structfirst(&savel, &n->type);
 	r = listfirst(&saver, &n->left);
@@ -3488,6 +3512,7 @@ loop:
 
 	a = nod(ODOT, var, newname(l->sym));
 	a = nod(OAS, a, r);
+	walktype(a, Etop);	// add any assignments in r to addtop
 	addtop = list(addtop, a);
 
 	l = structnext(&savel);
@@ -3605,3 +3630,115 @@ loop:
 	r = listnext(&saver);
 	goto loop;
 }
+
+/*
+ * the address of n has been taken and might be used after
+ * the current function returns.  mark any local vars
+ * as needing to move to the heap.
+ */
+static char *pnames[] = {
+[PAUTO]	"auto",
+[PPARAM]	"param",
+[PPARAMOUT] "param_out",
+};
+
+void
+addrescapes(Node *n)
+{
+	char buf[100];
+	switch(n->op) {
+	default:
+		dump("addrescapes", n);
+		break;
+
+	case ONAME:
+		if(n->noescape)
+			break;
+		switch(n->class) {
+		case PPARAMOUT:
+			yyerror("cannot take address of out parameter %s", n->sym->name);
+			break;
+		case PAUTO:
+		case PPARAM:
+			if(debug['E'])
+				print("%L %s %S escapes %p\n", n->lineno, pnames[n->class], n->sym, n);
+			n->class |= PHEAP;
+			n->addable = 0;
+			n->ullman = 2;
+			n->alloc = callnew(n->type);
+
+			// if func param, need separate temporary
+			// to hold heap pointer.
+			if(n->class == PPARAM+PHEAP) {
+				// expression to refer to stack copy
+				n->stackparam = nod(OPARAM, n, N);
+				n->stackparam->type = n->type;
+				n->stackparam->addable = 1;
+				n->stackparam->xoffset = n->xoffset;
+				n->xoffset = 0;
+			}
+
+			// create stack variable to hold pointer to heap
+			n->heapaddr = nod(0, N, N);
+			tempname(n->heapaddr, ptrto(n->type));
+			snprint(buf, sizeof buf, "&%S", n->sym);
+			n->heapaddr->sym = lookup(buf);
+			break;
+		}
+		break;
+
+	case OIND:
+	case ODOTPTR:
+		break;
+
+	case ODOT:
+	case OINDEX:
+		// ODOTPTR has already been
+		// introduced, so these are the non-pointer
+		// ODOT and OINDEX.
+		addrescapes(n->left);
+		break;
+	}
+}
+
+/*
+ * walk through argin parameters.
+ * generate and return code to allocate
+ * copies of escaped parameters to the heap.
+ */
+Node*
+paramstoheap(Type **argin)
+{
+	Type *t;
+	Iter savet;
+	Node *v, *nn;
+
+	nn = N;
+	for(t = structfirst(&savet, argin); t != T; t = structnext(&savet)) {
+		if(t->sym == S)
+			continue;
+		v = t->sym->oname;
+		if(v == N || !(v->class & PHEAP))
+			continue;
+
+		// generate allocation & copying code
+		nn = list(nn, nod(OAS, v->heapaddr, v->alloc));
+		nn = list(nn, nod(OAS, v, v->stackparam));
+	}
+	return nn;
+}
+
+/*
+ * take care of migrating any function in/out args
+ * between the stack and the heap.  adds code to
+ * curfn's before and after lists.
+ */
+void
+heapmoves(void)
+{
+	Node *nn;
+
+	nn = paramstoheap(getthis(curfn->type));
+	nn = list(nn, paramstoheap(getinarg(curfn->type)));
+	curfn->enter = list(curfn->enter, nn);
+}
diff --git a/src/runtime/print.c b/src/runtime/print.c
index 6b0000e21..bdd9abc95 100644
--- a/src/runtime/print.c
+++ b/src/runtime/print.c
@@ -237,8 +237,14 @@ sys·printpointer(void *p)
 void
 sys·printstring(string v)
 {
-	if(v != nil)
-		sys·write(1, v->str, v->len);
+	extern int32 maxstring;
+
+	if(v != nil) {
+		if(v->len > maxstring)
+			sys·write(1, "[invalid string]", 16);
+		else
+			sys·write(1, v->str, v->len);
+	}
 }
 
 void
diff --git a/src/runtime/string.c b/src/runtime/string.c
index b31e7cc78..e708d0203 100644
--- a/src/runtime/string.c
+++ b/src/runtime/string.c
@@ -17,6 +17,20 @@ findnull(byte *s)
 	return l;
 }
 
+int32 maxstring;
+
+string
+gostringsize(int32 l)
+{
+	string s;
+
+	s = mal(sizeof(s->len)+l+1);
+	s->len = l;
+	if(l > maxstring)
+		maxstring = l;
+	return s;
+}
+
 string
 gostring(byte *str)
 {
@@ -24,8 +38,7 @@ gostring(byte *str)
 	string s;
 
 	l = findnull(str);
-	s = mal(sizeof(s->len)+l+1);
-	s->len = l;
+	s = gostringsize(l);
 	mcpy(s->str, str, l+1);
 	return s;
 }
@@ -46,8 +59,7 @@ sys·catstring(string s1, string s2, string s3)
 
 	l = s1->len + s2->len;
 
-	s3 = mal(sizeof(s3->len)+l);
-	s3->len = l;
+	s3 = gostringsize(l);
 	mcpy(s3->str, s1->str, s1->len);
 	mcpy(s3->str+s1->len, s2->str, s2->len);
 
@@ -139,8 +151,7 @@ sys·slicestring(string si, int32 lindex, int32 hindex, string so)
 	}
 
 	l = hindex-lindex;
-	so = mal(sizeof(so->len)+l);
-	so->len = l;
+	so = gostringsize(l);
 	mcpy(so->str, si->str+lindex, l);
 	FLUSH(&so);
 }
@@ -164,7 +175,7 @@ sys·indexstring(string s, int32 i, byte b)
 void
 sys·intstring(int64 v, string s)
 {
-	s = mal(sizeof(s->len)+8);
+	s = gostringsize(8);
 	s->len = runetochar(s->str, v);
 	FLUSH(&s);
 }
@@ -172,8 +183,7 @@ sys·intstring(int64 v, string s)
 void
 sys·byteastring(byte *a, int32 l, string s)
 {
-	s = mal(sizeof(s->len)+l);
-	s->len = l;
+	s = gostringsize(l);
 	mcpy(s->str, a, l);
 	FLUSH(&s);
 }
@@ -181,8 +191,7 @@ sys·byteastring(byte *a, int32 l, string s)
 void
 sys·arraystring(Array b, string s)
 {
-	s = mal(sizeof(s->len)+b.nel);
-	s->len = b.nel;
+	s = gostringsize(b.nel);
 	mcpy(s->str, b.array, s->len);
 	FLUSH(&s);
 }
diff --git a/test/escape.go b/test/escape.go
new file mode 100644
index 000000000..d2534c60d
--- /dev/null
+++ b/test/escape.go
@@ -0,0 +1,175 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// check for correct heap-moving of escaped variables.
+// it is hard to check for the allocations, but it is easy
+// to check that if you call the function twice at the
+// same stack level, the pointers returned should be
+// different.
+
+var bad = false
+
+var allptr = make([]*int, 0, 100);
+
+func noalias(p, q *int, s string) {
+	n := len(allptr);
+	*p = -(n+1);
+	*q = -(n+2);
+	allptr = allptr[0:n+2];
+	allptr[n] = p;
+	allptr[n+1] = q;
+	n += 2;
+	for i := 0; i < n; i++ {
+		if allptr[i] != nil && *allptr[i] != -(i+1) {
+			println("aliased pointers", -(i+1), *allptr[i], "after", s);
+			allptr[i] = nil;
+			bad = true;
+		}
+	}
+}
+
+func val(p, q *int, v int, s string) {
+	if *p != v {
+		println("wrong value want", v, "got", *p, "after", s);
+		bad = true;
+	}
+	if *q != v+1 {
+		println("wrong value want", v+1, "got", *q, "after", s);
+		bad = true;
+	}
+}
+
+func chk(p, q *int, v int, s string) {
+	val(p, q, v, s);
+	noalias(p, q, s);
+}
+
+func chkalias(p, q *int, v int, s string) {
+	if p != q {
+		println("want aliased pointers but got different after", s);
+	}
+	if *q != v+1 {
+		println("wrong value want", v+1, "got", *q, "after", s);
+	}
+}
+
+func i_escapes(x int) *int {
+	var i int;
+	i = x;
+	return &i;
+}
+
+func j_escapes(x int) *int {
+	var j int = x;
+	j = x;
+	return &j;
+}
+
+func k_escapes(x int) *int {
+	k := x;
+	return &k;
+}
+
+func in_escapes(x int) *int {
+	return &x;
+}
+
+func send(c chan int, x int) {
+	c <- x;
+}
+
+func select_escapes(x int) *int {
+	c := make(chan int);
+	go send(c, x);
+	select {
+	case req := <-c:
+		return &req;
+	}
+	return nil;
+}
+
+func select_escapes1(x int, y int) (*int, *int) {
+	c := make(chan int);
+	var a [2]int;
+	var p [2]*int;
+	a[0] = x;
+	a[1] = y;
+	for i := 0; i < 2; i++ {
+		go send(c, a[i]);
+		select {
+		case req := <-c:
+			p[i] = &req;
+		}
+	}
+	return p[0], p[1]
+}
+
+func range_escapes(x int) *int {
+	var a [1]int;
+	a[0] = x;
+	for k, v := range a {
+		return &v;
+	}
+	return nil;
+}
+
+// *is* aliased
+func range_escapes2(x, y int) (*int, *int) {
+	var a [2]int;
+	var p [2]*int;
+	a[0] = x;
+	a[1] = y;
+	for k, v := range a {
+		p[k] = &v;
+	}
+	return p[0], p[1]
+}
+
+// *is* aliased
+func for_escapes2(x int, y int) (*int, *int) {
+	var p [2]*int;
+	n := 0;
+	for i := x; n < 2; i = y {
+		p[n] = &i;
+		n++;
+	}
+	return p[0], p[1]
+}
+
+func main() {
+	p, q := i_escapes(1), i_escapes(2);
+	chk(p, q, 1, "i_escapes");
+
+	p, q = j_escapes(3), j_escapes(4);
+	chk(p, q, 3, "j_escapes");
+
+	p, q = k_escapes(5), k_escapes(6);
+	chk(p, q, 5, "k_escapes");
+
+	p, q = in_escapes(7), in_escapes(8);
+	chk(p, q, 7, "in_escapes");
+
+	p, q = select_escapes(9), select_escapes(10);
+	chk(p, q, 9, "select_escapes");
+
+	p, q = select_escapes1(11, 12);
+	chk(p, q, 11, "select_escapes1");
+
+	p, q = range_escapes(13), range_escapes(14);
+	chk(p, q, 13, "range_escapes");
+
+	p, q = range_escapes2(101, 102);
+	chkalias(p, q, 101, "range_escapes2");
+
+	p, q = for_escapes2(103, 104);
+	chkalias(p, q, 103, "for_escapes2");
+
+	if bad {
+		panic("BUG: no escape");
+	}
+}
diff --git a/test/escape1.go b/test/escape1.go
new file mode 100644
index 000000000..28b5b1016
--- /dev/null
+++ b/test/escape1.go
@@ -0,0 +1,17 @@
+// errchk $G $D/$F.go
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func out_escapes() (x int, p *int) {
+	p = &x;	// ERROR "address.*out parameter"
+	return;
+}
+
+func out_escapes() (x int, p *int) {
+	return 2, &x;	// ERROR "address.*out parameter"
+}
+
diff --git a/test/golden.out b/test/golden.out
index d70df181d..80f325edc 100644
--- a/test/golden.out
+++ b/test/golden.out
@@ -172,7 +172,7 @@ bugs/bug129.go:6: syscall is package, not var
 BUG129
 
 =========== bugs/bug130.go
-bugs/bug130.go:14: fatal error: getoutarg: not a func RANGE
+bugs/bug130.go:14: fatal error: getoutarg: not a func *<T>
 BUG: should run
 
 =========== bugs/bug131.go