init context for composit literals

R=rsc
OCL=34462
CL=34462

src/cmd/gc/go.h

@@ -1012,6 +1012,7 @@ NodeList*	reorder1(NodeList*);
 NodeList*	reorder3(NodeList*);
 NodeList*	reorder4(NodeList*);
 void	anylit(Node*, Node*, NodeList**);
+int	oaslit(Node*, NodeList**);
 void	heapmoves(void);
 void	walkdeflist(NodeList*);
 void	walkdef(Node*);

src/cmd/gc/sinit.c

@@ -51,7 +51,7 @@ init1(Node *n, NodeList **out)
 		case OAS:
 			if(n->defn->left != n)
 				goto bad;
-			n->dodata = 1;
+			n->defn->dodata = 1;
 			init1(n->defn->right, out);
 			if(debug['j'])
 				print("%S\n", n->sym);

src/cmd/gc/walk.c

@@ -572,6 +572,8 @@ walkexpr(Node **np, NodeList **init)
 		*init = concat(*init, n->ninit);
 		n->ninit = nil;
 		walkexpr(&n->left, init);
+		if(oaslit(n, init))
+			goto ret;
 		walkexpr(&n->right, init);
 		l = n->left;
 		r = n->right;
@@ -2406,6 +2408,50 @@ anylit(Node *n, Node *var, NodeList **init)
 	}
 }
 
+int
+oaslit(Node *n, NodeList **init)
+{
+	Type *t;
+
+	if(n->left == N || n->right == N)
+		goto no;
+	if(!simplename(n->left))
+		goto no;
+	if(n->dodata == 1)
+		goto initctxt;
+
+no:
+	// not a special composit literal assignment
+	return 0;
+
+initctxt:
+	switch(n->right->op) {
+	default:
+		goto no;
+
+	case OSTRUCTLIT:
+		structlit(n->right, n->left, 3, init);
+		break;
+
+	case OARRAYLIT:
+		t = n->right->type;
+		if(t == T)
+			goto no;
+		if(t->bound < 0) {
+			slicelit(n->right, n->left, init);
+			break;
+		}
+		arraylit(n->right, n->left, 3, init);
+		break;
+
+	case OMAPLIT:
+		maplit(n->right, n->left, init);
+		break;
+	}
+	n->op = OEMPTY;
+	return 1;
+}
+
 /*
  * walk through argin parameters.
  * generate and return code to allocate