cmd/8g: fix erroneous LEAL nil.

Fixes #4399.

R=golang-dev, nigeltao
CC=golang-dev
https://golang.org/cl/6845053

src/cmd/8g/cgen.c

@@ -827,16 +827,19 @@ igen(Node *n, Node *a, Node *res)
 		return;
 
 	case ODOTPTR:
-		if(n->left->addable
-			|| n->left->op == OCALLFUNC
-			|| n->left->op == OCALLMETH
-			|| n->left->op == OCALLINTER) {
+		switch(n->left->op) {
+		case ODOT:
+		case ODOTPTR:
+		case OCALLFUNC:
+		case OCALLMETH:
+		case OCALLINTER:
 			// igen-able nodes.
 			igen(n->left, &n1, res);
 			regalloc(a, types[tptr], &n1);
 			gmove(&n1, a);
 			regfree(&n1);
-		} else {
+			break;
+		default:
 			regalloc(a, types[tptr], res);
 			cgen(n->left, a);
 		}

src/cmd/8g/gsubr.c

@@ -1747,7 +1747,7 @@ gins(int as, Node *f, Node *t)
 	
 	case ALEAL:
 		if(f != N && isconst(f, CTNIL))
-			fatal("gins LEAQ nil %T", f->type);
+			fatal("gins LEAL nil %T", f->type);
 		break;
 	}
 

test/fixedbugs/issue4399.go

+// compile
+
+// Copyright 2012 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.
+
+// Issue 4399: 8g would print "gins LEAQ nil *A".
+
+package main
+
+type A struct{ a int }
+
+func main() {
+	println(((*A)(nil)).a)
+}