cmd/gc: remove several copies of outervalue

Walk calls it outervalue, racewalk calls it basenod,
isstack does it manually and slightly differently.

Change-Id: Id5b5d32b8faf143fe9d34bd08457bfab6fb33daa
Reviewed-on: https://go-review.googlesource.com/3745
Reviewed-by: Russ Cox <rsc@golang.org>

src/cmd/gc/racewalk.c

@@ -24,7 +24,6 @@ static void racewalknode(Node **np, NodeList **init, int wr, int skip);
 static int callinstr(Node **n, NodeList **init, int wr, int skip);
 static Node* uintptraddr(Node *n);
 static void makeaddable(Node *n);
-static Node* basenod(Node *n);
 static void foreach(Node *n, void(*f)(Node*, void*), void *c);
 static void hascallspred(Node *n, void *c);
 static void appendinit(Node **np, NodeList *init);
@@ -155,12 +154,8 @@ racewalknode(Node **np, NodeList **init, int wr, int skip)
 	default:
 		fatal("racewalk: unknown node type %O", n->op);
 
-	case OASOP:
 	case OAS:
-	case OAS2:
-	case OAS2RECV:
 	case OAS2FUNC:
-	case OAS2MAPR:
 		racewalknode(&n->left, init, 1, 0);
 		racewalknode(&n->right, init, 0, 0);
 		goto ret;
@@ -350,7 +345,7 @@ racewalknode(Node **np, NodeList **init, int wr, int skip)
 		goto ret;
 
 	case OEFACE:
-		racewalknode(&n->left, init, 0, 0);
+		// n->left is Type* which is not interesting.
 		racewalknode(&n->right, init, 0, 0);
 		goto ret;
 
@@ -393,6 +388,10 @@ racewalknode(Node **np, NodeList **init, int wr, int skip)
 	case OARRAYLIT: // lowered to assignments
 	case OMAPLIT:
 	case OSTRUCTLIT:
+	case OAS2:
+	case OAS2RECV:
+	case OAS2MAPR:
+	case OASOP:
 		yyerror("racewalk: %O must be lowered by now", n->op);
 		goto ret;
 
@@ -489,7 +488,7 @@ callinstr(Node **np, NodeList **init, int wr, int skip)
 	if(isartificial(n))
 		return 0;
 
-	b = basenod(n);
+	b = outervalue(n);
 	// it skips e.g. stores to ... parameter array
 	if(isartificial(b))
 		return 0;
@@ -499,7 +498,7 @@ callinstr(Node **np, NodeList **init, int wr, int skip)
 	// that has got a pointer inside. Whether it points to
 	// the heap or not is impossible to know at compile time
 	if((class&PHEAP) || class == PPARAMREF || class == PEXTERN
-		|| b->op == OINDEX || b->op == ODOTPTR || b->op == OIND || b->op == OXDOT) {
+		|| b->op == OINDEX || b->op == ODOTPTR || b->op == OIND) {
 		hascalls = 0;
 		foreach(n, hascallspred, &hascalls);
 		if(hascalls) {
@@ -568,25 +567,6 @@ uintptraddr(Node *n)
 	return r;
 }
 
-// basenod returns the simplest child node of n pointing to the same
-// memory area.
-static Node*
-basenod(Node *n)
-{
-	for(;;) {
-		if(n->op == ODOT || n->op == OXDOT || n->op == OCONVNOP || n->op == OCONV || n->op == OPAREN) {
-			n = n->left;
-			continue;
-		}
-		if(n->op == OINDEX && isfixedarray(n->type)) {
-			n = n->left;
-			continue;
-		}
-		break;
-	}
-	return n;
-}
-
 static Node*
 detachexpr(Node *n, NodeList **init)
 {

src/cmd/gc/walk.c

@@ -1963,8 +1963,7 @@ isstack(Node *n)
 {
 	Node *defn;
 
-	while(n->op == ODOT || n->op == OPAREN || n->op == OCONVNOP || n->op == OINDEX && isfixedarray(n->left->type))
+	n = outervalue(n);
-		n = n->left;
 
 	// If n is *autotmp and autotmp = &foo, replace n with foo.
 	// We introduce such temps when initializing struct literals.
@@ -1995,8 +1994,7 @@ isstack(Node *n)
 static int
 isglobal(Node *n)
 {
-	while(n->op == ODOT || n->op == OPAREN || n->op == OCONVNOP || n->op == OINDEX && isfixedarray(n->left->type))
+	n = outervalue(n);
-		n = n->left;
 
 	switch(n->op) {
 	case ONAME:
@@ -2355,7 +2353,9 @@ Node*
 outervalue(Node *n)
 {	
 	for(;;) {
-		if(n->op == ODOT || n->op == OPAREN) {
+		if(n->op == OXDOT)
+			fatal("OXDOT in walk");
+		if(n->op == ODOT || n->op == OPAREN || n->op == OCONVNOP) {
 			n = n->left;
 			continue;
 		}