gc: select functions are no longer special

R=ken2
CC=golang-dev
https://golang.org/cl/4794049

src/cmd/gc/go.h

@@ -1106,7 +1106,6 @@ int	isinter(Type *t);
 int	isnil(Node *n);
 int	isnilinter(Type *t);
 int	isptrto(Type *t, int et);
-int	isselect(Node *n);
 int	isslice(Type *t);
 int	istype(Type *t, int et);
 void	linehist(char *file, int32 off, int relative);

src/cmd/gc/subr.c

@@ -1719,29 +1719,6 @@ isblank(Node *n)
 	return p[0] == '_' && p[1] == '\0';
 }
 
-int
-isselect(Node *n)
-{
-	Sym *s;
-
-	if(n == N)
-		return 0;
-	n = n->left;
-	s = pkglookup("selectsend", runtimepkg);
-	if(s == n->sym)
-		return 1;
-	s = pkglookup("selectrecv", runtimepkg);
-	if(s == n->sym)
-		return 1;
-	s = pkglookup("selectrecv2", runtimepkg);
-	if(s == n->sym)
-		return 1;
-	s = pkglookup("selectdefault", runtimepkg);
-	if(s == n->sym)
-		return 1;
-	return 0;
-}
-
 int
 isinter(Type *t)
 {

src/cmd/gc/walk.c

@@ -501,17 +501,6 @@ walkexpr(Node **np, NodeList **init)
 
 		ll = ascompatte(n->op, n->isddd, getinarg(t), n->list, 0, init);
 		n->list = reorder1(ll);
-		if(isselect(n)) {
-			// special prob with selectsend and selectrecv:
-			// if chan is nil, they don't know big the channel
-			// element is and therefore don't know how to find
-			// the output bool, so we clear it before the call.
-			Node *b;
-			b = nodbool(0);
-			typecheck(&b, Erv);
-			lr = ascompatte(n->op, 0, getoutarg(t), list1(b), 0, init);
-			n->list = concat(n->list, lr);
-		}
 		goto ret;
 
 	case OCALLMETH:

src/pkg/runtime/chan.c

@@ -632,6 +632,9 @@ static void selectsend(Select *sel, Hchan *c, void *pc, void *elem, int32 so);
 void
 runtime·selectsend(Select *sel, Hchan *c, void *elem, bool selected)
 {
+	selected = false;
+	FLUSH(&selected);
+
 	// nil cases do not compete
 	if(c == nil)
 		return;
@@ -670,6 +673,9 @@ static void selectrecv(Select *sel, Hchan *c, void *pc, void *elem, bool*, int32
 void
 runtime·selectrecv(Select *sel, Hchan *c, void *elem, bool selected)
 {
+	selected = false;
+	FLUSH(&selected);
+
 	// nil cases do not compete
 	if(c == nil)
 		return;
@@ -682,6 +688,9 @@ runtime·selectrecv(Select *sel, Hchan *c, void *elem, bool selected)
 void
 runtime·selectrecv2(Select *sel, Hchan *c, void *elem, bool *received, bool selected)
 {
+	selected = false;
+	FLUSH(&selected);
+
 	// nil cases do not compete
 	if(c == nil)
 		return;
@@ -721,6 +730,9 @@ static void selectdefault(Select*, void*, int32);
 void
 runtime·selectdefault(Select *sel, bool selected)
 {
+	selected = false;
+	FLUSH(&selected);
+
 	selectdefault(sel, runtime·getcallerpc(&sel), (byte*)&selected - (byte*)&sel);
 }