[dev.ssa] clarify ODCL todo, remove irrelevant colas todo

ODCL nodes are used as the point where the variable is allocated in
the old pass. colas is irrelevant at this point of the compile. All
the checks on it happen at parse time and an ODCL node will have been
inserted right before it.

Change-Id: I1aca053aaa4363bacd12e1156de86fa7b6190a55
Reviewed-on: https://go-review.googlesource.com/10901Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/gc/ssa.go

@@ -206,7 +206,8 @@ func (s *state) stmt(n *Node) {
 		s.stmtList(n.List)
 
 	case ODCL:
-		// TODO: ???  Assign 0?
+		// TODO: old gen pass uses dcl node as the point where
+		// escaping variables' new functions are called. Do that here
 
 	case OLABEL, OGOTO:
 		// get block at label, or make one
@@ -225,7 +226,6 @@ func (s *state) stmt(n *Node) {
 		}
 
 	case OAS, OASWB:
-		// TODO(khr): colas?
 		// TODO: do write barrier
 		var val *ssa.Value
 		if n.Right == nil {