[dev.ssa] cmd/compile: implement OIND

Change-Id: I15aee8095e6388822e2222f1995fe2278ac956ca
Reviewed-on: https://go-review.googlesource.com/12129Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

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

@@ -719,6 +719,10 @@ func (s *state) addr(n *Node) *ssa.Value {
 			s.boundsCheck(i, len)
 			return s.newValue2(ssa.OpPtrIndex, Ptrto(n.Left.Type.Type), a, i)
 		}
+	case OIND:
+		p := s.expr(n.Left)
+		s.nilCheck(p)
+		return p
 	case ODOT:
 		p := s.addr(n.Left)
 		return s.newValue2(ssa.OpAdd, p.Type, p, s.constInt(s.config.Uintptr, n.Xoffset))