byte multiply

R=r
OCL=18807
CL=18807
diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index e1b970b..4fb9e34 100644
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -122,7 +122,10 @@
 	case OADD:
 	case OMUL:
 		a = optoas(n->op, nl->type);
-		goto sbop;
+		if(a != AIMULB)
+			goto sbop;
+		cgen_bmul(n->op, nl, nr, res);
+		break;
 
 	// asymmetric binary
 	case OSUB: