thenStart, thenEnd := pvacfgbody(t, fset, cm, ifstmt.Body.List)
	var elseStart, elseEnd *pvacfgnode
	if ifstmt.Else != nil {
		switch els := ifstmt.Else.(type) {
		case *ast.IfStmt:
			elseStart, elseEnd = pvacfgif(t, fset, cm, els)
		case *ast.BlockStmt:
			elseStart, elseEnd = pvacfgbody(t, fset, cm, els.List)
		default:
			t.Fatalf("%s: unexpected statement %T", fset.Position(els.Pos()), els)