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Treat xvalues as they were lvalues

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Summary:
public
xvalues is concept introduced in C++11. While they are not same as lvalues, they have one common trait:
They have identity which means that:
> it's possible to determine whether the expression refers to the same entity as another expression, such as by comparing addresses of the objects or the functions they identify (obtained directly or indirectly);

It means that as far as backend is concerned, they should be treated in same way. Right now there is no concept of "move" in the backend and so we don't have
to differentiate between them.

Reference:
http://en.cppreference.com/w/cpp/language/value_category

Reviewed By: cristianoc

Differential Revision: D2895593

fb-gh-sync-id: 5101e28
master
Andrzej Kotulski 9 years ago committed by facebook-github-bot-5
parent 36fb1f202c
commit 8545a0310e
3 changed files with 25 additions and 19 deletions
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37
infer/src/clang/cTrans.ml
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@ -207,27 +207,32 @@ struct
{ empty_res_trans with
exps = [(Sil.Sizeof(expanded_type, Sil.Subtype.exact), Sil.Tint Sil.IULong)] }
let add_reference_if_lvalue typ expr_info =
match expr_info.Clang_ast_t.ei_value_kind, typ with
| `LValue, Sil.Tptr (_, Sil.Pk_reference) ->
let add_reference_if_glvalue typ expr_info =
(* glvalue definition per C++11:*)
(* http://en.cppreference.com/w/cpp/language/value_category *)
let is_glvalue = match expr_info.Clang_ast_t.ei_value_kind with
| `LValue | `XValue -> true
| `RValue -> false in
match is_glvalue, typ with
| true, Sil.Tptr (_, Sil.Pk_reference) ->
(* reference of reference is not allowed in C++ - it's most likely frontend *)
(* trying to add same reference to same type twice*)
(* this is hacky and should be fixed (t9838691) *)
typ
| `LValue, _ -> Sil.Tptr (typ, Sil.Pk_reference)
| true, _ -> Sil.Tptr (typ, Sil.Pk_reference)
| _ -> typ
(** Execute translation and then possibly adjust the type of the result of translation:
In C++, when expression returns reference to type T, it will be lvalue to T, not T&, but
infer needs it to be T& *)
let exec_with_lvalue_as_reference f trans_state stmt =
let exec_with_glvalue_as_reference f trans_state stmt =
let expr_info = match Clang_ast_proj.get_expr_tuple stmt with
| Some (_, _, ei) -> ei
| None -> assert false in
let res_trans = f trans_state stmt in
let (exp, typ) = extract_exp_from_list res_trans.exps
"[Warning] Need exactly one expression to add reference type\n" in
{ res_trans with exps = [(exp, add_reference_if_lvalue typ expr_info)] }
{ res_trans with exps = [(exp, add_reference_if_glvalue typ expr_info)] }
(* Execute translation of e forcing to release priority (if it's not free) and then setting it back.*)
(* This is used in conditional operators where we need to force the priority to be free for the *)
@ -715,7 +720,7 @@ struct
and callExpr_trans trans_state si stmt_list expr_info =
let context = trans_state.context in
let fn_type_no_ref = CTypes_decl.get_type_from_expr_info expr_info context.CContext.tenv in
let function_type = add_reference_if_lvalue fn_type_no_ref expr_info in
let function_type = add_reference_if_glvalue fn_type_no_ref expr_info in
let procname = Cfg.Procdesc.get_proc_name context.CContext.procdesc in
let sil_loc = CLocation.get_sil_location si context in
(* First stmt is the function expr and the rest are params *)
@ -750,7 +755,7 @@ struct
let params_stmt = if should_translate_args then params_stmt
else [] in
let result_trans_subexprs =
let instruction' = exec_with_self_exception (exec_with_lvalue_as_reference instruction) in
let instruction' = exec_with_self_exception (exec_with_glvalue_as_reference instruction) in
let res_trans_p = IList.map (instruction' trans_state_param) params_stmt in
res_trans_callee :: res_trans_p in
let sil_fe, is_cf_retain_release = CTrans_models.builtin_predefined_model fun_exp_stmt sil_fe in
@ -816,7 +821,7 @@ struct
let trans_state_param =
{ trans_state_pri with succ_nodes = []; var_exp = None } in
let result_trans_subexprs =
let instruction' = exec_with_self_exception (exec_with_lvalue_as_reference instruction) in
let instruction' = exec_with_self_exception (exec_with_glvalue_as_reference instruction) in
let res_trans_p = IList.map (instruction' trans_state_param) params_stmt in
result_trans_callee :: res_trans_p in
(* first expr is method address, rest are params including 'this' parameter *)
@ -852,7 +857,7 @@ struct
let trans_state_callee = { trans_state_pri with succ_nodes = [] } in
let result_trans_callee = instruction trans_state_callee fun_exp_stmt in
let fn_type_no_ref = CTypes_decl.get_type_from_expr_info expr_info context.CContext.tenv in
let function_type = add_reference_if_lvalue fn_type_no_ref expr_info in
let function_type = add_reference_if_glvalue fn_type_no_ref expr_info in
cxx_method_construct_call_trans trans_state_pri result_trans_callee params_stmt
si function_type
@ -929,7 +934,7 @@ struct
Ast_expressions.make_obj_c_message_expr_info_class selector class_name pointer in
obj_c_message_expr_info, empty_res_trans in
let instruction' =
exec_with_self_exception (exec_with_lvalue_as_reference instruction) in
exec_with_self_exception (exec_with_glvalue_as_reference instruction) in
let l = IList.map (instruction' trans_state_param) rest in
obj_c_message_expr_info, fst_res_trans :: l
| [] -> obj_c_message_expr_info, [empty_res_trans]
@ -940,7 +945,7 @@ struct
let context = trans_state.context in
let sil_loc = CLocation.get_sil_location si context in
let method_type_no_ref = CTypes_decl.get_type_from_expr_info expr_info context.CContext.tenv in
let method_type = add_reference_if_lvalue method_type_no_ref expr_info in
let method_type = add_reference_if_glvalue method_type_no_ref expr_info in
let trans_state_pri = PriorityNode.try_claim_priority_node trans_state si in
let trans_state_param = { trans_state_pri with succ_nodes = []; var_exp = None } in
let obj_c_message_expr_info, res_trans_subexpr_list =
@ -1038,7 +1043,7 @@ struct
| [cond; exp1; exp2] ->
let typ =
CTypes_decl.type_ptr_to_sil_type context.CContext.tenv expr_info.Clang_ast_t.ei_type_ptr in
let var_typ = add_reference_if_lvalue typ expr_info in
let var_typ = add_reference_if_glvalue typ expr_info in
let join_node = create_node (Cfg.Node.Join_node) [] [] sil_loc context in
Cfg.Node.set_succs_exn join_node succ_nodes [];
let pvar = mk_temp_var (Cfg.Node.get_id join_node) in
@ -1556,7 +1561,7 @@ struct
let res_trans_ie =
let trans_state' = { trans_state_pri with succ_nodes = []; var_exp = Some var_exp } in
let instruction' =
exec_with_self_exception (exec_with_lvalue_as_reference instruction) in
exec_with_self_exception (exec_with_glvalue_as_reference instruction) in
exec_with_block_priority_exception instruction' trans_state' ie var_stmt_info in
let (sil_e1', ie_typ) = extract_exp_from_list res_trans_ie.exps
"WARNING: In DeclStmt we expect only one expression returned in recursive call\n" in
@ -1701,7 +1706,7 @@ struct
(* with wrong value. For example, we don't want p to be initialized with X(1) for:*)
(* int p = X(1).field; *)
let trans_state' = { trans_state with var_exp = None } in
let result_trans_exp_stmt = exec_with_lvalue_as_reference instruction trans_state' exp_stmt in
let result_trans_exp_stmt = exec_with_glvalue_as_reference instruction trans_state' exp_stmt in
decl_ref_trans trans_state result_trans_exp_stmt stmt_info expr_info decl_ref
and objCIvarRefExpr_trans trans_state stmt_info expr_info stmt_list obj_c_ivar_ref_expr_info =
@ -1955,7 +1960,7 @@ struct
| _ -> assert false in
let builtin = Sil.Const (Sil.Cfun SymExec.ModelBuiltins.__cast) in
let stmt = match stmts with [stmt] -> stmt | _ -> assert false in
let res_trans_stmt = exec_with_lvalue_as_reference instruction trans_state' stmt in
let res_trans_stmt = exec_with_glvalue_as_reference instruction trans_state' stmt in
let exp = match res_trans_stmt.exps with | [e] -> e | _ -> assert false in
let args = [exp; (sizeof_expr, Sil.Tvoid)] in
let ret_id = Ident.create_fresh Ident.knormal in

1
infer/src/clang/cType_to_sil_type.ml
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@ -113,6 +113,7 @@ and sil_type_of_c_type translate_decl tenv c_type =
| None -> Sil.Tvoid)
| ObjCInterfaceType (type_info, pointer) ->
decl_ptr_to_sil_type translate_decl tenv pointer
| RValueReferenceType (type_info, type_ptr)
| LValueReferenceType (type_info, type_ptr) ->
let typ = type_ptr_to_sil_type translate_decl tenv type_ptr in
Sil.Tptr (typ, Sil.Pk_reference)

6
infer/tests/codetoanalyze/cpp/frontend/methods/return_struct.cpp.dot
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@ -1,5 +1,5 @@
digraph iCFG {
12 [label="12: DeclStmt \n n$2=*&a:class A * [line 22]\n _fun_A_get(n$2:class A *,1:int ,&SIL_materialize_temp__n$1:class X *) [line 22]\n _fun_X_X(&x:class X *,&SIL_materialize_temp__n$1:class X ) [line 22]\n REMOVE_TEMPS(n$2); [line 22]\n NULLIFY(&a,false); [line 22]\n " shape="box"]
12 [label="12: DeclStmt \n n$2=*&a:class A * [line 22]\n _fun_A_get(n$2:class A *,1:int ,&SIL_materialize_temp__n$1:class X *) [line 22]\n _fun_X_X(&x:class X *,&SIL_materialize_temp__n$1:class X &) [line 22]\n REMOVE_TEMPS(n$2); [line 22]\n NULLIFY(&a,false); [line 22]\n " shape="box"]
12 -> 11 ;
@ -18,7 +18,7 @@ digraph iCFG {
8 -> 7 ;
7 [label="7: Return Stmt \n n$0=*&__return_param:void * [line 17]\n _fun_X_X(n$0:class X *,&x:class X ) [line 17]\n REMOVE_TEMPS(n$0); [line 17]\n NULLIFY(&__return_param,false); [line 17]\n NULLIFY(&x,false); [line 17]\n APPLY_ABSTRACTION; [line 17]\n " shape="box"]
7 [label="7: Return Stmt \n n$0=*&__return_param:void * [line 17]\n _fun_X_X(n$0:class X *,&x:class X &) [line 17]\n REMOVE_TEMPS(n$0); [line 17]\n NULLIFY(&__return_param,false); [line 17]\n NULLIFY(&x,false); [line 17]\n APPLY_ABSTRACTION; [line 17]\n " shape="box"]
7 -> 6 ;
@ -32,7 +32,7 @@ digraph iCFG {
4 [label="4: Exit X_X \n " color=yellow style=filled]
3 [label="3: Start X_X\nFormals: this:class X * __param_0:void \nLocals: \n DECLARE_LOCALS(&return); [line 10]\n NULLIFY(&__param_0,false); [line 10]\n NULLIFY(&this,false); [line 10]\n " color=yellow style=filled]
3 [label="3: Start X_X\nFormals: this:class X * __param_0:class X &\nLocals: \n DECLARE_LOCALS(&return); [line 10]\n NULLIFY(&__param_0,false); [line 10]\n NULLIFY(&this,false); [line 10]\n " color=yellow style=filled]
3 -> 4 ;

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