[clang] cache of names of C++ temporaries

Summary:
Needed for next diff: we'll need to do 2 passes on the AST to collect
the temporaries to destroy at the end of an `ExprWithCleanups`, but the
SIL names of these temporaries are generated freshly on the fly so they
would get different names if we do it naively.

This adds a hashmap to the translation context so the temporary
corresponding to a given `MaterializeTemporyExpr` is only generated once
and then reused.

Reviewed By: mbouaziz

Differential Revision: D15674212

fbshipit-source-id: 0e16062d9

infer/src/clang/cContext.ml

@@ -7,16 +7,9 @@
 
 open! IStd
 module Hashtbl = Caml.Hashtbl
-
-(** Contains current class and current method to be translated as well as local variables, *)
-
-(** and the cg, cfg, and tenv corresponding to the current file. *)
-
 module StmtMap = ClangPointers.Map
 
-type pointer = int [@@deriving compare]
+type pointer = (* = Clang_ast_t.pointer *) int [@@deriving compare]
-
-(* = Clang_ast_t.pointer *)
 
 type curr_class = ContextClsDeclPtr of pointer | ContextNoCls [@@deriving compare]
 
@@ -32,7 +25,8 @@ type t =
   ; outer_context: t option
   ; mutable blocks_static_vars: (Pvar.t * Typ.t) list Typ.Procname.Map.t
   ; label_map: str_node_map
-  ; vars_to_destroy: Clang_ast_t.decl list StmtMap.t }
+  ; vars_to_destroy: Clang_ast_t.decl list StmtMap.t
+  ; temporary_names: (Clang_ast_t.pointer, Pvar.t * Typ.t) Hashtbl.t }
 
 let create_context translation_unit_context tenv cfg procdesc immediate_curr_class return_param_typ
     outer_context vars_to_destroy =
@@ -45,7 +39,8 @@ let create_context translation_unit_context tenv cfg procdesc immediate_curr_cla
   ; outer_context
   ; blocks_static_vars= Typ.Procname.Map.empty
   ; label_map= Hashtbl.create 17
-  ; vars_to_destroy }
+  ; vars_to_destroy
+  ; temporary_names= Hashtbl.create 0 }
 
 
 let rec is_objc_method context =

infer/src/clang/cContext.mli

@@ -7,9 +7,8 @@
 
 open! IStd
 
-(** Contains current class and current method to be translated as well as local variables, *)
+(** Contains current class and current method to be translated as well as local variables,
-
+    and the cfg, and tenv corresponding to the current file. *)
-(** and the cg, cfg, and tenv corresponding to the current file. *)
 
 module StmtMap = ClangPointers.Map
 
@@ -29,9 +28,9 @@ type t =
   ; mutable blocks_static_vars: (Pvar.t * Typ.t) list Typ.Procname.Map.t
   ; label_map: str_node_map
   ; vars_to_destroy: Clang_ast_t.decl list StmtMap.t
-        (** mapping from a statement to a list of variables, that go out of scope after the end of the
+        (** mapping from a statement to a list of variables, that go out of scope after the end of
-     statement *)
+            the statement *)
-  }
+  ; temporary_names: (Clang_ast_t.pointer, Pvar.t * Typ.t) Caml.Hashtbl.t }
 
 val get_curr_class : t -> curr_class
 

infer/src/clang/cTrans.ml

@@ -195,21 +195,12 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
     Ident.NameGenerator.set_current ident_state
 
 
-  let mk_temp_sil_var procdesc var_name_suffix =
+  let create_var_exp_tmp_var trans_state expr_info ~clang_pointer ~var_name =
-    let procname = Procdesc.get_proc_name procdesc in
-    Pvar.mk_tmp var_name_suffix procname
-
-
-  let mk_temp_sil_var_for_expr tenv procdesc var_name_prefix expr_info =
-    let qual_type = expr_info.Clang_ast_t.ei_qual_type in
-    let typ = CType_decl.qual_type_to_sil_type tenv qual_type in
-    (mk_temp_sil_var procdesc var_name_prefix, typ)
-
-
-  let create_var_exp_tmp_var trans_state expr_info var_name =
     let context = trans_state.context in
     let procdesc = context.CContext.procdesc in
-    let pvar, typ = mk_temp_sil_var_for_expr context.CContext.tenv procdesc var_name expr_info in
+    let pvar, typ =
+      CVar_decl.mk_temp_sil_var_for_expr context ~name:var_name ~clang_pointer expr_info
+    in
     let var_data =
       ProcAttributes.{name= Pvar.get_name pvar; typ; modify_in_block= false; is_constexpr= false}
     in
@@ -246,7 +237,7 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
               exp
           | _ ->
               let procdesc = trans_state.context.CContext.procdesc in
-              let pvar = mk_temp_sil_var procdesc "__temp_return_" in
+              let pvar = CVar_decl.mk_temp_sil_var procdesc ~name:"__temp_return_" in
               let var_data : ProcAttributes.var_data =
                 { name= Pvar.get_name pvar
                 ; typ= return_type
@@ -1541,7 +1532,7 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
             Procdesc.Node.Join_node []
         in
         Procdesc.node_set_succs_exn context.procdesc join_node succ_nodes [] ;
-        let pvar = mk_temp_sil_var procdesc "SIL_temp_conditional___" in
+        let pvar = CVar_decl.mk_temp_sil_var procdesc ~name:"SIL_temp_conditional___" in
         let var_data =
           ProcAttributes.
             {name= Pvar.get_name pvar; typ= var_typ; modify_in_block= false; is_constexpr= false}
@@ -2204,7 +2195,8 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
       | Some var_exp_typ ->
           var_exp_typ
       | None ->
-          create_var_exp_tmp_var trans_state expr_info "SIL_init_list__"
+          create_var_exp_tmp_var trans_state expr_info ~var_name:"SIL_init_list__"
+            ~clang_pointer:stmt_info.Clang_ast_t.si_pointer
     in
     if List.is_empty stmts then
       (* perform zero initialization of a primitive type, record types will have
@@ -2985,12 +2977,7 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
   and materializeTemporaryExpr_trans trans_state stmt_info stmt_list expr_info =
     let context = trans_state.context in
     let procdesc = context.CContext.procdesc in
-    (* typ_tmp is 'best guess' type of variable - translation may decide to use different type
+    let pvar, typ_tmp = CVar_decl.materialize_cpp_temporary context stmt_info expr_info in
-       later *)
-    let pvar, typ_tmp =
-      mk_temp_sil_var_for_expr context.CContext.tenv procdesc Pvar.materialized_cpp_temporary
-        expr_info
-    in
     let temp_exp = match stmt_list with [p] -> p | _ -> assert false in
     let var_exp_typ = (Exp.Lvar pvar, typ_tmp) in
     let res_trans = init_expr_trans trans_state var_exp_typ stmt_info (Some temp_exp) in
@@ -3002,11 +2989,14 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
     res_trans
 
 
-  and compoundLiteralExpr_trans trans_state stmt_list expr_info =
+  and compoundLiteralExpr_trans trans_state stmt_list stmt_info expr_info =
     let stmt = match stmt_list with [stmt] -> stmt | _ -> assert false in
     let var_exp_typ =
       if Option.is_some trans_state.var_exp_typ then trans_state.var_exp_typ
-      else Some (create_var_exp_tmp_var trans_state expr_info "SIL_compound_literal__")
+      else
+        Some
+          (create_var_exp_tmp_var trans_state expr_info ~var_name:"SIL_compound_literal__"
+             ~clang_pointer:stmt_info.Clang_ast_t.si_pointer)
     in
     let trans_state' = {trans_state with var_exp_typ} in
     instruction trans_state' stmt
@@ -3523,8 +3513,8 @@ module CTrans_funct (F : CModule_type.CFrontend) : CModule_type.CTranslation = s
         cxxDeleteExpr_trans trans_state stmt_info stmt_list delete_expr_info
     | MaterializeTemporaryExpr (stmt_info, stmt_list, expr_info, _) ->
         materializeTemporaryExpr_trans trans_state stmt_info stmt_list expr_info
-    | CompoundLiteralExpr (_, stmt_list, expr_info) ->
+    | CompoundLiteralExpr (stmt_info, stmt_list, expr_info) ->
-        compoundLiteralExpr_trans trans_state stmt_list expr_info
+        compoundLiteralExpr_trans trans_state stmt_list stmt_info expr_info
     | InitListExpr (stmt_info, stmts, expr_info) ->
         initListExpr_trans trans_state stmt_info expr_info stmts
     | CXXBindTemporaryExpr ({Clang_ast_t.si_source_range}, stmt_list, _, _) ->

infer/src/clang/cVar_decl.ml

@@ -118,3 +118,27 @@ let captured_vars_from_block_info context source_range captured_vars =
     List.map ~f:(fun cv -> Option.value_exn cv.Clang_ast_t.bcv_variable) captured_vars
   in
   List.filter_map ~f:(sil_var_of_captured_var context source_range procname) cv_decl_ref_list
+
+
+let mk_temp_sil_var procdesc ~name =
+  let procname = Procdesc.get_proc_name procdesc in
+  Pvar.mk_tmp name procname
+
+
+let mk_temp_sil_var_for_expr context ~name ~clang_pointer expr_info =
+  match Caml.Hashtbl.find_opt context.CContext.temporary_names clang_pointer with
+  | Some pvar_typ ->
+      pvar_typ
+  | None ->
+      let qual_type = expr_info.Clang_ast_t.ei_qual_type in
+      let typ = CType_decl.qual_type_to_sil_type context.CContext.tenv qual_type in
+      let pvar_typ = (mk_temp_sil_var context.CContext.procdesc ~name, typ) in
+      Caml.Hashtbl.add context.CContext.temporary_names clang_pointer pvar_typ ;
+      pvar_typ
+
+
+let materialize_cpp_temporary context stmt_info expr_info =
+  (* the type we get here is a 'best effort' type - the translation may decide to use different type
+     later *)
+  mk_temp_sil_var_for_expr context ~name:Pvar.materialized_cpp_temporary
+    ~clang_pointer:stmt_info.Clang_ast_t.si_pointer expr_info

infer/src/clang/cVar_decl.mli

@@ -30,3 +30,11 @@ val captured_vars_from_block_info :
   -> Clang_ast_t.source_range
   -> Clang_ast_t.block_captured_variable list
   -> (Pvar.t * Typ.t) list
+
+val mk_temp_sil_var : Procdesc.t -> name:string -> Pvar.t
+
+val mk_temp_sil_var_for_expr :
+  CContext.t -> name:string -> clang_pointer:int -> Clang_ast_t.expr_info -> Pvar.t * Typ.t
+
+val materialize_cpp_temporary :
+  CContext.t -> Clang_ast_t.stmt_info -> Clang_ast_t.expr_info -> Pvar.t * Typ.t