gcc/ada/exp_smem.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             E X P _ S M E M                              --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1998-2010, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT; see file COPYING3.  If not, go to --
  19 -- http://www.gnu.org/licenses for a complete copy of the license.          --
  20 --                                                                          --
  21 -- GNAT was originally developed  by the GNAT team at  New York University. --
  22 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  23 --                                                                          --
  24 ------------------------------------------------------------------------------
  25
  26 with Atree;    use Atree;
  27 with Einfo;    use Einfo;
  28 with Exp_Ch9;  use Exp_Ch9;
  29 with Exp_Util; use Exp_Util;
  30 with Nmake;    use Nmake;
  31 with Namet;    use Namet;
  32 with Nlists;   use Nlists;
  33 with Rtsfind;  use Rtsfind;
  34 with Sem;      use Sem;
  35 with Sem_Aux;  use Sem_Aux;
  36 with Sem_Util; use Sem_Util;
  37 with Sinfo;    use Sinfo;
  38 with Snames;   use Snames;
  39 with Stand;    use Stand;
  40 with Stringt;  use Stringt;
  41 with Tbuild;   use Tbuild;
  42
  43 package body Exp_Smem is
  44
  45    Insert_Node : Node_Id;
  46    --  Node after which a write call is to be inserted
  47
  48    -----------------------
  49    -- Local Subprograms --
  50    -----------------------
  51
  52    procedure Add_Read_Before (N : Node_Id);
  53    --  Insert a Shared_Var_ROpen call for variable before node N
  54
  55    procedure Add_Write_After (N : Node_Id);
  56    --  Insert a Shared_Var_WOpen call for variable after the node
  57    --  Insert_Node, as recorded by On_Lhs_Of_Assignment (where it points
  58    --  to the assignment statement) or Is_Out_Actual (where it points to
  59    --  the procedure call statement).
  60
  61    procedure Build_Full_Name (E : Entity_Id; N : out String_Id);
  62    --  Build the fully qualified string name of a shared variable
  63
  64    function On_Lhs_Of_Assignment (N : Node_Id) return Boolean;
  65    --  Determines if N is on the left hand of the assignment. This means
  66    --  that either it is a simple variable, or it is a record or array
  67    --  variable with a corresponding selected or indexed component on
  68    --  the left side of an assignment. If the result is True, then
  69    --  Insert_Node is set to point to the assignment
  70
  71    function Is_Out_Actual (N : Node_Id) return Boolean;
  72    --  In a similar manner, this function determines if N appears as an
  73    --  OUT or IN OUT parameter to a procedure call. If the result is
  74    --  True, then Insert_Node is set to point to the call.
  75
  76    function Build_Shared_Var_Proc_Call
  77      (Loc : Source_Ptr;
  78       E   : Node_Id;
  79       N   : Name_Id) return Node_Id;
  80    --  Build a call to support procedure N for shared object E (provided by
  81    --  the instance of System.Shared_Storage.Shared_Var_Procs associated to E).
  82
  83    --------------------------------
  84    -- Build_Shared_Var_Proc_Call --
  85    --------------------------------
  86
  87    function Build_Shared_Var_Proc_Call
  88      (Loc : Source_Ptr;
  89       E   : Entity_Id;
  90       N   : Name_Id) return Node_Id is
  91    begin
  92       return Make_Procedure_Call_Statement (Loc,
  93         Name => Make_Selected_Component (Loc,
  94           Prefix        =>
  95             New_Occurrence_Of (Shared_Var_Procs_Instance (E), Loc),
  96           Selector_Name => Make_Identifier (Loc, Chars => N)));
  97    end Build_Shared_Var_Proc_Call;
  98
  99    ---------------------
 100    -- Add_Read_Before --
 101    ---------------------
 102
 103    procedure Add_Read_Before (N : Node_Id) is
 104       Loc : constant Source_Ptr := Sloc (N);
 105       Ent : constant Node_Id    := Entity (N);
 106    begin
 107       if Present (Shared_Var_Procs_Instance (Ent)) then
 108          Insert_Action (N, Build_Shared_Var_Proc_Call (Loc, Ent, Name_Read));
 109       end if;
 110    end Add_Read_Before;
 111
 112    -------------------------------
 113    -- Add_Shared_Var_Lock_Procs --
 114    -------------------------------
 115
 116    procedure Add_Shared_Var_Lock_Procs (N : Node_Id) is
 117       Loc   : constant Source_Ptr := Sloc (N);
 118       Obj   : constant Entity_Id  := Entity (Expression (First_Actual (N)));
 119       Inode : Node_Id;
 120       Vnm   : String_Id;
 121
 122    begin
 123       --  We have to add Shared_Var_Lock and Shared_Var_Unlock calls around
 124       --  the procedure or function call node. First we locate the right
 125       --  place to do the insertion, which is the call itself in the
 126       --  procedure call case, or else the nearest non subexpression
 127       --  node that contains the function call.
 128
 129       Inode := N;
 130       while Nkind (Inode) /= N_Procedure_Call_Statement
 131         and then Nkind (Inode) in N_Subexpr
 132       loop
 133          Inode := Parent (Inode);
 134       end loop;
 135
 136       --  Now insert the Lock and Unlock calls and the read/write calls
 137
 138       --  Two concerns here. First we are not dealing with the exception
 139       --  case, really we need some kind of cleanup routine to do the
 140       --  Unlock. Second, these lock calls should be inside the protected
 141       --  object processing, not outside, otherwise they can be done at
 142       --  the wrong priority, resulting in dead lock situations ???
 143
 144       Build_Full_Name (Obj, Vnm);
 145
 146       --  First insert the Lock call before
 147
 148       Insert_Before_And_Analyze (Inode,
 149         Make_Procedure_Call_Statement (Loc,
 150           Name => New_Occurrence_Of (RTE (RE_Shared_Var_Lock), Loc),
 151           Parameter_Associations => New_List (
 152             Make_String_Literal (Loc, Vnm))));
 153
 154       --  Now, right after the Lock, insert a call to read the object
 155
 156       Insert_Before_And_Analyze (Inode,
 157         Build_Shared_Var_Proc_Call (Loc, Obj, Name_Read));
 158
 159       --  Now insert the Unlock call after
 160
 161       Insert_After_And_Analyze (Inode,
 162         Make_Procedure_Call_Statement (Loc,
 163           Name => New_Occurrence_Of (RTE (RE_Shared_Var_Unlock), Loc),
 164           Parameter_Associations => New_List (
 165             Make_String_Literal (Loc, Vnm))));
 166
 167       --  Now for a procedure call, but not a function call, insert the
 168       --  call to write the object just before the unlock.
 169
 170       if Nkind (N) = N_Procedure_Call_Statement then
 171          Insert_After_And_Analyze (Inode,
 172            Build_Shared_Var_Proc_Call (Loc, Obj, Name_Write));
 173       end if;
 174
 175    end Add_Shared_Var_Lock_Procs;
 176
 177    ---------------------
 178    -- Add_Write_After --
 179    ---------------------
 180
 181    procedure Add_Write_After (N : Node_Id) is
 182       Loc : constant Source_Ptr := Sloc (N);
 183       Ent : constant Node_Id    := Entity (N);
 184
 185    begin
 186       if Present (Shared_Var_Procs_Instance (Ent)) then
 187          Insert_After_And_Analyze (Insert_Node,
 188            Build_Shared_Var_Proc_Call (Loc, Ent, Name_Write));
 189       end if;
 190    end Add_Write_After;
 191
 192    ---------------------
 193    -- Build_Full_Name --
 194    ---------------------
 195
 196    procedure Build_Full_Name (E : Entity_Id; N : out String_Id) is
 197
 198       procedure Build_Name (E : Entity_Id);
 199       --  This is a recursive routine used to construct the fully qualified
 200       --  string name of the package corresponding to the shared variable.
 201
 202       ----------------
 203       -- Build_Name --
 204       ----------------
 205
 206       procedure Build_Name (E : Entity_Id) is
 207       begin
 208          if Scope (E) /= Standard_Standard then
 209             Build_Name (Scope (E));
 210             Store_String_Char ('.');
 211          end if;
 212
 213          Get_Decoded_Name_String (Chars (E));
 214          Store_String_Chars (Name_Buffer (1 .. Name_Len));
 215       end Build_Name;
 216
 217    --  Start of processing for Build_Full_Name
 218
 219    begin
 220       Start_String;
 221       Build_Name (E);
 222       N := End_String;
 223    end Build_Full_Name;
 224
 225    ------------------------------------
 226    -- Expand_Shared_Passive_Variable --
 227    ------------------------------------
 228
 229    procedure Expand_Shared_Passive_Variable (N : Node_Id) is
 230       Typ : constant Entity_Id := Etype (N);
 231
 232    begin
 233       --  Nothing to do for protected or limited objects
 234
 235       if Is_Limited_Type (Typ) or else Is_Concurrent_Type (Typ) then
 236          return;
 237
 238       --  If we are on the left hand side of an assignment, then we add
 239       --  the write call after the assignment.
 240
 241       elsif On_Lhs_Of_Assignment (N) then
 242          Add_Write_After (N);
 243
 244       --  If we are a parameter for an out or in out formal, then put
 245       --  the read before and the write after.
 246
 247       elsif Is_Out_Actual (N) then
 248          Add_Read_Before (N);
 249          Add_Write_After (N);
 250
 251       --  All other cases are simple reads
 252
 253       else
 254          Add_Read_Before (N);
 255       end if;
 256    end Expand_Shared_Passive_Variable;
 257
 258    -------------------
 259    -- Is_Out_Actual --
 260    -------------------
 261
 262    function Is_Out_Actual (N : Node_Id) return Boolean is
 263       Formal : Entity_Id;
 264       Call   : Node_Id;
 265
 266    begin
 267       Find_Actual (N, Formal, Call);
 268
 269       if No (Formal) then
 270          return False;
 271
 272       else
 273          if Ekind_In (Formal, E_Out_Parameter, E_In_Out_Parameter) then
 274             Insert_Node := Call;
 275             return True;
 276          else
 277             return False;
 278          end if;
 279       end if;
 280    end Is_Out_Actual;
 281
 282    ---------------------------
 283    -- Make_Shared_Var_Procs --
 284    ---------------------------
 285
 286    function Make_Shared_Var_Procs (N : Node_Id) return Node_Id is
 287       Loc     : constant Source_Ptr := Sloc (N);
 288       Ent     : constant Entity_Id  := Defining_Identifier (N);
 289       Typ     : constant Entity_Id  := Etype (Ent);
 290       Vnm     : String_Id;
 291       Obj     : Node_Id;
 292       Obj_Typ : Entity_Id;
 293
 294       After : constant Node_Id := Next (N);
 295       --  Node located right after N originally (after insertion of the SV
 296       --  procs this node is right after the last inserted node).
 297
 298       SVP_Instance : constant Entity_Id := Make_Defining_Identifier (Loc,
 299                        Chars => New_External_Name (Chars (Ent), 'G'));
 300       --  Instance of System.Shared_Storage.Shared_Var_Procs associated
 301       --  with Ent.
 302
 303       Instantiation : Node_Id;
 304       --  Package instantiation node for SVP_Instance
 305
 306    --  Start of processing for Make_Shared_Var_Procs
 307
 308    begin
 309       Build_Full_Name (Ent, Vnm);
 310
 311       --  We turn off Shared_Passive during construction and analysis of
 312       --  the generic package instantiation, to avoid improper attempts to
 313       --  process the variable references within these instantiation.
 314
 315       Set_Is_Shared_Passive (Ent, False);
 316
 317       --  Construct generic package instantiation
 318
 319       --  package varG is new Shared_Var_Procs (typ, var, "pkg.var");
 320
 321       Obj     := New_Occurrence_Of (Ent, Loc);
 322       Obj_Typ := Typ;
 323       if Is_Concurrent_Type (Typ) then
 324          Obj     := Convert_Concurrent (N => Obj, Typ => Typ);
 325          Obj_Typ := Corresponding_Record_Type (Typ);
 326       end if;
 327
 328       Instantiation :=
 329         Make_Package_Instantiation (Loc,
 330           Defining_Unit_Name   => SVP_Instance,
 331           Name                 =>
 332             New_Occurrence_Of (RTE (RE_Shared_Var_Procs), Loc),
 333           Generic_Associations => New_List (
 334             Make_Generic_Association (Loc,
 335               Explicit_Generic_Actual_Parameter =>
 336                 New_Occurrence_Of (Obj_Typ, Loc)),
 337             Make_Generic_Association (Loc,
 338               Explicit_Generic_Actual_Parameter => Obj),
 339             Make_Generic_Association (Loc,
 340               Explicit_Generic_Actual_Parameter =>
 341                 Make_String_Literal (Loc, Vnm))));
 342
 343       Insert_After_And_Analyze (N, Instantiation);
 344
 345       Set_Is_Shared_Passive (Ent, True);
 346       Set_Shared_Var_Procs_Instance
 347         (Ent, Defining_Entity (Instance_Spec (Instantiation)));
 348
 349       --  Return last node before After
 350
 351       declare
 352          Nod : Node_Id := Next (N);
 353
 354       begin
 355          while Next (Nod) /= After loop
 356             Nod := Next (Nod);
 357          end loop;
 358
 359          return Nod;
 360       end;
 361    end Make_Shared_Var_Procs;
 362
 363    --------------------------
 364    -- On_Lhs_Of_Assignment --
 365    --------------------------
 366
 367    function On_Lhs_Of_Assignment (N : Node_Id) return Boolean is
 368       P : constant Node_Id := Parent (N);
 369
 370    begin
 371       if Nkind (P) = N_Assignment_Statement then
 372          if N = Name (P) then
 373             Insert_Node := P;
 374             return True;
 375          else
 376             return False;
 377          end if;
 378
 379       elsif (Nkind (P) = N_Indexed_Component
 380                or else
 381              Nkind (P) = N_Selected_Component)
 382         and then N = Prefix (P)
 383       then
 384          return On_Lhs_Of_Assignment (P);
 385
 386       else
 387          return False;
 388       end if;
 389    end On_Lhs_Of_Assignment;
 390
 391 end Exp_Smem;