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) 1998-2008, 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_Util; use Exp_Util;
  29 with Nmake;    use Nmake;
  30 with Namet;    use Namet;
  31 with Nlists;   use Nlists;
  32 with Rtsfind;  use Rtsfind;
  33 with Sem;      use Sem;
  34 with Sem_Util; use Sem_Util;
  35 with Sinfo;    use Sinfo;
  36 with Snames;   use Snames;
  37 with Stand;    use Stand;
  38 with Stringt;  use Stringt;
  39 with Tbuild;   use Tbuild;
  40
  41 package body Exp_Smem is
  42
  43    Insert_Node : Node_Id;
  44    --  Node after which a write call is to be inserted
  45
  46    -----------------------
  47    -- Local Subprograms --
  48    -----------------------
  49
  50    procedure Add_Read_Before (N : Node_Id);
  51    --  Insert a Shared_Var_ROpen call for variable before node N
  52
  53    procedure Add_Write_After (N : Node_Id);
  54    --  Insert a Shared_Var_WOpen call for variable after the node
  55    --  Insert_Node, as recorded by On_Lhs_Of_Assignment (where it points
  56    --  to the assignment statement) or Is_Out_Actual (where it points to
  57    --  the procedure call statement).
  58
  59    procedure Build_Full_Name (E : Entity_Id; N : out String_Id);
  60    --  Build the fully qualified string name of a shared variable
  61
  62    function On_Lhs_Of_Assignment (N : Node_Id) return Boolean;
  63    --  Determines if N is on the left hand of the assignment. This means
  64    --  that either it is a simple variable, or it is a record or array
  65    --  variable with a corresponding selected or indexed component on
  66    --  the left side of an assignment. If the result is True, then
  67    --  Insert_Node is set to point to the assignment
  68
  69    function Is_Out_Actual (N : Node_Id) return Boolean;
  70    --  In a similar manner, this function determines if N appears as an
  71    --  OUT or IN OUT parameter to a procedure call. If the result is
  72    --  True, then Insert_Node is set to point to the call.
  73
  74    function Build_Shared_Var_Proc_Call
  75      (Loc : Source_Ptr;
  76       E   : Node_Id;
  77       N   : Name_Id) return Node_Id;
  78    --  Build a call to support procedure N for shared object E (provided by
  79    --  the instance of System.Shared_Storage.Shared_Var_Procs associated to E).
  80
  81    --------------------------------
  82    -- Build_Shared_Var_Proc_Call --
  83    --------------------------------
  84
  85    function Build_Shared_Var_Proc_Call
  86      (Loc : Source_Ptr;
  87       E   : Entity_Id;
  88       N   : Name_Id) return Node_Id is
  89    begin
  90       return Make_Procedure_Call_Statement (Loc,
  91         Name => Make_Selected_Component (Loc,
  92           Prefix        =>
  93             New_Occurrence_Of (Shared_Var_Procs_Instance (E), Loc),
  94           Selector_Name => Make_Identifier (Loc, Chars => N)));
  95    end Build_Shared_Var_Proc_Call;
  96
  97    ---------------------
  98    -- Add_Read_Before --
  99    ---------------------
 100
 101    procedure Add_Read_Before (N : Node_Id) is
 102       Loc : constant Source_Ptr := Sloc (N);
 103       Ent : constant Node_Id    := Entity (N);
 104    begin
 105       if Present (Shared_Var_Procs_Instance (Ent)) then
 106          Insert_Action (N, Build_Shared_Var_Proc_Call (Loc, Ent, Name_Read));
 107       end if;
 108    end Add_Read_Before;
 109
 110    -------------------------------
 111    -- Add_Shared_Var_Lock_Procs --
 112    -------------------------------
 113
 114    procedure Add_Shared_Var_Lock_Procs (N : Node_Id) is
 115       Loc   : constant Source_Ptr := Sloc (N);
 116       Obj   : constant Entity_Id  := Entity (Expression (First_Actual (N)));
 117       Inode : Node_Id;
 118       Vnm   : String_Id;
 119
 120    begin
 121       --  We have to add Shared_Var_Lock and Shared_Var_Unlock calls around
 122       --  the procedure or function call node. First we locate the right
 123       --  place to do the insertion, which is the call itself in the
 124       --  procedure call case, or else the nearest non subexpression
 125       --  node that contains the function call.
 126
 127       Inode := N;
 128       while Nkind (Inode) /= N_Procedure_Call_Statement
 129         and then Nkind (Inode) in N_Subexpr
 130       loop
 131          Inode := Parent (Inode);
 132       end loop;
 133
 134       --  Now insert the Lock and Unlock calls and the read/write calls
 135
 136       --  Two concerns here. First we are not dealing with the exception
 137       --  case, really we need some kind of cleanup routine to do the
 138       --  Unlock. Second, these lock calls should be inside the protected
 139       --  object processing, not outside, otherwise they can be done at
 140       --  the wrong priority, resulting in dead lock situations ???
 141
 142       Build_Full_Name (Obj, Vnm);
 143
 144       --  First insert the Lock call before
 145
 146       Insert_Before_And_Analyze (Inode,
 147         Make_Procedure_Call_Statement (Loc,
 148           Name => New_Occurrence_Of (RTE (RE_Shared_Var_Lock), Loc),
 149           Parameter_Associations => New_List (
 150             Make_String_Literal (Loc, Vnm))));
 151
 152       --  Now, right after the Lock, insert a call to read the object
 153
 154       Insert_Before_And_Analyze (Inode,
 155         Build_Shared_Var_Proc_Call (Loc, Obj, Name_Read));
 156
 157       --  Now insert the Unlock call after
 158
 159       Insert_After_And_Analyze (Inode,
 160         Make_Procedure_Call_Statement (Loc,
 161           Name => New_Occurrence_Of (RTE (RE_Shared_Var_Unlock), Loc),
 162           Parameter_Associations => New_List (
 163             Make_String_Literal (Loc, Vnm))));
 164
 165       --  Now for a procedure call, but not a function call, insert the
 166       --  call to write the object just before the unlock.
 167
 168       if Nkind (N) = N_Procedure_Call_Statement then
 169          Insert_After_And_Analyze (Inode,
 170            Build_Shared_Var_Proc_Call (Loc, Obj, Name_Write));
 171       end if;
 172
 173    end Add_Shared_Var_Lock_Procs;
 174
 175    ---------------------
 176    -- Add_Write_After --
 177    ---------------------
 178
 179    procedure Add_Write_After (N : Node_Id) is
 180       Loc : constant Source_Ptr := Sloc (N);
 181       Ent : constant Node_Id    := Entity (N);
 182
 183    begin
 184       if Present (Shared_Var_Procs_Instance (Ent)) then
 185          Insert_After_And_Analyze (Insert_Node,
 186            Build_Shared_Var_Proc_Call (Loc, Ent, Name_Write));
 187       end if;
 188    end Add_Write_After;
 189
 190    ---------------------
 191    -- Build_Full_Name --
 192    ---------------------
 193
 194    procedure Build_Full_Name (E : Entity_Id; N : out String_Id) is
 195
 196       procedure Build_Name (E : Entity_Id);
 197       --  This is a recursive routine used to construct the fully qualified
 198       --  string name of the package corresponding to the shared variable.
 199
 200       ----------------
 201       -- Build_Name --
 202       ----------------
 203
 204       procedure Build_Name (E : Entity_Id) is
 205       begin
 206          if Scope (E) /= Standard_Standard then
 207             Build_Name (Scope (E));
 208             Store_String_Char ('.');
 209          end if;
 210
 211          Get_Decoded_Name_String (Chars (E));
 212          Store_String_Chars (Name_Buffer (1 .. Name_Len));
 213       end Build_Name;
 214
 215    --  Start of processing for Build_Full_Name
 216
 217    begin
 218       Start_String;
 219       Build_Name (E);
 220       N := End_String;
 221    end Build_Full_Name;
 222
 223    ------------------------------------
 224    -- Expand_Shared_Passive_Variable --
 225    ------------------------------------
 226
 227    procedure Expand_Shared_Passive_Variable (N : Node_Id) is
 228       Typ : constant Entity_Id := Etype (N);
 229
 230    begin
 231       --  Nothing to do for protected or limited objects
 232
 233       if Is_Limited_Type (Typ) or else Is_Concurrent_Type (Typ) then
 234          return;
 235
 236       --  If we are on the left hand side of an assignment, then we add
 237       --  the write call after the assignment.
 238
 239       elsif On_Lhs_Of_Assignment (N) then
 240          Add_Write_After (N);
 241
 242       --  If we are a parameter for an out or in out formal, then put
 243       --  the read before and the write after.
 244
 245       elsif Is_Out_Actual (N) then
 246          Add_Read_Before (N);
 247          Add_Write_After (N);
 248
 249       --  All other cases are simple reads
 250
 251       else
 252          Add_Read_Before (N);
 253       end if;
 254    end Expand_Shared_Passive_Variable;
 255
 256    -------------------
 257    -- Is_Out_Actual --
 258    -------------------
 259
 260    function Is_Out_Actual (N : Node_Id) return Boolean is
 261       Formal : Entity_Id;
 262       Call   : Node_Id;
 263
 264    begin
 265       Find_Actual (N, Formal, Call);
 266
 267       if No (Formal) then
 268          return False;
 269
 270       else
 271          if Ekind (Formal) = E_Out_Parameter
 272               or else
 273             Ekind (Formal) = E_In_Out_Parameter
 274          then
 275             Insert_Node := Call;
 276             return True;
 277          else
 278             return False;
 279          end if;
 280       end if;
 281    end Is_Out_Actual;
 282
 283    ---------------------------
 284    -- Make_Shared_Var_Procs --
 285    ---------------------------
 286
 287    function Make_Shared_Var_Procs (N : Node_Id) return Node_Id is
 288       Loc : constant Source_Ptr := Sloc (N);
 289       Ent : constant Entity_Id  := Defining_Identifier (N);
 290       Typ : constant Entity_Id  := Etype (Ent);
 291       Vnm : String_Id;
 292
 293       After : constant Node_Id := Next (N);
 294       --  Node located right after N originally (after insertion of the SV
 295       --  procs this node is right after the last inserted node).
 296
 297       SVP_Instance : constant Entity_Id := Make_Defining_Identifier (Loc,
 298                        Chars => New_External_Name (Chars (Ent), 'G'));
 299       --  Instance of System.Shared_Storage.Shared_Var_Procs associated
 300       --  with Ent.
 301
 302       Instantiation : Node_Id;
 303       --  Package instanciation node for SVP_Instance
 304
 305    --  Start of processing for Make_Shared_Var_Procs
 306
 307    begin
 308       Build_Full_Name (Ent, Vnm);
 309
 310       --  We turn off Shared_Passive during construction and analysis of
 311       --  the generic package instantition, to avoid improper attempts to
 312       --  process the variable references within these instantiation.
 313
 314       Set_Is_Shared_Passive (Ent, False);
 315
 316       --  Construct generic package instantiation
 317
 318       --  package varG is new Shared_Var_Procs (Typ, var, "pkg.var");
 319
 320       Instantiation :=
 321         Make_Package_Instantiation (Loc,
 322           Defining_Unit_Name   => SVP_Instance,
 323           Name                 =>
 324             New_Occurrence_Of (RTE (RE_Shared_Var_Procs), Loc),
 325           Generic_Associations => New_List (
 326             Make_Generic_Association (Loc, Explicit_Generic_Actual_Parameter =>
 327               New_Occurrence_Of (Typ, Loc)),
 328             Make_Generic_Association (Loc, Explicit_Generic_Actual_Parameter =>
 329               New_Occurrence_Of (Ent, Loc)),
 330             Make_Generic_Association (Loc, Explicit_Generic_Actual_Parameter =>
 331               Make_String_Literal (Loc, Vnm))));
 332
 333       Insert_After_And_Analyze (N, Instantiation);
 334
 335       Set_Is_Shared_Passive (Ent, True);
 336       Set_Shared_Var_Procs_Instance
 337         (Ent, Defining_Entity (Instance_Spec (Instantiation)));
 338
 339       --  Return last node before After
 340
 341       declare
 342          Nod : Node_Id := Next (N);
 343
 344       begin
 345          while Next (Nod) /= After loop
 346             Nod := Next (Nod);
 347          end loop;
 348
 349          return Nod;
 350       end;
 351    end Make_Shared_Var_Procs;
 352
 353    --------------------------
 354    -- On_Lhs_Of_Assignment --
 355    --------------------------
 356
 357    function On_Lhs_Of_Assignment (N : Node_Id) return Boolean is
 358       P : constant Node_Id := Parent (N);
 359
 360    begin
 361       if Nkind (P) = N_Assignment_Statement then
 362          if N = Name (P) then
 363             Insert_Node := P;
 364             return True;
 365          else
 366             return False;
 367          end if;
 368
 369       elsif (Nkind (P) = N_Indexed_Component
 370                or else
 371              Nkind (P) = N_Selected_Component)
 372         and then N = Prefix (P)
 373       then
 374          return On_Lhs_Of_Assignment (P);
 375
 376       else
 377          return False;
 378       end if;
 379    end On_Lhs_Of_Assignment;
 380
 381 end Exp_Smem;