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) 1998-2000 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 2,  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 COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- GNAT was originally developed  by the GNAT team at  New York University. --
  23 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  24 --                                                                          --
  25 ------------------------------------------------------------------------------
  26
  27 with Atree;    use Atree;
  28 with Einfo;    use Einfo;
  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_Util; use Sem_Util;
  36 with Sinfo;    use Sinfo;
  37 with Snames;   use Snames;
  38 with Stand;    use Stand;
  39 with Stringt;  use Stringt;
  40 with Tbuild;   use Tbuild;
  41
  42 package body Exp_Smem is
  43
  44    Insert_Node : Node_Id;
  45    --  Node after which a write call is to be inserted
  46
  47    -----------------------
  48    -- Local Subprograms --
  49    -----------------------
  50
  51    procedure Add_Read_Before (N : Node_Id);
  52    --  Insert a Shared_Var_ROpen call for variable before node N
  53
  54    procedure Add_Write_After (N : Node_Id);
  55    --  Insert a Shared_Var_WOpen call for variable after the node
  56    --  Insert_Node, as recorded by On_Lhs_Of_Assigment (where it points
  57    --  to the assignment statement) or Is_Out_Actual (where it points to
  58    --  the procedure call statement).
  59
  60    procedure Build_Full_Name
  61      (E : in  Entity_Id;
  62       N : out String_Id);
  63    --  Build the fully qualified string name of a shared variable.
  64
  65    function On_Lhs_Of_Assignment (N : Node_Id) return Boolean;
  66    --  Determines if N is on the left hand of the assignment. This means
  67    --  that either it is a simple variable, or it is a record or array
  68    --  variable with a corresponding selected or indexed component on
  69    --  the left side of an assignment. If the result is True, then
  70    --  Insert_Node is set to point to the assignment
  71
  72    function Is_Out_Actual (N : Node_Id) return Boolean;
  73    --  In a similar manner, this function determines if N appears as an
  74    --  OUT or IN OUT parameter to a procedure call. If the result is
  75    --  True, then Insert_Node is set to point to the assignment.
  76
  77    ---------------------
  78    -- Add_Read_Before --
  79    ---------------------
  80
  81    procedure Add_Read_Before (N : Node_Id) is
  82       Loc : constant Source_Ptr := Sloc (N);
  83       Ent : constant Node_Id    := Entity (N);
  84
  85    begin
  86       if Present (Shared_Var_Read_Proc (Ent)) then
  87          Insert_Action (N,
  88            Make_Procedure_Call_Statement (Loc,
  89              Name =>
  90                New_Occurrence_Of (Shared_Var_Read_Proc (Ent), Loc),
  91              Parameter_Associations => Empty_List));
  92       end if;
  93    end Add_Read_Before;
  94
  95    -------------------------------
  96    -- Add_Shared_Var_Lock_Procs --
  97    -------------------------------
  98
  99    procedure Add_Shared_Var_Lock_Procs (N : Node_Id) is
 100       Loc   : constant Source_Ptr := Sloc (N);
 101       Obj   : constant Entity_Id  := Entity (Expression (First_Actual (N)));
 102       Inode : Node_Id;
 103       Vnm   : String_Id;
 104
 105    begin
 106       --  We have to add Shared_Var_Lock and Shared_Var_Unlock calls around
 107       --  the procedure or function call node. First we locate the right
 108       --  place to do the insertion, which is the call itself in the
 109       --  procedure call case, or else the nearest non subexpression
 110       --  node that contains the function call.
 111
 112       Inode := N;
 113       while Nkind (Inode) /= N_Procedure_Call_Statement
 114         and then Nkind (Inode) in N_Subexpr
 115       loop
 116          Inode := Parent (Inode);
 117       end loop;
 118
 119       --  Now insert the Lock and Unlock calls and the read/write calls
 120
 121       --  Two concerns here. First we are not dealing with the exception
 122       --  case, really we need some kind of cleanup routine to do the
 123       --  Unlock. Second, these lock calls should be inside the protected
 124       --  object processing, not outside, otherwise they can be done at
 125       --  the wrong priority, resulting in dead lock situations ???
 126
 127       Build_Full_Name (Obj, Vnm);
 128
 129       --  First insert the Lock call before
 130
 131       Insert_Before_And_Analyze (Inode,
 132         Make_Procedure_Call_Statement (Loc,
 133           Name => New_Occurrence_Of (RTE (RE_Shared_Var_Lock), Loc),
 134           Parameter_Associations => New_List (
 135             Make_String_Literal (Loc, Vnm))));
 136
 137       --  Now, right after the Lock, insert a call to read the object
 138
 139       Insert_Before_And_Analyze (Inode,
 140         Make_Procedure_Call_Statement (Loc,
 141           Name => New_Occurrence_Of (Shared_Var_Read_Proc (Obj), Loc)));
 142
 143       --  Now insert the Unlock call after
 144
 145       Insert_After_And_Analyze (Inode,
 146         Make_Procedure_Call_Statement (Loc,
 147           Name => New_Occurrence_Of (RTE (RE_Shared_Var_Unlock), Loc),
 148           Parameter_Associations => New_List (
 149             Make_String_Literal (Loc, Vnm))));
 150
 151       --  Now for a procedure call, but not a function call, insert the
 152       --  call to write the object just before the unlock.
 153
 154       if Nkind (N) = N_Procedure_Call_Statement then
 155          Insert_After_And_Analyze (Inode,
 156            Make_Procedure_Call_Statement (Loc,
 157              Name => New_Occurrence_Of (Shared_Var_Assign_Proc (Obj), Loc)));
 158       end if;
 159
 160    end Add_Shared_Var_Lock_Procs;
 161
 162    ---------------------
 163    -- Add_Write_After --
 164    ---------------------
 165
 166    procedure Add_Write_After (N : Node_Id) is
 167       Loc : constant Source_Ptr := Sloc (N);
 168       Ent : constant Node_Id    := Entity (N);
 169
 170    begin
 171       if Present (Shared_Var_Assign_Proc (Ent)) then
 172          Insert_After_And_Analyze (Insert_Node,
 173            Make_Procedure_Call_Statement (Loc,
 174              Name =>
 175                New_Occurrence_Of (Shared_Var_Assign_Proc (Ent), Loc),
 176              Parameter_Associations => Empty_List));
 177       end if;
 178    end Add_Write_After;
 179
 180    ---------------------
 181    -- Build_Full_Name --
 182    ---------------------
 183
 184    procedure Build_Full_Name
 185      (E : in  Entity_Id;
 186       N : out String_Id)
 187    is
 188
 189       procedure Build_Name (E : Entity_Id);
 190       --  This is a recursive routine used to construct the fully
 191       --  qualified string name of the package corresponding to the
 192       --  shared variable.
 193
 194       procedure Build_Name (E : Entity_Id) is
 195       begin
 196          if Scope (E) /= Standard_Standard then
 197             Build_Name (Scope (E));
 198             Store_String_Char ('.');
 199          end if;
 200
 201          Get_Decoded_Name_String (Chars (E));
 202          Store_String_Chars (Name_Buffer (1 .. Name_Len));
 203       end Build_Name;
 204
 205    begin
 206       Start_String;
 207       Build_Name (E);
 208       N := End_String;
 209    end Build_Full_Name;
 210
 211    ------------------------------------
 212    -- Expand_Shared_Passive_Variable --
 213    ------------------------------------
 214
 215    procedure Expand_Shared_Passive_Variable (N : Node_Id) is
 216       Typ : constant Entity_Id := Etype (N);
 217
 218    begin
 219       --  Nothing to do for protected or limited objects
 220
 221       if Is_Limited_Type (Typ) or else Is_Concurrent_Type (Typ) then
 222          return;
 223
 224       --  If we are on the left hand side of an assignment, then we add
 225       --  the write call after the assignment.
 226
 227       elsif On_Lhs_Of_Assignment (N) then
 228          Add_Write_After (N);
 229
 230       --  If we are a parameter for an out or in out formal, then put
 231       --  the read before and the write after.
 232
 233       elsif Is_Out_Actual (N) then
 234          Add_Read_Before (N);
 235          Add_Write_After (N);
 236
 237       --  All other cases are simple reads
 238
 239       else
 240          Add_Read_Before (N);
 241       end if;
 242    end Expand_Shared_Passive_Variable;
 243
 244    -------------------
 245    -- Is_Out_Actual --
 246    -------------------
 247
 248    function Is_Out_Actual (N : Node_Id) return Boolean is
 249       Parnt  : constant Node_Id := Parent (N);
 250       Formal : Entity_Id;
 251       Call   : Node_Id;
 252       Actual : Node_Id;
 253
 254    begin
 255       if (Nkind (Parnt) = N_Indexed_Component
 256             or else
 257           Nkind (Parnt) = N_Selected_Component)
 258         and then N = Prefix (Parnt)
 259       then
 260          return Is_Out_Actual (Parnt);
 261
 262       elsif Nkind (Parnt) = N_Parameter_Association
 263         and then N = Explicit_Actual_Parameter (Parnt)
 264       then
 265          Call := Parent (Parnt);
 266
 267       elsif Nkind (Parnt) = N_Procedure_Call_Statement then
 268          Call := Parnt;
 269
 270       else
 271          return False;
 272       end if;
 273
 274       --  Fall here if we are definitely a parameter
 275
 276       Actual := First_Actual (Call);
 277       Formal := First_Formal (Entity (Name (Call)));
 278
 279       loop
 280          if Actual = N then
 281             if Ekind (Formal) /= E_In_Parameter then
 282                Insert_Node := Call;
 283                return True;
 284             else
 285                return False;
 286             end if;
 287
 288          else
 289             Actual := Next_Actual (Actual);
 290             Formal := Next_Formal (Formal);
 291          end if;
 292       end loop;
 293    end Is_Out_Actual;
 294
 295    ---------------------------
 296    -- Make_Shared_Var_Procs --
 297    ---------------------------
 298
 299    procedure Make_Shared_Var_Procs (N : Node_Id) is
 300       Loc : constant Source_Ptr := Sloc (N);
 301       Ent : constant Entity_Id  := Defining_Identifier (N);
 302       Typ : constant Entity_Id  := Etype (Ent);
 303       Vnm : String_Id;
 304       Atr : Node_Id;
 305
 306       Assign_Proc : constant Entity_Id :=
 307                       Make_Defining_Identifier (Loc,
 308                         Chars => New_External_Name (Chars (Ent), 'A'));
 309
 310       Read_Proc : constant Entity_Id :=
 311                     Make_Defining_Identifier (Loc,
 312                       Chars => New_External_Name (Chars (Ent), 'R'));
 313
 314       S : Entity_Id;
 315
 316    --  Start of processing for Make_Shared_Var_Procs
 317
 318    begin
 319       Build_Full_Name (Ent, Vnm);
 320
 321       --  We turn off Shared_Passive during construction and analysis of
 322       --  the assign and read routines, to avoid improper attempts to
 323       --  process the variable references within these procedures.
 324
 325       Set_Is_Shared_Passive (Ent, False);
 326
 327       --  Construct assignment routine
 328
 329       --    procedure VarA is
 330       --       S : Ada.Streams.Stream_IO.Stream_Access;
 331       --    begin
 332       --       S := Shared_Var_WOpen ("pkg.var");
 333       --       typ'Write (S, var);
 334       --       Shared_Var_Close (S);
 335       --    end VarA;
 336
 337       S   := Make_Defining_Identifier (Loc, Name_uS);
 338
 339       Atr :=
 340         Make_Attribute_Reference (Loc,
 341           Prefix => New_Occurrence_Of (Typ, Loc),
 342           Attribute_Name => Name_Write,
 343           Expressions => New_List (
 344             New_Reference_To (S, Loc),
 345             New_Occurrence_Of (Ent, Loc)));
 346
 347       Set_OK_For_Stream (Atr, True);
 348
 349       Insert_After_And_Analyze (N,
 350         Make_Subprogram_Body (Loc,
 351           Specification =>
 352             Make_Procedure_Specification (Loc,
 353               Defining_Unit_Name => Assign_Proc),
 354
 355          --  S : Ada.Streams.Stream_IO.Stream_Access;
 356
 357           Declarations => New_List (
 358             Make_Object_Declaration (Loc,
 359               Defining_Identifier => S,
 360               Object_Definition =>
 361                 New_Occurrence_Of (RTE (RE_Stream_Access), Loc))),
 362
 363           Handled_Statement_Sequence =>
 364             Make_Handled_Sequence_Of_Statements (Loc,
 365               Statements => New_List (
 366
 367                --  S := Shared_Var_WOpen ("pkg.var");
 368
 369                 Make_Assignment_Statement (Loc,
 370                   Name => New_Reference_To (S, Loc),
 371                   Expression =>
 372                     Make_Function_Call (Loc,
 373                       Name =>
 374                         New_Occurrence_Of
 375                           (RTE (RE_Shared_Var_WOpen), Loc),
 376                       Parameter_Associations => New_List (
 377                         Make_String_Literal (Loc, Vnm)))),
 378
 379                 Atr,
 380
 381                --  Shared_Var_Close (S);
 382
 383                 Make_Procedure_Call_Statement (Loc,
 384                   Name =>
 385                     New_Occurrence_Of (RTE (RE_Shared_Var_Close), Loc),
 386                   Parameter_Associations =>
 387                     New_List (New_Reference_To (S, Loc)))))));
 388
 389       --  Construct read routine
 390
 391       --    procedure varR is
 392       --       S : Ada.Streams.Stream_IO.Stream_Access;
 393       --    begin
 394       --       S := Shared_Var_ROpen ("pkg.var");
 395       --       if S /= null then
 396       --          typ'Read (S, Var);
 397       --          Shared_Var_Close (S);
 398       --       end if;
 399       --    end varR;
 400
 401       S   := Make_Defining_Identifier (Loc, Name_uS);
 402
 403       Atr :=
 404         Make_Attribute_Reference (Loc,
 405           Prefix => New_Occurrence_Of (Typ, Loc),
 406           Attribute_Name => Name_Read,
 407           Expressions => New_List (
 408             New_Reference_To (S, Loc),
 409             New_Occurrence_Of (Ent, Loc)));
 410
 411       Set_OK_For_Stream (Atr, True);
 412
 413       Insert_After_And_Analyze (N,
 414         Make_Subprogram_Body (Loc,
 415           Specification =>
 416             Make_Procedure_Specification (Loc,
 417               Defining_Unit_Name => Read_Proc),
 418
 419          --  S : Ada.Streams.Stream_IO.Stream_Access;
 420
 421           Declarations => New_List (
 422             Make_Object_Declaration (Loc,
 423               Defining_Identifier => S,
 424               Object_Definition =>
 425                 New_Occurrence_Of (RTE (RE_Stream_Access), Loc))),
 426
 427           Handled_Statement_Sequence =>
 428             Make_Handled_Sequence_Of_Statements (Loc,
 429               Statements => New_List (
 430
 431                --  S := Shared_Var_ROpen ("pkg.var");
 432
 433                 Make_Assignment_Statement (Loc,
 434                   Name => New_Reference_To (S, Loc),
 435                   Expression =>
 436                     Make_Function_Call (Loc,
 437                       Name =>
 438                         New_Occurrence_Of
 439                           (RTE (RE_Shared_Var_ROpen), Loc),
 440                       Parameter_Associations => New_List (
 441                         Make_String_Literal (Loc, Vnm)))),
 442
 443                --  if S /= null then
 444
 445                 Make_Implicit_If_Statement (N,
 446                   Condition =>
 447                     Make_Op_Ne (Loc,
 448                       Left_Opnd  => New_Reference_To (S, Loc),
 449                       Right_Opnd => Make_Null (Loc)),
 450
 451                    Then_Statements => New_List (
 452
 453                      --  typ'Read (S, Var);
 454
 455                      Atr,
 456
 457                      --  Shared_Var_Close (S);
 458
 459                      Make_Procedure_Call_Statement (Loc,
 460                        Name =>
 461                          New_Occurrence_Of
 462                            (RTE (RE_Shared_Var_Close), Loc),
 463                        Parameter_Associations =>
 464                          New_List (New_Reference_To (S, Loc)))))))));
 465
 466       Set_Is_Shared_Passive      (Ent, True);
 467       Set_Shared_Var_Assign_Proc (Ent, Assign_Proc);
 468       Set_Shared_Var_Read_Proc   (Ent, Read_Proc);
 469    end Make_Shared_Var_Procs;
 470
 471    --------------------------
 472    -- On_Lhs_Of_Assignment --
 473    --------------------------
 474
 475    function On_Lhs_Of_Assignment (N : Node_Id) return Boolean is
 476       P : constant Node_Id := Parent (N);
 477
 478    begin
 479       if Nkind (P) = N_Assignment_Statement then
 480          if N = Name (P) then
 481             Insert_Node := P;
 482             return True;
 483          else
 484             return False;
 485          end if;
 486
 487       elsif (Nkind (P) = N_Indexed_Component
 488                or else
 489              Nkind (P) = N_Selected_Component)
 490         and then N = Prefix (P)
 491       then
 492          return On_Lhs_Of_Assignment (P);
 493
 494       else
 495          return False;
 496       end if;
 497    end On_Lhs_Of_Assignment;
 498
 499
 500 end Exp_Smem;