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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                             E X P _ S M E M                              --

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--          Copyright (C) 1998-2010, Free Software Foundation, Inc.         --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --

-- for  more details.  You should have  received  a copy of the GNU General --

-- Public License  distributed with GNAT; see file COPYING3.  If not, go to --

-- http://www.gnu.org/licenses for a complete copy of the license.          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

with Atree;    use Atree;

with Einfo;    use Einfo;

with Exp_Ch9;  use Exp_Ch9;

with Exp_Util; use Exp_Util;

with Nmake;    use Nmake;

with Namet;    use Namet;

with Nlists;   use Nlists;

with Rtsfind;  use Rtsfind;

with Sem;      use Sem;

with Sem_Aux;  use Sem_Aux;

with Sem_Util; use Sem_Util;

with Sinfo;    use Sinfo;

with Snames;   use Snames;

with Stand;    use Stand;

with Stringt;  use Stringt;

with Tbuild;   use Tbuild;

package body Exp_Smem is

   Insert_Node : Node_Id;

   --  Node after which a write call is to be inserted

   -----------------------

   -- Local Subprograms --

   -----------------------

   procedure Add_Read_Before (N : Node_Id);

   --  Insert a Shared_Var_ROpen call for variable before node N

   procedure Add_Write_After (N : Node_Id);

   --  Insert a Shared_Var_WOpen call for variable after the node

   --  Insert_Node, as recorded by On_Lhs_Of_Assignment (where it points

   --  to the assignment statement) or Is_Out_Actual (where it points to

   --  the procedure call statement).

   procedure Build_Full_Name (E : Entity_Id; N : out String_Id);

   --  Build the fully qualified string name of a shared variable

   function On_Lhs_Of_Assignment (N : Node_Id) return Boolean;

   --  Determines if N is on the left hand of the assignment. This means

   --  that either it is a simple variable, or it is a record or array

   --  variable with a corresponding selected or indexed component on

   --  the left side of an assignment. If the result is True, then

   --  Insert_Node is set to point to the assignment

   function Is_Out_Actual (N : Node_Id) return Boolean;

   --  In a similar manner, this function determines if N appears as an

   --  OUT or IN OUT parameter to a procedure call. If the result is

   --  True, then Insert_Node is set to point to the call.

   function Build_Shared_Var_Proc_Call

     (Loc : Source_Ptr;

      E   : Node_Id;

      N   : Name_Id) return Node_Id;

   --  Build a call to support procedure N for shared object E (provided by

   --  the instance of System.Shared_Storage.Shared_Var_Procs associated to E).

   --------------------------------

   -- Build_Shared_Var_Proc_Call --

   --------------------------------

   function Build_Shared_Var_Proc_Call

     (Loc : Source_Ptr;

      E   : Entity_Id;

      N   : Name_Id) return Node_Id is

   begin

      return Make_Procedure_Call_Statement (Loc,

        Name => Make_Selected_Component (Loc,

          Prefix        =>

            New_Occurrence_Of (Shared_Var_Procs_Instance (E), Loc),

          Selector_Name => Make_Identifier (Loc, N)));

   end Build_Shared_Var_Proc_Call;

   ---------------------

   -- Add_Read_Before --

   ---------------------

   procedure Add_Read_Before (N : Node_Id) is

      Loc : constant Source_Ptr := Sloc (N);

      Ent : constant Node_Id    := Entity (N);

   begin

      if Present (Shared_Var_Procs_Instance (Ent)) then

         Insert_Action (N, Build_Shared_Var_Proc_Call (Loc, Ent, Name_Read));

      end if;

   end Add_Read_Before;

   -------------------------------

   -- Add_Shared_Var_Lock_Procs --

   -------------------------------

   procedure Add_Shared_Var_Lock_Procs (N : Node_Id) is

      Loc   : constant Source_Ptr := Sloc (N);

      Obj   : constant Entity_Id  := Entity (Expression (First_Actual (N)));

      Inode : Node_Id;

      Vnm   : String_Id;

   begin

      --  We have to add Shared_Var_Lock and Shared_Var_Unlock calls around

      --  the procedure or function call node. First we locate the right

      --  place to do the insertion, which is the call itself in the

      --  procedure call case, or else the nearest non subexpression

      --  node that contains the function call.

      Inode := N;

      while Nkind (Inode) /= N_Procedure_Call_Statement

        and then Nkind (Inode) in N_Subexpr

      loop

         Inode := Parent (Inode);

      end loop;

      --  Now insert the Lock and Unlock calls and the read/write calls

      --  Two concerns here. First we are not dealing with the exception

      --  case, really we need some kind of cleanup routine to do the

      --  Unlock. Second, these lock calls should be inside the protected

      --  object processing, not outside, otherwise they can be done at

      --  the wrong priority, resulting in dead lock situations ???

      Build_Full_Name (Obj, Vnm);

      --  First insert the Lock call before

      Insert_Before_And_Analyze (Inode,

        Make_Procedure_Call_Statement (Loc,

          Name => New_Occurrence_Of (RTE (RE_Shared_Var_Lock), Loc),

          Parameter_Associations => New_List (

            Make_String_Literal (Loc, Vnm))));

      --  Now, right after the Lock, insert a call to read the object

      Insert_Before_And_Analyze (Inode,

        Build_Shared_Var_Proc_Call (Loc, Obj, Name_Read));

      --  Now insert the Unlock call after

      Insert_After_And_Analyze (Inode,

        Make_Procedure_Call_Statement (Loc,

          Name => New_Occurrence_Of (RTE (RE_Shared_Var_Unlock), Loc),

          Parameter_Associations => New_List (

            Make_String_Literal (Loc, Vnm))));

      --  Now for a procedure call, but not a function call, insert the

      --  call to write the object just before the unlock.

      if Nkind (N) = N_Procedure_Call_Statement then

         Insert_After_And_Analyze (Inode,

           Build_Shared_Var_Proc_Call (Loc, Obj, Name_Write));

      end if;

   end Add_Shared_Var_Lock_Procs;

   ---------------------

   -- Add_Write_After --

   ---------------------

   procedure Add_Write_After (N : Node_Id) is

      Loc : constant Source_Ptr := Sloc (N);

      Ent : constant Node_Id    := Entity (N);

   begin

      if Present (Shared_Var_Procs_Instance (Ent)) then

         Insert_After_And_Analyze (Insert_Node,

           Build_Shared_Var_Proc_Call (Loc, Ent, Name_Write));

      end if;

   end Add_Write_After;

   ---------------------

   -- Build_Full_Name --

   ---------------------

   procedure Build_Full_Name (E : Entity_Id; N : out String_Id) is

      procedure Build_Name (E : Entity_Id);

      --  This is a recursive routine used to construct the fully qualified

      --  string name of the package corresponding to the shared variable.

      ----------------

      -- Build_Name --

      ----------------

      procedure Build_Name (E : Entity_Id) is

      begin

         if Scope (E) /= Standard_Standard then

            Build_Name (Scope (E));

            Store_String_Char ('.');

         end if;

         Get_Decoded_Name_String (Chars (E));

         Store_String_Chars (Name_Buffer (1 .. Name_Len));

      end Build_Name;

   --  Start of processing for Build_Full_Name

   begin

      Start_String;

      Build_Name (E);

      N := End_String;

   end Build_Full_Name;

   ------------------------------------

   -- Expand_Shared_Passive_Variable --

   ------------------------------------

   procedure Expand_Shared_Passive_Variable (N : Node_Id) is

      Typ : constant Entity_Id := Etype (N);

   begin

      --  Nothing to do for protected or limited objects

      if Is_Limited_Type (Typ) or else Is_Concurrent_Type (Typ) then

         return;

      --  If we are on the left hand side of an assignment, then we add

      --  the write call after the assignment.

      elsif On_Lhs_Of_Assignment (N) then

         Add_Write_After (N);

      --  If we are a parameter for an out or in out formal, then put

      --  the read before and the write after.

      elsif Is_Out_Actual (N) then

         Add_Read_Before (N);

         Add_Write_After (N);

      --  All other cases are simple reads

      else

         Add_Read_Before (N);

      end if;

   end Expand_Shared_Passive_Variable;

   -------------------

   -- Is_Out_Actual --

   -------------------

   function Is_Out_Actual (N : Node_Id) return Boolean is

      Formal : Entity_Id;

      Call   : Node_Id;

   begin

      Find_Actual (N, Formal, Call);

      if No (Formal) then

         return False;

      else

         if Ekind_In (Formal, E_Out_Parameter, E_In_Out_Parameter) then

            Insert_Node := Call;

            return True;

         else

            return False;

         end if;

      end if;

   end Is_Out_Actual;

   ---------------------------

   -- Make_Shared_Var_Procs --

   ---------------------------

   function Make_Shared_Var_Procs (N : Node_Id) return Node_Id is

      Loc     : constant Source_Ptr := Sloc (N);

      Ent     : constant Entity_Id  := Defining_Identifier (N);

      Typ     : constant Entity_Id  := Etype (Ent);

      Vnm     : String_Id;

      Obj     : Node_Id;

      Obj_Typ : Entity_Id;

      After : constant Node_Id := Next (N);

      --  Node located right after N originally (after insertion of the SV

      --  procs this node is right after the last inserted node).

      SVP_Instance : constant Entity_Id := Make_Defining_Identifier (Loc,

                       Chars => New_External_Name (Chars (Ent), 'G'));

      --  Instance of System.Shared_Storage.Shared_Var_Procs associated

      --  with Ent.

      Instantiation : Node_Id;

      --  Package instantiation node for SVP_Instance

   --  Start of processing for Make_Shared_Var_Procs

   begin

      Build_Full_Name (Ent, Vnm);

      --  We turn off Shared_Passive during construction and analysis of

      --  the generic package instantiation, to avoid improper attempts to

      --  process the variable references within these instantiation.

      Set_Is_Shared_Passive (Ent, False);

      --  Construct generic package instantiation

      --  package varG is new Shared_Var_Procs (typ, var, "pkg.var");

      Obj     := New_Occurrence_Of (Ent, Loc);

      Obj_Typ := Typ;

      if Is_Concurrent_Type (Typ) then

         Obj     := Convert_Concurrent (N => Obj, Typ => Typ);

         Obj_Typ := Corresponding_Record_Type (Typ);

      end if;

      Instantiation :=

        Make_Package_Instantiation (Loc,

          Defining_Unit_Name   => SVP_Instance,

          Name                 =>

            New_Occurrence_Of (RTE (RE_Shared_Var_Procs), Loc),

          Generic_Associations => New_List (

            Make_Generic_Association (Loc,

              Explicit_Generic_Actual_Parameter =>

                New_Occurrence_Of (Obj_Typ, Loc)),

            Make_Generic_Association (Loc,

              Explicit_Generic_Actual_Parameter => Obj),

            Make_Generic_Association (Loc,

              Explicit_Generic_Actual_Parameter =>

                Make_String_Literal (Loc, Vnm))));

      Insert_After_And_Analyze (N, Instantiation);

      Set_Is_Shared_Passive (Ent, True);

      Set_Shared_Var_Procs_Instance

        (Ent, Defining_Entity (Instance_Spec (Instantiation)));

      --  Return last node before After

      declare

         Nod : Node_Id := Next (N);

      begin

         while Next (Nod) /= After loop

            Nod := Next (Nod);

         end loop;

         return Nod;

      end;

   end Make_Shared_Var_Procs;

   --------------------------

   -- On_Lhs_Of_Assignment --

   --------------------------

   function On_Lhs_Of_Assignment (N : Node_Id) return Boolean is

      P : constant Node_Id := Parent (N);

   begin

      if Nkind (P) = N_Assignment_Statement then

         if N = Name (P) then

            Insert_Node := P;

            return True;

         else

            return False;

         end if;

      elsif (Nkind (P) = N_Indexed_Component

               or else

             Nkind (P) = N_Selected_Component)

        and then N = Prefix (P)

      then

         return On_Lhs_Of_Assignment (P);

      else

         return False;

      end if;

   end On_Lhs_Of_Assignment;

end Exp_Smem;