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

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

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

--                                                                          --

--                                 B o d y                                  --

--                                                                          --

--          Copyright (C) 1998-2005, 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 2,  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 COPYING.  If not, write --

-- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --

-- Boston, MA 02110-1301, USA.                                              --

--                                                                          --

-- 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_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_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_Assigment (where it points

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

   --  the procedure call statement).

   procedure Build_Full_Name

     (E : in  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 assignment.

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

   -- 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_Read_Proc (Ent)) then

         Insert_Action (N,

           Make_Procedure_Call_Statement (Loc,

             Name =>

               New_Occurrence_Of (Shared_Var_Read_Proc (Ent), Loc),

             Parameter_Associations => Empty_List));

      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,

        Make_Procedure_Call_Statement (Loc,

          Name => New_Occurrence_Of (Shared_Var_Read_Proc (Obj), Loc)));

      --  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,

           Make_Procedure_Call_Statement (Loc,

             Name => New_Occurrence_Of (Shared_Var_Assign_Proc (Obj), Loc)));

      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_Assign_Proc (Ent)) then

         Insert_After_And_Analyze (Insert_Node,

           Make_Procedure_Call_Statement (Loc,

             Name =>

               New_Occurrence_Of (Shared_Var_Assign_Proc (Ent), Loc),

             Parameter_Associations => Empty_List));

      end if;

   end Add_Write_After;

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

   -- Build_Full_Name --

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

   procedure Build_Full_Name

     (E : in  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.

      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;

   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

      Parnt  : constant Node_Id := Parent (N);

      Formal : Entity_Id;

      Call   : Node_Id;

      Actual : Node_Id;

   begin

      if (Nkind (Parnt) = N_Indexed_Component

            or else

          Nkind (Parnt) = N_Selected_Component)

        and then N = Prefix (Parnt)

      then

         return Is_Out_Actual (Parnt);

      elsif Nkind (Parnt) = N_Parameter_Association

        and then N = Explicit_Actual_Parameter (Parnt)

      then

         Call := Parent (Parnt);

      elsif Nkind (Parnt) = N_Procedure_Call_Statement then

         Call := Parnt;

      else

         return False;

      end if;

      --  Fall here if we are definitely a parameter

      Actual := First_Actual (Call);

      Formal := First_Formal (Entity (Name (Call)));

      loop

         if Actual = N then

            if Ekind (Formal) /= E_In_Parameter then

               Insert_Node := Call;

               return True;

            else

               return False;

            end if;

         else

            Actual := Next_Actual (Actual);

            Formal := Next_Formal (Formal);

         end if;

      end loop;

   end Is_Out_Actual;

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

   -- Make_Shared_Var_Procs --

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

   procedure Make_Shared_Var_Procs (N : 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;

      Atr : Node_Id;

      Assign_Proc : constant Entity_Id :=

                      Make_Defining_Identifier (Loc,

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

      Read_Proc : constant Entity_Id :=

                    Make_Defining_Identifier (Loc,

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

      S : Entity_Id;

   --  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 assign and read routines, to avoid improper attempts to

      --  process the variable references within these procedures.

      Set_Is_Shared_Passive (Ent, False);

      --  Construct assignment routine

      --    procedure VarA is

      --       S : Ada.Streams.Stream_IO.Stream_Access;

      --    begin

      --       S := Shared_Var_WOpen ("pkg.var");

      --       typ'Write (S, var);

      --       Shared_Var_Close (S);

      --    end VarA;

      S   := Make_Defining_Identifier (Loc, Name_uS);

      Atr :=

        Make_Attribute_Reference (Loc,

          Prefix => New_Occurrence_Of (Typ, Loc),

          Attribute_Name => Name_Write,

          Expressions => New_List (

            New_Reference_To (S, Loc),

            New_Occurrence_Of (Ent, Loc)));

      Insert_After_And_Analyze (N,

        Make_Subprogram_Body (Loc,

          Specification =>

            Make_Procedure_Specification (Loc,

              Defining_Unit_Name => Assign_Proc),

         --  S : Ada.Streams.Stream_IO.Stream_Access;

          Declarations => New_List (

            Make_Object_Declaration (Loc,

              Defining_Identifier => S,

              Object_Definition =>

                New_Occurrence_Of (RTE (RE_Stream_Access), Loc))),

          Handled_Statement_Sequence =>

            Make_Handled_Sequence_Of_Statements (Loc,

              Statements => New_List (

               --  S := Shared_Var_WOpen ("pkg.var");

                Make_Assignment_Statement (Loc,

                  Name => New_Reference_To (S, Loc),

                  Expression =>

                    Make_Function_Call (Loc,

                      Name =>

                        New_Occurrence_Of

                          (RTE (RE_Shared_Var_WOpen), Loc),

                      Parameter_Associations => New_List (

                        Make_String_Literal (Loc, Vnm)))),

                Atr,

               --  Shared_Var_Close (S);

                Make_Procedure_Call_Statement (Loc,

                  Name =>

                    New_Occurrence_Of (RTE (RE_Shared_Var_Close), Loc),

                  Parameter_Associations =>

                    New_List (New_Reference_To (S, Loc)))))));

      --  Construct read routine

      --    procedure varR is

      --       S : Ada.Streams.Stream_IO.Stream_Access;

      --    begin

      --       S := Shared_Var_ROpen ("pkg.var");

      --       if S /= null then

      --          typ'Read (S, Var);

      --          Shared_Var_Close (S);

      --       end if;

      --    end varR;

      S   := Make_Defining_Identifier (Loc, Name_uS);

      Atr :=

        Make_Attribute_Reference (Loc,

          Prefix => New_Occurrence_Of (Typ, Loc),

          Attribute_Name => Name_Read,

          Expressions => New_List (

            New_Reference_To (S, Loc),

            New_Occurrence_Of (Ent, Loc)));

      Insert_After_And_Analyze (N,

        Make_Subprogram_Body (Loc,

          Specification =>

            Make_Procedure_Specification (Loc,

              Defining_Unit_Name => Read_Proc),

         --  S : Ada.Streams.Stream_IO.Stream_Access;

          Declarations => New_List (

            Make_Object_Declaration (Loc,

              Defining_Identifier => S,

              Object_Definition =>

                New_Occurrence_Of (RTE (RE_Stream_Access), Loc))),

          Handled_Statement_Sequence =>

            Make_Handled_Sequence_Of_Statements (Loc,

              Statements => New_List (

               --  S := Shared_Var_ROpen ("pkg.var");

                Make_Assignment_Statement (Loc,

                  Name => New_Reference_To (S, Loc),

                  Expression =>

                    Make_Function_Call (Loc,

                      Name =>

                        New_Occurrence_Of

                          (RTE (RE_Shared_Var_ROpen), Loc),

                      Parameter_Associations => New_List (

                        Make_String_Literal (Loc, Vnm)))),

               --  if S /= null then

                Make_Implicit_If_Statement (N,

                  Condition =>

                    Make_Op_Ne (Loc,

                      Left_Opnd  => New_Reference_To (S, Loc),

                      Right_Opnd => Make_Null (Loc)),

                   Then_Statements => New_List (

                     --  typ'Read (S, Var);

                     Atr,

                     --  Shared_Var_Close (S);

                     Make_Procedure_Call_Statement (Loc,

                       Name =>

                         New_Occurrence_Of

                           (RTE (RE_Shared_Var_Close), Loc),

                       Parameter_Associations =>

                         New_List (New_Reference_To (S, Loc)))))))));

      Set_Is_Shared_Passive      (Ent, True);

      Set_Shared_Var_Assign_Proc (Ent, Assign_Proc);

      Set_Shared_Var_Read_Proc   (Ent, Read_Proc);

   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;