------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                             E X P _ I N T R                              --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--          Copyright (C) 1992-2019, 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 Checks;   use Checks;
with Einfo;    use Einfo;
with Elists;   use Elists;
with Expander; use Expander;
with Exp_Atag; use Exp_Atag;
with Exp_Ch4;  use Exp_Ch4;
with Exp_Ch7;  use Exp_Ch7;
with Exp_Ch11; use Exp_Ch11;
with Exp_Code; use Exp_Code;
with Exp_Fixd; use Exp_Fixd;
with Exp_Util; use Exp_Util;
with Freeze;   use Freeze;
with Inline;   use Inline;
with Nmake;    use Nmake;
with Nlists;   use Nlists;
with Opt;      use Opt;
with Restrict; use Restrict;
with Rident;   use Rident;
with Rtsfind;  use Rtsfind;
with Sem;      use Sem;
with Sem_Aux;  use Sem_Aux;
with Sem_Eval; use Sem_Eval;
with Sem_Res;  use Sem_Res;
with Sem_Type; use Sem_Type;
with Sem_Util; use Sem_Util;
with Sinfo;    use Sinfo;
with Sinput;   use Sinput;
with Snames;   use Snames;
with Stand;    use Stand;
with Tbuild;   use Tbuild;
with Uintp;    use Uintp;
with Urealp;   use Urealp;

package body Exp_Intr is

   -----------------------
   -- Local Subprograms --
   -----------------------

   procedure Expand_Binary_Operator_Call (N : Node_Id);
   --  Expand a call to an intrinsic arithmetic operator when the operand
   --  types or sizes are not identical.

   procedure Expand_Is_Negative (N : Node_Id);
   --  Expand a call to the intrinsic Is_Negative function

   procedure Expand_Dispatching_Constructor_Call (N : Node_Id);
   --  Expand a call to an instantiation of Generic_Dispatching_Constructor
   --  into a dispatching call to the actual subprogram associated with the
   --  Constructor formal subprogram, passing it the Parameters actual of
   --  the call to the instantiation and dispatching based on call's Tag
   --  parameter.

   procedure Expand_Exception_Call (N : Node_Id; Ent : RE_Id);
   --  Expand a call to Exception_Information/Message/Name. The first
   --  parameter, N, is the node for the function call, and Ent is the
   --  entity for the corresponding routine in the Ada.Exceptions package.

   procedure Expand_Import_Call (N : Node_Id);
   --  Expand a call to Import_Address/Longest_Integer/Value. The parameter
   --  N is the node for the function call.

   procedure Expand_Shift (N : Node_Id; E : Entity_Id; K : Node_Kind);
   --  Expand an intrinsic shift operation, N and E are from the call to
   --  Expand_Intrinsic_Call (call node and subprogram spec entity) and
   --  K is the kind for the shift node

   procedure Expand_Unc_Conversion (N : Node_Id; E : Entity_Id);
   --  Expand a call to an instantiation of Unchecked_Conversion into a node
   --  N_Unchecked_Type_Conversion.

   procedure Expand_Unc_Deallocation (N : Node_Id);
   --  Expand a call to an instantiation of Unchecked_Deallocation into a node
   --  N_Free_Statement and appropriate context.

   procedure Expand_To_Address (N : Node_Id);
   procedure Expand_To_Pointer (N : Node_Id);
   --  Expand a call to corresponding function, declared in an instance of
   --  System.Address_To_Access_Conversions.

   procedure Expand_Source_Info (N : Node_Id; Nam : Name_Id);
   --  Rewrite the node as the appropriate string literal or positive
   --  constant. Nam is the name of one of the intrinsics declared in
   --  GNAT.Source_Info; see g-souinf.ads for documentation of these
   --  intrinsics.

   ---------------------
   -- Add_Source_Info --
   ---------------------

   procedure Add_Source_Info
     (Buf : in out Bounded_String;
      Loc : Source_Ptr;
      Nam : Name_Id)
   is
   begin
      case Nam is
         when Name_Line =>
            Append (Buf, Nat (Get_Logical_Line_Number (Loc)));

         when Name_File =>
            Append (Buf, Reference_Name (Get_Source_File_Index (Loc)));

         when Name_Source_Location =>
            Build_Location_String (Buf, Loc);

         when Name_Enclosing_Entity =>

            --  Skip enclosing blocks to reach enclosing unit

            declare
               Ent : Entity_Id := Current_Scope;
            begin
               while Present (Ent) loop
                  exit when not Ekind_In (Ent, E_Block, E_Loop);
                  Ent := Scope (Ent);
               end loop;

               --  Ent now points to the relevant defining entity

               Append_Entity_Name (Buf, Ent);
            end;

         when Name_Compilation_ISO_Date =>
            Append (Buf, Opt.Compilation_Time (1 .. 10));

         when Name_Compilation_Date =>
            declare
               subtype S13 is String (1 .. 3);
               Months : constant array (1 .. 12) of S13 :=
                          ("Jan", "Feb", "Mar", "Apr", "May", "Jun",
                           "Jul", "Aug", "Sep", "Oct", "Nov", "Dec");

               M1 : constant Character := Opt.Compilation_Time (6);
               M2 : constant Character := Opt.Compilation_Time (7);

               MM : constant Natural range 1 .. 12 :=
                      (Character'Pos (M1) - Character'Pos ('0')) * 10 +
                      (Character'Pos (M2) - Character'Pos ('0'));

            begin
               --  Reformat ISO date into MMM DD YYYY (__DATE__) format

               Append (Buf, Months (MM));
               Append (Buf, ' ');
               Append (Buf, Opt.Compilation_Time (9 .. 10));
               Append (Buf, ' ');
               Append (Buf, Opt.Compilation_Time (1 .. 4));
            end;

         when Name_Compilation_Time =>
            Append (Buf, Opt.Compilation_Time (12 .. 19));

         when others =>
            raise Program_Error;
      end case;
   end Add_Source_Info;

   ---------------------------------
   -- Expand_Binary_Operator_Call --
   ---------------------------------

   procedure Expand_Binary_Operator_Call (N : Node_Id) is
      T1  : constant Entity_Id := Underlying_Type (Etype (Left_Opnd  (N)));
      T2  : constant Entity_Id := Underlying_Type (Etype (Right_Opnd (N)));
      TR  : constant Entity_Id := Etype (N);
      T3  : Entity_Id;
      Res : Node_Id;

      Siz : constant Uint := UI_Max (RM_Size (T1), RM_Size (T2));
      --  Maximum of operand sizes

   begin
      --  Nothing to do if the operands have the same modular type

      if Base_Type (T1) = Base_Type (T2)
        and then Is_Modular_Integer_Type (T1)
      then
         return;
      end if;

      --  Use Unsigned_32 for sizes of 32 or below, else Unsigned_64

      if Siz > 32 then
         T3 := RTE (RE_Unsigned_64);
      else
         T3 := RTE (RE_Unsigned_32);
      end if;

      --  Copy operator node, and reset type and entity fields, for
      --  subsequent reanalysis.

      Res := New_Copy (N);
      Set_Etype (Res, T3);

      case Nkind (N) is
         when N_Op_And => Set_Entity (Res, Standard_Op_And);
         when N_Op_Or  => Set_Entity (Res, Standard_Op_Or);
         when N_Op_Xor => Set_Entity (Res, Standard_Op_Xor);
         when others   => raise Program_Error;
      end case;

      --  Convert operands to large enough intermediate type

      Set_Left_Opnd (Res,
        Unchecked_Convert_To (T3, Relocate_Node (Left_Opnd (N))));
      Set_Right_Opnd (Res,
        Unchecked_Convert_To (T3, Relocate_Node (Right_Opnd (N))));

      --  Analyze and resolve result formed by conversion to target type

      Rewrite (N, Unchecked_Convert_To (TR, Res));
      Analyze_And_Resolve (N, TR);
   end Expand_Binary_Operator_Call;

   -----------------------------------------
   -- Expand_Dispatching_Constructor_Call --
   -----------------------------------------

   --  Transform a call to an instantiation of Generic_Dispatching_Constructor
   --  of the form:

   --     GDC_Instance (The_Tag, Parameters'Access)

   --  to a class-wide conversion of a dispatching call to the actual
   --  associated with the formal subprogram Construct, designating The_Tag
   --  as the controlling tag of the call:

   --     T'Class (Construct'Actual (Params)) -- Controlling tag is The_Tag

   --  which will eventually be expanded to the following:

   --     T'Class (The_Tag.all (Construct'Actual'Index).all (Params))

   --  A class-wide membership test is also generated, preceding the call, to
   --  ensure that the controlling tag denotes a type in T'Class.

   procedure Expand_Dispatching_Constructor_Call (N : Node_Id) is
      Loc        : constant Source_Ptr := Sloc (N);
      Tag_Arg    : constant Node_Id    := First_Actual (N);
      Param_Arg  : constant Node_Id    := Next_Actual (Tag_Arg);
      Subp_Decl  : constant Node_Id    := Parent (Parent (Entity (Name (N))));
      Inst_Pkg   : constant Node_Id    := Parent (Subp_Decl);
      Act_Rename : Node_Id;
      Act_Constr : Entity_Id;
      Iface_Tag  : Node_Id := Empty;
      Cnstr_Call : Node_Id;
      Result_Typ : Entity_Id;

   begin
      --  Remove side effects from tag argument early, before rewriting
      --  the dispatching constructor call, as Remove_Side_Effects relies
      --  on Tag_Arg's Parent link properly attached to the tree (once the
      --  call is rewritten, the Parent is inconsistent as it points to the
      --  rewritten node, which is not the syntactic parent of the Tag_Arg
      --  anymore).

      Remove_Side_Effects (Tag_Arg);

      --  Check that we have a proper tag

      Insert_Action (N,
        Make_Implicit_If_Statement (N,
          Condition       => Make_Op_Eq (Loc,
            Left_Opnd  => New_Copy_Tree (Tag_Arg),
            Right_Opnd => New_Occurrence_Of (RTE (RE_No_Tag), Loc)),

          Then_Statements => New_List (
            Make_Raise_Statement (Loc,
              New_Occurrence_Of (RTE (RE_Tag_Error), Loc)))));

      --  Check that it is not the tag of an abstract type

      Insert_Action (N,
        Make_Implicit_If_Statement (N,
          Condition       => Make_Function_Call (Loc,
             Name                   =>
               New_Occurrence_Of (RTE (RE_Is_Abstract), Loc),
             Parameter_Associations => New_List (New_Copy_Tree (Tag_Arg))),

          Then_Statements => New_List (
            Make_Raise_Statement (Loc,
              New_Occurrence_Of (RTE (RE_Tag_Error), Loc)))));

      --  The subprogram is the third actual in the instantiation, and is
      --  retrieved from the corresponding renaming declaration. However,
      --  freeze nodes may appear before, so we retrieve the declaration
      --  with an explicit loop.

      Act_Rename := First (Visible_Declarations (Inst_Pkg));
      while Nkind (Act_Rename) /= N_Subprogram_Renaming_Declaration loop
         Next (Act_Rename);
      end loop;

      Act_Constr := Entity (Name (Act_Rename));
      Result_Typ := Class_Wide_Type (Etype (Act_Constr));

      --  Check that the accessibility level of the tag is no deeper than that
      --  of the constructor function (unless CodePeer_Mode)

      if not CodePeer_Mode then
         Insert_Action (N,
           Make_Implicit_If_Statement (N,
             Condition       =>
               Make_Op_Gt (Loc,
                 Left_Opnd  =>
                   Build_Get_Access_Level (Loc, New_Copy_Tree (Tag_Arg)),
                 Right_Opnd =>
                   Make_Integer_Literal (Loc, Scope_Depth (Act_Constr))),

             Then_Statements => New_List (
               Make_Raise_Statement (Loc,
                 New_Occurrence_Of (RTE (RE_Tag_Error), Loc)))));
      end if;

      if Is_Interface (Etype (Act_Constr)) then

         --  If the result type is not known to be a parent of Tag_Arg then we
         --  need to locate the tag of the secondary dispatch table.

         if not Is_Ancestor (Etype (Result_Typ), Etype (Tag_Arg),
                             Use_Full_View => True)
           and then Tagged_Type_Expansion
         then
            --  Obtain the reference to the Ada.Tags service before generating
            --  the Object_Declaration node to ensure that if this service is
            --  not available in the runtime then we generate a clear error.

            declare
               Fname : constant Node_Id :=
                         New_Occurrence_Of (RTE (RE_Secondary_Tag), Loc);

            begin
               pragma Assert (not Is_Interface (Etype (Tag_Arg)));

               --  The tag is the first entry in the dispatch table of the
               --  return type of the constructor.

               Iface_Tag :=
                 Make_Object_Declaration (Loc,
                   Defining_Identifier => Make_Temporary (Loc, 'V'),
                   Object_Definition   =>
                     New_Occurrence_Of (RTE (RE_Tag), Loc),
                   Expression          =>
                     Make_Function_Call (Loc,
                       Name                   => Fname,
                       Parameter_Associations => New_List (
                         Relocate_Node (Tag_Arg),
                         New_Occurrence_Of
                           (Node (First_Elmt
                                    (Access_Disp_Table (Etype (Act_Constr)))),
                            Loc))));
               Insert_Action (N, Iface_Tag);
            end;
         end if;
      end if;

      --  Create the call to the actual Constructor function

      Cnstr_Call :=
        Make_Function_Call (Loc,
          Name                   => New_Occurrence_Of (Act_Constr, Loc),
          Parameter_Associations => New_List (Relocate_Node (Param_Arg)));

      --  Establish its controlling tag from the tag passed to the instance
      --  The tag may be given by a function call, in which case a temporary
      --  should be generated now, to prevent out-of-order insertions during
      --  the expansion of that call when stack-checking is enabled.

      if Present (Iface_Tag) then
         Set_Controlling_Argument (Cnstr_Call,
           New_Occurrence_Of (Defining_Identifier (Iface_Tag), Loc));
      else
         Set_Controlling_Argument (Cnstr_Call,
           Relocate_Node (Tag_Arg));
      end if;

      --  Rewrite and analyze the call to the instance as a class-wide
      --  conversion of the call to the actual constructor. When the result
      --  type is a class-wide interface type this conversion is required to
      --  force the displacement of the pointer to the object to reference the
      --  corresponding dispatch table.

      Rewrite (N, Convert_To (Result_Typ, Cnstr_Call));

      --  Do not generate a run-time check on the built object if tag
      --  checks are suppressed for the result type or tagged type expansion
      --  is disabled or if CodePeer_Mode.

      if Tag_Checks_Suppressed (Etype (Result_Typ))
        or else not Tagged_Type_Expansion
        or else CodePeer_Mode
      then
         null;

      --  Generate a class-wide membership test to ensure that the call's tag
      --  argument denotes a type within the class. We must keep separate the
      --  case in which the Result_Type of the constructor function is a tagged
      --  type from the case in which it is an abstract interface because the
      --  run-time subprogram required to check these cases differ (and have
      --  one difference in their parameters profile).

      --  Call CW_Membership if the Result_Type is a tagged type to look for
      --  the tag in the table of ancestor tags.

      elsif not Is_Interface (Result_Typ) then
         declare
            Obj_Tag_Node : Node_Id := New_Copy_Tree (Tag_Arg);
            CW_Test_Node : Node_Id;

         begin
            Build_CW_Membership (Loc,
              Obj_Tag_Node => Obj_Tag_Node,
              Typ_Tag_Node =>
                New_Occurrence_Of (
                   Node (First_Elmt (Access_Disp_Table (
                                       Root_Type (Result_Typ)))), Loc),
              Related_Nod => N,
              New_Node    => CW_Test_Node);

            Insert_Action (N,
              Make_Implicit_If_Statement (N,
                Condition =>
                  Make_Op_Not (Loc, CW_Test_Node),
                Then_Statements =>
                  New_List (Make_Raise_Statement (Loc,
                              New_Occurrence_Of (RTE (RE_Tag_Error), Loc)))));
         end;

      --  Call IW_Membership test if the Result_Type is an abstract interface
      --  to look for the tag in the table of interface tags.

      else
         Insert_Action (N,
           Make_Implicit_If_Statement (N,
             Condition =>
               Make_Op_Not (Loc,
                 Make_Function_Call (Loc,
                    Name => New_Occurrence_Of (RTE (RE_IW_Membership), Loc),
                    Parameter_Associations => New_List (
                      Make_Attribute_Reference (Loc,
                        Prefix         => New_Copy_Tree (Tag_Arg),
                        Attribute_Name => Name_Address),

                      New_Occurrence_Of (
                        Node (First_Elmt (Access_Disp_Table (
                                            Root_Type (Result_Typ)))), Loc)))),
             Then_Statements =>
               New_List (
                 Make_Raise_Statement (Loc,
                   Name => New_Occurrence_Of (RTE (RE_Tag_Error), Loc)))));
      end if;

      Analyze_And_Resolve (N, Etype (Act_Constr));
   end Expand_Dispatching_Constructor_Call;

   ---------------------------
   -- Expand_Exception_Call --
   ---------------------------

   --  If the function call is not within an exception handler, then the call
   --  is replaced by a null string. Otherwise the appropriate routine in
   --  Ada.Exceptions is called passing the choice parameter specification
   --  from the enclosing handler. If the enclosing handler lacks a choice
   --  parameter, then one is supplied.

   procedure Expand_Exception_Call (N : Node_Id; Ent : RE_Id) is
      Loc : constant Source_Ptr := Sloc (N);
      P   : Node_Id;
      E   : Entity_Id;

   begin
      --  Climb up parents to see if we are in exception handler

      P := Parent (N);
      loop
         --  Case of not in exception handler, replace by null string

         if No (P) then
            Rewrite (N,
              Make_String_Literal (Loc,
                Strval => ""));
            exit;

         --  Case of in exception handler

         elsif Nkind (P) = N_Exception_Handler then

            --  Handler cannot be used for a local raise, and furthermore, this
            --  is a violation of the No_Exception_Propagation restriction.

            Set_Local_Raise_Not_OK (P);
            Check_Restriction (No_Exception_Propagation, N);

            --  If no choice parameter present, then put one there. Note that
            --  we do not need to put it on the entity chain, since no one will
            --  be referencing it by normal visibility methods.

            if No (Choice_Parameter (P)) then
               E := Make_Temporary (Loc, 'E');
               Set_Choice_Parameter (P, E);
               Set_Ekind (E, E_Variable);
               Set_Etype (E, RTE (RE_Exception_Occurrence));
               Set_Scope (E, Current_Scope);
            end if;

            Rewrite (N,
              Make_Function_Call (Loc,
                Name => New_Occurrence_Of (RTE (Ent), Loc),
                Parameter_Associations => New_List (
                  New_Occurrence_Of (Choice_Parameter (P), Loc))));
            exit;

         --  Keep climbing

         else
            P := Parent (P);
         end if;
      end loop;

      Analyze_And_Resolve (N, Standard_String);
   end Expand_Exception_Call;

   ------------------------
   -- Expand_Import_Call --
   ------------------------

   --  The function call must have a static string as its argument. We create
   --  a dummy variable which uses this string as the external name in an
   --  Import pragma. The result is then obtained as the address of this
   --  dummy variable, converted to the appropriate target type.

   procedure Expand_Import_Call (N : Node_Id) is
      Loc : constant Source_Ptr := Sloc (N);
      Ent : constant Entity_Id  := Entity (Name (N));
      Str : constant Node_Id    := First_Actual (N);
      Dum : constant Entity_Id  := Make_Temporary (Loc, 'D');

   begin
      Insert_Actions (N, New_List (
        Make_Object_Declaration (Loc,
          Defining_Identifier => Dum,
          Object_Definition   =>
            New_Occurrence_Of (Standard_Character, Loc)),

        Make_Pragma (Loc,
          Chars                        => Name_Import,
          Pragma_Argument_Associations => New_List (
            Make_Pragma_Argument_Association (Loc,
              Expression => Make_Identifier (Loc, Name_Ada)),

            Make_Pragma_Argument_Association (Loc,
              Expression => Make_Identifier (Loc, Chars (Dum))),

            Make_Pragma_Argument_Association (Loc,
              Chars => Name_Link_Name,
              Expression => Relocate_Node (Str))))));

      Rewrite (N,
        Unchecked_Convert_To (Etype (Ent),
          Make_Attribute_Reference (Loc,
            Prefix         => Make_Identifier (Loc, Chars (Dum)),
            Attribute_Name => Name_Address)));

      Analyze_And_Resolve (N, Etype (Ent));
   end Expand_Import_Call;

   ---------------------------
   -- Expand_Intrinsic_Call --
   ---------------------------

   procedure Expand_Intrinsic_Call (N : Node_Id; E : Entity_Id) is
      Nam : Name_Id;

   begin
      --  If an external name is specified for the intrinsic, it is handled
      --  by the back-end: leave the call node unchanged for now.

      if Present (Interface_Name (E)) then
         return;
      end if;

      --  If the intrinsic subprogram is generic, gets its original name

      if Present (Parent (E))
        and then Present (Generic_Parent (Parent (E)))
      then
         Nam := Chars (Generic_Parent (Parent (E)));
      else
         Nam := Chars (E);
      end if;

      if Nam = Name_Asm then
         Expand_Asm_Call (N);

      elsif Nam = Name_Divide then
         Expand_Decimal_Divide_Call (N);

      elsif Nam = Name_Exception_Information then
         Expand_Exception_Call (N, RE_Exception_Information);

      elsif Nam = Name_Exception_Message then
         Expand_Exception_Call (N, RE_Exception_Message);

      elsif Nam = Name_Exception_Name then
         Expand_Exception_Call (N, RE_Exception_Name_Simple);

      elsif Nam = Name_Generic_Dispatching_Constructor then
         Expand_Dispatching_Constructor_Call (N);

      elsif Nam_In (Nam, Name_Import_Address,
                         Name_Import_Largest_Value,
                         Name_Import_Value)
      then
         Expand_Import_Call (N);

      elsif Nam = Name_Is_Negative then
         Expand_Is_Negative (N);

      elsif Nam = Name_Rotate_Left then
         Expand_Shift (N, E, N_Op_Rotate_Left);

      elsif Nam = Name_Rotate_Right then
         Expand_Shift (N, E, N_Op_Rotate_Right);

      elsif Nam = Name_Shift_Left then
         Expand_Shift (N, E, N_Op_Shift_Left);

      elsif Nam = Name_Shift_Right then
         Expand_Shift (N, E, N_Op_Shift_Right);

      elsif Nam = Name_Shift_Right_Arithmetic then
         Expand_Shift (N, E, N_Op_Shift_Right_Arithmetic);

      elsif Nam = Name_Unchecked_Conversion then
         Expand_Unc_Conversion (N, E);

      elsif Nam = Name_Unchecked_Deallocation then
         Expand_Unc_Deallocation (N);

      elsif Nam = Name_To_Address then
         Expand_To_Address (N);

      elsif Nam = Name_To_Pointer then
         Expand_To_Pointer (N);

      elsif Nam_In (Nam, Name_File,
                         Name_Line,
                         Name_Source_Location,
                         Name_Enclosing_Entity,
                         Name_Compilation_ISO_Date,
                         Name_Compilation_Date,
                         Name_Compilation_Time)
      then
         Expand_Source_Info (N, Nam);

         --  If we have a renaming, expand the call to the original operation,
         --  which must itself be intrinsic, since renaming requires matching
         --  conventions and this has already been checked.

      elsif Present (Alias (E)) then
         Expand_Intrinsic_Call (N, Alias (E));

      elsif Nkind (N) in N_Binary_Op then
         Expand_Binary_Operator_Call (N);

         --  The only other case is where an external name was specified, since
         --  this is the only way that an otherwise unrecognized name could
         --  escape the checking in Sem_Prag. Nothing needs to be done in such
         --  a case, since we pass such a call to the back end unchanged.

      else
         null;
      end if;
   end Expand_Intrinsic_Call;

   ------------------------
   -- Expand_Is_Negative --
   ------------------------

   procedure Expand_Is_Negative (N : Node_Id) is
      Loc   : constant Source_Ptr := Sloc (N);
      Opnd  : constant Node_Id    := Relocate_Node (First_Actual (N));

   begin

      --  We replace the function call by the following expression

      --    if Opnd < 0.0 then
      --       True
      --    else
      --       if Opnd > 0.0 then
      --          False;
      --       else
      --          Float_Unsigned!(Float (Opnd)) /= 0
      --       end if;
      --    end if;

      Rewrite (N,
        Make_If_Expression (Loc,
          Expressions => New_List (
            Make_Op_Lt (Loc,
              Left_Opnd  => Duplicate_Subexpr (Opnd),
              Right_Opnd => Make_Real_Literal (Loc, Ureal_0)),

            New_Occurrence_Of (Standard_True, Loc),

            Make_If_Expression (Loc,
             Expressions => New_List (
               Make_Op_Gt (Loc,
                 Left_Opnd  => Duplicate_Subexpr_No_Checks (Opnd),
                 Right_Opnd => Make_Real_Literal (Loc, Ureal_0)),

               New_Occurrence_Of (Standard_False, Loc),

                Make_Op_Ne (Loc,
                  Left_Opnd =>
                    Unchecked_Convert_To
                      (RTE (RE_Float_Unsigned),
                       Convert_To
                         (Standard_Float,
                          Duplicate_Subexpr_No_Checks (Opnd))),
                  Right_Opnd =>
                    Make_Integer_Literal (Loc, 0)))))));

      Analyze_And_Resolve (N, Standard_Boolean);
   end Expand_Is_Negative;

   ------------------
   -- Expand_Shift --
   ------------------

   --  This procedure is used to convert a call to a shift function to the
   --  corresponding operator node. This conversion is not done by the usual
   --  circuit for converting calls to operator functions (e.g. "+"(1,2)) to
   --  operator nodes, because shifts are not predefined operators.

   --  As a result, whenever a shift is used in the source program, it will
   --  remain as a call until converted by this routine to the operator node
   --  form which the back end is expecting to see.

   --  Note: it is possible for the expander to generate shift operator nodes
   --  directly, which will be analyzed in the normal manner by calling Analyze
   --  and Resolve. Such shift operator nodes will not be seen by Expand_Shift.

   procedure Expand_Shift (N : Node_Id; E : Entity_Id; K : Node_Kind) is
      Entyp : constant Entity_Id  := Etype (E);
      Left  : constant Node_Id    := First_Actual (N);
      Loc   : constant Source_Ptr := Sloc (N);
      Right : constant Node_Id    := Next_Actual (Left);
      Ltyp  : constant Node_Id    := Etype (Left);
      Rtyp  : constant Node_Id    := Etype (Right);
      Typ   : constant Entity_Id  := Etype (N);
      Snode : Node_Id;

   begin
      Snode := New_Node (K, Loc);
      Set_Right_Opnd (Snode, Relocate_Node (Right));
      Set_Chars      (Snode, Chars (E));
      Set_Etype      (Snode, Base_Type (Entyp));
      Set_Entity     (Snode, E);

      if Compile_Time_Known_Value (Type_High_Bound (Rtyp))
        and then Expr_Value (Type_High_Bound (Rtyp)) < Esize (Ltyp)
      then
         Set_Shift_Count_OK (Snode, True);
      end if;

      if Typ = Entyp then

         --  Note that we don't call Analyze and Resolve on this node, because
         --  it already got analyzed and resolved when it was a function call.

         Set_Left_Opnd (Snode, Relocate_Node (Left));
         Rewrite (N, Snode);
         Set_Analyzed (N);

         --  However, we do call the expander, so that the expansion for
         --  rotates and shift_right_arithmetic happens if Modify_Tree_For_C
         --  is set.

         if Expander_Active then
            Expand (N);
         end if;

      else
         --  If the context type is not the type of the operator, it is an
         --  inherited operator for a derived type. Wrap the node in a
         --  conversion so that it is type-consistent for possible further
         --  expansion (e.g. within a lock-free protected type).

         Set_Left_Opnd (Snode,
           Unchecked_Convert_To (Base_Type (Entyp), Relocate_Node (Left)));
         Rewrite (N, Unchecked_Convert_To (Typ, Snode));

         --  Analyze and resolve result formed by conversion to target type

         Analyze_And_Resolve (N, Typ);
      end if;
   end Expand_Shift;

   ------------------------
   -- Expand_Source_Info --
   ------------------------

   procedure Expand_Source_Info (N : Node_Id; Nam : Name_Id) is
      Loc : constant Source_Ptr := Sloc (N);
   begin
      --  Integer cases

      if Nam = Name_Line then
         Rewrite (N,
           Make_Integer_Literal (Loc,
             Intval => UI_From_Int (Int (Get_Logical_Line_Number (Loc)))));
         Analyze_And_Resolve (N, Standard_Positive);

      --  String cases

      else
         declare
            Buf : Bounded_String;
         begin
            Add_Source_Info (Buf, Loc, Nam);
            Rewrite (N, Make_String_Literal (Loc, Strval => +Buf));
            Analyze_And_Resolve (N, Standard_String);
         end;
      end if;

      Set_Is_Static_Expression (N);
   end Expand_Source_Info;

   ---------------------------
   -- Expand_Unc_Conversion --
   ---------------------------

   procedure Expand_Unc_Conversion (N : Node_Id; E : Entity_Id) is
      Func : constant Entity_Id  := Entity (Name (N));
      Conv : Node_Id;
      Ftyp : Entity_Id;
      Ttyp : Entity_Id;

   begin
      --  Rewrite as unchecked conversion node. Note that we must convert
      --  the operand to the formal type of the input parameter of the
      --  function, so that the resulting N_Unchecked_Type_Conversion
      --  call indicates the correct types for Gigi.

      --  Right now, we only do this if a scalar type is involved. It is
      --  not clear if it is needed in other cases. If we do attempt to
      --  do the conversion unconditionally, it crashes 3411-018. To be
      --  investigated further ???

      Conv := Relocate_Node (First_Actual (N));
      Ftyp := Etype (First_Formal (Func));

      if Is_Scalar_Type (Ftyp) then
         Conv := Convert_To (Ftyp, Conv);
         Set_Parent (Conv, N);
         Analyze_And_Resolve (Conv);
      end if;

      --  The instantiation of Unchecked_Conversion creates a wrapper package,
      --  and the target type is declared as a subtype of the actual. Recover
      --  the actual, which is the subtype indic. in the subtype declaration
      --  for the target type. This is semantically correct, and avoids
      --  anomalies with access subtypes. For entities, leave type as is.

      --  We do the analysis here, because we do not want the compiler
      --  to try to optimize or otherwise reorganize the unchecked
      --  conversion node.

      Ttyp := Etype (E);

      if Is_Entity_Name (Conv) then
         null;

      elsif Nkind (Parent (Ttyp)) = N_Subtype_Declaration then
         Ttyp := Entity (Subtype_Indication (Parent (Etype (E))));

      elsif Is_Itype (Ttyp) then
         Ttyp :=
           Entity (Subtype_Indication (Associated_Node_For_Itype (Ttyp)));
      else
         raise Program_Error;
      end if;

      Rewrite (N, Unchecked_Convert_To (Ttyp, Conv));
      Set_Etype (N, Ttyp);
      Set_Analyzed (N);

      if Nkind (N) = N_Unchecked_Type_Conversion then
         Expand_N_Unchecked_Type_Conversion (N);
      end if;
   end Expand_Unc_Conversion;

   -----------------------------
   -- Expand_Unc_Deallocation --
   -----------------------------

   procedure Expand_Unc_Deallocation (N : Node_Id) is
      Arg       : constant Node_Id    := First_Actual (N);
      Loc       : constant Source_Ptr := Sloc (N);
      Typ       : constant Entity_Id  := Etype (Arg);
      Desig_Typ : constant Entity_Id  :=
                    Available_View (Designated_Type (Typ));
      Needs_Fin : constant Boolean    := Needs_Finalization (Desig_Typ);
      Root_Typ  : constant Entity_Id  := Underlying_Type (Root_Type (Typ));
      Pool      : constant Entity_Id  := Associated_Storage_Pool (Root_Typ);
      Stmts     : constant List_Id    := New_List;

      Arg_Known_Non_Null : constant Boolean := Known_Non_Null (N);
      --  This captures whether we know the argument to be non-null so that
      --  we can avoid the test. The reason that we need to capture this is
      --  that we analyze some generated statements before properly attaching
      --  them to the tree, and that can disturb current value settings.

      Exceptions_OK : constant Boolean :=
                        not Restriction_Active (No_Exception_Propagation);

      Abrt_Blk    : Node_Id := Empty;
      Abrt_Blk_Id : Entity_Id;
      Abrt_HSS    : Node_Id;
      AUD         : Entity_Id;
      Fin_Blk     : Node_Id;
      Fin_Call    : Node_Id;
      Fin_Data    : Finalization_Exception_Data;
      Free_Arg    : Node_Id;
      Free_Nod    : Node_Id;
      Gen_Code    : Node_Id;
      Obj_Ref     : Node_Id;

   begin
      --  Nothing to do if we know the argument is null

      if Known_Null (N) then
         return;
      end if;

      --  Processing for pointer to controlled types. Generate:

      --    Abrt   : constant Boolean := ...;
      --    Ex     : Exception_Occurrence;
      --    Raised : Boolean := False;

      --    begin
      --       Abort_Defer;

      --       begin
      --          [Deep_]Finalize (Obj_Ref);

      --       exception
      --          when others =>
      --             if not Raised then
      --                Raised := True;
      --                Save_Occurrence (Ex, Get_Current_Excep.all.all);
      --       end;
      --    at end
      --       Abort_Undefer_Direct;
      --    end;

      --  Depending on whether exception propagation is enabled and/or aborts
      --  are allowed, the generated code may lack block statements.

      if Needs_Fin then

         --  Ada 2005 (AI-251): In case of abstract interface type we displace
         --  the pointer to reference the base of the object to deallocate its
         --  memory, unless we're targetting a VM, in which case no special
         --  processing is required.

         if Is_Interface (Directly_Designated_Type (Typ))
           and then Tagged_Type_Expansion
         then
            Obj_Ref :=
              Make_Explicit_Dereference (Loc,
                Prefix =>
                  Unchecked_Convert_To (Typ,
                    Make_Function_Call (Loc,
                      Name                   =>
                        New_Occurrence_Of (RTE (RE_Base_Address), Loc),
                      Parameter_Associations => New_List (
                        Unchecked_Convert_To (RTE (RE_Address),
                          Duplicate_Subexpr_No_Checks (Arg))))));

         else
            Obj_Ref :=
              Make_Explicit_Dereference (Loc,
                Prefix => Duplicate_Subexpr_No_Checks (Arg));
         end if;

         --  If the designated type is tagged, the finalization call must
         --  dispatch because the designated type may not be the actual type
         --  of the object. If the type is synchronized, the deallocation
         --  applies to the corresponding record type.

         if Is_Tagged_Type (Desig_Typ) then
            if Is_Concurrent_Type (Desig_Typ) then
               Obj_Ref :=
                 Unchecked_Convert_To
                   (Class_Wide_Type (Corresponding_Record_Type (Desig_Typ)),
                      Obj_Ref);

            elsif not Is_Class_Wide_Type (Desig_Typ) then
               Obj_Ref :=
                 Unchecked_Convert_To (Class_Wide_Type (Desig_Typ), Obj_Ref);
            end if;

         --  Otherwise the designated type is untagged. Set the type of the
         --  dereference explicitly to force a conversion when needed given
         --  that [Deep_]Finalize may be inherited from a parent type.

         else
            Set_Etype (Obj_Ref, Desig_Typ);
         end if;

         --  Generate:
         --    [Deep_]Finalize (Obj_Ref);

         Fin_Call := Make_Final_Call (Obj_Ref => Obj_Ref, Typ => Desig_Typ);

         --  Generate:
         --    Abrt   : constant Boolean := ...;
         --    Ex     : Exception_Occurrence;
         --    Raised : Boolean := False;

         --    begin
         --       <Fin_Call>

         --    exception
         --       when others =>
         --          if not Raised then
         --             Raised := True;
         --             Save_Occurrence (Ex, Get_Current_Excep.all.all);
         --    end;

         if Exceptions_OK then
            Build_Object_Declarations (Fin_Data, Stmts, Loc);

            Fin_Blk :=
              Make_Block_Statement (Loc,
                Handled_Statement_Sequence =>
                  Make_Handled_Sequence_Of_Statements (Loc,
                    Statements         => New_List (Fin_Call),
                    Exception_Handlers => New_List (
                      Build_Exception_Handler (Fin_Data))));

         --  Otherwise exception propagation is not allowed

         else
            Fin_Blk := Fin_Call;
         end if;

         --  The finalization action must be protected by an abort defer and
         --  undefer pair when aborts are allowed. Generate:

         --    begin
         --       Abort_Defer;
         --       <Fin_Blk>
         --    at end
         --       Abort_Undefer_Direct;
         --    end;

         if Abort_Allowed then
            AUD := RTE (RE_Abort_Undefer_Direct);

            Abrt_HSS :=
              Make_Handled_Sequence_Of_Statements (Loc,
                Statements  => New_List (
                  Build_Runtime_Call (Loc, RE_Abort_Defer),
                  Fin_Blk),
                At_End_Proc => New_Occurrence_Of (AUD, Loc));

            Abrt_Blk :=
              Make_Block_Statement (Loc,
                Handled_Statement_Sequence => Abrt_HSS);

            Add_Block_Identifier  (Abrt_Blk, Abrt_Blk_Id);
            Expand_At_End_Handler (Abrt_HSS, Abrt_Blk_Id);

            --  Present the Abort_Undefer_Direct function to the backend so
            --  that it can inline the call to the function.

            Add_Inlined_Body (AUD, N);

         --  Otherwise aborts are not allowed

         else
            Abrt_Blk := Fin_Blk;
         end if;

         Append_To (Stmts, Abrt_Blk);
      end if;

      --  For a task type, call Free_Task before freeing the ATCB. We used to
      --  detect the case of Abort followed by a Free here, because the Free
      --  wouldn't actually free if it happens before the aborted task actually
      --  terminates. The warning was removed, because Free now works properly
      --  (the task will be freed once it terminates).

      if Is_Task_Type (Desig_Typ) then
         Append_To (Stmts,
           Cleanup_Task (N, Duplicate_Subexpr_No_Checks (Arg)));

      --  For composite types that contain tasks, recurse over the structure
      --  to build the selectors for the task subcomponents.

      elsif Has_Task (Desig_Typ) then
         if Is_Array_Type (Desig_Typ) then
            Append_List_To (Stmts, Cleanup_Array (N, Arg, Desig_Typ));

         elsif Is_Record_Type (Desig_Typ) then
            Append_List_To (Stmts, Cleanup_Record (N, Arg, Desig_Typ));
         end if;
      end if;

      --  Same for simple protected types. Eventually call Finalize_Protection
      --  before freeing the PO for each protected component.

      if Is_Simple_Protected_Type (Desig_Typ) then
         Append_To (Stmts,
           Cleanup_Protected_Object (N, Duplicate_Subexpr_No_Checks (Arg)));

      elsif Has_Simple_Protected_Object (Desig_Typ) then
         if Is_Array_Type (Desig_Typ) then
            Append_List_To (Stmts, Cleanup_Array (N, Arg, Desig_Typ));

         elsif Is_Record_Type (Desig_Typ) then
            Append_List_To (Stmts, Cleanup_Record (N, Arg, Desig_Typ));
         end if;
      end if;

      --  Normal processing for non-controlled types. The argument to free is
      --  a renaming rather than a constant to ensure that the original context
      --  is always set to null after the deallocation takes place.

      Free_Arg := Duplicate_Subexpr_No_Checks (Arg, Renaming_Req => True);
      Free_Nod := Make_Free_Statement (Loc, Empty);
      Append_To (Stmts, Free_Nod);
      Set_Storage_Pool (Free_Nod, Pool);

      --  Attach to tree before analysis of generated subtypes below

      Set_Parent (Stmts, Parent (N));

      --  Deal with storage pool

      if Present (Pool) then

         --  Freeing the secondary stack is meaningless

         if Is_RTE (Pool, RE_SS_Pool) then
            null;

         --  If the pool object is of a simple storage pool type, then attempt
         --  to locate the type's Deallocate procedure, if any, and set the
         --  free operation's procedure to call. If the type doesn't have a
         --  Deallocate (which is allowed), then the actual will simply be set
         --  to null.

         elsif Present
                 (Get_Rep_Pragma (Etype (Pool), Name_Simple_Storage_Pool_Type))
         then
            declare
               Pool_Typ : constant Entity_Id := Base_Type (Etype (Pool));
               Dealloc  : Entity_Id;

            begin
               Dealloc := Get_Name_Entity_Id (Name_Deallocate);
               while Present (Dealloc) loop
                  if Scope (Dealloc) = Scope (Pool_Typ)
                    and then Present (First_Formal (Dealloc))
                    and then Etype (First_Formal (Dealloc)) = Pool_Typ
                  then
                     Set_Procedure_To_Call (Free_Nod, Dealloc);
                     exit;
                  else
                     Dealloc := Homonym (Dealloc);
                  end if;
               end loop;
            end;

         --  Case of a class-wide pool type: make a dispatching call to
         --  Deallocate through the class-wide Deallocate_Any.

         elsif Is_Class_Wide_Type (Etype (Pool)) then
            Set_Procedure_To_Call (Free_Nod, RTE (RE_Deallocate_Any));

         --  Case of a specific pool type: make a statically bound call

         else
            Set_Procedure_To_Call
              (Free_Nod, Find_Prim_Op (Etype (Pool), Name_Deallocate));
         end if;
      end if;

      if Present (Procedure_To_Call (Free_Nod)) then

         --  For all cases of a Deallocate call, the back-end needs to be able
         --  to compute the size of the object being freed. This may require
         --  some adjustments for objects of dynamic size.
         --
         --  If the type is class wide, we generate an implicit type with the
         --  right dynamic size, so that the deallocate call gets the right
         --  size parameter computed by GIGI. Same for an access to
         --  unconstrained packed array.

         if Is_Class_Wide_Type (Desig_Typ)
           or else
            (Is_Array_Type (Desig_Typ)
              and then not Is_Constrained (Desig_Typ)
              and then Is_Packed (Desig_Typ))
         then
            declare
               Deref    : constant Node_Id :=
                            Make_Explicit_Dereference (Loc,
                              Duplicate_Subexpr_No_Checks (Arg));
               D_Subtyp : Node_Id;
               D_Type   : Entity_Id;

            begin
               --  Perform minor decoration as it is needed by the side effect
               --  removal mechanism.

               Set_Etype  (Deref, Desig_Typ);
               Set_Parent (Deref, Free_Nod);
               D_Subtyp := Make_Subtype_From_Expr (Deref, Desig_Typ);

               if Nkind (D_Subtyp) in N_Has_Entity then
                  D_Type := Entity (D_Subtyp);

               else
                  D_Type := Make_Temporary (Loc, 'A');
                  Insert_Action (Deref,
                    Make_Subtype_Declaration (Loc,
                      Defining_Identifier => D_Type,
                      Subtype_Indication  => D_Subtyp));
               end if;

               --  Force freezing at the point of the dereference. For the
               --  class wide case, this avoids having the subtype frozen
               --  before the equivalent type.

               Freeze_Itype (D_Type, Deref);

               Set_Actual_Designated_Subtype (Free_Nod, D_Type);
            end;
         end if;
      end if;

      --  Ada 2005 (AI-251): In case of abstract interface type we must
      --  displace the pointer to reference the base of the object to
      --  deallocate its memory, unless we're targetting a VM, in which case
      --  no special processing is required.

      --  Generate:
      --    free (Base_Address (Obj_Ptr))

      if Is_Interface (Directly_Designated_Type (Typ))
        and then Tagged_Type_Expansion
      then
         Set_Expression (Free_Nod,
           Unchecked_Convert_To (Typ,
             Make_Function_Call (Loc,
               Name                   =>
                 New_Occurrence_Of (RTE (RE_Base_Address), Loc),
               Parameter_Associations => New_List (
                 Unchecked_Convert_To (RTE (RE_Address), Free_Arg)))));

      --  Generate:
      --    free (Obj_Ptr)

      else
         Set_Expression (Free_Nod, Free_Arg);
      end if;

      --  Only remaining step is to set result to null, or generate a raise of
      --  Constraint_Error if the target object is "not null".

      if Can_Never_Be_Null (Etype (Arg)) then
         Append_To (Stmts,
           Make_Raise_Constraint_Error (Loc,
             Reason => CE_Access_Check_Failed));

      else
         declare
            Lhs : constant Node_Id := Duplicate_Subexpr_No_Checks (Arg);
         begin
            Set_Assignment_OK (Lhs);
            Append_To (Stmts,
              Make_Assignment_Statement (Loc,
                Name       => Lhs,
                Expression => Make_Null (Loc)));
         end;
      end if;

      --  Generate a test of whether any earlier finalization raised an
      --  exception, and in that case raise Program_Error with the previous
      --  exception occurrence.

      --  Generate:
      --    if Raised and then not Abrt then
      --       raise Program_Error;                  --  for restricted RTS
      --         <or>
      --       Raise_From_Controlled_Operation (E);  --  all other cases
      --    end if;

      if Needs_Fin and then Exceptions_OK then
         Append_To (Stmts, Build_Raise_Statement (Fin_Data));
      end if;

      --  If we know the argument is non-null, then make a block statement
      --  that contains the required statements, no need for a test.

      if Arg_Known_Non_Null then
         Gen_Code :=
           Make_Block_Statement (Loc,
             Handled_Statement_Sequence =>
               Make_Handled_Sequence_Of_Statements (Loc,
             Statements => Stmts));

      --  If the argument may be null, wrap the statements inside an IF that
      --  does an explicit test to exclude the null case.

      else
         Gen_Code :=
           Make_Implicit_If_Statement (N,
             Condition       =>
               Make_Op_Ne (Loc,
                 Left_Opnd  => Duplicate_Subexpr (Arg),
                 Right_Opnd => Make_Null (Loc)),
             Then_Statements => Stmts);
      end if;

      --  Rewrite the call

      Rewrite (N, Gen_Code);
      Analyze (N);
   end Expand_Unc_Deallocation;

   -----------------------
   -- Expand_To_Address --
   -----------------------

   procedure Expand_To_Address (N : Node_Id) is
      Loc : constant Source_Ptr := Sloc (N);
      Arg : constant Node_Id := First_Actual (N);
      Obj : Node_Id;

   begin
      Remove_Side_Effects (Arg);

      Obj := Make_Explicit_Dereference (Loc, Relocate_Node (Arg));

      Rewrite (N,
        Make_If_Expression (Loc,
          Expressions => New_List (
            Make_Op_Eq (Loc,
              Left_Opnd => New_Copy_Tree (Arg),
              Right_Opnd => Make_Null (Loc)),
            New_Occurrence_Of (RTE (RE_Null_Address), Loc),
            Make_Attribute_Reference (Loc,
              Prefix         => Obj,
              Attribute_Name => Name_Address))));

      Analyze_And_Resolve (N, RTE (RE_Address));
   end Expand_To_Address;

   -----------------------
   -- Expand_To_Pointer --
   -----------------------

   procedure Expand_To_Pointer (N : Node_Id) is
      Arg : constant Node_Id := First_Actual (N);

   begin
      Rewrite (N, Unchecked_Convert_To (Etype (N), Arg));
      Analyze (N);
   end Expand_To_Pointer;

end Exp_Intr;