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--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                               L A Y O U T                                --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 2000-2007, 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.      --

--                                                                          --

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--  This package does front-end layout of types and objects. The result is

--  to annotate the tree with information on size and alignment of types

--  and objects. How much layout is performed depends on the setting of the

--  target dependent parameter Backend_Layout.

with Types; use Types;

package Layout is

   --  The following procedures are called from Freeze, so all entities

   --  for types and objects that get frozen (which should be all such

   --  entities which are seen by the back end) will get layed out by one

   --  of these two procedures.

   procedure Layout_Type (E : Entity_Id);

   --  This procedure may set or adjust the fields Esize, RM_Size and

   --  Alignment in the non-generic type or subtype entity E. If the

   --  Backend_Layout switch is False, then it is guaranteed that all

   --  three fields will be properly set on return. Regardless of the

   --  Backend_Layout value, it is guaranteed that all discrete types

   --  will have both Esize and RM_Size fields set on return (since

   --  these are static values). Note that Layout_Type is not called

   --  for generic types, since these play no part in code generation,

   --  and hence representation aspects are irrelevant.

   procedure Layout_Object (E : Entity_Id);

   --  E is either a variable (E_Variable), a constant (E_Constant),

   --  a loop parameter (E_Loop_Parameter), or a formal parameter of

   --  a non-generic subprogram (E_In_Parameter, E_In_Out_Parameter,

   --  or E_Out_Parameter). This procedure may set or adjust the

   --  Esize and Alignment fields of E. If Backend_Layout is False,

   --  then it is guaranteed that both fields will be properly set

   --  on return. If the Esize is still unknown in the latter case,

   --  it means that the object must be allocated dynamically, since

   --  its length is not known at compile time.

   --  The following are utility routines, called from various places

   procedure Adjust_Esize_Alignment (E : Entity_Id);

   --  E is the entity for a type or object. This procedure checks that the

   --  size and alignment are compatible, and if not either gives an error

   --  message if they cannot be adjusted or else adjusts them appropriately.

   procedure Set_Discrete_RM_Size (Def_Id : Entity_Id);

   --  Set proper RM_Size for discrete size, this is normally the minimum

   --  number of bits to accommodate the range given, except in the case

   --  where the subtype statically matches the first subtype, in which

   --  case the size must be copied from the first subtype. For generic

   --  types, the RM_Size is simply set to zero. This routine also sets

   --  the Is_Constrained flag in Def_Id.

   procedure Set_Elem_Alignment (E : Entity_Id);

   --  The front end always sets alignments for elementary types by calling

   --  this procedure. Note that we have to do this for discrete types (since

   --  the Alignment attribute is static), so we might as well do it for all

   --  elementary types, since the processing is the same.

end Layout;