1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                               L A Y O U T                                --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 2000-2007, 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 3,  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 COPYING3.  If not, go to --
19-- http://www.gnu.org/licenses for a complete copy of the license.          --
20--                                                                          --
21-- GNAT was originally developed  by the GNAT team at  New York University. --
22-- Extensive contributions were provided by Ada Core Technologies Inc.      --
23--                                                                          --
24------------------------------------------------------------------------------
25
26--  This package does front-end layout of types and objects. The result is
27--  to annotate the tree with information on size and alignment of types
28--  and objects. How much layout is performed depends on the setting of the
29--  target dependent parameter Backend_Layout.
30
31with Types; use Types;
32
33package Layout is
34
35   --  The following procedures are called from Freeze, so all entities
36   --  for types and objects that get frozen (which should be all such
37   --  entities which are seen by the back end) will get layed out by one
38   --  of these two procedures.
39
40   procedure Layout_Type (E : Entity_Id);
41   --  This procedure may set or adjust the fields Esize, RM_Size and
42   --  Alignment in the non-generic type or subtype entity E. If the
43   --  Backend_Layout switch is False, then it is guaranteed that all
44   --  three fields will be properly set on return. Regardless of the
45   --  Backend_Layout value, it is guaranteed that all discrete types
46   --  will have both Esize and RM_Size fields set on return (since
47   --  these are static values). Note that Layout_Type is not called
48   --  for generic types, since these play no part in code generation,
49   --  and hence representation aspects are irrelevant.
50
51   procedure Layout_Object (E : Entity_Id);
52   --  E is either a variable (E_Variable), a constant (E_Constant),
53   --  a loop parameter (E_Loop_Parameter), or a formal parameter of
54   --  a non-generic subprogram (E_In_Parameter, E_In_Out_Parameter,
55   --  or E_Out_Parameter). This procedure may set or adjust the
56   --  Esize and Alignment fields of E. If Backend_Layout is False,
57   --  then it is guaranteed that both fields will be properly set
58   --  on return. If the Esize is still unknown in the latter case,
59   --  it means that the object must be allocated dynamically, since
60   --  its length is not known at compile time.
61
62   --  The following are utility routines, called from various places
63
64   procedure Adjust_Esize_Alignment (E : Entity_Id);
65   --  E is the entity for a type or object. This procedure checks that the
66   --  size and alignment are compatible, and if not either gives an error
67   --  message if they cannot be adjusted or else adjusts them appropriately.
68
69   procedure Set_Discrete_RM_Size (Def_Id : Entity_Id);
70   --  Set proper RM_Size for discrete size, this is normally the minimum
71   --  number of bits to accommodate the range given, except in the case
72   --  where the subtype statically matches the first subtype, in which
73   --  case the size must be copied from the first subtype. For generic
74   --  types, the RM_Size is simply set to zero. This routine also sets
75   --  the Is_Constrained flag in Def_Id.
76
77   procedure Set_Elem_Alignment (E : Entity_Id);
78   --  The front end always sets alignments for elementary types by calling
79   --  this procedure. Note that we have to do this for discrete types (since
80   --  the Alignment attribute is static), so we might as well do it for all
81   --  elementary types, since the processing is the same.
82
83end Layout;
84