gcc/ada/layout.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                               L A Y O U T                                --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --                            $Revision: 1.2 $
  10 --                                                                          --
  11 --          Copyright (C) 2000-2001 Free Software Foundation, Inc.          --
  12 --                                                                          --
  13 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  14 -- terms of the  GNU General Public License as published  by the Free Soft- --
  15 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  16 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  17 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  21 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- GNAT was originally developed  by the GNAT team at  New York University. --
  25 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  26 --                                                                          --
  27 ------------------------------------------------------------------------------
  28
  29 --  This package does front-end layout of types and objects. The result is
  30 --  to annotate the tree with information on size and alignment of types
  31 --  and objects. How much layout is performed depends on the setting of the
  32 --  target dependent parameter Backend_Layout.
  33
  34 with Types; use Types;
  35
  36 package Layout is
  37
  38    --  The following procedures are called from Freeze, so all entities
  39    --  for types and objects that get frozen (which should be all such
  40    --  entities which are seen by the back end) will get layed out by one
  41    --  of these two procedures.
  42
  43    procedure Layout_Type (E : Entity_Id);
  44    --  This procedure may set or adjust the fields Esize, RM_Size and
  45    --  Alignment in the non-generic type or subtype entity E. If the
  46    --  Backend_Layout switch is False, then it is guaranteed that all
  47    --  three fields will be properly set on return. Regardless of the
  48    --  Backend_Layout value, it is guaranteed that all discrete types
  49    --  will have both Esize and RM_Size fields set on return (since
  50    --  these are static values). Note that Layout_Type is not called
  51    --  for generic types, since these play no part in code generation,
  52    --  and hence representation aspects are irrelevant.
  53
  54    procedure Layout_Object (E : Entity_Id);
  55    --  E is either a variable (E_Variable), a constant (E_Constant),
  56    --  a loop parameter (E_Loop_Parameter), or a formal parameter of
  57    --  a non-generic subprogram (E_In_Parameter, E_In_Out_Parameter,
  58    --  or E_Out_Parameter). This procedure may set or adjust the
  59    --  Esize and Alignment fields of E. If Backend_Layout is False,
  60    --  then it is guaranteed that both fields will be properly set
  61    --  on return. If the Esize is still unknown in the latter case,
  62    --  it means that the object must be allocated dynamically, since
  63    --  its length is not known at compile time.
  64
  65    procedure Set_Discrete_RM_Size (Def_Id : Entity_Id);
  66    --  Set proper RM_Size for discrete size, this is normally the minimum
  67    --  number of bits to accommodate the range given, except in the case
  68    --  where the subtype statically matches the first subtype, in which
  69    --  case the size must be copied from the first subtype. For generic
  70    --  types, the RM_Size is simply set to zero. This routine also sets
  71    --  the Is_Constrained flag in Def_Id.
  72
  73    procedure Set_Prim_Alignment (E : Entity_Id);
  74    --  The front end always sets alignments for primitive types by calling this
  75    --  procedure. Note that we have to do this for discrete types (since the
  76    --  Alignment attribute is static), so we might as well do it for all
  77    --  scalar types, since the processing is the same.
  78
  79 end Layout;