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 --          Copyright (C) 2000-2004 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 2,  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 COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, USA.                                              --
  21 --                                                                          --
  22 -- GNAT was originally developed  by the GNAT team at  New York University. --
  23 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  24 --                                                                          --
  25 ------------------------------------------------------------------------------
  26
  27 --  This package does front-end layout of types and objects. The result is
  28 --  to annotate the tree with information on size and alignment of types
  29 --  and objects. How much layout is performed depends on the setting of the
  30 --  target dependent parameter Backend_Layout.
  31
  32 with Types; use Types;
  33
  34 package Layout is
  35
  36    --  The following procedures are called from Freeze, so all entities
  37    --  for types and objects that get frozen (which should be all such
  38    --  entities which are seen by the back end) will get layed out by one
  39    --  of these two procedures.
  40
  41    procedure Layout_Type (E : Entity_Id);
  42    --  This procedure may set or adjust the fields Esize, RM_Size and
  43    --  Alignment in the non-generic type or subtype entity E. If the
  44    --  Backend_Layout switch is False, then it is guaranteed that all
  45    --  three fields will be properly set on return. Regardless of the
  46    --  Backend_Layout value, it is guaranteed that all discrete types
  47    --  will have both Esize and RM_Size fields set on return (since
  48    --  these are static values). Note that Layout_Type is not called
  49    --  for generic types, since these play no part in code generation,
  50    --  and hence representation aspects are irrelevant.
  51
  52    procedure Layout_Object (E : Entity_Id);
  53    --  E is either a variable (E_Variable), a constant (E_Constant),
  54    --  a loop parameter (E_Loop_Parameter), or a formal parameter of
  55    --  a non-generic subprogram (E_In_Parameter, E_In_Out_Parameter,
  56    --  or E_Out_Parameter). This procedure may set or adjust the
  57    --  Esize and Alignment fields of E. If Backend_Layout is False,
  58    --  then it is guaranteed that both fields will be properly set
  59    --  on return. If the Esize is still unknown in the latter case,
  60    --  it means that the object must be allocated dynamically, since
  61    --  its length is not known at compile time.
  62
  63    procedure Set_Discrete_RM_Size (Def_Id : Entity_Id);
  64    --  Set proper RM_Size for discrete size, this is normally the minimum
  65    --  number of bits to accommodate the range given, except in the case
  66    --  where the subtype statically matches the first subtype, in which
  67    --  case the size must be copied from the first subtype. For generic
  68    --  types, the RM_Size is simply set to zero. This routine also sets
  69    --  the Is_Constrained flag in Def_Id.
  70
  71    procedure Set_Elem_Alignment (E : Entity_Id);
  72    --  The front end always sets alignments for elementary types by calling
  73    --  this procedure. Note that we have to do this for discrete types (since
  74    --  the Alignment attribute is static), so we might as well do it for all
  75    --  elementary types, since the processing is the same.
  76
  77 end Layout;