gcc/ada/sem_ch13.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             S E M _ C H 1 3                              --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2008, 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 with Types; use Types;
  27 with Uintp; use Uintp;
  28
  29 package Sem_Ch13 is
  30    procedure Analyze_At_Clause                          (N : Node_Id);
  31    procedure Analyze_Attribute_Definition_Clause        (N : Node_Id);
  32    procedure Analyze_Enumeration_Representation_Clause  (N : Node_Id);
  33    procedure Analyze_Free_Statement                     (N : Node_Id);
  34    procedure Analyze_Record_Representation_Clause       (N : Node_Id);
  35    procedure Analyze_Code_Statement                     (N : Node_Id);
  36
  37    procedure Adjust_Record_For_Reverse_Bit_Order (R : Entity_Id);
  38    --  Called from Freeze where R is a record entity for which reverse bit
  39    --  order is specified and there is at least one component clause. Adjusts
  40    --  component positions according to Ada 2005 AI-133. Note that this is only
  41    --  called in Ada 2005 mode. The Ada 95 handling for bit order is entirely
  42    --  contained in Freeze.
  43
  44    procedure Initialize;
  45    --  Initialize internal tables for new compilation
  46
  47    procedure Set_Enum_Esize (T : Entity_Id);
  48    --  This routine sets the Esize field for an enumeration type T, based
  49    --  on the current representation information available for T. Note that
  50    --  the setting of the RM_Size field is not affected. This routine also
  51    --  initializes the alignment field to zero.
  52
  53    function Minimum_Size
  54      (T      : Entity_Id;
  55       Biased : Boolean := False) return Nat;
  56    --  Given an elementary type, determines the minimum number of bits required
  57    --  to represent all values of the type. This function may not be called
  58    --  with any other types. If the flag Biased is set True, then the minimum
  59    --  size calculation that biased representation is used in the case of a
  60    --  discrete type, e.g. the range 7..8 gives a minimum size of 4 with
  61    --  Biased set to False, and 1 with Biased set to True. Note that the
  62    --  biased parameter only has an effect if the type is not biased, it
  63    --  causes Minimum_Size to indicate the minimum size of an object with
  64    --  the given type, of the size the type would have if it were biased. If
  65    --  the type is already biased, then Minimum_Size returns the biased size,
  66    --  regardless of the setting of Biased. Also, fixed-point types are never
  67    --  biased in the current implementation. If the size is not known at
  68    --  compile time, this function returns 0.
  69
  70    procedure Check_Constant_Address_Clause (Expr : Node_Id; U_Ent : Entity_Id);
  71    --  Expr is an expression for an address clause. This procedure checks
  72    --  that the expression is constant, in the limited sense that it is safe
  73    --  to evaluate it at the point the object U_Ent is declared, rather than
  74    --  at the point of the address clause. The condition for this to be true
  75    --  is that the expression has no variables, no constants declared after
  76    --  U_Ent, and no calls to non-pure functions. If this condition is not
  77    --  met, then an appropriate error message is posted. This check is applied
  78    --  at the point an object with an address clause is frozen, as well as for
  79    --  address clauses for tasks and entries.
  80
  81    procedure Check_Size
  82      (N      : Node_Id;
  83       T      : Entity_Id;
  84       Siz    : Uint;
  85       Biased : out Boolean);
  86    --  Called when size Siz is specified for subtype T. This subprogram checks
  87    --  that the size is appropriate, posting errors on node N as required.
  88    --  This check is effective for elementary types and bit-packed arrays.
  89    --  For other non-elementary types, a check is only made if an explicit
  90    --  size has been given for the type (and the specified size must match).
  91    --  The parameter Biased is set False if the size specified did not require
  92    --  the use of biased representation, and True if biased representation
  93    --  was required to meet the size requirement. Note that Biased is only
  94    --  set if the type is not currently biased, but biasing it is the only
  95    --  way to meet the requirement. If the type is currently biased, then
  96    --  this biased size is used in the initial check, and Biased is False.
  97    --  If the size is too small, and an error message is given, then both
  98    --  Esize and RM_Size are reset to the allowed minimum value in T.
  99
 100    function Rep_Item_Too_Early (T : Entity_Id; N : Node_Id) return Boolean;
 101    --  Called at the start of processing a representation clause or a
 102    --  representation pragma. Used to check that the representation item
 103    --  is not being applied to an incomplete type or to a generic formal
 104    --  type or a type derived from a generic formal type. Returns False if
 105    --  no such error occurs. If this error does occur, appropriate error
 106    --  messages are posted on node N, and True is returned.
 107
 108    function Rep_Item_Too_Late
 109      (T     : Entity_Id;
 110       N     : Node_Id;
 111       FOnly : Boolean := False) return Boolean;
 112    --  Called at the start of processing a representation clause or a
 113    --  representation pragma. Used to check that a representation item
 114    --  for entity T does not appear too late (according to the rules in
 115    --  RM 13.1(9) and RM 13.1(10)). N is the associated node, which in
 116    --  the pragma case is the pragma or representation clause itself, used
 117    --  for placing error messages if the item is too late.
 118    --
 119    --  Fonly is a flag that causes only the freezing rule (para 9) to be
 120    --  applied, and the tests of para 10 are skipped. This is appropriate
 121    --  for both subtype related attributes (Alignment and Size) and for
 122    --  stream attributes, which, although certainly not subtype related
 123    --  attributes, clearly should not be subject to the para 10 restrictions
 124    --  (see AI95-00137). Similarly, we also skip the para 10 restrictions for
 125    --  the Storage_Size case where they also clearly do not apply, and for
 126    --  Stream_Convert which is in the same category as the stream attributes.
 127    --
 128    --  If the rep item is too late, an appropriate message is output and
 129    --  True is returned, which is a signal that the caller should abandon
 130    --  processing for the item. If the item is not too late, then False
 131    --  is returned, and the caller can continue processing the item.
 132    --
 133    --  If no error is detected, this call also as a side effect links the
 134    --  representation item onto the head of the representation item chain
 135    --  (referenced by the First_Rep_Item field of the entity).
 136    --
 137    --  Note: Rep_Item_Too_Late must be called with the underlying type in
 138    --  the case of a private or incomplete type. The protocol is to first
 139    --  check for Rep_Item_Too_Early using the initial entity, then take the
 140    --  underlying type, then call Rep_Item_Too_Late on the result.
 141
 142    function Same_Representation (Typ1, Typ2 : Entity_Id) return Boolean;
 143    --  Given two types, where the two types are related by possible derivation,
 144    --  determines if the two types have the same representation, or different
 145    --  representations, requiring the special processing for representation
 146    --  change. A False result is possible only for array, enumeration or
 147    --  record types.
 148
 149    procedure Validate_Unchecked_Conversion
 150      (N        : Node_Id;
 151       Act_Unit : Entity_Id);
 152    --  Validate a call to unchecked conversion. N is the node for the actual
 153    --  instantiation, which is used only for error messages. Act_Unit is the
 154    --  entity for the instantiation, from which the actual types etc. for this
 155    --  instantiation can be determined. This procedure makes an entry in a
 156    --  table and/or generates an N_Validate_Unchecked_Conversion node. The
 157    --  actual checking is done in Validate_Unchecked_Conversions or in the
 158    --  back end as required.
 159
 160    procedure Validate_Unchecked_Conversions;
 161    --  This routine is called after calling the backend to validate
 162    --  unchecked conversions for size and alignment appropriateness.
 163    --  The reason it is called that late is to take advantage of any
 164    --  back-annotation of size and alignment performed by the backend.
 165
 166    procedure Validate_Address_Clauses;
 167    --  This is called after the back end has been called (and thus after the
 168    --  alignments of objects have been back annotated). It goes through the
 169    --  table of saved address clauses checking for suspicious alignments and
 170    --  if necessary issuing warnings.
 171
 172 end Sem_Ch13;