------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ C H 1 3 --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2010, 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. --
-- --
------------------------------------------------------------------------------
with Table;
with Types; use Types;
with Uintp; use Uintp;
package Sem_Ch13 is
procedure Analyze_At_Clause (N : Node_Id);
procedure Analyze_Attribute_Definition_Clause (N : Node_Id);
procedure Analyze_Enumeration_Representation_Clause (N : Node_Id);
procedure Analyze_Free_Statement (N : Node_Id);
procedure Analyze_Freeze_Entity (N : Node_Id);
procedure Analyze_Record_Representation_Clause (N : Node_Id);
procedure Analyze_Code_Statement (N : Node_Id);
procedure Analyze_Aspect_Specifications
(N : Node_Id;
E : Entity_Id;
L : List_Id);
-- This procedure is called to analyze aspect specifications for node N. E
-- is the corresponding entity declared by the declaration node N, and L is
-- the list of aspect specifications for this node. If L is No_List, the
-- call is ignored. Note that we can't use a simpler interface of just
-- passing the node N, since the analysis of the node may cause it to be
-- rewritten to a node not permitting aspect specifications.
procedure Adjust_Record_For_Reverse_Bit_Order (R : Entity_Id);
-- Called from Freeze where R is a record entity for which reverse bit
-- order is specified and there is at least one component clause. Adjusts
-- component positions according to either Ada 95 or Ada 2005 (AI-133).
procedure Build_Invariant_Procedure (Typ : Entity_Id; N : Node_Id);
-- Typ is a private type with invariants (indicated by Has_Invariants being
-- set for Typ, indicating the presence of pragma Invariant entries on the
-- rep chain, note that Invariant aspects have already been converted to
-- pragma Invariant), then this procedure builds the spec and body for the
-- corresponding Invariant procedure, inserting them at appropriate points
-- in the package specification N. Invariant_Procedure is set for Typ. Note
-- that this procedure is called at the end of processing the declarations
-- in the visible part (i.e. the right point for visibility analysis of
-- the invariant expression).
procedure Check_Record_Representation_Clause (N : Node_Id);
-- This procedure completes the analysis of a record representation clause
-- N. It is called at freeze time after adjustment of component clause bit
-- positions for possible non-standard bit order. In the case of Ada 2005
-- (machine scalar) mode, this adjustment can make substantial changes, so
-- some checks, in particular for component overlaps cannot be done at the
-- time the record representation clause is first seen, but must be delayed
-- till freeze time, and in particular is called after calling the above
-- procedure for adjusting record bit positions for reverse bit order.
procedure Initialize;
-- Initialize internal tables for new compilation
procedure Set_Enum_Esize (T : Entity_Id);
-- This routine sets the Esize field for an enumeration type T, based
-- on the current representation information available for T. Note that
-- the setting of the RM_Size field is not affected. This routine also
-- initializes the alignment field to zero.
function Minimum_Size
(T : Entity_Id;
Biased : Boolean := False) return Nat;
-- Given an elementary type, determines the minimum number of bits required
-- to represent all values of the type. This function may not be called
-- with any other types. If the flag Biased is set True, then the minimum
-- size calculation that biased representation is used in the case of a
-- discrete type, e.g. the range 7..8 gives a minimum size of 4 with
-- Biased set to False, and 1 with Biased set to True. Note that the
-- biased parameter only has an effect if the type is not biased, it
-- causes Minimum_Size to indicate the minimum size of an object with
-- the given type, of the size the type would have if it were biased. If
-- the type is already biased, then Minimum_Size returns the biased size,
-- regardless of the setting of Biased. Also, fixed-point types are never
-- biased in the current implementation. If the size is not known at
-- compile time, this function returns 0.
procedure Check_Constant_Address_Clause (Expr : Node_Id; U_Ent : Entity_Id);
-- Expr is an expression for an address clause. This procedure checks
-- that the expression is constant, in the limited sense that it is safe
-- to evaluate it at the point the object U_Ent is declared, rather than
-- at the point of the address clause. The condition for this to be true
-- is that the expression has no variables, no constants declared after
-- U_Ent, and no calls to non-pure functions. If this condition is not
-- met, then an appropriate error message is posted. This check is applied
-- at the point an object with an address clause is frozen, as well as for
-- address clauses for tasks and entries.
procedure Check_Size
(N : Node_Id;
T : Entity_Id;
Siz : Uint;
Biased : out Boolean);
-- Called when size Siz is specified for subtype T. This subprogram checks
-- that the size is appropriate, posting errors on node N as required.
-- This check is effective for elementary types and bit-packed arrays.
-- For other non-elementary types, a check is only made if an explicit
-- size has been given for the type (and the specified size must match).
-- The parameter Biased is set False if the size specified did not require
-- the use of biased representation, and True if biased representation
-- was required to meet the size requirement. Note that Biased is only
-- set if the type is not currently biased, but biasing it is the only
-- way to meet the requirement. If the type is currently biased, then
-- this biased size is used in the initial check, and Biased is False.
-- If the size is too small, and an error message is given, then both
-- Esize and RM_Size are reset to the allowed minimum value in T.
function Rep_Item_Too_Early (T : Entity_Id; N : Node_Id) return Boolean;
-- Called at the start of processing a representation clause or a
-- representation pragma. Used to check that the representation item
-- is not being applied to an incomplete type or to a generic formal
-- type or a type derived from a generic formal type. Returns False if
-- no such error occurs. If this error does occur, appropriate error
-- messages are posted on node N, and True is returned.
function Rep_Item_Too_Late
(T : Entity_Id;
N : Node_Id;
FOnly : Boolean := False) return Boolean;
-- Called at the start of processing a representation clause or a
-- representation pragma. Used to check that a representation item
-- for entity T does not appear too late (according to the rules in
-- RM 13.1(9) and RM 13.1(10)). N is the associated node, which in
-- the pragma case is the pragma or representation clause itself, used
-- for placing error messages if the item is too late.
--
-- Fonly is a flag that causes only the freezing rule (para 9) to be
-- applied, and the tests of para 10 are skipped. This is appropriate
-- for both subtype related attributes (Alignment and Size) and for
-- stream attributes, which, although certainly not subtype related
-- attributes, clearly should not be subject to the para 10 restrictions
-- (see AI95-00137). Similarly, we also skip the para 10 restrictions for
-- the Storage_Size case where they also clearly do not apply, and for
-- Stream_Convert which is in the same category as the stream attributes.
--
-- If the rep item is too late, an appropriate message is output and
-- True is returned, which is a signal that the caller should abandon
-- processing for the item. If the item is not too late, then False
-- is returned, and the caller can continue processing the item.
--
-- If no error is detected, this call also as a side effect links the
-- representation item onto the head of the representation item chain
-- (referenced by the First_Rep_Item field of the entity).
--
-- Note: Rep_Item_Too_Late must be called with the underlying type in
-- the case of a private or incomplete type. The protocol is to first
-- check for Rep_Item_Too_Early using the initial entity, then take the
-- underlying type, then call Rep_Item_Too_Late on the result.
--
-- Note: Calls to Rep_Item_Too_Late are ignored for the case of attribute
-- definition clauses which have From_Aspect_Specification set. This is
-- because such clauses are linked on to the Rep_Item chain in procedure
-- Sem_Ch13.Analyze_Aspect_Specifications. See that procedure for details.
function Same_Representation (Typ1, Typ2 : Entity_Id) return Boolean;
-- Given two types, where the two types are related by possible derivation,
-- determines if the two types have the same representation, or different
-- representations, requiring the special processing for representation
-- change. A False result is possible only for array, enumeration or
-- record types.
procedure Validate_Unchecked_Conversion
(N : Node_Id;
Act_Unit : Entity_Id);
-- Validate a call to unchecked conversion. N is the node for the actual
-- instantiation, which is used only for error messages. Act_Unit is the
-- entity for the instantiation, from which the actual types etc. for this
-- instantiation can be determined. This procedure makes an entry in a
-- table and/or generates an N_Validate_Unchecked_Conversion node. The
-- actual checking is done in Validate_Unchecked_Conversions or in the
-- back end as required.
procedure Validate_Unchecked_Conversions;
-- This routine is called after calling the backend to validate unchecked
-- conversions for size and alignment appropriateness. The reason it is
-- called that late is to take advantage of any back-annotation of size
-- and alignment performed by the backend.
procedure Validate_Address_Clauses;
-- This is called after the back end has been called (and thus after the
-- alignments of objects have been back annotated). It goes through the
-- table of saved address clauses checking for suspicious alignments and
-- if necessary issuing warnings.
procedure Validate_Independence;
-- This is called after the back end has been called (and thus after the
-- layout of components has been back annotated). It goes through the
-- table of saved pragma Independent[_Component] entries, checking that
-- independence can be achieved, and if necessary issuing error messages.
-------------------------------------
-- Table for Validate_Independence --
-------------------------------------
-- If a legal pragma Independent or Independent_Components is given for
-- an entity, then an entry is made in this table, to be checked by a
-- call to Validate_Independence after back annotation of layout is done.
type Independence_Check_Record is record
N : Node_Id;
-- The pragma Independent or Independent_Components
E : Entity_Id;
-- The entity to which it applies
end record;
package Independence_Checks is new Table.Table (
Table_Component_Type => Independence_Check_Record,
Table_Index_Type => Int,
Table_Low_Bound => 1,
Table_Initial => 20,
Table_Increment => 200,
Table_Name => "Independence_Checks");
end Sem_Ch13;