1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
|
------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ C H 1 3 --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2004 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 2, 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 COPYING. If not, write --
-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
-- Boston, MA 02110-1301, USA. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
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_Record_Representation_Clause (N : Node_Id);
procedure Analyze_Code_Statement (N : Node_Id);
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.
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 incompleted 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.
--
-- 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.
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.
end Sem_Ch13;
|
