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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT RUN-TIME COMPONENTS --
4 -- --
5 -- S Y S T E M . H I E _ B A C K _ E N D --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 2001-2009, 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. --
17 -- --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
21 -- --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
26 -- --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
29 -- --
30 ------------------------------------------------------------------------------
32 -- This package provides an interface used in HI-E mode to determine
33 -- whether or not the back end can handle certain constructs in a manner
34 -- that is consistent with certification requirements.
36 -- The approach is to define entities which may or may not be present in
37 -- a HI-E configured library. If the entity is present then the compiler
38 -- operating in HI-E mode will allow the corresponding operation. If the
39 -- entity is not present, the corresponding construct will be flagged as
40 -- not permitted in High Integrity mode.
42 -- The default version of this unit delivered with the HI-E compiler is
43 -- configured in a manner appropriate for the target, but it is possible
44 -- to reconfigure the run-time to change the settings as required.
46 -- This unit is not used and never accessed by the compiler unless it is
47 -- operating in HI-E mode, so the settings are irrelevant. However, we
48 -- do include a standard version with all entities present in the standard
49 -- run-time for use when pragma No_Run_Time is specified.
51 package System.HIE_Back_End is
53 type Dummy is null record;
54 pragma Suppress_Initialization (Dummy);
55 -- This is the type used for the entities below. No properties of this
56 -- type are ever referenced, and in particular, the entities are defined
57 -- as variables, but their values are never referenced
59 HIE_64_Bit_Divides : Dummy;
60 -- This entity controls whether the front end allows 64-bit integer
61 -- divide operations, including the case where division of 32-bit
62 -- fixed-point operands requires 64-bit arithmetic. This can safely
63 -- be set as High_Integrity on 64-bit machines which provide this
64 -- operation as a native instruction, but on most 32-bit machines
65 -- a run time call (e.g. to __divdi3 in gcclib) is required. If a
66 -- certifiable version of this routine is available, then setting
67 -- this entity to High_Integrity with a pragma will cause appropriate
68 -- calls to be generated, allowing 64-bit integer division operations.
70 HIE_Long_Shifts : Dummy;
71 -- This entity controls whether the front end allows generation of
72 -- long shift instructions, i.e. shifts that operate on 64-bit values.
73 -- Such shifts are required for the implementation of fixed-point
74 -- types longer than 32 bits. This can safely be set as High_Integrity
75 -- on 64-bit machines that provide this operation at the hardware level,
76 -- but on some 32-bit machines a run time call is required. If there
77 -- is a certifiable version available of the relevant run-time routines,
78 -- then setting this entity to High_Integrity with a pragma will cause
79 -- appropriate calls to be generated, allowing the declaration and use
80 -- of fixed-point types longer than 32 bits.
82 HIE_Aggregates : Dummy;
83 -- In the general case, the use of aggregates may generate calls
84 -- to run-time routines in the C library, including memset, memcpy,
85 -- memmove, and bcopy. This entity can be set to High_Integrity with
86 -- a pragma if certifiable versions of all these routines are available,
87 -- in which case aggregates are permitted in HI-E mode. Otherwise the
88 -- HI-E compiler will reject any use of aggregates.
90 HIE_Composite_Assignments : Dummy;
91 -- The assignment of composite objects other than small records and
92 -- arrays whose size is 64-bits or less and is set by an explicit
93 -- size clause may generate calls to memcpy, memmove, and bcopy.
94 -- If certifiable versions of all these routines are available, then
95 -- this entity may be set to High_Integrity using a pragma, in which
96 -- case such assignments are permitted. Otherwise the HI-E compiler
97 -- will reject any such composite assignments.
99 end System.HIE_Back_End;