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
|
/* Definitions of target machine for GNU compiler, for CRIS.
Copyright (C) 2002-2021 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful,
but WITHOUT 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
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
/* Node: Condition Code */
/* The mode used for condition-codes depends on both the way the
condition-codes are generated (the CC-setter, typically the compare
instruction), and used (the CC-user, typically a branch). For CRIS, we
have ordinary compares and incidental condition-code settings from
preceding instructions, setting a subset of N, Z, V and C to usable
values, from the perspective of comparing the result against zero
(referred to below as "fpcraz"). The two subsets meaningful to gcc are
all of N, Z, V, C versus just N, Z; some CC-users care only about N
and/or Z and some that care about at least one of those flags together
with V and/or C.
The plain "CC_MODE (CC)" (which is always present in gcc), is used to
reflect the "unoptimized" state, where the CC-setter is a compare
against zero and the CC-user is any branch or s<condition> instruction,
before reload. After reload, a need for C or V is reflected as
CC_NZVCmode in both setters and users, and others remain CCmode, until
or if optimization of CC-setter and CC-users, when CCmode setters can
be changed or replaced by either CC_NZmode or CC_NZVCmode. To wit, all
users that require CC_NZVCmode must match only that mode at any time.
All other users must match all of CCmode, CC_NZmode, and CC_NZVCmode.
All setters that set only CC_NZmode must match setting only that mode.
All other setters must match setting all of CCmode, CC_NZmode, and
CC_NZVCmode.
There's also other modes (i.e. CC_ZnNmode) with a separate set of
setters and users not matched by the others. */
/* Z and N flags only. For a condition-code setter: only the Z and N
flags are set to usable values, fpcraz. For a condition-code user: the
operation using the condition codes only care about the Z and N flags. */
CC_MODE (CC_NZ);
/* Z and N *and* V and C flags. For a condition-code setter: all flags
are set to usable values, fpcraz. For a condition-code user: at least
one of V and C are used and possibly N and Z too. */
CC_MODE (CC_NZVC);
/* The result of a btst / btstq instruction for extracting a single bit
goes negated into the N flag, or in olde cc0-parlance, CC_Z_IN_NOT_N. */
CC_MODE (CC_ZnN);
|
