source: trunk/third/gcc/conditions.h @ 8834

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1/* Definitions for condition code handling in final.c and output routines.
2   Copyright (C) 1987 Free Software Foundation, Inc.
3
4This file is part of GNU CC.
5
6GNU CC is free software; you can redistribute it and/or modify
7it under the terms of the GNU General Public License as published by
8the Free Software Foundation; either version 2, or (at your option)
9any later version.
10
11GNU CC is distributed in the hope that it will be useful,
12but WITHOUT ANY WARRANTY; without even the implied warranty of
13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14GNU General Public License for more details.
15
16You should have received a copy of the GNU General Public License
17along with GNU CC; see the file COPYING.  If not, write to
18the Free Software Foundation, 59 Temple Place - Suite 330,
19Boston, MA 02111-1307, USA.  */
20
21/* None of the things in the files exist if we don't use CC0.  */
22
23#ifdef HAVE_cc0
24
25/* The variable cc_status says how to interpret the condition code.
26   It is set by output routines for an instruction that sets the cc's
27   and examined by output routines for jump instructions.
28
29   cc_status contains two components named `value1' and `value2'
30   that record two equivalent expressions for the values that the
31   condition codes were set from.  (Either or both may be null if
32   there is no useful expression to record.)  These fields are
33   used for eliminating redundant test and compare instructions
34   in the cases where the condition codes were already set by the
35   previous instruction.
36
37   cc_status.flags contains flags which say that the condition codes
38   were set in a nonstandard manner.  The output of jump instructions
39   uses these flags to compensate and produce the standard result
40   with the nonstandard condition codes.  Standard flags are defined here.
41   The tm.h file can also define other machine-dependent flags.
42
43   cc_status also contains a machine-dependent component `mdep'
44   whose type, `CC_STATUS_MDEP', may be defined as a macro in the
45   tm.h file.  */
46
47#ifndef CC_STATUS_MDEP
48#define CC_STATUS_MDEP int
49#endif
50
51#ifndef CC_STATUS_MDEP_INIT
52#define CC_STATUS_MDEP_INIT 0
53#endif
54
55typedef struct {int flags; rtx value1, value2; CC_STATUS_MDEP mdep;} CC_STATUS;
56
57/* While outputting an insn as assembler code,
58   this is the status BEFORE that insn.  */
59extern CC_STATUS cc_prev_status;
60
61/* While outputting an insn as assembler code,
62   this is being altered to the status AFTER that insn.  */
63extern CC_STATUS cc_status;
64
65/* These are the machine-independent flags:  */
66
67/* Set if the sign of the cc value is inverted:
68   output a following jump-if-less as a jump-if-greater, etc.  */
69#define CC_REVERSED 1
70
71/* This bit means that the current setting of the N bit is bogus
72   and conditional jumps should use the Z bit in its place.
73   This state obtains when an extraction of a signed single-bit field
74   or an arithmetic shift right of a byte by 7 bits
75   is turned into a btst, because btst does not set the N bit.  */
76#define CC_NOT_POSITIVE 2
77
78/* This bit means that the current setting of the N bit is bogus
79   and conditional jumps should pretend that the N bit is clear.
80   Used after extraction of an unsigned bit
81   or logical shift right of a byte by 7 bits is turned into a btst.
82   The btst does not alter the N bit, but the result of that shift
83   or extract is never negative.  */
84#define CC_NOT_NEGATIVE 4
85
86/* This bit means that the current setting of the overflow flag
87   is bogus and conditional jumps should pretend there is no overflow.  */
88#define CC_NO_OVERFLOW 010
89
90/* This bit means that what ought to be in the Z bit
91   should be tested as the complement of the N bit.  */
92#define CC_Z_IN_NOT_N 020
93
94/* This bit means that what ought to be in the Z bit
95   should be tested as the N bit.  */
96#define CC_Z_IN_N 040
97
98/* Nonzero if we must invert the sense of the following branch, i.e.
99   change EQ to NE.  This is not safe for IEEE floating point operations!
100   It is intended for use only when a combination of arithmetic
101   or logical insns can leave the condition codes set in a fortuitous
102   (though inverted) state.  */
103#define CC_INVERTED 0100
104
105/* Nonzero if we must convert signed condition operators to unsigned.
106   This is only used by machine description files. */
107#define CC_NOT_SIGNED 0200
108
109/* This is how to initialize the variable cc_status.
110   final does this at appropriate moments.  */
111
112#define CC_STATUS_INIT  \
113 (cc_status.flags = 0, cc_status.value1 = 0, cc_status.value2 = 0,  \
114  CC_STATUS_MDEP_INIT)
115
116#endif
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