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1.1 root 1: /* Definitions for condition code handling in final.c and output routines.
2: Copyright (C) 1987 Free Software Foundation, Inc.
3:
4: This file is part of GNU CC.
5:
6: GNU CC is free software; you can redistribute it and/or modify
7: it under the terms of the GNU General Public License as published by
8: the Free Software Foundation; either version 2, or (at your option)
9: any later version.
10:
11: GNU CC is distributed in the hope that it will be useful,
12: but WITHOUT ANY WARRANTY; without even the implied warranty of
13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14: GNU General Public License for more details.
15:
16: You should have received a copy of the GNU General Public License
17: along with GNU CC; see the file COPYING. If not, write to
1.1.1.4 ! root 18: the Free Software Foundation, 59 Temple Place - Suite 330,
! 19: Boston, MA 02111-1307, USA. */
1.1 root 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:
55: typedef 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. */
59: extern 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. */
63: extern 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!
1.1.1.2 root 100: It is intended for use only when a combination of arithmetic
1.1 root 101: or logical insns can leave the condition codes set in a fortuitous
102: (though inverted) state. */
103: #define CC_INVERTED 0100
104:
1.1.1.3 root 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:
1.1 root 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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