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1 /* Definitions for condition code handling in final.c and output routines.
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145
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2 Copyright (C) 1987-2020 Free Software Foundation, Inc.
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3
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4 This file is part of GCC.
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5
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6 GCC is free software; you can redistribute it and/or modify it under
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7 the terms of the GNU General Public License as published by the Free
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8 Software Foundation; either version 3, or (at your option) any later
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9 version.
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10
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11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
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13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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14 for more details.
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15
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16 You should have received a copy of the GNU General Public License
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17 along with GCC; see the file COPYING3. If not see
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18 <http://www.gnu.org/licenses/>. */
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19
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111
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20 #ifndef GCC_CONDITIONS_H
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21 #define GCC_CONDITIONS_H
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0
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22
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23 /* The variable cc_status says how to interpret the condition code.
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24 It is set by output routines for an instruction that sets the cc's
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25 and examined by output routines for jump instructions.
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26
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27 cc_status contains two components named `value1' and `value2'
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28 that record two equivalent expressions for the values that the
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29 condition codes were set from. (Either or both may be null if
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30 there is no useful expression to record.) These fields are
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31 used for eliminating redundant test and compare instructions
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32 in the cases where the condition codes were already set by the
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33 previous instruction.
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34
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35 cc_status.flags contains flags which say that the condition codes
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36 were set in a nonstandard manner. The output of jump instructions
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37 uses these flags to compensate and produce the standard result
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38 with the nonstandard condition codes. Standard flags are defined here.
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39 The tm.h file can also define other machine-dependent flags.
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40
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41 cc_status also contains a machine-dependent component `mdep'
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42 whose type, `CC_STATUS_MDEP', may be defined as a macro in the
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43 tm.h file. */
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44
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45 #ifndef CC_STATUS_MDEP
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46 #define CC_STATUS_MDEP int
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47 #endif
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48
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49 #ifndef CC_STATUS_MDEP_INIT
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50 #define CC_STATUS_MDEP_INIT 0
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51 #endif
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52
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111
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53 struct CC_STATUS {int flags; rtx value1, value2; CC_STATUS_MDEP mdep;};
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0
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54
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55 /* While outputting an insn as assembler code,
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56 this is the status BEFORE that insn. */
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57 extern CC_STATUS cc_prev_status;
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58
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59 /* While outputting an insn as assembler code,
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60 this is being altered to the status AFTER that insn. */
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61 extern CC_STATUS cc_status;
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62
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63 /* These are the machine-independent flags: */
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64
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65 /* Set if the sign of the cc value is inverted:
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66 output a following jump-if-less as a jump-if-greater, etc. */
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67 #define CC_REVERSED 1
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68
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69 /* This bit means that the current setting of the N bit is bogus
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70 and conditional jumps should use the Z bit in its place.
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71 This state obtains when an extraction of a signed single-bit field
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72 or an arithmetic shift right of a byte by 7 bits
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73 is turned into a btst, because btst does not set the N bit. */
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74 #define CC_NOT_POSITIVE 2
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75
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76 /* This bit means that the current setting of the N bit is bogus
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77 and conditional jumps should pretend that the N bit is clear.
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78 Used after extraction of an unsigned bit
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79 or logical shift right of a byte by 7 bits is turned into a btst.
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80 The btst does not alter the N bit, but the result of that shift
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81 or extract is never negative. */
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82 #define CC_NOT_NEGATIVE 4
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83
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84 /* This bit means that the current setting of the overflow flag
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85 is bogus and conditional jumps should pretend there is no overflow. */
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86 /* ??? Note that for most targets this macro is misnamed as it applies
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87 to the carry flag, not the overflow flag. */
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88 #define CC_NO_OVERFLOW 010
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89
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90 /* This bit means that what ought to be in the Z bit
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91 should be tested as the complement of the N bit. */
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92 #define CC_Z_IN_NOT_N 020
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93
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94 /* This bit means that what ought to be in the Z bit
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95 should be tested as the N bit. */
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96 #define CC_Z_IN_N 040
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97
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98 /* Nonzero if we must invert the sense of the following branch, i.e.
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99 change EQ to NE. This is not safe for IEEE floating point operations!
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100 It is intended for use only when a combination of arithmetic
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101 or logical insns can leave the condition codes set in a fortuitous
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102 (though inverted) state. */
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103 #define CC_INVERTED 0100
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104
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105 /* Nonzero if we must convert signed condition operators to unsigned.
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106 This is only used by machine description files. */
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107 #define CC_NOT_SIGNED 0200
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108
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109 /* This is how to initialize the variable cc_status.
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110 final does this at appropriate moments. */
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111
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111
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112 /* FIXME: We want to get rid of these ifndefs. */
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113 #ifndef CC_STATUS_INIT
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0
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114 #define CC_STATUS_INIT \
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115 (cc_status.flags = 0, cc_status.value1 = 0, cc_status.value2 = 0, \
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116 CC_STATUS_MDEP_INIT)
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117 #endif
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111
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118 #endif /* GCC_CONDITIONS_H */
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