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1 /* Definitions for condition code handling in final.c and output routines.
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2 Copyright (C) 1987, 2007 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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20 /* None of the things in the files exist if we don't use CC0. */
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21
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22 #ifdef HAVE_cc0
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23
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24 /* The variable cc_status says how to interpret the condition code.
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25 It is set by output routines for an instruction that sets the cc's
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26 and examined by output routines for jump instructions.
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27
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28 cc_status contains two components named `value1' and `value2'
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29 that record two equivalent expressions for the values that the
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30 condition codes were set from. (Either or both may be null if
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31 there is no useful expression to record.) These fields are
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32 used for eliminating redundant test and compare instructions
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33 in the cases where the condition codes were already set by the
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34 previous instruction.
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35
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36 cc_status.flags contains flags which say that the condition codes
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37 were set in a nonstandard manner. The output of jump instructions
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38 uses these flags to compensate and produce the standard result
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39 with the nonstandard condition codes. Standard flags are defined here.
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40 The tm.h file can also define other machine-dependent flags.
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41
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42 cc_status also contains a machine-dependent component `mdep'
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43 whose type, `CC_STATUS_MDEP', may be defined as a macro in the
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44 tm.h file. */
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45
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46 #ifndef CC_STATUS_MDEP
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47 #define CC_STATUS_MDEP int
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48 #endif
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49
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50 #ifndef CC_STATUS_MDEP_INIT
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51 #define CC_STATUS_MDEP_INIT 0
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52 #endif
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53
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54 typedef struct {int flags; rtx value1, value2; CC_STATUS_MDEP mdep;} CC_STATUS;
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55
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56 /* While outputting an insn as assembler code,
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57 this is the status BEFORE that insn. */
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58 extern CC_STATUS cc_prev_status;
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59
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60 /* While outputting an insn as assembler code,
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61 this is being altered to the status AFTER that insn. */
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62 extern CC_STATUS cc_status;
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63
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64 /* These are the machine-independent flags: */
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65
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66 /* Set if the sign of the cc value is inverted:
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67 output a following jump-if-less as a jump-if-greater, etc. */
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68 #define CC_REVERSED 1
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69
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70 /* This bit means that the current setting of the N bit is bogus
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71 and conditional jumps should use the Z bit in its place.
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72 This state obtains when an extraction of a signed single-bit field
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73 or an arithmetic shift right of a byte by 7 bits
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74 is turned into a btst, because btst does not set the N bit. */
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75 #define CC_NOT_POSITIVE 2
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76
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77 /* This bit means that the current setting of the N bit is bogus
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78 and conditional jumps should pretend that the N bit is clear.
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79 Used after extraction of an unsigned bit
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80 or logical shift right of a byte by 7 bits is turned into a btst.
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81 The btst does not alter the N bit, but the result of that shift
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82 or extract is never negative. */
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83 #define CC_NOT_NEGATIVE 4
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84
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85 /* This bit means that the current setting of the overflow flag
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86 is bogus and conditional jumps should pretend there is no overflow. */
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87 /* ??? Note that for most targets this macro is misnamed as it applies
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88 to the carry flag, not the overflow flag. */
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89 #define CC_NO_OVERFLOW 010
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90
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91 /* This bit means that what ought to be in the Z bit
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92 should be tested as the complement of the N bit. */
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93 #define CC_Z_IN_NOT_N 020
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94
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95 /* This bit means that what ought to be in the Z bit
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96 should be tested as the N bit. */
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97 #define CC_Z_IN_N 040
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98
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99 /* Nonzero if we must invert the sense of the following branch, i.e.
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100 change EQ to NE. This is not safe for IEEE floating point operations!
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101 It is intended for use only when a combination of arithmetic
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102 or logical insns can leave the condition codes set in a fortuitous
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103 (though inverted) state. */
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104 #define CC_INVERTED 0100
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105
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106 /* Nonzero if we must convert signed condition operators to unsigned.
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107 This is only used by machine description files. */
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108 #define CC_NOT_SIGNED 0200
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109
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110 /* This is how to initialize the variable cc_status.
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111 final does this at appropriate moments. */
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112
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113 #define CC_STATUS_INIT \
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114 (cc_status.flags = 0, cc_status.value1 = 0, cc_status.value2 = 0, \
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115 CC_STATUS_MDEP_INIT)
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116
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117 #endif
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