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1 /* Register note definitions.
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2 Copyright (C) 2004, 2005, 2006, 2007, 2008 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 /* This file defines all the codes that may appear on individual
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21 EXPR_LIST rtxes in the REG_NOTES chain of an insn. The codes are
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22 stored in the mode field of the EXPR_LIST. Source files define
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23 DEF_REG_NOTE appropriately before including this file. */
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24
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25 /* Shorthand. */
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26 #define REG_NOTE(NAME) DEF_REG_NOTE (REG_##NAME)
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27
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28 /* REG_DEP_TRUE is used in scheduler dependencies lists to represent a
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29 read-after-write dependency (i.e. a true data dependency). This is
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30 here, not grouped with REG_DEP_ANTI and REG_DEP_OUTPUT, because some
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31 passes use a literal 0 for it. */
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32 REG_NOTE (DEP_TRUE)
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33
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34 /* The value in REG dies in this insn (i.e., it is not needed past
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35 this insn). If REG is set in this insn, the REG_DEAD note may,
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36 but need not, be omitted. */
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37 REG_NOTE (DEAD)
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38
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39 /* The REG is autoincremented or autodecremented in this insn. */
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40 REG_NOTE (INC)
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41
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42 /* Describes the insn as a whole; it says that the insn sets a
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43 register to a constant value or to be equivalent to a memory
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44 address. If the register is spilled to the stack then the constant
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45 value should be substituted for it. The contents of the REG_EQUIV
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46 is the constant value or memory address, which may be different
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47 from the source of the SET although it has the same value. A
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48 REG_EQUIV note may also appear on an insn which copies a register
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49 parameter to a pseudo-register, if there is a memory address which
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50 could be used to hold that pseudo-register throughout the function. */
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51 REG_NOTE (EQUIV)
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52
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53 /* Like REG_EQUIV except that the destination is only momentarily
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54 equal to the specified rtx. Therefore, it cannot be used for
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55 substitution; but it can be used for cse. */
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56 REG_NOTE (EQUAL)
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57
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58 /* The register is always nonnegative during the containing loop.
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59 This is used in branches so that decrement and branch instructions
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60 terminating on zero can be matched. There must be an insn pattern
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61 in the md file named `decrement_and_branch_until_zero' or else this
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62 will never be added to any instructions. */
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63 REG_NOTE (NONNEG)
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64
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65 /* Identifies a register set in this insn and never used. */
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66 REG_NOTE (UNUSED)
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67
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68 /* REG_CC_SETTER and REG_CC_USER link a pair of insns that set and use
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69 CC0, respectively. Normally, these are required to be consecutive
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70 insns, but we permit putting a cc0-setting insn in the delay slot
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71 of a branch as long as only one copy of the insn exists. In that
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72 case, these notes point from one to the other to allow code
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73 generation to determine what any require information and to
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74 properly update CC_STATUS. These notes are INSN_LISTs. */
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75 REG_NOTE (CC_SETTER)
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76 REG_NOTE (CC_USER)
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77
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78 /* Points to a CODE_LABEL. Used by JUMP_INSNs to say that the CODE_LABEL
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79 contained in the REG_LABEL_TARGET note is a possible jump target of
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80 this insn. This note is an INSN_LIST. */
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81 REG_NOTE (LABEL_TARGET)
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82
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83 /* Points to a CODE_LABEL. Used by any insn to say that the CODE_LABEL
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84 contained in the REG_LABEL_OPERAND note is used by the insn, but as an
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85 operand, not as a jump target (though it may indirectly be a jump
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86 target for a later jump insn). This note is an INSN_LIST. */
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87 REG_NOTE (LABEL_OPERAND)
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88
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89 /* REG_DEP_OUTPUT and REG_DEP_ANTI are used in scheduler dependencies lists
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90 to represent write-after-write and write-after-read dependencies
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91 respectively. */
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92 REG_NOTE (DEP_OUTPUT)
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93 REG_NOTE (DEP_ANTI)
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94
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95 /* REG_BR_PROB is attached to JUMP_INSNs and CALL_INSNs. It has an
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96 integer value. For jumps, it is the probability that this is a
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97 taken branch. For calls, it is the probability that this call
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98 won't return. */
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99 REG_NOTE (BR_PROB)
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100
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101 /* REG_VALUE_PROFILE is attached when the profile is read in to an
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102 insn before that the code to profile the value is inserted. It
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103 contains the results of profiling. */
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104 REG_NOTE (VALUE_PROFILE)
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105
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106 /* Attached to a call insn; indicates that the call is malloc-like and
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107 that the pointer returned cannot alias anything else. */
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108 REG_NOTE (NOALIAS)
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109
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110 /* REG_BR_PRED is attached to JUMP_INSNs and CALL_INSNSs. It contains
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111 CONCAT of two integer value. First specifies the branch predictor
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112 that added the note, second specifies the predicted hitrate of
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113 branch in the same format as REG_BR_PROB note uses. */
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114 REG_NOTE (BR_PRED)
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115
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116 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
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117 for DWARF to interpret what they imply. The attached rtx is used
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118 instead of intuition. */
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119 REG_NOTE (FRAME_RELATED_EXPR)
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120
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121 /* Indicates that REG holds the exception context for the function.
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122 This context is shared by inline functions, so the code to acquire
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123 the real exception context is delayed until after inlining. */
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124 REG_NOTE (EH_CONTEXT)
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125
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126 /* Indicates what exception region an INSN belongs in. This is used
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127 to indicate what region to which a call may throw. REGION 0
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128 indicates that a call cannot throw at all. REGION -1 indicates
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129 that it cannot throw, nor will it execute a non-local goto. */
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130 REG_NOTE (EH_REGION)
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131
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132 /* Used by haifa-sched to save NOTE_INSN notes across scheduling. */
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133 REG_NOTE (SAVE_NOTE)
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134
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135 /* Indicates that a call does not return. */
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136 REG_NOTE (NORETURN)
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137
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138 /* Indicates that an indirect jump is a non-local goto instead of a
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139 computed goto. */
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140 REG_NOTE (NON_LOCAL_GOTO)
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141
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142 /* Indicates that a jump crosses between hot and cold sections in a
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143 (partitioned) assembly or .o file, and therefore should not be
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144 reduced to a simpler jump by optimizations. */
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145 REG_NOTE (CROSSING_JUMP)
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146
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147 /* This kind of note is generated at each to `setjmp', and similar
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148 functions that can return twice. */
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149 REG_NOTE (SETJMP)
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