gcc/reg-notes.def

   1 /* Register note definitions.
   2    Copyright (C) 2004-2020 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 /* This file defines all the codes that may appear on individual
  21    EXPR_LIST, INSN_LIST and INT_LIST rtxes in the REG_NOTES chain of an insn.
  22    The codes are stored in the mode field of the rtx.  Source files
  23    define DEF_REG_NOTE appropriately before including this file.
  24
  25    CFA related notes meant for RTX_FRAME_RELATED_P instructions
  26    should be declared with REG_CFA_NOTE macro instead of REG_NOTE.  */
  27
  28 /* Shorthand.  */
  29 #define REG_NOTE(NAME) DEF_REG_NOTE (REG_##NAME)
  30 #ifndef REG_CFA_NOTE
  31 # define REG_CFA_NOTE(NAME) REG_NOTE (NAME)
  32 #endif
  33
  34 /* REG_DEP_TRUE is used in scheduler dependencies lists to represent a
  35    read-after-write dependency (i.e. a true data dependency).  This is
  36    here, not grouped with REG_DEP_ANTI and REG_DEP_OUTPUT, because some
  37    passes use a literal 0 for it.  */
  38 REG_NOTE (DEP_TRUE)
  39
  40 /* The value in REG dies in this insn (i.e., it is not needed past
  41    this insn).  If REG is set in this insn, the REG_DEAD note may,
  42    but need not, be omitted.  */
  43 REG_NOTE (DEAD)
  44
  45 /* The REG is autoincremented or autodecremented in this insn.  */
  46 REG_NOTE (INC)
  47
  48 /* Describes the insn as a whole; it says that the insn sets a
  49    register to a constant value or to be equivalent to a memory
  50    address.  If the register is spilled to the stack then the constant
  51    value should be substituted for it.  The contents of the REG_EQUIV
  52    is the constant value or memory address, which may be different
  53    from the source of the SET although it has the same value.  A
  54    REG_EQUIV note may also appear on an insn which copies a register
  55    parameter to a pseudo-register, if there is a memory address which
  56    could be used to hold that pseudo-register throughout the function.  */
  57 REG_NOTE (EQUIV)
  58
  59 /* Like REG_EQUIV except that the destination is only momentarily
  60    equal to the specified rtx.  Therefore, it cannot be used for
  61    substitution; but it can be used for cse.  */
  62 REG_NOTE (EQUAL)
  63
  64 /* The register is always nonnegative during the containing loop.
  65    This is used in branches so that decrement and branch instructions
  66    terminating on zero can be matched.  There must be an insn pattern
  67    in the md file named `decrement_and_branch_until_zero' or else this
  68    will never be added to any instructions.  */
  69 REG_NOTE (NONNEG)
  70
  71 /* Identifies a register set in this insn and never used.  */
  72 REG_NOTE (UNUSED)
  73
  74 /* REG_CC_SETTER and REG_CC_USER link a pair of insns that set and use
  75    CC0, respectively.  Normally, these are required to be consecutive
  76    insns, but we permit putting a cc0-setting insn in the delay slot
  77    of a branch as long as only one copy of the insn exists.  In that
  78    case, these notes point from one to the other to allow code
  79    generation to determine what any require information and to
  80    properly update CC_STATUS.  These notes are INSN_LISTs.  */
  81 REG_NOTE (CC_SETTER)
  82 REG_NOTE (CC_USER)
  83
  84 /* Points to a CODE_LABEL.  Used by JUMP_INSNs to say that the CODE_LABEL
  85    contained in the REG_LABEL_TARGET note is a possible jump target of
  86    this insn.  This note is an INSN_LIST.  */
  87 REG_NOTE (LABEL_TARGET)
  88
  89 /* Points to a CODE_LABEL.  Used by any insn to say that the CODE_LABEL
  90    contained in the REG_LABEL_OPERAND note is used by the insn, but as an
  91    operand, not as a jump target (though it may indirectly be a jump
  92    target for a later jump insn).  This note is an INSN_LIST.  */
  93 REG_NOTE (LABEL_OPERAND)
  94
  95 /* REG_DEP_OUTPUT and REG_DEP_ANTI are used in scheduler dependencies lists
  96    to represent write-after-write and write-after-read dependencies
  97    respectively.  */
  98 REG_NOTE (DEP_OUTPUT)
  99 REG_NOTE (DEP_ANTI)
 100 REG_NOTE (DEP_CONTROL)
 101
 102 /* REG_BR_PROB is attached to JUMP_INSNs.  It has an
 103    integer value (in an INT_LIST).  For jumps, it is the probability
 104    that this is a taken branch. The integer represents a value of
 105    profile_probability type. Use to_reg_br_prob_note and from_reg_br_prob_note
 106    to extract the actual value.  */
 107 REG_NOTE (BR_PROB)
 108
 109 /* Attached to a call insn; indicates that the call is malloc-like and
 110    that the pointer returned cannot alias anything else.  */
 111 REG_NOTE (NOALIAS)
 112
 113 /* REG_BR_PRED is attached to JUMP_INSNs.  It contains
 114    CONCAT of two integer value.  First specifies the branch predictor
 115    that added the note, second specifies the predicted hitrate of
 116    branch in a fixed point arithmetic based on REG_BR_PROB_BASE.  */
 117 REG_NOTE (BR_PRED)
 118
 119 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 120    for DWARF to interpret what they imply.  The attached rtx is used
 121    instead of intuition.  */
 122 REG_CFA_NOTE (FRAME_RELATED_EXPR)
 123
 124 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 125    for FRAME_RELATED_EXPR intuition.  The insn's first pattern must be
 126    a SET, and the destination must be the CFA register.  The attached
 127    rtx is an expression that defines the CFA.  In the simplest case, the
 128    rtx could be just the stack_pointer_rtx; more common would be a PLUS
 129    with a base register and a constant offset.  In the most complicated
 130    cases, this will result in a DW_CFA_def_cfa_expression with the rtx
 131    expression rendered in a dwarf location expression.  */
 132 REG_CFA_NOTE (CFA_DEF_CFA)
 133
 134 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 135    for FRAME_RELATED_EXPR intuition.  This note adjusts the expression
 136    from which the CFA is computed.  The attached rtx defines a new CFA
 137    expression, relative to the old CFA expression.  This rtx must be of
 138    the form (SET new-cfa-reg (PLUS old-cfa-reg const_int)).  If the note
 139    rtx is NULL, we use the first SET of the insn.  */
 140 REG_CFA_NOTE (CFA_ADJUST_CFA)
 141
 142 /* Similar to FRAME_RELATED_EXPR, with the additional information that
 143    this is a save to memory, i.e. will result in DW_CFA_offset or the
 144    like.  The pattern or the insn should be a simple store relative to
 145    the CFA.  */
 146 REG_CFA_NOTE (CFA_OFFSET)
 147
 148 /* Similar to FRAME_RELATED_EXPR, with the additional information that this
 149    is a save to a register, i.e. will result in DW_CFA_register.  The insn
 150    or the pattern should be simple reg-reg move.  */
 151 REG_CFA_NOTE (CFA_REGISTER)
 152
 153 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 154    for FRAME_RELATED_EXPR intuition.  This is a save to memory, i.e. will
 155    result in a DW_CFA_expression.  The pattern or the insn should be a
 156    store of a register to an arbitrary (non-validated) memory address.  */
 157 REG_CFA_NOTE (CFA_EXPRESSION)
 158
 159 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 160    for FRAME_RELATED_EXPR intuition.  The DWARF expression computes the value of
 161    the given register.  */
 162 REG_CFA_NOTE (CFA_VAL_EXPRESSION)
 163
 164 /* Attached to insns that are RTX_FRAME_RELATED_P, with the information
 165    that this is a restore operation, i.e. will result in DW_CFA_restore
 166    or the like.  Either the attached rtx, or the destination of the insn's
 167    first pattern is the register to be restored.  */
 168 REG_CFA_NOTE (CFA_RESTORE)
 169
 170 /* Attached to insns that are RTX_FRAME_RELATED_P, marks insn that sets
 171    vDRAP from DRAP.  If vDRAP is a register, vdrap_reg is initalized
 172    to the argument, if it is a MEM, it is ignored.  */
 173 REG_CFA_NOTE (CFA_SET_VDRAP)
 174
 175 /* Attached to insns that are RTX_FRAME_RELATED_P, indicating a window
 176    save operation, i.e. will result in a DW_CFA_GNU_window_save.
 177    The argument is ignored.  */
 178 REG_CFA_NOTE (CFA_WINDOW_SAVE)
 179
 180 /* Attached to insns that are RTX_FRAME_RELATED_P, marks the insn as
 181    requiring that all queued information should be flushed *before* insn,
 182    regardless of what is visible in the rtl.  The argument is ignored.
 183    This is normally used for a call instruction which is not exposed to
 184    the rest of the compiler as a CALL_INSN.  */
 185 REG_CFA_NOTE (CFA_FLUSH_QUEUE)
 186
 187 /* Attached to insns that are RTX_FRAME_RELATED_P, toggling the mangling status
 188    of return address.  Currently it's only used by AArch64.  The argument is
 189    ignored.  */
 190 REG_CFA_NOTE (CFA_TOGGLE_RA_MANGLE)
 191
 192 /* Indicates what exception region an INSN belongs in.  This is used
 193    to indicate what region to which a call may throw.  REGION 0
 194    indicates that a call cannot throw at all.  REGION -1 indicates
 195    that it cannot throw, nor will it execute a non-local goto.  */
 196 REG_NOTE (EH_REGION)
 197
 198 /* Used by haifa-sched to save NOTE_INSN notes across scheduling.  */
 199 REG_NOTE (SAVE_NOTE)
 200
 201 /* Indicates that a call does not return.  */
 202 REG_NOTE (NORETURN)
 203
 204 /* Indicates that an indirect jump is a non-local goto instead of a
 205    computed goto.  */
 206 REG_NOTE (NON_LOCAL_GOTO)
 207
 208 /* This kind of note is generated at each to `setjmp', and similar
 209    functions that can return twice.  */
 210 REG_NOTE (SETJMP)
 211
 212 /* This kind of note is generated at each transactional memory
 213    builtin, to indicate we need to generate transaction restart
 214    edges for this insn.  */
 215 REG_NOTE (TM)
 216
 217 /* Indicates the cumulative offset of the stack pointer accounting
 218    for pushed arguments.  This will only be generated when
 219    ACCUMULATE_OUTGOING_ARGS is false.  */
 220 REG_NOTE (ARGS_SIZE)
 221
 222 /* Used for communication between IRA and caller-save.c, indicates
 223    that the return value of a call can be used to reinitialize a
 224    pseudo reg.  */
 225 REG_NOTE (RETURNED)
 226
 227 /* Indicates the instruction is a stack check probe that should not
 228    be combined with other stack adjustments.  */
 229 REG_NOTE (STACK_CHECK)
 230
 231 /* Used to mark a call with the function decl called by the call.
 232    The decl might not be available in the call due to splitting of the call
 233    insn.  This note is a SYMBOL_REF.  */
 234 REG_NOTE (CALL_DECL)
 235
 236 /* Indicate that a call should not be verified for control-flow consistency.
 237    The target address of the call is assumed as a valid address and no check
 238    to validate a branch to the target address is needed.  The call is marked
 239    when a called function has a 'notrack' attribute.  This note is used by the
 240    compiler when the option -fcf-protection=branch is specified.  */
 241 REG_NOTE (CALL_NOCF_CHECK)
 242
 243 /* The values passed to callee, for debuginfo purposes.  */
 244 REG_NOTE (CALL_ARG_LOCATION)