gcc/reg-notes.def

   1 /* Register note definitions.
   2    Copyright (C) 2004-2024 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 /* Points to a CODE_LABEL.  Used by JUMP_INSNs to say that the CODE_LABEL
  75    contained in the REG_LABEL_TARGET note is a possible jump target of
  76    this insn.  This note is an INSN_LIST.  */
  77 REG_NOTE (LABEL_TARGET)
  78
  79 /* Points to a CODE_LABEL.  Used by any insn to say that the CODE_LABEL
  80    contained in the REG_LABEL_OPERAND note is used by the insn, but as an
  81    operand, not as a jump target (though it may indirectly be a jump
  82    target for a later jump insn).  This note is an INSN_LIST.  */
  83 REG_NOTE (LABEL_OPERAND)
  84
  85 /* REG_DEP_OUTPUT and REG_DEP_ANTI are used in scheduler dependencies lists
  86    to represent write-after-write and write-after-read dependencies
  87    respectively.  */
  88 REG_NOTE (DEP_OUTPUT)
  89 REG_NOTE (DEP_ANTI)
  90 REG_NOTE (DEP_CONTROL)
  91
  92 /* REG_BR_PROB is attached to JUMP_INSNs.  It has an
  93    integer value (in an INT_LIST).  For jumps, it is the probability
  94    that this is a taken branch. The integer represents a value of
  95    profile_probability type. Use to_reg_br_prob_note and from_reg_br_prob_note
  96    to extract the actual value.  */
  97 REG_NOTE (BR_PROB)
  98
  99 /* Attached to a move insn which receives the result of a call; indicates that
 100    the call is malloc-like and that the pointer returned cannot alias anything
 101    else.  */
 102 REG_NOTE (NOALIAS)
 103
 104 /* REG_BR_PRED is attached to JUMP_INSNs.  It contains
 105    CONCAT of two integer value.  First specifies the branch predictor
 106    that added the note, second specifies the predicted hitrate of
 107    branch in a fixed point arithmetic based on REG_BR_PROB_BASE.  */
 108 REG_NOTE (BR_PRED)
 109
 110 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 111    for DWARF to interpret what they imply.  The attached rtx is used
 112    instead of intuition.  */
 113 REG_CFA_NOTE (FRAME_RELATED_EXPR)
 114
 115 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 116    for FRAME_RELATED_EXPR intuition.  The insn's first pattern must be
 117    a SET, and the destination must be the CFA register.  The attached
 118    rtx is an expression that defines the CFA.  In the simplest case, the
 119    rtx could be just the stack_pointer_rtx; more common would be a PLUS
 120    with a base register and a constant offset.  In the most complicated
 121    cases, this will result in a DW_CFA_def_cfa_expression with the rtx
 122    expression rendered in a dwarf location expression.  */
 123 REG_CFA_NOTE (CFA_DEF_CFA)
 124
 125 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 126    for FRAME_RELATED_EXPR intuition.  This note adjusts the expression
 127    from which the CFA is computed.  The attached rtx defines a new CFA
 128    expression, relative to the old CFA expression.  This rtx must be of
 129    the form (SET new-cfa-reg (PLUS old-cfa-reg const_int)).  If the note
 130    rtx is NULL, we use the first SET of the insn.  */
 131 REG_CFA_NOTE (CFA_ADJUST_CFA)
 132
 133 /* Similar to FRAME_RELATED_EXPR, with the additional information that
 134    this is a save to memory, i.e. will result in DW_CFA_offset or the
 135    like.  The pattern or the insn should be a simple store relative to
 136    the CFA.  */
 137 REG_CFA_NOTE (CFA_OFFSET)
 138
 139 /* Similar to FRAME_RELATED_EXPR, with the additional information that this
 140    is a save to a register, i.e. will result in DW_CFA_register.  The insn
 141    or the pattern should be simple reg-reg move.  */
 142 REG_CFA_NOTE (CFA_REGISTER)
 143
 144 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 145    for FRAME_RELATED_EXPR intuition.  This is a save to memory, i.e. will
 146    result in a DW_CFA_expression.  The pattern or the insn should be a
 147    store of a register to an arbitrary (non-validated) memory address.  */
 148 REG_CFA_NOTE (CFA_EXPRESSION)
 149
 150 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 151    for FRAME_RELATED_EXPR intuition.  The DWARF expression computes the value of
 152    the given register.  */
 153 REG_CFA_NOTE (CFA_VAL_EXPRESSION)
 154
 155 /* Attached to insns that are RTX_FRAME_RELATED_P, with the information
 156    that this is a restore operation, i.e. will result in DW_CFA_restore
 157    or the like.  Either the attached rtx, or the destination of the insn's
 158    first pattern is the register to be restored.  */
 159 REG_CFA_NOTE (CFA_RESTORE)
 160
 161 /* Like CFA_RESTORE but without actually emitting CFI.  This can be
 162    used to tell the verification infrastructure that a register is
 163    saved without intending to restore it.  */
 164 REG_CFA_NOTE (CFA_NO_RESTORE)
 165
 166 /* Attached to insns that are RTX_FRAME_RELATED_P, marks insn that sets
 167    vDRAP from DRAP.  If vDRAP is a register, vdrap_reg is initalized
 168    to the argument, if it is a MEM, it is ignored.  */
 169 REG_CFA_NOTE (CFA_SET_VDRAP)
 170
 171 /* Attached to insns that are RTX_FRAME_RELATED_P, indicating a window
 172    save operation, i.e. will result in a DW_CFA_GNU_window_save.
 173    The argument is ignored.  */
 174 REG_CFA_NOTE (CFA_WINDOW_SAVE)
 175
 176 /* Attached to insns that are RTX_FRAME_RELATED_P, marks the insn as
 177    requiring that all queued information should be flushed *before* insn,
 178    regardless of what is visible in the rtl.  The argument is ignored.
 179    This is normally used for a call instruction which is not exposed to
 180    the rest of the compiler as a CALL_INSN.  */
 181 REG_CFA_NOTE (CFA_FLUSH_QUEUE)
 182
 183 /* Attached to insns that are RTX_FRAME_RELATED_P, toggling the mangling status
 184    of return address.  Currently it's only used by AArch64.  The argument is
 185    ignored.  */
 186 REG_CFA_NOTE (CFA_TOGGLE_RA_MANGLE)
 187
 188 /* Indicates what exception region an INSN belongs in.  This is used
 189    to indicate what region to which a call may throw.  REGION 0
 190    indicates that a call cannot throw at all.  REGION -1 indicates
 191    that it cannot throw, nor will it execute a non-local goto.  */
 192 REG_NOTE (EH_REGION)
 193
 194 /* Used by haifa-sched to save NOTE_INSN notes across scheduling.  */
 195 REG_NOTE (SAVE_NOTE)
 196
 197 /* Indicates that a call does not return.  */
 198 REG_NOTE (NORETURN)
 199
 200 /* Indicates that an indirect jump is a non-local goto instead of a
 201    computed goto.  */
 202 REG_NOTE (NON_LOCAL_GOTO)
 203
 204 /* This kind of note is generated at each to `setjmp', and similar
 205    functions that can return twice.  */
 206 REG_NOTE (SETJMP)
 207
 208 /* This kind of note is generated at each transactional memory
 209    builtin, to indicate we need to generate transaction restart
 210    edges for this insn.  */
 211 REG_NOTE (TM)
 212
 213 /* Indicates the cumulative offset of the stack pointer accounting
 214    for pushed arguments.  This will only be generated when
 215    ACCUMULATE_OUTGOING_ARGS is false.  */
 216 REG_NOTE (ARGS_SIZE)
 217
 218 /* Used for communication between IRA and caller-save.cc, indicates
 219    that the return value of a call can be used to reinitialize a
 220    pseudo reg.  */
 221 REG_NOTE (RETURNED)
 222
 223 /* Indicates the instruction is a stack check probe that should not
 224    be combined with other stack adjustments.  */
 225 REG_NOTE (STACK_CHECK)
 226
 227 /* Used to mark a call with the function decl called by the call.
 228    The decl might not be available in the call due to splitting of the call
 229    insn.  This note is a SYMBOL_REF.  */
 230 REG_NOTE (CALL_DECL)
 231
 232 /* Indicates that the call is an untyped_call.  These calls are special
 233    in that they set all of the target ABI's return value registers to a
 234    defined value without explicitly saying so.  For example, a typical
 235    untyped_call sequence has the form:
 236
 237        (call (mem (symbol_ref "foo")))
 238        (set (reg pseudo1) (reg result1))
 239        ...
 240        (set (reg pseudon) (reg resultn))
 241
 242    The ABI specifies that result1..resultn are clobbered by the call,
 243    but the RTL does not indicate that result1..resultn are the results
 244    of the call.  */
 245 REG_NOTE (UNTYPED_CALL)
 246
 247 /* Indicate that a call should not be verified for control-flow consistency.
 248    The target address of the call is assumed as a valid address and no check
 249    to validate a branch to the target address is needed.  The call is marked
 250    when a called function has a 'notrack' attribute.  This note is used by the
 251    compiler when the option -fcf-protection=branch is specified.  */
 252 REG_NOTE (CALL_NOCF_CHECK)
 253
 254 /* The values passed to callee, for debuginfo purposes.  */
 255 REG_NOTE (CALL_ARG_LOCATION)