gcc/reg-notes.def

   1 /* Register note definitions.
   2    Copyright (C) 2004-2023 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 call insn; indicates that the call is malloc-like and
 100    that the pointer returned cannot alias anything else.  */
 101 REG_NOTE (NOALIAS)
 102
 103 /* REG_BR_PRED is attached to JUMP_INSNs.  It contains
 104    CONCAT of two integer value.  First specifies the branch predictor
 105    that added the note, second specifies the predicted hitrate of
 106    branch in a fixed point arithmetic based on REG_BR_PROB_BASE.  */
 107 REG_NOTE (BR_PRED)
 108
 109 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 110    for DWARF to interpret what they imply.  The attached rtx is used
 111    instead of intuition.  */
 112 REG_CFA_NOTE (FRAME_RELATED_EXPR)
 113
 114 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 115    for FRAME_RELATED_EXPR intuition.  The insn's first pattern must be
 116    a SET, and the destination must be the CFA register.  The attached
 117    rtx is an expression that defines the CFA.  In the simplest case, the
 118    rtx could be just the stack_pointer_rtx; more common would be a PLUS
 119    with a base register and a constant offset.  In the most complicated
 120    cases, this will result in a DW_CFA_def_cfa_expression with the rtx
 121    expression rendered in a dwarf location expression.  */
 122 REG_CFA_NOTE (CFA_DEF_CFA)
 123
 124 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 125    for FRAME_RELATED_EXPR intuition.  This note adjusts the expression
 126    from which the CFA is computed.  The attached rtx defines a new CFA
 127    expression, relative to the old CFA expression.  This rtx must be of
 128    the form (SET new-cfa-reg (PLUS old-cfa-reg const_int)).  If the note
 129    rtx is NULL, we use the first SET of the insn.  */
 130 REG_CFA_NOTE (CFA_ADJUST_CFA)
 131
 132 /* Similar to FRAME_RELATED_EXPR, with the additional information that
 133    this is a save to memory, i.e. will result in DW_CFA_offset or the
 134    like.  The pattern or the insn should be a simple store relative to
 135    the CFA.  */
 136 REG_CFA_NOTE (CFA_OFFSET)
 137
 138 /* Similar to FRAME_RELATED_EXPR, with the additional information that this
 139    is a save to a register, i.e. will result in DW_CFA_register.  The insn
 140    or the pattern should be simple reg-reg move.  */
 141 REG_CFA_NOTE (CFA_REGISTER)
 142
 143 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 144    for FRAME_RELATED_EXPR intuition.  This is a save to memory, i.e. will
 145    result in a DW_CFA_expression.  The pattern or the insn should be a
 146    store of a register to an arbitrary (non-validated) memory address.  */
 147 REG_CFA_NOTE (CFA_EXPRESSION)
 148
 149 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 150    for FRAME_RELATED_EXPR intuition.  The DWARF expression computes the value of
 151    the given register.  */
 152 REG_CFA_NOTE (CFA_VAL_EXPRESSION)
 153
 154 /* Attached to insns that are RTX_FRAME_RELATED_P, with the information
 155    that this is a restore operation, i.e. will result in DW_CFA_restore
 156    or the like.  Either the attached rtx, or the destination of the insn's
 157    first pattern is the register to be restored.  */
 158 REG_CFA_NOTE (CFA_RESTORE)
 159
 160 /* Like CFA_RESTORE but without actually emitting CFI.  This can be
 161    used to tell the verification infrastructure that a register is
 162    saved without intending to restore it.  */
 163 REG_CFA_NOTE (CFA_NO_RESTORE)
 164
 165 /* Attached to insns that are RTX_FRAME_RELATED_P, marks insn that sets
 166    vDRAP from DRAP.  If vDRAP is a register, vdrap_reg is initalized
 167    to the argument, if it is a MEM, it is ignored.  */
 168 REG_CFA_NOTE (CFA_SET_VDRAP)
 169
 170 /* Attached to insns that are RTX_FRAME_RELATED_P, indicating a window
 171    save operation, i.e. will result in a DW_CFA_GNU_window_save.
 172    The argument is ignored.  */
 173 REG_CFA_NOTE (CFA_WINDOW_SAVE)
 174
 175 /* Attached to insns that are RTX_FRAME_RELATED_P, marks the insn as
 176    requiring that all queued information should be flushed *before* insn,
 177    regardless of what is visible in the rtl.  The argument is ignored.
 178    This is normally used for a call instruction which is not exposed to
 179    the rest of the compiler as a CALL_INSN.  */
 180 REG_CFA_NOTE (CFA_FLUSH_QUEUE)
 181
 182 /* Attached to insns that are RTX_FRAME_RELATED_P, toggling the mangling status
 183    of return address.  Currently it's only used by AArch64.  The argument is
 184    ignored.  */
 185 REG_CFA_NOTE (CFA_TOGGLE_RA_MANGLE)
 186
 187 /* Indicates what exception region an INSN belongs in.  This is used
 188    to indicate what region to which a call may throw.  REGION 0
 189    indicates that a call cannot throw at all.  REGION -1 indicates
 190    that it cannot throw, nor will it execute a non-local goto.  */
 191 REG_NOTE (EH_REGION)
 192
 193 /* Used by haifa-sched to save NOTE_INSN notes across scheduling.  */
 194 REG_NOTE (SAVE_NOTE)
 195
 196 /* Indicates that a call does not return.  */
 197 REG_NOTE (NORETURN)
 198
 199 /* Indicates that an indirect jump is a non-local goto instead of a
 200    computed goto.  */
 201 REG_NOTE (NON_LOCAL_GOTO)
 202
 203 /* This kind of note is generated at each to `setjmp', and similar
 204    functions that can return twice.  */
 205 REG_NOTE (SETJMP)
 206
 207 /* This kind of note is generated at each transactional memory
 208    builtin, to indicate we need to generate transaction restart
 209    edges for this insn.  */
 210 REG_NOTE (TM)
 211
 212 /* Indicates the cumulative offset of the stack pointer accounting
 213    for pushed arguments.  This will only be generated when
 214    ACCUMULATE_OUTGOING_ARGS is false.  */
 215 REG_NOTE (ARGS_SIZE)
 216
 217 /* Used for communication between IRA and caller-save.cc, indicates
 218    that the return value of a call can be used to reinitialize a
 219    pseudo reg.  */
 220 REG_NOTE (RETURNED)
 221
 222 /* Indicates the instruction is a stack check probe that should not
 223    be combined with other stack adjustments.  */
 224 REG_NOTE (STACK_CHECK)
 225
 226 /* Used to mark a call with the function decl called by the call.
 227    The decl might not be available in the call due to splitting of the call
 228    insn.  This note is a SYMBOL_REF.  */
 229 REG_NOTE (CALL_DECL)
 230
 231 /* Indicates that the call is an untyped_call.  These calls are special
 232    in that they set all of the target ABI's return value registers to a
 233    defined value without explicitly saying so.  For example, a typical
 234    untyped_call sequence has the form:
 235
 236        (call (mem (symbol_ref "foo")))
 237        (set (reg pseudo1) (reg result1))
 238        ...
 239        (set (reg pseudon) (reg resultn))
 240
 241    The ABI specifies that result1..resultn are clobbered by the call,
 242    but the RTL does not indicate that result1..resultn are the results
 243    of the call.  */
 244 REG_NOTE (UNTYPED_CALL)
 245
 246 /* Indicate that a call should not be verified for control-flow consistency.
 247    The target address of the call is assumed as a valid address and no check
 248    to validate a branch to the target address is needed.  The call is marked
 249    when a called function has a 'notrack' attribute.  This note is used by the
 250    compiler when the option -fcf-protection=branch is specified.  */
 251 REG_NOTE (CALL_NOCF_CHECK)
 252
 253 /* The values passed to callee, for debuginfo purposes.  */
 254 REG_NOTE (CALL_ARG_LOCATION)