gcc/reg-notes.def

   1 /* Register note definitions.
   2    Copyright (C) 2004-2017 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 and CALL_INSNs.  It has an
 103    integer value (in an INT_LIST).  For jumps, it is the probability
 104    that this is a taken branch.  For calls, it is the probability that
 105    this call won't return.  */
 106 REG_NOTE (BR_PROB)
 107
 108 /* Attached to a call insn; indicates that the call is malloc-like and
 109    that the pointer returned cannot alias anything else.  */
 110 REG_NOTE (NOALIAS)
 111
 112 /* REG_BR_PRED is attached to JUMP_INSNs and CALL_INSNSs.  It contains
 113    CONCAT of two integer value.  First specifies the branch predictor
 114    that added the note, second specifies the predicted hitrate of
 115    branch in the same format as REG_BR_PROB note uses.  */
 116 REG_NOTE (BR_PRED)
 117
 118 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 119    for DWARF to interpret what they imply.  The attached rtx is used
 120    instead of intuition.  */
 121 REG_CFA_NOTE (FRAME_RELATED_EXPR)
 122
 123 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 124    for FRAME_RELATED_EXPR intuition.  The insn's first pattern must be
 125    a SET, and the destination must be the CFA register.  The attached
 126    rtx is an expression that defines the CFA.  In the simplest case, the
 127    rtx could be just the stack_pointer_rtx; more common would be a PLUS
 128    with a base register and a constant offset.  In the most complicated
 129    cases, this will result in a DW_CFA_def_cfa_expression with the rtx
 130    expression rendered in a dwarf location expression.  */
 131 REG_CFA_NOTE (CFA_DEF_CFA)
 132
 133 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 134    for FRAME_RELATED_EXPR intuition.  This note adjusts the expression
 135    from which the CFA is computed.  The attached rtx defines a new CFA
 136    expression, relative to the old CFA expression.  This rtx must be of
 137    the form (SET new-cfa-reg (PLUS old-cfa-reg const_int)).  If the note
 138    rtx is NULL, we use the first SET of the insn.  */
 139 REG_CFA_NOTE (CFA_ADJUST_CFA)
 140
 141 /* Similar to FRAME_RELATED_EXPR, with the additional information that
 142    this is a save to memory, i.e. will result in DW_CFA_offset or the
 143    like.  The pattern or the insn should be a simple store relative to
 144    the CFA.  */
 145 REG_CFA_NOTE (CFA_OFFSET)
 146
 147 /* Similar to FRAME_RELATED_EXPR, with the additional information that this
 148    is a save to a register, i.e. will result in DW_CFA_register.  The insn
 149    or the pattern should be simple reg-reg move.  */
 150 REG_CFA_NOTE (CFA_REGISTER)
 151
 152 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 153    for FRAME_RELATED_EXPR intuition.  This is a save to memory, i.e. will
 154    result in a DW_CFA_expression.  The pattern or the insn should be a
 155    store of a register to an arbitrary (non-validated) memory address.  */
 156 REG_CFA_NOTE (CFA_EXPRESSION)
 157
 158 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 159    for FRAME_RELATED_EXPR intuition.  The DWARF expression computes the value of
 160    the given register.  */
 161 REG_CFA_NOTE (CFA_VAL_EXPRESSION)
 162
 163 /* Attached to insns that are RTX_FRAME_RELATED_P, with the information
 164    that this is a restore operation, i.e. will result in DW_CFA_restore
 165    or the like.  Either the attached rtx, or the destination of the insn's
 166    first pattern is the register to be restored.  */
 167 REG_CFA_NOTE (CFA_RESTORE)
 168
 169 /* Attached to insns that are RTX_FRAME_RELATED_P, marks insn that sets
 170    vDRAP from DRAP.  If vDRAP is a register, vdrap_reg is initalized
 171    to the argument, if it is a MEM, it is ignored.  */
 172 REG_CFA_NOTE (CFA_SET_VDRAP)
 173
 174 /* Attached to insns that are RTX_FRAME_RELATED_P, indicating a window
 175    save operation, i.e. will result in a DW_CFA_GNU_window_save.
 176    The argument is ignored.  */
 177 REG_CFA_NOTE (CFA_WINDOW_SAVE)
 178
 179 /* Attached to insns that are RTX_FRAME_RELATED_P, marks the insn as
 180    requiring that all queued information should be flushed *before* insn,
 181    regardless of what is visible in the rtl.  The argument is ignored.
 182    This is normally used for a call instruction which is not exposed to
 183    the rest of the compiler as a CALL_INSN.  */
 184 REG_CFA_NOTE (CFA_FLUSH_QUEUE)
 185
 186 /* Attached to insns that are RTX_FRAME_RELATED_P, toggling the mangling status
 187    of return address.  Currently it's only used by AArch64.  The argument is
 188    ignored.  */
 189 REG_CFA_NOTE (CFA_TOGGLE_RA_MANGLE)
 190
 191 /* Indicates what exception region an INSN belongs in.  This is used
 192    to indicate what region to which a call may throw.  REGION 0
 193    indicates that a call cannot throw at all.  REGION -1 indicates
 194    that it cannot throw, nor will it execute a non-local goto.  */
 195 REG_NOTE (EH_REGION)
 196
 197 /* Used by haifa-sched to save NOTE_INSN notes across scheduling.  */
 198 REG_NOTE (SAVE_NOTE)
 199
 200 /* Indicates that a call does not return.  */
 201 REG_NOTE (NORETURN)
 202
 203 /* Indicates that an indirect jump is a non-local goto instead of a
 204    computed goto.  */
 205 REG_NOTE (NON_LOCAL_GOTO)
 206
 207 /* This kind of note is generated at each to `setjmp', and similar
 208    functions that can return twice.  */
 209 REG_NOTE (SETJMP)
 210
 211 /* This kind of note is generated at each transactional memory
 212    builtin, to indicate we need to generate transaction restart
 213    edges for this insn.  */
 214 REG_NOTE (TM)
 215
 216 /* Indicates the cumulative offset of the stack pointer accounting
 217    for pushed arguments.  This will only be generated when
 218    ACCUMULATE_OUTGOING_ARGS is false.  */
 219 REG_NOTE (ARGS_SIZE)
 220
 221 /* Used for communication between IRA and caller-save.c, indicates
 222    that the return value of a call can be used to reinitialize a
 223    pseudo reg.  */
 224 REG_NOTE (RETURNED)
 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)