gcc/reg-notes.def

   1 /* Register note definitions.
   2    Copyright (C) 2004, 2005, 2006, 2007, 2008 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 rtxes in the REG_NOTES chain of an insn.  The codes are
  22    stored in the mode field of the EXPR_LIST.  Source files define
  23    DEF_REG_NOTE appropriately before including this file.  */
  24
  25 /* Shorthand.  */
  26 #define REG_NOTE(NAME) DEF_REG_NOTE (REG_##NAME)
  27
  28 /* REG_DEP_TRUE is used in scheduler dependencies lists to represent a
  29    read-after-write dependency (i.e. a true data dependency).  This is
  30    here, not grouped with REG_DEP_ANTI and REG_DEP_OUTPUT, because some
  31    passes use a literal 0 for it.  */
  32 REG_NOTE (DEP_TRUE)
  33
  34 /* The value in REG dies in this insn (i.e., it is not needed past
  35    this insn).  If REG is set in this insn, the REG_DEAD note may,
  36    but need not, be omitted.  */
  37 REG_NOTE (DEAD)
  38
  39 /* The REG is autoincremented or autodecremented in this insn.  */
  40 REG_NOTE (INC)
  41
  42 /* Describes the insn as a whole; it says that the insn sets a
  43    register to a constant value or to be equivalent to a memory
  44    address.  If the register is spilled to the stack then the constant
  45    value should be substituted for it.  The contents of the REG_EQUIV
  46    is the constant value or memory address, which may be different
  47    from the source of the SET although it has the same value.  A
  48    REG_EQUIV note may also appear on an insn which copies a register
  49    parameter to a pseudo-register, if there is a memory address which
  50    could be used to hold that pseudo-register throughout the function.  */
  51 REG_NOTE (EQUIV)
  52
  53 /* Like REG_EQUIV except that the destination is only momentarily
  54    equal to the specified rtx.  Therefore, it cannot be used for
  55    substitution; but it can be used for cse.  */
  56 REG_NOTE (EQUAL)
  57
  58 /* The register is always nonnegative during the containing loop.
  59    This is used in branches so that decrement and branch instructions
  60    terminating on zero can be matched.  There must be an insn pattern
  61    in the md file named `decrement_and_branch_until_zero' or else this
  62    will never be added to any instructions.  */
  63 REG_NOTE (NONNEG)
  64
  65 /* Identifies a register set in this insn and never used.  */
  66 REG_NOTE (UNUSED)
  67
  68 /* REG_CC_SETTER and REG_CC_USER link a pair of insns that set and use
  69    CC0, respectively.  Normally, these are required to be consecutive
  70    insns, but we permit putting a cc0-setting insn in the delay slot
  71    of a branch as long as only one copy of the insn exists.  In that
  72    case, these notes point from one to the other to allow code
  73    generation to determine what any require information and to
  74    properly update CC_STATUS.  These notes are INSN_LISTs.  */
  75 REG_NOTE (CC_SETTER)
  76 REG_NOTE (CC_USER)
  77
  78 /* Points to a CODE_LABEL.  Used by JUMP_INSNs to say that the CODE_LABEL
  79    contained in the REG_LABEL_TARGET note is a possible jump target of
  80    this insn.  This note is an INSN_LIST.  */
  81 REG_NOTE (LABEL_TARGET)
  82
  83 /* Points to a CODE_LABEL.  Used by any insn to say that the CODE_LABEL
  84    contained in the REG_LABEL_OPERAND note is used by the insn, but as an
  85    operand, not as a jump target (though it may indirectly be a jump
  86    target for a later jump insn).  This note is an INSN_LIST.  */
  87 REG_NOTE (LABEL_OPERAND)
  88
  89 /* REG_DEP_OUTPUT and REG_DEP_ANTI are used in scheduler dependencies lists
  90    to represent write-after-write and write-after-read dependencies
  91    respectively.  */
  92 REG_NOTE (DEP_OUTPUT)
  93 REG_NOTE (DEP_ANTI)
  94
  95 /* REG_BR_PROB is attached to JUMP_INSNs and CALL_INSNs.  It has an
  96    integer value.  For jumps, it is the probability that this is a
  97    taken branch.  For calls, it is the probability that this call
  98    won't return.  */
  99 REG_NOTE (BR_PROB)
 100
 101 /* REG_VALUE_PROFILE is attached when the profile is read in to an
 102    insn before that the code to profile the value is inserted.  It
 103    contains the results of profiling.  */
 104 REG_NOTE (VALUE_PROFILE)
 105
 106 /* Attached to a call insn; indicates that the call is malloc-like and
 107    that the pointer returned cannot alias anything else.  */
 108 REG_NOTE (NOALIAS)
 109
 110 /* REG_BR_PRED is attached to JUMP_INSNs and CALL_INSNSs.  It contains
 111    CONCAT of two integer value.  First specifies the branch predictor
 112    that added the note, second specifies the predicted hitrate of
 113    branch in the same format as REG_BR_PROB note uses.  */
 114 REG_NOTE (BR_PRED)
 115
 116 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 117    for DWARF to interpret what they imply.  The attached rtx is used
 118    instead of intuition.  */
 119 REG_NOTE (FRAME_RELATED_EXPR)
 120
 121 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 122    for FRAME_RELATED_EXPR intuition.  The insn's first pattern must be
 123    a SET, and the destination must be the CFA register.  The attached
 124    rtx is an expression that defines the CFA.  In the simplest case, the
 125    rtx could be just the stack_pointer_rtx; more common would be a PLUS
 126    with a base register and a constant offset.  In the most complicated
 127    cases, this will result in a DW_CFA_def_cfa_expression with the rtx
 128    expression rendered in a dwarf location expression.  */
 129 REG_NOTE (CFA_DEF_CFA)
 130
 131 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 132    for FRAME_RELATED_EXPR intuition.  This note adjusts the expression
 133    from which the CFA is computed.  The attached rtx defines a new CFA
 134    expression, relative to the old CFA expression.  This rtx must be of
 135    the form (SET new-cfa-reg (PLUS old-cfa-reg const_int)).  If the note
 136    rtx is NULL, we use the first SET of the insn.  */
 137 REG_NOTE (CFA_ADJUST_CFA)
 138
 139 /* Similar to FRAME_RELATED_EXPR, with the additional information that
 140    this is a save to memory, i.e. will result in DW_CFA_offset or the
 141    like.  The pattern or the insn should be a simple store relative to
 142    the CFA.  */
 143 REG_NOTE (CFA_OFFSET)
 144
 145 /* Similar to FRAME_RELATED_EXPR, with the additional information that this
 146    is a save to a register, i.e. will result in DW_CFA_register.  The insn
 147    or the pattern should be simple reg-reg move.  */
 148 REG_NOTE (CFA_REGISTER)
 149
 150 /* Attached to insns that are RTX_FRAME_RELATED_P, with the information
 151    that this is a restore operation, i.e. will result in DW_CFA_restore
 152    or the like.  Either the attached rtx, or the destination of the insn's
 153    first pattern is the register to be restored.  */
 154 REG_NOTE (CFA_RESTORE)
 155
 156 /* Indicates that REG holds the exception context for the function.
 157    This context is shared by inline functions, so the code to acquire
 158    the real exception context is delayed until after inlining.  */
 159 REG_NOTE (EH_CONTEXT)
 160
 161 /* Indicates what exception region an INSN belongs in.  This is used
 162    to indicate what region to which a call may throw.  REGION 0
 163    indicates that a call cannot throw at all.  REGION -1 indicates
 164    that it cannot throw, nor will it execute a non-local goto.  */
 165 REG_NOTE (EH_REGION)
 166
 167 /* Used by haifa-sched to save NOTE_INSN notes across scheduling.  */
 168 REG_NOTE (SAVE_NOTE)
 169
 170 /* Indicates that a call does not return.  */
 171 REG_NOTE (NORETURN)
 172
 173 /* Indicates that an indirect jump is a non-local goto instead of a
 174    computed goto.  */
 175 REG_NOTE (NON_LOCAL_GOTO)
 176
 177 /* Indicates that a jump crosses between hot and cold sections in a
 178    (partitioned) assembly or .o file, and therefore should not be
 179    reduced to a simpler jump by optimizations.  */
 180 REG_NOTE (CROSSING_JUMP)
 181
 182 /* This kind of note is generated at each to `setjmp', and similar
 183    functions that can return twice.  */
 184 REG_NOTE (SETJMP)