gcc/reg-notes.def

   1 /* Register note definitions.
   2    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010
   3    Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 /* This file defines all the codes that may appear on individual
  22    EXPR_LIST rtxes in the REG_NOTES chain of an insn.  The codes are
  23    stored in the mode field of the EXPR_LIST.  Source files define
  24    DEF_REG_NOTE appropriately before including this file.  */
  25
  26 /* Shorthand.  */
  27 #define REG_NOTE(NAME) DEF_REG_NOTE (REG_##NAME)
  28
  29 /* REG_DEP_TRUE is used in scheduler dependencies lists to represent a
  30    read-after-write dependency (i.e. a true data dependency).  This is
  31    here, not grouped with REG_DEP_ANTI and REG_DEP_OUTPUT, because some
  32    passes use a literal 0 for it.  */
  33 REG_NOTE (DEP_TRUE)
  34
  35 /* The value in REG dies in this insn (i.e., it is not needed past
  36    this insn).  If REG is set in this insn, the REG_DEAD note may,
  37    but need not, be omitted.  */
  38 REG_NOTE (DEAD)
  39
  40 /* The REG is autoincremented or autodecremented in this insn.  */
  41 REG_NOTE (INC)
  42
  43 /* Describes the insn as a whole; it says that the insn sets a
  44    register to a constant value or to be equivalent to a memory
  45    address.  If the register is spilled to the stack then the constant
  46    value should be substituted for it.  The contents of the REG_EQUIV
  47    is the constant value or memory address, which may be different
  48    from the source of the SET although it has the same value.  A
  49    REG_EQUIV note may also appear on an insn which copies a register
  50    parameter to a pseudo-register, if there is a memory address which
  51    could be used to hold that pseudo-register throughout the function.  */
  52 REG_NOTE (EQUIV)
  53
  54 /* Like REG_EQUIV except that the destination is only momentarily
  55    equal to the specified rtx.  Therefore, it cannot be used for
  56    substitution; but it can be used for cse.  */
  57 REG_NOTE (EQUAL)
  58
  59 /* The register is always nonnegative during the containing loop.
  60    This is used in branches so that decrement and branch instructions
  61    terminating on zero can be matched.  There must be an insn pattern
  62    in the md file named `decrement_and_branch_until_zero' or else this
  63    will never be added to any instructions.  */
  64 REG_NOTE (NONNEG)
  65
  66 /* Identifies a register set in this insn and never used.  */
  67 REG_NOTE (UNUSED)
  68
  69 /* REG_CC_SETTER and REG_CC_USER link a pair of insns that set and use
  70    CC0, respectively.  Normally, these are required to be consecutive
  71    insns, but we permit putting a cc0-setting insn in the delay slot
  72    of a branch as long as only one copy of the insn exists.  In that
  73    case, these notes point from one to the other to allow code
  74    generation to determine what any require information and to
  75    properly update CC_STATUS.  These notes are INSN_LISTs.  */
  76 REG_NOTE (CC_SETTER)
  77 REG_NOTE (CC_USER)
  78
  79 /* Points to a CODE_LABEL.  Used by JUMP_INSNs to say that the CODE_LABEL
  80    contained in the REG_LABEL_TARGET note is a possible jump target of
  81    this insn.  This note is an INSN_LIST.  */
  82 REG_NOTE (LABEL_TARGET)
  83
  84 /* Points to a CODE_LABEL.  Used by any insn to say that the CODE_LABEL
  85    contained in the REG_LABEL_OPERAND note is used by the insn, but as an
  86    operand, not as a jump target (though it may indirectly be a jump
  87    target for a later jump insn).  This note is an INSN_LIST.  */
  88 REG_NOTE (LABEL_OPERAND)
  89
  90 /* REG_DEP_OUTPUT and REG_DEP_ANTI are used in scheduler dependencies lists
  91    to represent write-after-write and write-after-read dependencies
  92    respectively.  */
  93 REG_NOTE (DEP_OUTPUT)
  94 REG_NOTE (DEP_ANTI)
  95
  96 /* REG_BR_PROB is attached to JUMP_INSNs and CALL_INSNs.  It has an
  97    integer value.  For jumps, it is the probability that this is a
  98    taken branch.  For calls, it is the probability that this call
  99    won't return.  */
 100 REG_NOTE (BR_PROB)
 101
 102 /* Attached to a call insn; indicates that the call is malloc-like and
 103    that the pointer returned cannot alias anything else.  */
 104 REG_NOTE (NOALIAS)
 105
 106 /* REG_BR_PRED is attached to JUMP_INSNs and CALL_INSNSs.  It contains
 107    CONCAT of two integer value.  First specifies the branch predictor
 108    that added the note, second specifies the predicted hitrate of
 109    branch in the same format as REG_BR_PROB note uses.  */
 110 REG_NOTE (BR_PRED)
 111
 112 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 113    for DWARF to interpret what they imply.  The attached rtx is used
 114    instead of intuition.  */
 115 REG_NOTE (FRAME_RELATED_EXPR)
 116
 117 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 118    for FRAME_RELATED_EXPR intuition.  The insn's first pattern must be
 119    a SET, and the destination must be the CFA register.  The attached
 120    rtx is an expression that defines the CFA.  In the simplest case, the
 121    rtx could be just the stack_pointer_rtx; more common would be a PLUS
 122    with a base register and a constant offset.  In the most complicated
 123    cases, this will result in a DW_CFA_def_cfa_expression with the rtx
 124    expression rendered in a dwarf location expression.  */
 125 REG_NOTE (CFA_DEF_CFA)
 126
 127 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 128    for FRAME_RELATED_EXPR intuition.  This note adjusts the expression
 129    from which the CFA is computed.  The attached rtx defines a new CFA
 130    expression, relative to the old CFA expression.  This rtx must be of
 131    the form (SET new-cfa-reg (PLUS old-cfa-reg const_int)).  If the note
 132    rtx is NULL, we use the first SET of the insn.  */
 133 REG_NOTE (CFA_ADJUST_CFA)
 134
 135 /* Similar to FRAME_RELATED_EXPR, with the additional information that
 136    this is a save to memory, i.e. will result in DW_CFA_offset or the
 137    like.  The pattern or the insn should be a simple store relative to
 138    the CFA.  */
 139 REG_NOTE (CFA_OFFSET)
 140
 141 /* Similar to FRAME_RELATED_EXPR, with the additional information that this
 142    is a save to a register, i.e. will result in DW_CFA_register.  The insn
 143    or the pattern should be simple reg-reg move.  */
 144 REG_NOTE (CFA_REGISTER)
 145
 146 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 147    for FRAME_RELATED_EXPR intuition.  This is a save to memory, i.e. will
 148    result in a DW_CFA_expression.  The pattern or the insn should be a
 149    store of a register to an arbitrary (non-validated) memory address.  */
 150 REG_NOTE (CFA_EXPRESSION)
 151
 152 /* Attached to insns that are RTX_FRAME_RELATED_P, with the information
 153    that this is a restore operation, i.e. will result in DW_CFA_restore
 154    or the like.  Either the attached rtx, or the destination of the insn's
 155    first pattern is the register to be restored.  */
 156 REG_NOTE (CFA_RESTORE)
 157
 158 /* Attached to insn that is RTX_FRAME_RELATED_P, marks insn that sets
 159    vDRAP from DRAP.  If vDRAP is a register, vdrap_reg is initalized
 160    to the argument, if it is a MEM, it is ignored.  */
 161 REG_NOTE (CFA_SET_VDRAP)
 162
 163 /* Indicates that REG holds the exception context for the function.
 164    This context is shared by inline functions, so the code to acquire
 165    the real exception context is delayed until after inlining.  */
 166 REG_NOTE (EH_CONTEXT)
 167
 168 /* Indicates what exception region an INSN belongs in.  This is used
 169    to indicate what region to which a call may throw.  REGION 0
 170    indicates that a call cannot throw at all.  REGION -1 indicates
 171    that it cannot throw, nor will it execute a non-local goto.  */
 172 REG_NOTE (EH_REGION)
 173
 174 /* Used by haifa-sched to save NOTE_INSN notes across scheduling.  */
 175 REG_NOTE (SAVE_NOTE)
 176
 177 /* Indicates that a call does not return.  */
 178 REG_NOTE (NORETURN)
 179
 180 /* Indicates that an indirect jump is a non-local goto instead of a
 181    computed goto.  */
 182 REG_NOTE (NON_LOCAL_GOTO)
 183
 184 /* Indicates that a jump crosses between hot and cold sections in a
 185    (partitioned) assembly or .o file, and therefore should not be
 186    reduced to a simpler jump by optimizations.  */
 187 REG_NOTE (CROSSING_JUMP)
 188
 189 /* This kind of note is generated at each to `setjmp', and similar
 190    functions that can return twice.  */
 191 REG_NOTE (SETJMP)