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 /* REG_VALUE_PROFILE is attached when the profile is read in to an
 103    insn before that the code to profile the value is inserted.  It
 104    contains the results of profiling.  */
 105 REG_NOTE (VALUE_PROFILE)
 106
 107 /* Attached to a call insn; indicates that the call is malloc-like and
 108    that the pointer returned cannot alias anything else.  */
 109 REG_NOTE (NOALIAS)
 110
 111 /* REG_BR_PRED is attached to JUMP_INSNs and CALL_INSNSs.  It contains
 112    CONCAT of two integer value.  First specifies the branch predictor
 113    that added the note, second specifies the predicted hitrate of
 114    branch in the same format as REG_BR_PROB note uses.  */
 115 REG_NOTE (BR_PRED)
 116
 117 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 118    for DWARF to interpret what they imply.  The attached rtx is used
 119    instead of intuition.  */
 120 REG_NOTE (FRAME_RELATED_EXPR)
 121
 122 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 123    for FRAME_RELATED_EXPR intuition.  The insn's first pattern must be
 124    a SET, and the destination must be the CFA register.  The attached
 125    rtx is an expression that defines the CFA.  In the simplest case, the
 126    rtx could be just the stack_pointer_rtx; more common would be a PLUS
 127    with a base register and a constant offset.  In the most complicated
 128    cases, this will result in a DW_CFA_def_cfa_expression with the rtx
 129    expression rendered in a dwarf location expression.  */
 130 REG_NOTE (CFA_DEF_CFA)
 131
 132 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 133    for FRAME_RELATED_EXPR intuition.  This note adjusts the expression
 134    from which the CFA is computed.  The attached rtx defines a new CFA
 135    expression, relative to the old CFA expression.  This rtx must be of
 136    the form (SET new-cfa-reg (PLUS old-cfa-reg const_int)).  If the note
 137    rtx is NULL, we use the first SET of the insn.  */
 138 REG_NOTE (CFA_ADJUST_CFA)
 139
 140 /* Similar to FRAME_RELATED_EXPR, with the additional information that
 141    this is a save to memory, i.e. will result in DW_CFA_offset or the
 142    like.  The pattern or the insn should be a simple store relative to
 143    the CFA.  */
 144 REG_NOTE (CFA_OFFSET)
 145
 146 /* Similar to FRAME_RELATED_EXPR, with the additional information that this
 147    is a save to a register, i.e. will result in DW_CFA_register.  The insn
 148    or the pattern should be simple reg-reg move.  */
 149 REG_NOTE (CFA_REGISTER)
 150
 151 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 152    for FRAME_RELATED_EXPR intuition.  This is a save to memory, i.e. will
 153    result in a DW_CFA_expression.  The pattern or the insn should be a
 154    store of a register to an arbitrary (non-validated) memory address.  */
 155 REG_NOTE (CFA_EXPRESSION)
 156
 157 /* Attached to insns that are RTX_FRAME_RELATED_P, with the information
 158    that this is a restore operation, i.e. will result in DW_CFA_restore
 159    or the like.  Either the attached rtx, or the destination of the insn's
 160    first pattern is the register to be restored.  */
 161 REG_NOTE (CFA_RESTORE)
 162
 163 /* Attached to insn that is RTX_FRAME_RELATED_P, marks insn that sets
 164    vDRAP from DRAP.  If vDRAP is a register, vdrap_reg is initalized
 165    to the argument, if it is a MEM, it is ignored.  */
 166 REG_NOTE (CFA_SET_VDRAP)
 167
 168 /* Indicates that REG holds the exception context for the function.
 169    This context is shared by inline functions, so the code to acquire
 170    the real exception context is delayed until after inlining.  */
 171 REG_NOTE (EH_CONTEXT)
 172
 173 /* Indicates what exception region an INSN belongs in.  This is used
 174    to indicate what region to which a call may throw.  REGION 0
 175    indicates that a call cannot throw at all.  REGION -1 indicates
 176    that it cannot throw, nor will it execute a non-local goto.  */
 177 REG_NOTE (EH_REGION)
 178
 179 /* Used by haifa-sched to save NOTE_INSN notes across scheduling.  */
 180 REG_NOTE (SAVE_NOTE)
 181
 182 /* Indicates that a call does not return.  */
 183 REG_NOTE (NORETURN)
 184
 185 /* Indicates that an indirect jump is a non-local goto instead of a
 186    computed goto.  */
 187 REG_NOTE (NON_LOCAL_GOTO)
 188
 189 /* Indicates that a jump crosses between hot and cold sections in a
 190    (partitioned) assembly or .o file, and therefore should not be
 191    reduced to a simpler jump by optimizations.  */
 192 REG_NOTE (CROSSING_JUMP)
 193
 194 /* This kind of note is generated at each to `setjmp', and similar
 195    functions that can return twice.  */
 196 REG_NOTE (SETJMP)