gcc/reg-notes.def

   1 /* Register note definitions.
   2    Copyright (C) 2004, 2005, 2006, 2007 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.  Together with a
  56    REG_RETVAL note, it means that the insn sets the full contents of
  57    the libcall value.  */
  58 REG_NOTE (EQUAL)
  59
  60 /* This insn copies the return-value of a library call out of the hard
  61    reg for return values.  This note is actually an INSN_LIST and it
  62    points to the first insn involved in setting up arguments for the
  63    call.  flow.c uses this to delete the entire library call when its
  64    result is dead.  */
  65 REG_NOTE (RETVAL)
  66
  67 /* The inverse of REG_RETVAL: it goes on the first insn of the library
  68    call and points at the one that has the REG_RETVAL.  This note is
  69    also an INSN_LIST.  */
  70 REG_NOTE (LIBCALL)
  71
  72 /* The register is always nonnegative during the containing loop.
  73    This is used in branches so that decrement and branch instructions
  74    terminating on zero can be matched.  There must be an insn pattern
  75    in the md file named `decrement_and_branch_until_zero' or else this
  76    will never be added to any instructions.  */
  77 REG_NOTE (NONNEG)
  78
  79 /* Identifies a register set in this insn and never used.  */
  80 REG_NOTE (UNUSED)
  81
  82 /* REG_CC_SETTER and REG_CC_USER link a pair of insns that set and use
  83    CC0, respectively.  Normally, these are required to be consecutive
  84    insns, but we permit putting a cc0-setting insn in the delay slot
  85    of a branch as long as only one copy of the insn exists.  In that
  86    case, these notes point from one to the other to allow code
  87    generation to determine what any require information and to
  88    properly update CC_STATUS.  These notes are INSN_LISTs.  */
  89 REG_NOTE (CC_SETTER)
  90 REG_NOTE (CC_USER)
  91
  92 /* Points to a CODE_LABEL.  Used by JUMP_INSNs to say that the CODE_LABEL
  93    contained in the REG_LABEL_TARGET note is a possible jump target of
  94    this insn.  This note is an INSN_LIST.  */
  95 REG_NOTE (LABEL_TARGET)
  96
  97 /* Points to a CODE_LABEL.  Used by any insn to say that the CODE_LABEL
  98    contained in the REG_LABEL_OPERAND note is used by the insn, but as an
  99    operand, not as a jump target (though it may indirectly be a jump
 100    target for a later jump insn).  This note is an INSN_LIST.  */
 101 REG_NOTE (LABEL_OPERAND)
 102
 103 /* REG_DEP_OUTPUT and REG_DEP_ANTI are used in scheduler dependencies lists
 104    to represent write-after-write and write-after-read dependencies
 105    respectively.  */
 106 REG_NOTE (DEP_OUTPUT)
 107 REG_NOTE (DEP_ANTI)
 108
 109 /* REG_BR_PROB is attached to JUMP_INSNs and CALL_INSNs.  It has an
 110    integer value.  For jumps, it is the probability that this is a
 111    taken branch.  For calls, it is the probability that this call
 112    won't return.  */
 113 REG_NOTE (BR_PROB)
 114
 115 /* REG_VALUE_PROFILE is attached when the profile is read in to an
 116    insn before that the code to profile the value is inserted.  It
 117    contains the results of profiling.  */
 118 REG_NOTE (VALUE_PROFILE)
 119
 120 /* Attached to a call insn; indicates that the call is malloc-like and
 121    that the pointer returned cannot alias anything else.  */
 122 REG_NOTE (NOALIAS)
 123
 124 /* REG_BR_PRED is attached to JUMP_INSNs and CALL_INSNSs.  It contains
 125    CONCAT of two integer value.  First specifies the branch predictor
 126    that added the note, second specifies the predicted hitrate of
 127    branch in the same format as REG_BR_PROB note uses.  */
 128 REG_NOTE (BR_PRED)
 129
 130 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 131    for DWARF to interpret what they imply.  The attached rtx is used
 132    instead of intuition.  */
 133 REG_NOTE (FRAME_RELATED_EXPR)
 134
 135 /* Indicates that REG holds the exception context for the function.
 136    This context is shared by inline functions, so the code to acquire
 137    the real exception context is delayed until after inlining.  */
 138 REG_NOTE (EH_CONTEXT)
 139
 140 /* Indicates what exception region an INSN belongs in.  This is used
 141    to indicate what region to which a call may throw.  REGION 0
 142    indicates that a call cannot throw at all.  REGION -1 indicates
 143    that it cannot throw, nor will it execute a non-local goto.  */
 144 REG_NOTE (EH_REGION)
 145
 146 /* Used by haifa-sched to save NOTE_INSN notes across scheduling.  */
 147 REG_NOTE (SAVE_NOTE)
 148
 149 /* Indicates that a call does not return.  */
 150 REG_NOTE (NORETURN)
 151
 152 /* Indicates that an indirect jump is a non-local goto instead of a
 153    computed goto.  */
 154 REG_NOTE (NON_LOCAL_GOTO)
 155
 156 /* Indicates that a jump crosses between hot and cold sections in a
 157    (partitioned) assembly or .o file, and therefore should not be
 158    reduced to a simpler jump by optimizations.  */
 159 REG_NOTE (CROSSING_JUMP)
 160
 161 /* This kind of note is generated at each to `setjmp', and similar
 162    functions that can return twice.  */
 163 REG_NOTE (SETJMP)