gcc/reg-notes.def

   1 /* Register note definitions.
   2    Copyright (C) 2004 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 2, 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 COPYING.  If not, write to the Free
  18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  19 02111-1307, USA.  */
  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 /* The value in REG dies in this insn (i.e., it is not needed past
  30    this insn).  If REG is set in this insn, the REG_DEAD note may,
  31    but need not, be omitted.  */
  32 REG_NOTE (DEAD)
  33
  34 /* The REG is autoincremented or autodecremented in this insn.  */
  35 REG_NOTE (INC)
  36
  37 /* Describes the insn as a whole; it says that the insn sets a
  38    register to a constant value or to be equivalent to a memory
  39    address.  If the register is spilled to the stack then the constant
  40    value should be substituted for it.  The contents of the REG_EQUIV
  41    is the constant value or memory address, which may be different
  42    from the source of the SET although it has the same value.  A
  43    REG_EQUIV note may also appear on an insn which copies a register
  44    parameter to a pseudo-register, if there is a memory address which
  45    could be used to hold that pseudo-register throughout the function.  */
  46 REG_NOTE (EQUIV)
  47
  48 /* Like REG_EQUIV except that the destination is only momentarily
  49    equal to the specified rtx.  Therefore, it cannot be used for
  50    substitution; but it can be used for cse.  */
  51 REG_NOTE (EQUAL)
  52
  53 /* This insn copies the return-value of a library call out of the hard
  54    reg for return values.  This note is actually an INSN_LIST and it
  55    points to the first insn involved in setting up arguments for the
  56    call.  flow.c uses this to delete the entire library call when its
  57    result is dead.  */
  58 REG_NOTE (RETVAL)
  59
  60 /* The inverse of REG_RETVAL: it goes on the first insn of the library
  61    call and points at the one that has the REG_RETVAL.  This note is
  62    also an INSN_LIST.  */
  63 REG_NOTE (LIBCALL)
  64
  65 /* The register is always nonnegative during the containing loop.
  66    This is used in branches so that decrement and branch instructions
  67    terminating on zero can be matched.  There must be an insn pattern
  68    in the md file named `decrement_and_branch_until_zero' or else this
  69    will never be added to any instructions.  */
  70 REG_NOTE (NONNEG)
  71
  72 /* There is no conflict *after this insn* between the register in the
  73    note and the destination of this insn.  */
  74 REG_NOTE (NO_CONFLICT)
  75
  76 /* Identifies a register set in this insn and never used.  */
  77 REG_NOTE (UNUSED)
  78
  79 /* REG_CC_SETTER and REG_CC_USER link a pair of insns that set and use
  80    CC0, respectively.  Normally, these are required to be consecutive
  81    insns, but we permit putting a cc0-setting insn in the delay slot
  82    of a branch as long as only one copy of the insn exists.  In that
  83    case, these notes point from one to the other to allow code
  84    generation to determine what any require information and to
  85    properly update CC_STATUS.  These notes are INSN_LISTs.  */
  86 REG_NOTE (CC_SETTER)
  87 REG_NOTE (CC_USER)
  88
  89 /* Points to a CODE_LABEL.  Used by non-JUMP_INSNs to say that the
  90    CODE_LABEL contained in the REG_LABEL note is used by the insn.
  91    This note is an INSN_LIST.  */
  92 REG_NOTE (LABEL)
  93
  94 /* REG_DEP_ANTI and REG_DEP_OUTPUT are used in LOG_LINKS to represent
  95    write-after-read and write-after-write dependencies respectively.
  96    Data dependencies, which are the only type of LOG_LINK created by
  97    flow, are represented by a 0 reg note kind.  */
  98 REG_NOTE (DEP_ANTI)
  99 REG_NOTE (DEP_OUTPUT)
 100
 101 /* REG_BR_PROB is attached to JUMP_INSNs and CALL_INSNs.  It has an
 102    integer value.  For jumps, it is the probability that this is a
 103    taken branch.  For calls, it is the probability that this call
 104    won't return.  */
 105 REG_NOTE (BR_PROB)
 106
 107 /* REG_VALUE_PROFILE is attached when the profile is read in to an
 108    insn before that the code to profile the value is inserted.  It
 109    contains the results of profiling.  */
 110 REG_NOTE (VALUE_PROFILE)
 111
 112 /* Attached to a call insn; indicates that the call is malloc-like and
 113    that the pointer returned cannot alias anything else.  */
 114 REG_NOTE (NOALIAS)
 115
 116 /* Used to optimize rtl generated by dynamic stack allocations for
 117    targets where SETJMP_VIA_SAVE_AREA is true.  */
 118 REG_NOTE (SAVE_AREA)
 119
 120 /* REG_BR_PRED is attached to JUMP_INSNs and CALL_INSNSs.  It contains
 121    CONCAT of two integer value.  First specifies the branch predictor
 122    that added the note, second specifies the predicted hitrate of
 123    branch in the same format as REG_BR_PROB note uses.  */
 124 REG_NOTE (BR_PRED)
 125
 126 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 127    for DWARF to interpret what they imply.  The attached rtx is used
 128    instead of intuition.  */
 129 REG_NOTE (FRAME_RELATED_EXPR)
 130
 131 /* Indicates that REG holds the exception context for the function.
 132    This context is shared by inline functions, so the code to acquire
 133    the real exception context is delayed until after inlining.  */
 134 REG_NOTE (EH_CONTEXT)
 135
 136 /* Indicates what exception region an INSN belongs in.  This is used
 137    to indicate what region to which a call may throw.  REGION 0
 138    indicates that a call cannot throw at all.  REGION -1 indicates
 139    that it cannot throw, nor will it execute a non-local goto.  */
 140 REG_NOTE (EH_REGION)
 141
 142 /* Used by haifa-sched to save NOTE_INSN notes across scheduling.  */
 143 REG_NOTE (SAVE_NOTE)
 144
 145 /* Indicates that this insn (which is part of the prologue) computes a
 146    value which might not be used later, and if so it's OK to delete
 147    the insn.  Normally, deleting any insn in the prologue is an error.
 148    At present the parameter is unused and set to (const_int 0).  */
 149 REG_NOTE (MAYBE_DEAD)
 150
 151 /* Indicates that a call does not return.  */
 152 REG_NOTE (NORETURN)
 153
 154 /* Indicates that an indirect jump is a non-local goto instead of a
 155    computed goto.  */
 156 REG_NOTE (NON_LOCAL_GOTO)
 157
 158 /* Indicates that a jump crosses between hot and cold sections in a
 159    (partitioned) assembly or .o file, and therefore should not be
 160    reduced to a simpler jump by optimizations.  */
 161 REG_NOTE (CROSSING_JUMP)
 162
 163 /* This kind of note is generated at each to `setjmp', and similar
 164    functions that can return twice.  */
 165 REG_NOTE (SETJMP)
 166
 167 /* Indicate calls that always returns.  */
 168 REG_NOTE (ALWAYS_RETURN)