gcc/reg-notes.def

   1 /* Register note definitions.
   2    Copyright (C) 2004, 2005 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, 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301, 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 /* REG_DEP_TRUE is used in LOG_LINKS to represent a read-after-write
  30    dependency (i.e. a true data dependency).  This is here, not
  31    grouped with REG_DEP_ANTI and REG_DEP_OUTPUT, because some passes
  32    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 /* This insn copies the return-value of a library call out of the hard
  60    reg for return values.  This note is actually an INSN_LIST and it
  61    points to the first insn involved in setting up arguments for the
  62    call.  flow.c uses this to delete the entire library call when its
  63    result is dead.  */
  64 REG_NOTE (RETVAL)
  65
  66 /* The inverse of REG_RETVAL: it goes on the first insn of the library
  67    call and points at the one that has the REG_RETVAL.  This note is
  68    also an INSN_LIST.  */
  69 REG_NOTE (LIBCALL)
  70
  71 /* The register is always nonnegative during the containing loop.
  72    This is used in branches so that decrement and branch instructions
  73    terminating on zero can be matched.  There must be an insn pattern
  74    in the md file named `decrement_and_branch_until_zero' or else this
  75    will never be added to any instructions.  */
  76 REG_NOTE (NONNEG)
  77
  78 /* There is no conflict *after this insn* between the register in the
  79    note and the destination of this insn.  */
  80 REG_NOTE (NO_CONFLICT)
  81
  82 /* Identifies a register set in this insn and never used.  */
  83 REG_NOTE (UNUSED)
  84
  85 /* REG_CC_SETTER and REG_CC_USER link a pair of insns that set and use
  86    CC0, respectively.  Normally, these are required to be consecutive
  87    insns, but we permit putting a cc0-setting insn in the delay slot
  88    of a branch as long as only one copy of the insn exists.  In that
  89    case, these notes point from one to the other to allow code
  90    generation to determine what any require information and to
  91    properly update CC_STATUS.  These notes are INSN_LISTs.  */
  92 REG_NOTE (CC_SETTER)
  93 REG_NOTE (CC_USER)
  94
  95 /* Points to a CODE_LABEL.  Used by non-JUMP_INSNs to say that the
  96    CODE_LABEL contained in the REG_LABEL note is used by the insn.
  97    This note is an INSN_LIST.  */
  98 REG_NOTE (LABEL)
  99
 100 /* REG_DEP_ANTI and REG_DEP_OUTPUT are used in LOG_LINKS to represent
 101    write-after-read and write-after-write dependencies respectively.  */
 102 REG_NOTE (DEP_OUTPUT)
 103 REG_NOTE (DEP_ANTI)
 104
 105 /* REG_BR_PROB is attached to JUMP_INSNs and CALL_INSNs.  It has an
 106    integer value.  For jumps, it is the probability that this is a
 107    taken branch.  For calls, it is the probability that this call
 108    won't return.  */
 109 REG_NOTE (BR_PROB)
 110
 111 /* REG_VALUE_PROFILE is attached when the profile is read in to an
 112    insn before that the code to profile the value is inserted.  It
 113    contains the results of profiling.  */
 114 REG_NOTE (VALUE_PROFILE)
 115
 116 /* Attached to a call insn; indicates that the call is malloc-like and
 117    that the pointer returned cannot alias anything else.  */
 118 REG_NOTE (NOALIAS)
 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)