gcc/reg-notes.def

   1 /* Register note definitions.
   2    Copyright (C) 2004, 2005, 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 LOG_LINKS to represent a read-after-write
  29    dependency (i.e. a true data dependency).  This is here, not
  30    grouped with REG_DEP_ANTI and REG_DEP_OUTPUT, because some passes
  31    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.  */
  56 REG_NOTE (EQUAL)
  57
  58 /* This insn copies the return-value of a library call out of the hard
  59    reg for return values.  This note is actually an INSN_LIST and it
  60    points to the first insn involved in setting up arguments for the
  61    call.  flow.c uses this to delete the entire library call when its
  62    result is dead.  */
  63 REG_NOTE (RETVAL)
  64
  65 /* The inverse of REG_RETVAL: it goes on the first insn of the library
  66    call and points at the one that has the REG_RETVAL.  This note is
  67    also an INSN_LIST.  */
  68 REG_NOTE (LIBCALL)
  69
  70 /* The register is always nonnegative during the containing loop.
  71    This is used in branches so that decrement and branch instructions
  72    terminating on zero can be matched.  There must be an insn pattern
  73    in the md file named `decrement_and_branch_until_zero' or else this
  74    will never be added to any instructions.  */
  75 REG_NOTE (NONNEG)
  76
  77 /* There is no conflict *after this insn* between the register in the
  78    note and the destination of this insn.  */
  79 REG_NOTE (NO_CONFLICT)
  80
  81 /* Identifies a register set in this insn and never used.  */
  82 REG_NOTE (UNUSED)
  83
  84 /* REG_CC_SETTER and REG_CC_USER link a pair of insns that set and use
  85    CC0, respectively.  Normally, these are required to be consecutive
  86    insns, but we permit putting a cc0-setting insn in the delay slot
  87    of a branch as long as only one copy of the insn exists.  In that
  88    case, these notes point from one to the other to allow code
  89    generation to determine what any require information and to
  90    properly update CC_STATUS.  These notes are INSN_LISTs.  */
  91 REG_NOTE (CC_SETTER)
  92 REG_NOTE (CC_USER)
  93
  94 /* Points to a CODE_LABEL.  Used by non-JUMP_INSNs to say that the
  95    CODE_LABEL contained in the REG_LABEL note is used by the insn.
  96    This note is an INSN_LIST.  */
  97 REG_NOTE (LABEL)
  98
  99 /* REG_DEP_ANTI and REG_DEP_OUTPUT are used in LOG_LINKS to represent
 100    write-after-read and write-after-write dependencies respectively.  */
 101 REG_NOTE (DEP_OUTPUT)
 102 REG_NOTE (DEP_ANTI)
 103
 104 /* REG_BR_PROB is attached to JUMP_INSNs and CALL_INSNs.  It has an
 105    integer value.  For jumps, it is the probability that this is a
 106    taken branch.  For calls, it is the probability that this call
 107    won't return.  */
 108 REG_NOTE (BR_PROB)
 109
 110 /* REG_VALUE_PROFILE is attached when the profile is read in to an
 111    insn before that the code to profile the value is inserted.  It
 112    contains the results of profiling.  */
 113 REG_NOTE (VALUE_PROFILE)
 114
 115 /* Attached to a call insn; indicates that the call is malloc-like and
 116    that the pointer returned cannot alias anything else.  */
 117 REG_NOTE (NOALIAS)
 118
 119 /* REG_BR_PRED is attached to JUMP_INSNs and CALL_INSNSs.  It contains
 120    CONCAT of two integer value.  First specifies the branch predictor
 121    that added the note, second specifies the predicted hitrate of
 122    branch in the same format as REG_BR_PROB note uses.  */
 123 REG_NOTE (BR_PRED)
 124
 125 /* Attached to insns that are RTX_FRAME_RELATED_P, but are too complex
 126    for DWARF to interpret what they imply.  The attached rtx is used
 127    instead of intuition.  */
 128 REG_NOTE (FRAME_RELATED_EXPR)
 129
 130 /* Indicates that REG holds the exception context for the function.
 131    This context is shared by inline functions, so the code to acquire
 132    the real exception context is delayed until after inlining.  */
 133 REG_NOTE (EH_CONTEXT)
 134
 135 /* Indicates what exception region an INSN belongs in.  This is used
 136    to indicate what region to which a call may throw.  REGION 0
 137    indicates that a call cannot throw at all.  REGION -1 indicates
 138    that it cannot throw, nor will it execute a non-local goto.  */
 139 REG_NOTE (EH_REGION)
 140
 141 /* Used by haifa-sched to save NOTE_INSN notes across scheduling.  */
 142 REG_NOTE (SAVE_NOTE)
 143
 144 /* Indicates that this insn (which is part of the prologue) computes a
 145    value which might not be used later, and if so it's OK to delete
 146    the insn.  Normally, deleting any insn in the prologue is an error.
 147    At present the parameter is unused and set to (const_int 0).  */
 148 REG_NOTE (MAYBE_DEAD)
 149
 150 /* Indicates that a call does not return.  */
 151 REG_NOTE (NORETURN)
 152
 153 /* Indicates that an indirect jump is a non-local goto instead of a
 154    computed goto.  */
 155 REG_NOTE (NON_LOCAL_GOTO)
 156
 157 /* Indicates that a jump crosses between hot and cold sections in a
 158    (partitioned) assembly or .o file, and therefore should not be
 159    reduced to a simpler jump by optimizations.  */
 160 REG_NOTE (CROSSING_JUMP)
 161
 162 /* This kind of note is generated at each to `setjmp', and similar
 163    functions that can return twice.  */
 164 REG_NOTE (SETJMP)