gcc/config/cris/cris-modes.def

   1 /* Definitions of target machine for GNU compiler, for CRIS.
   2    Copyright (C) 2002-2020 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
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 3, or (at your option)
   9 any later version.
  10
  11 GCC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License 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 /* Node: Condition Code */
  21
  22 /* The mode used for condition-codes depends on both the way the
  23    condition-codes are generated (the CC-setter, typically the compare
  24    instruction), and used (the CC-user, typically a branch).  For CRIS, we
  25    have ordinary compares and incidental condition-code settings from
  26    preceding instructions, setting a subset of N, Z, V and C to usable
  27    values, from the perspective of comparing the result against zero
  28    (fpcraz).  The two subsets meaningful to gcc are all of N, Z, V, C
  29    versus just N, Z; some CC-users care only about N and/or Z and some
  30    that care about at least one of those flags together with V and/or C.
  31    (FIXME: the result of testing a single bit using the btst instruction
  32    should be described as a separate mode.)
  33
  34    The plain "CC_MODE (CC)" (which is always present in gcc), is used to
  35    reflect the "unoptimized" state, where the CC-setter is a compare
  36    against zero and the CC-user is any branch or s<condition> instruction,
  37    before reload.  After reload, a need for C or V is reflected as
  38    CC_NZVCmode in both setters and users, and others remain CCmode, until
  39    or if optimization of CC-setter and CC-users, when CCmode setters can
  40    be changed or replaced by either CC_NZmode or CC_NZVCmode.  To wit, all
  41    users that require CC_NZVCmode must match only that mode at any time.
  42    All other users must match all CCmodes.  All setters that set only
  43    CC_NZmode must set only that mode.  All other setters must match
  44    setting all CCmodes.  */
  45
  46 /* Z and N flags only.  For a condition-code setter: only the Z and N
  47    flags are set to usable values, fpcraz.  For a condition-code user: the
  48    operation using the condition codes only care about the Z and N flags.  */
  49 CC_MODE (CC_NZ);
  50
  51 /* Z and N *and* V and C flags.  For a condition-code setter: all flags
  52    are set to usable values, fpcraz.  For a condition-code user: at least
  53    one of V and C are used and possibly N and Z too.  */
  54 CC_MODE (CC_NZVC);