gcc/config/avr/avr-passes.def

   1 /* Description of target passes for AVR.
   2    Copyright (C) 2016-2024 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 /* A post reload optimization pass that fuses PLUS insns with CONST_INT
  21    addend with a load or store insn to get POST_INC or PRE_DEC addressing.
  22    It can also fuse two PLUSes to a single one, which may occur due to
  23    splits from `avr_split_tiny_move'.  We do this in an own pass because
  24    it can find more cases than peephole2, for example when there are
  25    unrelated insns between the interesting ones.  */
  26
  27 INSERT_PASS_BEFORE (pass_peephole2, 1, avr_pass_fuse_add);
  28
  29 /* An analysis pass that runs prior to prologue / epilogue generation.
  30    Computes cfun->machine->gasisr.maybe which is used in prologue and
  31    epilogue generation provided -mgas-isr-prologues is on.  */
  32
  33 INSERT_PASS_BEFORE (pass_thread_prologue_and_epilogue, 1, avr_pass_pre_proep);
  34
  35 /* This avr-specific pass (re)computes insn notes, in particular REG_DEAD
  36    notes which are used by `avr.cc::reg_unused_after' and branch offset
  37    computations.  These notes must be correct, i.e. there must be no
  38    dangling REG_DEAD notes; otherwise wrong code might result, cf. PR64331.
  39
  40    DF needs (correct) CFG, hence right before free_cfg is the last
  41    opportunity to rectify notes.  */
  42
  43 INSERT_PASS_BEFORE (pass_free_cfg, 1, avr_pass_recompute_notes);
  44
  45 /* casesi uses a SImode switch index which is quite costly as most code will
  46    work on HImode or QImode.  The following pass runs right after .expand and
  47    tries to fix such situations by operating on the original mode.  This
  48    reduces code size and register pressure.
  49
  50    The assertion is that the code generated by casesi is unaltered and a
  51    a sign-extend or zero-extend from QImode or HImode precedes the casesi
  52    insns withaout any insns in between.  */
  53
  54 INSERT_PASS_AFTER (pass_expand, 1, avr_pass_casesi);
  55
  56 /* If-else decision trees generated for switch / case may produce sequences
  57    like
  58
  59       SREG = compare (reg, val);
  60           if (SREG == 0)  goto label1;
  61       SREG = compare (reg, 1 + val);
  62           if (SREG >= 0)  goto label2;
  63
  64    which can be optimized to
  65
  66       SREG = compare (reg, val);
  67           if (SREG == 0)  goto label1;
  68           if (SREG >= 0)  goto label2;
  69
  70    The optimal place for such a pass would be directly after expand, but
  71    it's not possible for a jump insn to target more than one code label.
  72    Hence, run a mini pass right before split2 which introduces REG_CC.  */
  73
  74 INSERT_PASS_BEFORE (pass_split_after_reload, 1, avr_pass_ifelse);