freepascal.compiler/compiler/i386/aopt386.pas

{
    $Id$
    Copyright (c) 1998-2000 by Jonas Maebe

    This unit calls the optimization procedures to optimize the assembler
    code for i386+

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 ****************************************************************************
}
Unit aopt386;

{$i defines.inc}

Interface

Uses
  aasm;

Procedure Optimize(AsmL: TAasmOutput);


Implementation

Uses
  globtype,
  globals,
  DAOpt386,POpt386,CSOpt386;


Procedure Optimize(AsmL: TAAsmOutput);
Var
  BlockStart, BlockEnd, HP: Tai;
  pass: longint;
  slowopt, changed, lastLoop: boolean;
Begin
  slowopt := (cs_slowoptimize in aktglobalswitches);
  pass := 0;
  changed := false;
  repeat
     lastLoop :=
       not(slowopt) or
       (not changed and (pass > 2)) or
      { prevent endless loops }
       (pass = 4);
     changed := false;
   { Setup labeltable, always necessary }
     BlockStart := Tai(AsmL.First);
     BlockEnd := DFAPass1(AsmL, BlockStart);
   { Blockend now either contains an ait_marker with Kind = AsmBlockStart, }
   { or nil                                                                }
     While Assigned(BlockStart) Do
       Begin
         if pass = 0 then
           PrePeepHoleOpts(AsmL, BlockStart, BlockEnd);
        { Peephole optimizations }
         PeepHoleOptPass1(AsmL, BlockStart, BlockEnd);
        { Only perform them twice in the first pass }
         if pass = 0 then
           PeepHoleOptPass1(AsmL, BlockStart, BlockEnd);
        { Data flow analyzer }
         If (cs_fastoptimize in aktglobalswitches) Then
           Begin
             If DFAPass2(
{$ifdef statedebug}
                         AsmL,
{$endif statedebug}
                               BlockStart, BlockEnd) Then
              { common subexpression elimination }
               changed := CSE(asmL, blockStart, blockEnd, pass) or changed;
           End;
        { More peephole optimizations }
         PeepHoleOptPass2(AsmL, BlockStart, BlockEnd);
         if lastLoop then
           PostPeepHoleOpts(AsmL, BlockStart, BlockEnd);
        { Dispose labeltabel }
         ShutDownDFA;
        { Continue where we left off, BlockEnd is either the start of an }
        { assembler block or nil                                         }
         BlockStart := BlockEnd;
         While Assigned(BlockStart) And
               (BlockStart.typ = ait_Marker) And
               (Tai_Marker(BlockStart).Kind = AsmBlockStart) Do
           Begin
           { We stopped at an assembler block, so skip it }
            Repeat
              BlockStart := Tai(BlockStart.Next);
            Until (BlockStart.Typ = Ait_Marker) And
                  (Tai_Marker(Blockstart).Kind = AsmBlockEnd);
           { Blockstart now contains a Tai_marker(asmblockend) }
             If GetNextInstruction(BlockStart, HP) And
                ((HP.typ <> ait_Marker) Or
                 (Tai_Marker(HP).Kind <> AsmBlockStart)) Then
             { There is no assembler block anymore after the current one, so }
             { optimize the next block of "normal" instructions              }
               BlockEnd := DFAPass1(AsmL, BlockStart)
             { Otherwise, skip the next assembler block }
             Else BlockStart := HP;
           End;
       End;
     inc(pass);
  until lastLoop;
End;

End.
{
  $Log$
  Revision 1.3  2000-12-25 00:07:31  peter
    + new tlinkedlist class (merge of old tstringqueue,tcontainer and
      tlinkedlist objects)

  Revision 1.2  2000/10/24 10:40:53  jonas
    + register renaming ("fixes" bug1088)
    * changed command line options meanings for optimizer:
        O2 now means peepholopts, CSE and register renaming in 1 pass
        O3 is the same, but repeated until no further optimizations are
          possible or until 5 passes have been done (to avoid endless loops)
    * changed aopt386 so it does this looping
    * added some procedures from csopt386 to the interface because they're
      used by rropt386 as well
    * some changes to csopt386 and daopt386 so that newly added instructions
      by the CSE get optimizer info (they were simply skipped previously),
      this fixes some bugs

  Revision 1.1  2000/10/15 09:47:42  peter
    * moved to i386/

  Revision 1.5  2000/09/24 15:06:11  peter
    * use defines.inc

  Revision 1.4  2000/08/19 09:10:08  jonas
    * for all optimization levels > 1, all passes are done twice (the
      result improves the most if -Or is used as well)

  Revision 1.3  2000/07/14 05:11:48  michael
  + Patch to 1.1

  Revision 1.2  2000/07/13 11:32:31  michael
  + removed logs

}