{
    $Id$
    Copyright (C) 1993-98 by Florian Klaempfl

    This unit handles the temporary variables stuff 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 tgeni386;

  interface

    uses
       cobjects,globals,tree,hcodegen,verbose,files,aasm
{$ifdef i386}
       ,i386
{$endif}
       ;

    type
       tregisterset = set of tregister;

       tpushed = array[R_EAX..R_MM6] of boolean;

    const
       usablereg32 : byte = 4;
{$ifdef SUPPORT_MMX}
       usableregmmx : byte = 8;
{$endif SUPPORT_MMX}

    function getregister32 : tregister;
    procedure ungetregister32(r : tregister);
{$ifdef SUPPORT_MMX}
    function getregistermmx : tregister;
    procedure ungetregistermmx(r : tregister);
{$endif SUPPORT_MMX}

    procedure ungetregister(r : tregister);

    procedure cleartempgen;
    procedure del_reference(const ref : treference);
    procedure del_locref(const location : tlocation);


    { pushs and restores registers }
    procedure pushusedregisters(var pushed : tpushed;b : byte);
    procedure popusedregisters(const pushed : tpushed);

    var
       unused,usableregs : tregisterset;
       c_usableregs : longint;

       { uses only 1 byte while a set uses in FPC 32 bytes }
       usedinproc : byte;

       { count, how much a register must be pushed if it is used as register }
       { variable                                                            }
{$ifdef SUPPORT_MMX}
       reg_pushes : array[R_EAX..R_MM6] of longint;
       is_reg_var : array[R_EAX..R_MM6] of boolean;
{$else SUPPORT_MMX}
       reg_pushes : array[R_EAX..R_EDI] of longint;
       is_reg_var : array[R_EAX..R_EDI] of boolean;
{$endif SUPPORT_MMX}
  implementation

    procedure pushusedregisters(var pushed : tpushed;b : byte);

      var
         r : tregister;
{$ifdef SUPPORT_MMX}
         hr : preference;
{$endif SUPPORT_MMX}

      begin
         usedinproc:=usedinproc or b;
         for r:=R_EAX to R_EBX do
           begin
              pushed[r]:=false;
              { if the register is used by the calling subroutine    }
              if ((b and ($80 shr byte(r)))<>0) then
                begin
                   { and is present in use }
                   if not(r in unused) then
                     begin
                        { then save it }
                        exprasmlist^.concat(new(pai386,op_reg(A_PUSH,S_L,r)));
                        { here was a big problem  !!!!!}
                        { you cannot do that for a register that is
                        globally assigned to a var
                        this also means that you must push it much more
                        often, but there must be a better way
                        maybe by putting the value back to the stack !! }
                        if not(is_reg_var[r]) then
                          unused:=unused+[r];
                        pushed[r]:=true;
                     end;
                end;
           end;
{$ifdef SUPPORT_MMX}
         for r:=R_MM0 to R_MM6 do
           begin
              pushed[r]:=false;
              { if the mmx register is in use, save it }
              if not(r in unused) then
                begin
                   exprasmlist^.concat(new(pai386,op_const_reg(
                     A_SUB,S_L,8,R_ESP)));
                   new(hr);
                   reset_reference(hr^);
                   hr^.base:=R_ESP;
                   exprasmlist^.concat(new(pai386,op_reg_ref(
                     A_MOVQ,S_NO,r,hr)));
                   if not(is_reg_var[r]) then
                     unused:=unused+[r];
                   pushed[r]:=true;
                end;
           end;
{$endif SUPPORT_MMX}
      end;

    procedure popusedregisters(const pushed : tpushed);

      var
         r : tregister;
{$ifdef SUPPORT_MMX}
         hr : preference;
{$endif SUPPORT_MMX}
      begin
         { restore in reverse order: }
{$ifdef SUPPORT_MMX}
         for r:=R_MM6 downto R_MM0 do
           begin
              if pushed[r] then
                begin
                   new(hr);
                   reset_reference(hr^);
                   hr^.base:=R_ESP;
                   exprasmlist^.concat(new(pai386,op_ref_reg(
                     A_MOVQ,S_NO,hr,r)));
                   exprasmlist^.concat(new(pai386,op_const_reg(
                     A_ADD,S_L,8,R_ESP)));
                   unused:=unused-[r];
                end;
           end;
{$endif SUPPORT_MMX}
         for r:=R_EBX downto R_EAX do
           if pushed[r] then
             begin
                exprasmlist^.concat(new(pai386,op_reg(A_POP,S_L,r)));
                unused:=unused-[r];
             end;
      end;

    procedure ungetregister(r : tregister);

      begin
         if r in [R_EAX,R_ECX,R_EDX,R_EBX,R_ESP,R_EBP,R_ESI,R_EDI] then
           ungetregister32(r)
         else if r in [R_AX,R_CX,R_DX,R_BX,R_SP,R_BP,R_SI,R_DI] then
           ungetregister32(reg16toreg32(r))
         else if r in [R_AL,R_BL,R_CL,R_DL] then
           ungetregister32(reg8toreg32(r))
{$ifdef SUPPORT_MMX}
         else if r in [R_MM0..R_MM6] then
           ungetregistermmx(r)
{$endif SUPPORT_MMX}
         else internalerror(18);
      end;

    procedure ungetregister32(r : tregister);

      begin
         if cs_maxoptimieren in aktswitches then
           begin
              { takes much time }
              if not(r in usableregs) then
                exit;
              unused:=unused+[r];
              inc(usablereg32);
           end
         else
           begin
              if not(r in [R_EAX,R_EBX,R_ECX,R_EDX]) then
                exit;
              unused:=unused+[r];
              inc(usablereg32);
           end;
{$ifdef REGALLOC}
         exprasmlist^.concat(new(pairegdealloc,init(r)));
{$endif REGALLOC}
      end;

{$ifdef SUPPORT_MMX}
    function getregistermmx : tregister;

      var
         r : tregister;

      begin
         dec(usableregmmx);
         for r:=R_MM0 to R_MM6 do
           if r in unused then
             begin
                unused:=unused-[r];
                usedinproc:=usedinproc or ($80 shr byte(R_EAX));
                getregistermmx:=r;
                exit;
             end;
         internalerror(10);
      end;

    procedure ungetregistermmx(r : tregister);

      begin
         if cs_maxoptimieren in aktswitches then
           begin
              { takes much time }
              if not(r in usableregs) then
                exit;
              unused:=unused+[r];
              inc(usableregmmx);
           end
         else
           begin
              unused:=unused+[r];
              inc(usableregmmx);
           end;
      end;
{$endif SUPPORT_MMX}

    procedure del_reference(const ref : treference);

      begin
         if ref.isintvalue then
           exit;
         ungetregister32(ref.base);
         ungetregister32(ref.index);
         { ref.segment:=R_DEFAULT_SEG; }
      end;

    procedure del_locref(const location : tlocation);

      begin
         if (location.loc<>loc_mem) and (location.loc<>loc_reference) then
           exit;
         if location.reference.isintvalue then
           exit;
         ungetregister32(location.reference.base);
         ungetregister32(location.reference.index);
         { ref.segment:=R_DEFAULT_SEG; }
      end;

    function getregister32 : tregister;

      begin
         dec(usablereg32);
         if R_EAX in unused then
           begin
              unused:=unused-[R_EAX];
              usedinproc:=usedinproc or ($80 shr byte(R_EAX));
              getregister32:=R_EAX;
           end
         else if R_EDX in unused then
           begin
              unused:=unused-[R_EDX];
              usedinproc:=usedinproc or ($80 shr byte(R_EDX));
              getregister32:=R_EDX;
           end
         else if R_EBX in unused then
           begin
              unused:=unused-[R_EBX];
              usedinproc:=usedinproc or ($80 shr byte(R_EBX));
              getregister32:=R_EBX;
           end
         else if R_ECX in unused then
           begin
              unused:=unused-[R_ECX];
              usedinproc:=usedinproc or ($80 shr byte(R_ECX));
              getregister32:=R_ECX;
           end
         else internalerror(10);
      end;

    procedure cleartempgen;

      begin
         unused:=usableregs;
         usablereg32:=c_usableregs;
      end;


begin
   usableregs:=[R_EAX,R_EBX,R_ECX,R_EDX];
{$ifdef SUPPORT_MMX}
   usableregs:=usableregs+[R_MM0..R_MM6];
{$endif SUPPORT_MMX}
   c_usableregs:=4;
end.
{
  $Log$
  Revision 1.7  1998-06-08 13:13:47  pierre
    + temporary variables now in temp_gen.pas unit
      because it is processor independent
    * mppc68k.bat modified to undefine i386 and support_mmx
      (which are defaults for i386)

  Revision 1.6  1998/05/20 09:42:38  pierre
    + UseTokenInfo now default
    * unit in interface uses and implementation uses gives error now
    * only one error for unknown symbol (uses lastsymknown boolean)
      the problem came from the label code !
    + first inlined procedures and function work
      (warning there might be allowed cases were the result is still wrong !!)
    * UseBrower updated gives a global list of all position of all used symbols
      with switch -gb

  Revision 1.5  1998/05/11 13:07:58  peter
    + $ifdef NEWPPU for the new ppuformat
    + $define GDB not longer required
    * removed all warnings and stripped some log comments
    * no findfirst/findnext anymore to remove smartlink *.o files

  Revision 1.4  1998/04/29 10:34:08  pierre
    + added some code for ansistring (not complete nor working yet)
    * corrected operator overloading
    * corrected nasm output
    + started inline procedures
    + added starstarn : use ** for exponentiation (^ gave problems)
    + started UseTokenInfo cond to get accurate positions

  Revision 1.3  1998/04/09 22:16:36  florian
    * problem with previous REGALLOC solved
    * improved property support

  Revision 1.2  1998/04/09 15:46:39  florian
    + register allocation tracing stuff added
}