fpc/compiler/pass_2.pas

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

    This unit handles the codegeneration pass

    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.

 ****************************************************************************
}
{$ifdef TP}
  {$E+,F+,N+}
{$endif}
unit pass_2;
interface

uses
  tree;

{ produces assembler for the expression in variable p }
{ and produces an assembler node at the end        }
procedure generatecode(var p : ptree);

{ produces the actual code }
function do_secondpass(var p : ptree) : boolean;
procedure secondpass(var p : ptree);


implementation

   uses
     globtype,systems,
     cobjects,comphook,verbose,globals,files,
     symconst,symtable,types,aasm,scanner,
     pass_1,hcodegen,temp_gen,cpubase,cpuasm
{$ifdef GDB}
     ,gdb
{$endif}
{$ifdef i386}
     ,tgeni386,cgai386
     ,cg386con,cg386mat,cg386cnv,cg386set,cg386add
     ,cg386mem,cg386cal,cg386ld,cg386flw,cg386inl
{$endif}
{$ifdef m68k}
     ,tgen68k,cga68k
     ,cg68kcon,cg68kmat,cg68kcnv,cg68kset,cg68kadd
     ,cg68kmem,cg68kcal,cg68kld,cg68kflw,cg68kinl
{$endif}
     ;

{*****************************************************************************
                              SecondPass
*****************************************************************************}

    type
       secondpassproc = procedure(var p : ptree);

    procedure secondnothing(var p : ptree);

      begin
      end;

    procedure seconderror(var p : ptree);

      begin
         p^.error:=true;
         codegenerror:=true;
      end;


    procedure secondstatement(var p : ptree);

      var
         hp : ptree;
      begin
         hp:=p;
         while assigned(hp) do
          begin
            if assigned(hp^.right) then
             begin
               cleartempgen;
               {!!!!!!
               oldrl:=temptoremove;
               temptoremove:=new(plinkedlist,init);
               }
               secondpass(hp^.right);
               { !!!!!!!
                 some temporary data which can't be released elsewhere
               removetemps(exprasmlist,temptoremove);
               dispose(temptoremove,done);
               temptoremove:=oldrl;
               }
             end;
            hp:=hp^.left;
          end;
      end;


    procedure secondblockn(var p : ptree);
      begin
      { do second pass on left node }
        if assigned(p^.left) then
         secondpass(p^.left);
      end;


    procedure secondasm(var p : ptree);
      var
        hp,hp2 : pai;
        localfixup,parafixup,
        i : longint;
        r : preference;
      begin
         if (pocall_inline in aktprocsym^.definition^.proccalloptions) then
           begin
             localfixup:=aktprocsym^.definition^.localst^.address_fixup;
             parafixup:=aktprocsym^.definition^.parast^.address_fixup;
             hp:=pai(p^.p_asm^.first);
             while assigned(hp) do
              begin
                hp2:=pai(hp^.getcopy);
                case hp2^.typ of
                  ait_instruction :
                     begin
                       { fixup the references }
                       for i:=1 to pai386(hp2)^.ops do
                        if pai386(hp2)^.oper[i-1].typ=top_ref then
                         begin
                           r:=pai386(hp2)^.oper[i-1].ref;
                           case r^.options of
                             ref_parafixup :
                               r^.offsetfixup:=parafixup;
                             ref_localfixup :
                               r^.offsetfixup:=localfixup;
                           end;
                         end;
                       exprasmlist^.concat(hp2);
                     end;
                   ait_marker :
                     begin
                     { it's not an assembler block anymore }
                       if not(pai_marker(hp2)^.kind in [AsmBlockStart, AsmBlockEnd]) then
                        exprasmlist^.concat(hp2);
                     end;
                   else
                     exprasmlist^.concat(hp2);
                end;
                hp:=pai(hp^.next);
              end
           end
         else
           exprasmlist^.concatlist(p^.p_asm);
         if not p^.object_preserved then
          begin
{$ifdef i386}
            maybe_loadesi;
{$endif}
{$ifdef m68k}
            maybe_loada5;
{$endif}
          end;
       end;


     procedure secondpass(var p : ptree);
       const
         procedures : array[ttreetyp] of secondpassproc =
            (secondadd,  {addn}
             secondadd,  {muln}
             secondadd,  {subn}
             secondmoddiv,      {divn}
             secondadd,  {symdifn}
             secondmoddiv,      {modn}
             secondassignment,  {assignn}
             secondload,        {loadn}
             secondnothing,     {range}
             secondadd,  {ltn}
             secondadd,  {lten}
             secondadd,  {gtn}
             secondadd,  {gten}
             secondadd,  {equaln}
             secondadd,  {unequaln}
             secondin,    {inn}
             secondadd,  {orn}
             secondadd,  {xorn}
             secondshlshr,      {shrn}
             secondshlshr,      {shln}
             secondadd,  {slashn}
             secondadd,  {andn}
             secondsubscriptn,  {subscriptn}
             secondderef,       {derefn}
             secondaddr,        {addrn}
             seconddoubleaddr,  {doubleaddrn}
             secondordconst,    {ordconstn}
             secondtypeconv,    {typeconvn}
             secondcalln,       {calln}
             secondnothing,     {callparan}
             secondrealconst,   {realconstn}
             secondfixconst,    {fixconstn}
             secondumminus,     {umminusn}
             secondasm,  {asmn}
             secondvecn,        {vecn}
             secondstringconst, {stringconstn}
             secondfuncret,     {funcretn}
             secondselfn,       {selfn}
             secondnot,  {notn}
             secondinline,      {inlinen}
             secondniln,        {niln}
             seconderror,       {errorn}
             secondnothing,     {typen}
             secondhnewn,       {hnewn}
             secondhdisposen,   {hdisposen}
             secondnewn,        {newn}
             secondsimplenewdispose, {simpledisposen}
             secondsetelement,  {setelementn}
             secondsetconst,    {setconstn}
             secondblockn,      {blockn}
             secondstatement,   {statementn}
             secondnothing,     {loopn}
             secondifn,  {ifn}
             secondbreakn,      {breakn}
             secondcontinuen,   {continuen}
             second_while_repeatn, {repeatn}
             second_while_repeatn, {whilen}
             secondfor,  {forn}
             secondexitn,       {exitn}
             secondwith,        {withn}
             secondcase,        {casen}
             secondlabel,       {labeln}
             secondgoto,        {goton}
             secondsimplenewdispose, {simplenewn}
             secondtryexcept,   {tryexceptn}
             secondraise,       {raisen}
             secondnothing,     {switchesn}
             secondtryfinally,  {tryfinallyn}
             secondon,    {onn}
             secondis,    {isn}
             secondas,    {asn}
             seconderror,       {caretn}
             secondfail,        {failn}
             secondadd,  {starstarn}
             secondprocinline,  {procinlinen}
             secondarrayconstruct, {arrayconstructn}
             secondnothing,     {arrayconstructrangen}
             secondnothing,     {nothingn}
             secondloadvmt      {loadvmtn}
             );
      var
         oldcodegenerror  : boolean;
         oldlocalswitches : tlocalswitches;
         oldpos    : tfileposinfo;
      begin
         if not(p^.error) then
          begin
            oldcodegenerror:=codegenerror;
            oldlocalswitches:=aktlocalswitches;
            oldpos:=aktfilepos;

            aktfilepos:=p^.fileinfo;
            aktlocalswitches:=p^.localswitches;
            codegenerror:=false;
            procedures[p^.treetype](p);
            p^.error:=codegenerror;

            codegenerror:=codegenerror or oldcodegenerror;
            aktlocalswitches:=oldlocalswitches;
            aktfilepos:=oldpos;
          end
         else
           codegenerror:=true;
      end;


    function do_secondpass(var p : ptree) : boolean;
      begin
         codegenerror:=false;
         if not(p^.error) then
           secondpass(p);
         do_secondpass:=codegenerror;
      end;

    var
       { the array ranges are oveestimated !!!  }
       { max(maxvarregs,maxfpuvarregs) would be }
       { enough                                 }
       regvars : array[1..maxvarregs+maxfpuvarregs] of pvarsym;
       regvars_para : array[1..maxvarregs+maxfpuvarregs] of boolean;
       regvars_refs : array[1..maxvarregs+maxfpuvarregs] of longint;
       parasym : boolean;

    procedure searchregvars(p : pnamedindexobject);
      var
         i,j,k : longint;
      begin
         if (psym(p)^.typ=varsym) and (vo_regable in pvarsym(p)^.varoptions) then
           begin
              { walk through all momentary register variables }
              for i:=1 to maxvarregs do
                begin
                   { free register ? }
                   if regvars[i]=nil then
                     begin
                        regvars[i]:=pvarsym(p);
                        regvars_para[i]:=parasym;
                        break;
                     end;
                   { else throw out a variable ? }
                       j:=pvarsym(p)^.refs;
                   { parameter get a less value }
                   if parasym then
                     begin
                        if cs_littlesize in aktglobalswitches  then
                          dec(j,1)
                        else
                          dec(j,100);
                     end;
                   if (j>regvars_refs[i]) and (j>0) then
                     begin
                        for k:=maxvarregs-1 downto i do
                          begin
                             regvars[k+1]:=regvars[k];
                             regvars_para[k+1]:=regvars_para[k];
                          end;
                        { calc the new refs
                        pvarsym(p)^.refs:=j; }
                        regvars[i]:=pvarsym(p);
                        regvars_para[i]:=parasym;
                        regvars_refs[i]:=j;
                        break;
                     end;
                end;
           end;
      end;


    procedure searchfpuregvars(p : pnamedindexobject);
      var
         i,j,k : longint;
      begin
         if (psym(p)^.typ=varsym) and (vo_fpuregable in pvarsym(p)^.varoptions) then
           begin
              { walk through all momentary register variables }
              for i:=1 to maxfpuvarregs do
                begin
                   { free register ? }
                   if regvars[i]=nil then
                     begin
                        regvars[i]:=pvarsym(p);
                        regvars_para[i]:=parasym;
                        break;
                     end;
                   { else throw out a variable ? }
                       j:=pvarsym(p)^.refs;
                   { parameter get a less value }
                   if parasym then
                     begin
                        if cs_littlesize in aktglobalswitches  then
                          dec(j,1)
                        else
                          dec(j,100);
                     end;
                   if (j>regvars_refs[i]) and (j>0) then
                     begin
                        for k:=maxfpuvarregs-1 downto i do
                          begin
                             regvars[k+1]:=regvars[k];
                             regvars_para[k+1]:=regvars_para[k];
                          end;
                        { calc the new refs
                        pvarsym(p)^.refs:=j; }
                        regvars[i]:=pvarsym(p);
                        regvars_para[i]:=parasym;
                        regvars_refs[i]:=j;
                        break;
                     end;
                end;
           end;
      end;


    procedure generatecode(var p : ptree);
      var
         i       : longint;
         regsize : topsize;
         hr      : preference;
      label
         nextreg;
      begin
         {!!!!!!!! temptoremove:=nil; }
         cleartempgen;
         { when size optimization only count occurrence }
         if cs_littlesize in aktglobalswitches then
           t_times:=1
         else
           { reference for repetition is 100 }
           t_times:=100;
         { clear register count }
         clearregistercount;
         use_esp_stackframe:=false;

         if not(do_firstpass(p)) then
           begin
              { max. optimizations     }
              { only if no asm is used }
              { and no try statement   }
              if (cs_regalloc in aktglobalswitches) and
                ((procinfo.flags and (pi_uses_asm or pi_uses_exceptions))=0) then
                begin
                   { can we omit the stack frame ? }
                   { conditions:
                     1. procedure (not main block)
                     2. no constructor or destructor
                     3. no call to other procedures
                     4. no interrupt handler
                   }
                   if assigned(aktprocsym) then
                     begin
                       if not(aktprocsym^.definition^.proctypeoption in [potype_constructor,potype_destructor]) and
                          not(po_interrupt in aktprocsym^.definition^.procoptions) and
                          ((procinfo.flags and pi_do_call)=0) and
                          (lexlevel>=normal_function_level) then
                       begin
                         { use ESP as frame pointer }
                         procinfo.framepointer:=stack_pointer;
                         use_esp_stackframe:=true;

                         { calc parameter distance new }
                         dec(procinfo.framepointer_offset,4);
                         dec(procinfo.ESI_offset,4);

                         { is this correct ???}
                         { retoffset can be negativ for results in eax !! }
                         { the value should be decreased only if positive }
                         if procinfo.retoffset>=0 then
                           dec(procinfo.retoffset,4);

                         dec(procinfo.call_offset,4);
                         aktprocsym^.definition^.parast^.address_fixup:=procinfo.call_offset;
                       end;
                     end;
                   if (p^.registers32<4) then
                     begin
                        for i:=1 to maxvarregs do
                          regvars[i]:=nil;
                        parasym:=false;
                        symtablestack^.foreach({$ifndef TP}@{$endif}searchregvars);
                        { copy parameter into a register ? }
                        parasym:=true;
                        symtablestack^.next^.foreach({$ifndef TP}@{$endif}searchregvars);
                        { hold needed registers free }
                        for i:=maxvarregs downto maxvarregs-p^.registers32+1 do
                          regvars[i]:=nil;
                        { now assign register }
                        for i:=1 to maxvarregs-p^.registers32 do
                          begin
                             if assigned(regvars[i]) then
                               begin
                                  { it is nonsens, to copy the variable to }
                                  { a register because we need then much   }
                                  { too pushes ?                           }
                                  if reg_pushes[varregs[i]]>=regvars[i]^.refs then
                                    begin
                                       regvars[i]:=nil;
                                       goto nextreg;
                                    end;

                                  { register is no longer available for }
                                  { expressions                  }
                                  { search the register which is the most }
                                  { unused                              }
                                  usableregs:=usableregs-[varregs[i]];
{$ifdef i386}
                                  procinfo.aktentrycode^.concat(new(pairegalloc,alloc(varregs[i])));
{$endif i386}
                                  is_reg_var[varregs[i]]:=true;
                                  dec(c_usableregs);

                                  { possibly no 32 bit register are needed }
                                  { call by reference/const ? }
                                  if (regvars[i]^.varspez=vs_var) or
                                     ((regvars[i]^.varspez=vs_const) and
                                       push_addr_param(regvars[i]^.definition)) then
                                    begin
                                       regvars[i]^.reg:=varregs[i];
                                       regsize:=S_L;
                                    end
                                  else
                                   if (regvars[i]^.definition^.deftype=orddef) and
                                      (porddef(regvars[i]^.definition)^.size=1) then
                                    begin
{$ifdef i386}
                                       regvars[i]^.reg:=reg32toreg8(varregs[i]);
{$endif}
                                       regsize:=S_B;
                                    end
                                  else
                                   if (regvars[i]^.definition^.deftype=orddef) and
                                      (porddef(regvars[i]^.definition)^.size=2) then
                                    begin
{$ifdef i386}
                                       regvars[i]^.reg:=reg32toreg16(varregs[i]);
{$endif}
                                       regsize:=S_W;
                                    end
                                  else
                                    begin
                                       regvars[i]^.reg:=varregs[i];
                                       regsize:=S_L;
                                    end;
                                  { parameter must be load }
                                  if regvars_para[i] then
                                    begin
                                       { procinfo is there actual,      }
                                       { because we can't never be in a }
                                       { nested procedure              }
                                       { when loading parameter to reg  }
                                       new(hr);
                                       reset_reference(hr^);
                                       hr^.offset:=pvarsym(regvars[i])^.address+procinfo.call_offset;
                                       hr^.base:=procinfo.framepointer;
{$ifdef i386}
                                       procinfo.aktentrycode^.concat(new(pai386,op_ref_reg(A_MOV,regsize,
                                         hr,regvars[i]^.reg)));
{$endif i386}
{$ifdef m68k}
                                       procinfo.aktentrycode^.concat(new(pai68k,op_ref_reg(A_MOVE,regsize,
                                         hr,regvars[i]^.reg)));
{$endif m68k}
                                       unused:=unused - [regvars[i]^.reg];
                                    end;
                                  { procedure uses this register }
{$ifdef i386}
                                  usedinproc:=usedinproc or ($80 shr byte(varregs[i]));
{$endif i386}
{$ifdef m68k}
                                  usedinproc:=usedinproc or ($800 shr word(varregs[i]));
{$endif m68k}
                               end;
                             nextreg:
                               { dummy }
                               regsize:=S_W;
                          end;
                        for i:=1 to maxvarregs do
                          begin
                             if assigned(regvars[i]) then
                               begin
                                  if cs_asm_source in aktglobalswitches then
                                    procinfo.aktentrycode^.insert(new(pai_asm_comment,init(strpnew(regvars[i]^.name+
                                      ' with weight '+tostr(regvars[i]^.refs)+' assigned to register '+
                                      reg2str(regvars[i]^.reg)))));
                                  if (status.verbosity and v_debug)=v_debug then
                                    Message3(cg_d_register_weight,reg2str(regvars[i]^.reg),
                                      tostr(regvars[i]^.refs),regvars[i]^.name);
                               end;
                          end;
                     end;
                   if (p^.registersfpu<maxfpuvarregs-2) then
                     begin
                        for i:=1 to maxfpuvarregs do
                          regvars[i]:=nil;
                        parasym:=false;
                        symtablestack^.foreach({$ifndef TP}@{$endif}searchfpuregvars);
{$ifdef dummy}
                        { copy parameter into a register ? }
                        parasym:=true;
                        symtablestack^.next^.foreach({$ifndef TP}@{$endif}searchregvars);
{$endif dummy}
                        { hold needed registers free }
                        for i:=maxfpuvarregs downto maxfpuvarregs-p^.registersfpu+1 do
                          regvars[i]:=nil;
                        { now assign register }
                        for i:=1 to maxfpuvarregs-p^.registersfpu do
                          begin
                             if assigned(regvars[i]) then
                               begin
                                  regvars[i]^.reg:=correct_fpuregister(R_ST0,i-1);
{$ifdef dummy}
                                  { parameter must be load }
                                  if regvars_para[i] then
                                    begin
                                       { procinfo is there actual,      }
                                       { because we can't never be in a }
                                       { nested procedure              }
                                       { when loading parameter to reg  }
                                       new(hr);
                                       reset_reference(hr^);
                                       hr^.offset:=pvarsym(regvars[i])^.address+procinfo.call_offset;
                                       hr^.base:=procinfo.framepointer;
{$ifdef i386}
                                       procinfo.aktentrycode^.concat(new(pai386,op_ref_reg(A_MOV,regsize,
                                         hr,regvars[i]^.reg)));
{$endif i386}
{$ifdef m68k}
                                       procinfo.aktentrycode^.concat(new(pai68k,op_ref_reg(A_MOVE,regsize,
                                         hr,regvars[i]^.reg)));
{$endif m68k}
                                    end;
{$endif dummy}
                               end;
                          end;
                       if cs_asm_source in aktglobalswitches then
                         procinfo.aktentrycode^.insert(new(pai_asm_comment,init(strpnew(tostr(p^.registersfpu)+
                         ' registers on FPU stack used by temp. expressions'))));
                        for i:=1 to maxfpuvarregs do
                          begin
                             if assigned(regvars[i]) then
                               begin
                                  if cs_asm_source in aktglobalswitches then
                                    procinfo.aktentrycode^.insert(new(pai_asm_comment,init(strpnew(regvars[i]^.name+
                                      ' with weight '+tostr(regvars[i]^.refs)+' assigned to register '+
                                      reg2str(regvars[i]^.reg)))));
                                  if (status.verbosity and v_debug)=v_debug then
                                    Message3(cg_d_register_weight,reg2str(regvars[i]^.reg),
                                      tostr(regvars[i]^.refs),regvars[i]^.name);
                               end;
                          end;
                        if cs_asm_source in aktglobalswitches then
                          procinfo.aktentrycode^.insert(new(pai_asm_comment,init(strpnew('Register variable assignment:'))));
                     end;
                end;
              if assigned(aktprocsym) and
                 (pocall_inline in aktprocsym^.definition^.proccalloptions) then
                make_const_global:=true;
              do_secondpass(p);

              if assigned(procinfo.def) then
                procinfo.def^.fpu_used:=p^.registersfpu;

              { all registers can be used again }
              resetusableregisters;
           end;
         procinfo.aktproccode^.concatlist(exprasmlist);
         make_const_global:=false;
      end;

end.
{
  $Log$
  Revision 1.30  1999-08-04 14:21:07  florian
    * now every available fpu register is used for
      fpu register variables

  Revision 1.29  1999/08/04 13:45:28  florian
    + floating point register variables !!
    * pairegalloc is now generated for register variables

  Revision 1.28  1999/08/04 00:23:10  florian
    * renamed i386asm and i386base to cpuasm and cpubase

  Revision 1.27  1999/08/03 22:02:55  peter
    * moved bitmask constants to sets
    * some other type/const renamings

  Revision 1.26  1999/06/02 22:44:08  pierre
   * previous wrong log corrected

  Revision 1.25  1999/06/02 22:25:41  pierre
  * changed $ifdef FPC @ into $ifndef TP

  Revision 1.24  1999/06/01 14:45:50  peter
    * @procvar is now always needed for FPC

  Revision 1.23  1999/05/27 19:44:43  peter
    * removed oldasm
    * plabel -> pasmlabel
    * -a switches to source writing automaticly
    * assembler readers OOPed
    * asmsymbol automaticly external
    * jumptables and other label fixes for asm readers

  Revision 1.22  1999/05/18 14:15:50  peter
    * containsself fixes
    * checktypes()

  Revision 1.21  1999/05/17 21:57:11  florian
    * new temporary ansistring handling

  Revision 1.20  1999/05/02 21:33:54  florian
    * several bugs regarding -Or fixed

  Revision 1.19  1999/05/01 13:24:28  peter
    * merged nasm compiler
    * old asm moved to oldasm/

  Revision 1.18  1999/04/28 06:02:04  florian
    * changes of Bruessel:
       + message handler can now take an explicit self
       * typinfo fixed: sometimes the type names weren't written
       * the type checking for pointer comparisations and subtraction
         and are now more strict (was also buggy)
       * small bug fix to link.pas to support compiling on another
         drive
       * probable bug in popt386 fixed: call/jmp => push/jmp
         transformation didn't count correctly the jmp references
       + threadvar support
       * warning if ln/sqrt gets an invalid constant argument

  Revision 1.17  1999/03/31 13:55:11  peter
    * assembler inlining working for ag386bin

  Revision 1.16  1999/03/24 23:17:11  peter
    * fixed bugs 212,222,225,227,229,231,233

  Revision 1.15  1999/02/22 02:15:25  peter
    * updates for ag386bin

  Revision 1.14  1999/01/23 23:29:37  florian
    * first running version of the new code generator
    * when compiling exceptions under Linux fixed

  Revision 1.13  1998/12/30 13:41:09  peter
    * released valuepara

  Revision 1.12  1998/12/19 00:23:51  florian
    * ansistring memory leaks fixed

  Revision 1.11  1998/12/11 00:03:28  peter
    + globtype,tokens,version unit splitted from globals

  Revision 1.10  1998/11/18 15:44:14  peter
    * VALUEPARA for tp7 compatible value parameters

  Revision 1.9  1998/11/13 15:40:21  pierre
    + added -Se in Makefile cvstest target
    + lexlevel cleanup
      normal_function_level main_program_level and unit_init_level defined
    * tins_cache grown to A_EMMS (gave range check error in asm readers)
      (test added in code !)
    * -Un option was wrong
    * _FAIL and _SELF only keyword inside
      constructors and methods respectively

  Revision 1.8  1998/10/29 15:42:49  florian
    + partial disposing of temp. ansistrings

  Revision 1.7  1998/10/26 22:58:19  florian
    * new introduded problem with classes fix, the parent class wasn't set
      correct, if the class was defined forward before

  Revision 1.6  1998/09/23 09:58:52  peter
    * first working array of const things

  Revision 1.5  1998/09/21 10:01:06  peter
    * check if procinfo.def is assigned before storing registersfpu

  Revision 1.4  1998/09/21 08:45:16  pierre
    + added vmt_offset in tobjectdef.write for fututre use
      (first steps to have objects without vmt if no virtual !!)
    + added fpu_used field for tabstractprocdef  :
      sets this level to 2 if the functions return with value in FPU
      (is then set to correct value at parsing of implementation)
      THIS MIGHT refuse some code with FPU expression too complex
      that were accepted before and even in some cases
      that don't overflow in fact
      ( like if f : float; is a forward that finally in implementation
       only uses one fpu register !!)
      Nevertheless I think that it will improve security on
      FPU operations !!
    * most other changes only for UseBrowser code
      (added symtable references for record and objects)
      local switch for refs to args and local of each function
      (static symtable still missing)
      UseBrowser still not stable and probably broken by
      the definition hash array !!

  Revision 1.3  1998/09/17 09:42:40  peter
    + pass_2 for cg386
    * Message() -> CGMessage() for pass_1/pass_2

  Revision 1.2  1998/09/07 18:46:07  peter
    * update smartlinking, uses getdatalabel
    * renamed ptree.value vars to value_str,value_real,value_set

  Revision 1.1  1998/09/01 09:07:12  peter
    * m68k fixes, splitted cg68k like cgi386

}