freepascal.compiler/compiler/i386/n386set.pas

{
    Copyright (c) 1998-2002 by Florian Klaempfl

    Generate i386 assembler for in set/case nodes

    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 n386set;

{$i fpcdefs.inc}

interface

    uses
      globtype,
      node,nset,pass_1,nx86set;

    type
      ti386casenode = class(tx86casenode)
         procedure optimizevalues(var max_linear_list:aint;var max_dist:aword);override;
         procedure genlinearlist(hp : pcaselabel);override;
      end;


implementation

    uses
      systems,
      verbose,globals,constexp,
      symconst,symdef,defutil,
      aasmbase,aasmtai,aasmdata,aasmcpu,
      cgbase,pass_2,
      ncon,
      cpubase,cpuinfo,procinfo,
      cga,cgutils,cgobj,ncgutil,
      cgx86;


{*****************************************************************************
                            TI386CASENODE
*****************************************************************************}

    procedure ti386casenode.optimizevalues(var max_linear_list:aint;var max_dist:aword);
      begin
        { a jump table crashes the pipeline! }
        if current_settings.optimizecputype=cpu_386 then
          inc(max_linear_list,3)
        else if current_settings.optimizecputype=cpu_Pentium then
          inc(max_linear_list,6)
        else if current_settings.optimizecputype in [cpu_Pentium2,cpu_Pentium3] then
          inc(max_linear_list,9)
        else if current_settings.optimizecputype=cpu_Pentium4 then
          inc(max_linear_list,14);
      end;


    procedure ti386casenode.genlinearlist(hp : pcaselabel);
      var
        first : boolean;
        lastrange : boolean;
        last : TConstExprInt;
        cond_lt,cond_le : tresflags;
        opcgsize: tcgsize;

        procedure genitem(t : pcaselabel);
          begin
             opcgsize:=def_cgsize(opsize);
             if assigned(t^.less) then
               genitem(t^.less);
             { need we to test the first value }
             if first and (t^._low>get_min_value(left.resultdef)) then
               begin
                 cg.a_cmp_const_reg_label(current_asmdata.CurrAsmList,opcgsize,jmp_lt,aint(t^._low.svalue),hregister,elselabel);
               end;
             if t^._low=t^._high then
               begin
                  if t^._low-last=0 then
                    cg.a_cmp_const_reg_label(current_asmdata.CurrAsmList, opcgsize, OC_EQ,0,hregister,blocklabel(t^.blockid))
                  else
                    begin
                      cg.a_op_const_reg(current_asmdata.CurrAsmList, OP_SUB, opcgsize, aint(t^._low.svalue-last.svalue), hregister);
                      cg.a_jmp_flags(current_asmdata.CurrAsmList,F_E,blocklabel(t^.blockid));
                    end;
                  last:=t^._low;
                  lastrange:=false;
               end
             else
               begin
                  { it begins with the smallest label, if the value }
                  { is even smaller then jump immediately to the    }
                  { ELSE-label                                }
                  if first then
                    begin
                       { have we to ajust the first value ? }
                       if (t^._low>get_min_value(left.resultdef)) or (get_min_value(left.resultdef)<>0) then
                         cg.a_op_const_reg(current_asmdata.CurrAsmList, OP_SUB, opcgsize, aint(t^._low.svalue), hregister);
                    end
                  else
                    begin
                      { if there is no unused label between the last and the }
                      { present label then the lower limit can be checked    }
                      { immediately. else check the range in between:       }

                      cg.a_op_const_reg(current_asmdata.CurrAsmList, OP_SUB, opcgsize, aint(t^._low.svalue-last.svalue), hregister);
                      { no jump necessary here if the new range starts at }
                      { at the value following the previous one           }
                      if ((t^._low-last) <> 1) or
                         (not lastrange) then
                        cg.a_jmp_flags(current_asmdata.CurrAsmList,cond_lt,elselabel);
                    end;
                  {we need to use A_SUB, because A_DEC does not set the correct flags, therefor
                   using a_op_const_reg(OP_SUB) is not possible }
                  emit_const_reg(A_SUB,TCGSize2OpSize[opcgsize],aint(t^._high.svalue-t^._low.svalue),hregister);
                  cg.a_jmp_flags(current_asmdata.CurrAsmList,cond_le,blocklabel(t^.blockid));
                  last:=t^._high;
                  lastrange:=true;
               end;
             first:=false;
             if assigned(t^.greater) then
               genitem(t^.greater);
          end;

        begin
           if with_sign then
             begin
                cond_lt:=F_L;
                cond_le:=F_LE;
             end
           else
              begin
                cond_lt:=F_B;
                cond_le:=F_BE;
             end;
           { do we need to generate cmps? }
           if (with_sign and (min_label<0)) then
             genlinearcmplist(hp)
           else
             begin
                last:=0;
                lastrange:=false;
                first:=true;
                genitem(hp);
                cg.a_jmp_always(current_asmdata.CurrAsmList,elselabel);
             end;
        end;

begin
   ccasenode:=ti386casenode;
end.