fpc/compiler/jvm/cpupara.pas

{
    Copyright (c) 1998-2010 by Florian Klaempfl, Jonas Maebe

    Calling conventions for the JVM

    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 cpupara;

{$i fpcdefs.inc}

interface

    uses
      globtype,
      cclasses,
      aasmtai,aasmdata,
      cpubase,cpuinfo,
      symconst,symbase,symsym,symtype,symdef,paramgr,parabase,cgbase,cgutils;

    type

      { TJVMParaManager }

      TJVMParaManager=class(TParaManager)
        function  push_high_param(varspez:tvarspez;def : tdef;calloption : tproccalloption) : boolean;override;
        function  push_addr_param(varspez:tvarspez;def : tdef;calloption : tproccalloption) : boolean;override;
        function  push_size(varspez: tvarspez; def: tdef; calloption: tproccalloption): longint;override;
        {Returns a structure giving the information on the storage of the parameter
        (which must be an integer parameter)
        @param(nr Parameter number of routine, starting from 1)}
        procedure getintparaloc(calloption : tproccalloption; nr : longint;var cgpara : TCGPara);override;
        function  create_paraloc_info(p : TAbstractProcDef; side: tcallercallee):longint;override;
        function  get_funcretloc(p : tabstractprocdef; side: tcallercallee; def: tdef): tcgpara;override;
        function param_use_paraloc(const cgpara: tcgpara): boolean; override;
        function ret_in_param(def: tdef; calloption: tproccalloption): boolean; override;
        function is_stack_paraloc(paraloc: pcgparalocation): boolean;override;
      private
        procedure create_funcretloc_info(p : tabstractprocdef; side: tcallercallee);
        procedure create_paraloc_info_intern(p : tabstractprocdef; side: tcallercallee; paras: tparalist;
                                             var parasize:longint);
      end;

implementation

    uses
      cutils,verbose,systems,
      defutil,jvmdef,
      cgobj;


    procedure TJVMParaManager.GetIntParaLoc(calloption : tproccalloption; nr : longint;var cgpara : tcgpara);
      begin
        { don't know whether it's an actual integer or a pointer (necessary for cgpara.def) }
        internalerror(2010121001);
      end;

    function TJVMParaManager.push_high_param(varspez: tvarspez; def: tdef; calloption: tproccalloption): boolean;
      begin
        { we don't need a separate high parameter, since all arrays in Java
          have an implicit associated length }
        if not is_open_array(def) then
          result:=inherited
        else
          result:=false;
      end;


    { true if a parameter is too large to copy and only the address is pushed }
    function TJVMParaManager.push_addr_param(varspez:tvarspez;def : tdef;calloption : tproccalloption) : boolean;
      begin
        result:=jvmimplicitpointertype(def);
      end;


    function TJVMParaManager.push_size(varspez: tvarspez; def: tdef; calloption: tproccalloption): longint;
      begin
        { all aggregate types are emulated using indirect pointer types }
        if def.typ in [arraydef,recorddef,setdef,stringdef] then
          result:=4
        else
          result:=inherited;
      end;


    procedure TJVMParaManager.create_funcretloc_info(p : tabstractprocdef; side: tcallercallee);
      begin
        p.funcretloc[side]:=get_funcretloc(p,side,p.returndef);
      end;


    function TJVMParaManager.get_funcretloc(p : tabstractprocdef; side: tcallercallee; def: tdef): tcgpara;
      var
        paraloc : pcgparalocation;
        retcgsize  : tcgsize;
      begin
        result.init;
        result.alignment:=get_para_align(p.proccalloption);
        result.def:=def;
        { void has no location }
        if is_void(def) then
          begin
            paraloc:=result.add_location;
            result.size:=OS_NO;
            result.intsize:=0;
            paraloc^.size:=OS_NO;
            paraloc^.loc:=LOC_VOID;
            exit;
          end;
        { Constructors return self instead of a boolean }
        if (p.proctypeoption=potype_constructor) then
          begin
            retcgsize:=OS_INT;
            result.intsize:=sizeof(pint);
          end
        else
          begin
            retcgsize:=def_cgsize(def);
            result.intsize:=def.size;
          end;
        result.size:=retcgsize;

        paraloc:=result.add_location;
        { all values are returned on the evaluation stack }
        paraloc^.loc:=LOC_REFERENCE;
        paraloc^.reference.index:=NR_EVAL_STACK_BASE;
        paraloc^.reference.offset:=0;
      end;

    function TJVMParaManager.param_use_paraloc(const cgpara: tcgpara): boolean;
      begin
        { all parameters are copied by the VM to local variable locations }
        result:=true;
      end;

    function TJVMParaManager.ret_in_param(def: tdef; calloption: tproccalloption): boolean;
      begin
        { not as efficient as returning in param for jvmimplicitpointertypes,
          but in the latter case the routines are harder to use from Java
          (especially for arrays), because the caller then manually has to
          allocate the instance/array of the right size }
        Result:=false;
      end;

    function TJVMParaManager.is_stack_paraloc(paraloc: pcgparalocation): boolean;
      begin
        { all parameters are passed on the evaluation stack }
        result:=true;
      end;


    procedure TJVMParaManager.create_paraloc_info_intern(p : tabstractprocdef; side: tcallercallee;paras:tparalist;
                                                           var parasize:longint);
      var
        paraloc      : pcgparalocation;
        i            : integer;
        hp           : tparavarsym;
        paracgsize   : tcgsize;
        paraofs      : longint;
      begin
        paraofs:=0;
        for i:=0 to paras.count-1 do
          begin
            hp:=tparavarsym(paras[i]);
            paracgsize:=def_cgsize(hp.vardef);
            if paracgsize=OS_NO then
              paracgsize:=OS_ADDR;
            hp.paraloc[side].reset;
            hp.paraloc[side].size:=paracgsize;
            hp.paraloc[side].def:=hp.vardef;
            hp.paraloc[side].alignment:=std_param_align;
            hp.paraloc[side].intsize:=tcgsize2size[paracgsize];
            paraloc:=hp.paraloc[side].add_location;
            { All parameters are passed on the evaluation stack, pushed from
              left to right (including self, if applicable). At the callee side,
              they're available as local variables 0..n-1 (with 64 bit values
              taking up two slots) }
            paraloc^.loc:=LOC_REFERENCE;;
            paraloc^.reference.offset:=paraofs;
            case side of
              callerside:
                begin
                  paraloc^.loc:=LOC_REFERENCE;
                  { we use a fake loc_reference to indicate the stack location;
                    the offset (set above) will be used by ncal to order the
                    parameters so they will be pushed in the right order }
                  paraloc^.reference.index:=NR_EVAL_STACK_BASE;
                end;
              calleeside:
                begin
                  paraloc^.loc:=LOC_REFERENCE;
                  paraloc^.reference.index:=NR_STACK_POINTER_REG;
                end;
            end;
            { 2 slots for 64 bit integers and floats, 1 slot for the rest }
            if not(is_64bit(hp.vardef) or
                   ((hp.vardef.typ=floatdef) and
                    (tfloatdef(hp.vardef).floattype=s64real))) then
              inc(paraofs)
            else
              inc(paraofs,2);
          end;
        parasize:=paraofs;
      end;


    function TJVMParaManager.create_paraloc_info(p : tabstractprocdef; side: tcallercallee):longint;
      var
        parasize : longint;
      begin
        parasize:=0;
        create_paraloc_info_intern(p,side,p.paras,parasize);
        { Create Function result paraloc }
        create_funcretloc_info(p,side);
        { We need to return the size allocated on the stack }
        result:=parasize;
      end;


begin
   ParaManager:=TJVMParaManager.create;
end.