freepascal.compiler/compiler/cgobj.pas

{
    $Id$

    Copyright (c) 1998-2002 by Florian Klaempfl
    Member of the Free Pascal development team

    This unit implements the basic code generator object

    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.

 ****************************************************************************
}
{# @abstract(Abstract code generator unit)
   Abstreact code generator unit. This contains the base class
   to implement for all new supported processors.

   WARNING: None of the routines implemented in these modules,
   or their descendants, should use the temp. allocator, as
   these routines may be called inside genentrycode, and the
   stack frame is already setup!
}
unit cgobj;

{$i fpcdefs.inc}

  interface

    uses
       cclasses,aasmbase,aasmtai,aasmcpu,symtable,
       cpubase,cpuinfo,cpupara,
       cginfo,
       symconst,symbase,symtype,node
{$ifdef delphi}
       ,dmisc
{$endif}
       ;

    type
       talignment = (AM_NATURAL,AM_NONE,AM_2BYTE,AM_4BYTE,AM_8BYTE);


       {# @abstract(Abstract code generator)
          This class implements an abstract instruction generator. Some of
          the methods of this class are generic, while others must
          be overriden for all new processors which will be supported
          by Free Pascal. For 32-bit processors, the base class
          sould be @link(tcg64f32) and not @var(tcg).
       }
       tcg = class
          scratch_register_array_pointer : aword;
          {# List of currently unused scratch registers }
          unusedscratchregisters : tregisterset;

          alignment : talignment;
          {************************************************}
          {                 basic routines                 }
          constructor create;

          { returns the tcgsize corresponding with the size of reg }
          class function reg_cgsize(const reg: tregister) : tcgsize; virtual;

          {# Emit a label to the instruction stream. }
          procedure a_label(list : taasmoutput;l : tasmlabel);virtual;

          {# Allocates register r by inserting a pai_realloc record }
          procedure a_reg_alloc(list : taasmoutput;r : tregister);
          {# Deallocates register r by inserting a pa_regdealloc record}
          procedure a_reg_dealloc(list : taasmoutput;r : tregister);

          {# @abstract(Returns an int register for use as scratch register)
             This routine returns a register which can be used by
             the code generator as a general purpose scratch register.
             Since scratch_registers are scarce resources, the register
             should be freed by calling @link(free_scratch_reg) as
             soon as it is no longer required.
          }
          function get_scratch_reg_int(list : taasmoutput) : tregister;virtual;
          {# @abstract(Returns an address register for use as scratch register)
             This routine returns a register which can be used by
             the code generator as a pointer scratch register.
             Since scratch_registers are scarce resources, the register
             should be freed by calling @link(free_scratch_reg) as
             soon as it is no longer required.
          }
          function get_scratch_reg_address(list : taasmoutput) : tregister;virtual;
          {# @abstract(Releases a scratch register)

             Releases a scratch register.
             This routine is used to free a register which
             was previously allocated using @link(get_scratch_reg).
          }
          procedure free_scratch_reg(list : taasmoutput;r : tregister);
          {# Pass a parameter, which is located in a register, to a routine.

             This routine should push/send the parameter to the routine, as
             required by the specific processor ABI and routine modifiers.
             This must be overriden for each CPU target.

             @param(size size of the operand in the register)
             @param(r register source of the operand)
             @param(locpara where the parameter will be stored)
          }
          procedure a_param_reg(list : taasmoutput;size : tcgsize;r : tregister;const locpara : tparalocation);virtual;
          {# Pass a parameter, which is a constant, to a routine.

             A generic version is provided. This routine should
             be overriden for optimization purposes if the cpu
             permits directly sending this type of parameter.

             @param(size size of the operand in constant)
             @param(a value of constant to send)
             @param(locpara where the parameter will be stored)
          }
          procedure a_param_const(list : taasmoutput;size : tcgsize;a : aword;const locpara : tparalocation);virtual;
          {# Pass the value of a parameter, which is located in memory, to a routine.

             A generic version is provided. This routine should
             be overriden for optimization purposes if the cpu
             permits directly sending this type of parameter.

             @param(size size of the operand in constant)
             @param(r Memory reference of value to send)
             @param(locpara where the parameter will be stored)
          }
          procedure a_param_ref(list : taasmoutput;size : tcgsize;const r : treference;const locpara : tparalocation);virtual;
          {# Pass the value of a parameter, which can be located either in a register or memory location,
             to a routine.

             A generic version is provided.

             @param(l location of the operand to send)
             @param(nr parameter number (starting from one) of routine (from left to right))
             @param(locpara where the parameter will be stored)
          }
          procedure a_param_loc(list : taasmoutput;const l : tlocation;const locpara : tparalocation);
          {# Pass the address of a reference to a routine. This routine
             will calculate the address of the reference, and pass this
             calculated address as a parameter.

             A generic version is provided. This routine should
             be overriden for optimization purposes if the cpu
             permits directly sending this type of parameter.

             @param(r reference to get address from)
             @param(nr parameter number (starting from one) of routine (from left to right))
          }
          procedure a_paramaddr_ref(list : taasmoutput;const r : treference;const locpara : tparalocation);virtual;

          (* Remarks:
            * If a method specifies a size you have only to take care
              of that number of bits, i.e. load_const_reg with OP_8 must
              only load the lower 8 bit of the specified register
              the rest of the register can be undefined
              if  necessary the compiler will call a method
              to zero or sign extend the register
            * The a_load_XX_XX with OP_64 needn't to be
              implemented for 32 bit
              processors, the code generator takes care of that
            * the addr size is for work with the natural pointer
              size
            * the procedures without fpu/mm are only for integer usage
            * normally the first location is the source and the
              second the destination
          *)

          {# Emits instruction to call the method specified by symbol name.
             This routine must be overriden for each new target cpu.
          }
          procedure a_call_name(list : taasmoutput;const s : string);virtual; abstract;
          procedure a_call_ref(list : taasmoutput;const ref : treference);virtual;abstract;
          procedure a_call_reg(list : taasmoutput;reg : tregister);virtual;abstract;
          procedure a_call_loc(list : taasmoutput;const loc:tlocation);


          { move instructions }
          procedure a_load_const_reg(list : taasmoutput;size : tcgsize;a : aword;register : tregister);virtual; abstract;
          procedure a_load_const_ref(list : taasmoutput;size : tcgsize;a : aword;const ref : treference);virtual;
          procedure a_load_const_loc(list : taasmoutput;a : aword;const loc : tlocation);
          procedure a_load_reg_ref(list : taasmoutput;size : tcgsize;register : tregister;const ref : treference);virtual; abstract;
          procedure a_load_reg_reg(list : taasmoutput;fromsize, tosize : tcgsize;reg1,reg2 : tregister);virtual; abstract;
          procedure a_load_reg_loc(list : taasmoutput;size : tcgsize;reg : tregister;const loc: tlocation);
          procedure a_load_ref_reg(list : taasmoutput;size : tcgsize;const ref : treference;register : tregister);virtual; abstract;
          procedure a_load_ref_ref(list : taasmoutput;size : tcgsize;const sref : treference;const dref : treference);virtual;
          procedure a_load_loc_reg(list : taasmoutput;const loc: tlocation; reg : tregister);
          procedure a_load_loc_ref(list : taasmoutput;const loc: tlocation; const ref : treference);
          procedure a_loadaddr_ref_reg(list : taasmoutput;const ref : treference;r : tregister);virtual; abstract;

          { fpu move instructions }
          procedure a_loadfpu_reg_reg(list: taasmoutput; reg1, reg2: tregister); virtual; abstract;
          procedure a_loadfpu_ref_reg(list: taasmoutput; size: tcgsize; const ref: treference; reg: tregister); virtual; abstract;
          procedure a_loadfpu_reg_ref(list: taasmoutput; size: tcgsize; reg: tregister; const ref: treference); virtual; abstract;
          procedure a_loadfpu_loc_reg(list: taasmoutput; const loc: tlocation; const reg: tregister);
          procedure a_loadfpu_reg_loc(list: taasmoutput; size: tcgsize; const reg: tregister; const loc: tlocation);

          { vector register move instructions }
          procedure a_loadmm_reg_reg(list: taasmoutput; reg1, reg2: tregister); virtual; abstract;
          procedure a_loadmm_ref_reg(list: taasmoutput; const ref: treference; reg: tregister); virtual; abstract;
          procedure a_loadmm_reg_ref(list: taasmoutput; reg: tregister; const ref: treference); virtual; abstract;
          procedure a_parammm_reg(list: taasmoutput; reg: tregister); virtual; abstract;

          { basic arithmetic operations }
          { note: for operators which require only one argument (not, neg), use }
          { the op_reg_reg, op_reg_ref or op_reg_loc methods and keep in mind   }
          { that in this case the *second* operand is used as both source and   }
          { destination (JM)                                                    }
          procedure a_op_const_reg(list : taasmoutput; Op: TOpCG; a: AWord; reg: TRegister); virtual; abstract;
          procedure a_op_const_ref(list : taasmoutput; Op: TOpCG; size: TCGSize; a: AWord; const ref: TReference); virtual;
          procedure a_op_const_loc(list : taasmoutput; Op: TOpCG; a: AWord; const loc: tlocation);
          procedure a_op_reg_reg(list : taasmoutput; Op: TOpCG; size: TCGSize; reg1, reg2: TRegister); virtual; abstract;
          procedure a_op_reg_ref(list : taasmoutput; Op: TOpCG; size: TCGSize; reg: TRegister; const ref: TReference); virtual;
          procedure a_op_ref_reg(list : taasmoutput; Op: TOpCG; size: TCGSize; const ref: TReference; reg: TRegister); virtual;
          procedure a_op_reg_loc(list : taasmoutput; Op: TOpCG; reg: tregister; const loc: tlocation);
          procedure a_op_ref_loc(list : taasmoutput; Op: TOpCG; const ref: TReference; const loc: tlocation);

          { trinary operations for processors that support them, 'emulated' }
          { on others. None with "ref" arguments since I don't think there  }
          { are any processors that support it (JM)                         }
          procedure a_op_const_reg_reg(list: taasmoutput; op: TOpCg;
            size: tcgsize; a: aword; src, dst: tregister); virtual;
          procedure a_op_reg_reg_reg(list: taasmoutput; op: TOpCg;
            size: tcgsize; src1, src2, dst: tregister); virtual;

          {  comparison operations }
          procedure a_cmp_const_reg_label(list : taasmoutput;size : tcgsize;cmp_op : topcmp;a : aword;reg : tregister;
            l : tasmlabel);virtual; abstract;
          procedure a_cmp_const_ref_label(list : taasmoutput;size : tcgsize;cmp_op : topcmp;a : aword;const ref : treference;
            l : tasmlabel); virtual;
          procedure a_cmp_const_loc_label(list: taasmoutput; size: tcgsize;cmp_op: topcmp; a: aword; const loc: tlocation;
            l : tasmlabel);
          procedure a_cmp_reg_reg_label(list : taasmoutput;size : tcgsize;cmp_op : topcmp;reg1,reg2 : tregister;l : tasmlabel); virtual; abstract;
          procedure a_cmp_ref_reg_label(list : taasmoutput;size : tcgsize;cmp_op : topcmp; const ref: treference; reg : tregister; l : tasmlabel); virtual;
          procedure a_cmp_loc_reg_label(list : taasmoutput;size : tcgsize;cmp_op : topcmp; const loc: tlocation; reg : tregister; l : tasmlabel);
          procedure a_cmp_ref_loc_label(list: taasmoutput; size: tcgsize;cmp_op: topcmp; const ref: treference; const loc: tlocation;
            l : tasmlabel);

          procedure a_jmp_always(list : taasmoutput;l: tasmlabel); virtual; abstract;
          procedure a_jmp_flags(list : taasmoutput;const f : TResFlags;l: tasmlabel); virtual; abstract;

          {# Depending on the value to check in the flags, either sets the register reg to one (if the flag is set)
             or zero (if the flag is cleared). The size parameter indicates the destination size register.
          }
          procedure g_flags2reg(list: taasmoutput; size: TCgSize; const f: tresflags; reg: TRegister); virtual; abstract;
          procedure g_flags2ref(list: taasmoutput; size: TCgSize; const f: tresflags; const ref:TReference); virtual;

          {
             This routine tries to optimize the const_reg opcode, and should be
             called at the start of a_op_const_reg. It returns the actual opcode
             to emit, and the constant value to emit. If this routine returns
             TRUE, @var(no) instruction should be emitted (.eg : imul reg by 1 )

             @param(op The opcode to emit, returns the opcode which must be emitted)
             @param(a  The constant which should be emitted, returns the constant which must
                    be emitted)
             @param(reg The register to emit the opcode with, returns the register with
                   which the opcode will be emitted)
          }
          function optimize_op_const_reg(list: taasmoutput; var op: topcg; var a : aword; var reg: tregister): boolean;virtual;

         {#
             This routine is used in exception management nodes. It should
             save the exception reason currently in the accumulator. The
             save should be done either to a temp (pointed to by href).
             or on the stack (pushing the value on the stack).

             The size of the value to save is OS_S32. The default version
             saves the exception reason to a temp. memory area.
          }
         procedure g_exception_reason_save(list : taasmoutput; const href : treference);virtual;
         {#
             This routine is used in exception management nodes. It should
             save the exception reason constant. The
             save should be done either to a temp (pointed to by href).
             or on the stack (pushing the value on the stack).

             The size of the value to save is OS_S32. The default version
             saves the exception reason to a temp. memory area.
          }
         procedure g_exception_reason_save_const(list : taasmoutput; const href : treference; a: aword);virtual;
         {#
             This routine is used in exception management nodes. It should
             load the exception reason to the accumulator. The saved value
             should either be in the temp. area (pointed to by href , href should
             *NOT* be freed) or on the stack (the value should be popped).

             The size of the value to save is OS_S32. The default version
             saves the exception reason to a temp. memory area.
          }
         procedure g_exception_reason_load(list : taasmoutput; const href : treference);virtual;


          procedure g_maybe_loadself(list : taasmoutput);virtual;
          procedure g_maybe_testself(list : taasmoutput);virtual;
          {# This should emit the opcode to copy len bytes from the source
             to destination, if loadref is true, it assumes that it first must load
             the source address from the memory location where
             source points to.

             It must be overriden for each new target processor.

             @param(source Source reference of copy)
             @param(dest Destination reference of copy)
             @param(delsource Indicates if the source reference's resources should be freed)
             @param(loadref Is the source reference a pointer to the actual source (TRUE), is it the actual source address (FALSE))

          }
          procedure g_concatcopy(list : taasmoutput;const source,dest : treference;len : aword;delsource,loadref : boolean);virtual; abstract;
          {# This should emit the opcode to a shortrstring from the source
             to destination, if loadref is true, it assumes that it first must load
             the source address from the memory location where
             source points to.

             @param(source Source reference of copy)
             @param(dest Destination reference of copy)
             @param(delsource Indicates if the source reference's resources should be freed)
             @param(loadref Is the source reference a pointer to the actual source (TRUE), is it the actual source address (FALSE))

          }
          procedure g_copyshortstring(list : taasmoutput;const source,dest : treference;len:byte;delsource,loadref : boolean);

          procedure g_incrrefcount(list : taasmoutput;t: tdef; const ref: treference);
          procedure g_decrrefcount(list : taasmoutput;t: tdef; const ref: treference);
          procedure g_initialize(list : taasmoutput;t : tdef;const ref : treference;loadref : boolean);
          procedure g_finalize(list : taasmoutput;t : tdef;const ref : treference;loadref : boolean);

          {# Emits the call to the stack checking routine of
             the runtime library. The default behavior
             does not need to be modified, as it is generic
             for all platforms.

             @param(stackframesize Number of bytes which will be allocated on the stack)
          }
          procedure g_stackcheck(list : taasmoutput;stackframesize : longint);virtual;

          {# Generates range checking code. It is to note
             that this routine does not need to be overriden,
             as it takes care of everything.

             @param(p Node which contains the value to check)
             @param(todef Type definition of node to range check)
          }
          procedure g_rangecheck(list: taasmoutput; const p: tnode;
            const todef: tdef); virtual;

          {# Generates overflow checking code for a node }
          procedure g_overflowcheck(list: taasmoutput; const p: tnode); virtual; abstract;

          procedure g_copyvaluepara_openarray(list : taasmoutput;const ref:treference;elesize:integer);virtual;abstract;
          procedure g_removevaluepara_openarray(list : taasmoutput;const ref:treference;elesize:integer);virtual;abstract;
          {# Emits instructions which should be emitted when entering
             a routine declared as @var(interrupt). The default
             behavior does nothing, should be overriden as required.
          }
          procedure g_interrupt_stackframe_entry(list : taasmoutput);virtual;

          {# Emits instructions which should be emitted when exiting
             a routine declared as @var(interrupt). The default
             behavior does nothing, should be overriden as required.
          }
          procedure g_interrupt_stackframe_exit(list : taasmoutput;selfused,accused,acchiused:boolean);virtual;

          {# Emits instructions when compilation is done in profile
             mode (this is set as a command line option). The default
             behavior does nothing, should be overriden as required.
          }
          procedure g_profilecode(list : taasmoutput);virtual;
          {# Emits instruction for allocating the locals in entry
             code of a routine. This is one of the first
             routine called in @var(genentrycode).

             @param(localsize Number of bytes to allocate as locals)
          }
          procedure g_stackframe_entry(list : taasmoutput;localsize : longint);virtual; abstract;
          {# Emits instructiona for restoring the frame pointer
             at routine exit. For some processors, this routine
             may do nothing at all.
          }
          procedure g_restore_frame_pointer(list : taasmoutput);virtual; abstract;
          {# Emits instructions for returning from a subroutine.
             Should also restore the stack.

             @param(parasize  Number of bytes of parameters to deallocate from stack)
          }
          procedure g_return_from_proc(list : taasmoutput;parasize : aword);virtual; abstract;
          procedure g_call_constructor_helper(list : taasmoutput);virtual;
          procedure g_call_destructor_helper(list : taasmoutput);virtual;
          procedure g_call_fail_helper(list : taasmoutput);virtual;
          {# This routine is called when generating the code for the entry point
             of a routine. It should save all registers which are not used in this
             routine, and which should be declared as saved in the std_saved_registers
             set.

             This routine is mainly used when linking to code which is generated
             by ABI-compliant compilers (like GCC), to make sure that the reserved
             registers of that ABI are not clobbered.

             @param(usedinproc Registers which are used in the code of this routine)
          }
          procedure g_save_standard_registers(list : taasmoutput; usedinproc : tregisterset);virtual;abstract;
          {# This routine is called when generating the code for the exit point
             of a routine. It should restore all registers which were previously
             saved in @var(g_save_standard_registers).

             @param(usedinproc Registers which are used in the code of this routine)
          }
          procedure g_restore_standard_registers(list : taasmoutput; usedinproc : tregisterset);virtual;abstract;
          procedure g_save_all_registers(list : taasmoutput);virtual;abstract;
          procedure g_restore_all_registers(list : taasmoutput;selfused,accused,acchiused:boolean);virtual;abstract;
       end;

    {# @abstract(Abstract code generator for 64 Bit operations)
       This class implements an abstract code generator class
       for 64 Bit operations.
    }
    tcg64 = class
        { Allocates 64 Bit register r by inserting a pai_realloc record }
        procedure a_reg_alloc(list : taasmoutput;r : tregister64);virtual;abstract;
        { Deallocates 64 Bit register r by inserting a pa_regdealloc record}
        procedure a_reg_dealloc(list : taasmoutput;r : tregister64);virtual;abstract;
        procedure a_load64_const_ref(list : taasmoutput;value : qword;const ref : treference);virtual;abstract;
        procedure a_load64_reg_ref(list : taasmoutput;reg : tregister64;const ref : treference);virtual;abstract;
        procedure a_load64_ref_reg(list : taasmoutput;const ref : treference;reg : tregister64);virtual;abstract;
        procedure a_load64_reg_reg(list : taasmoutput;regsrc,regdst : tregister64);virtual;abstract;
        procedure a_load64_const_reg(list : taasmoutput;value : qword;reg : tregister64);virtual;abstract;
        procedure a_load64_loc_reg(list : taasmoutput;const l : tlocation;reg : tregister64);virtual;abstract;
        procedure a_load64_loc_ref(list : taasmoutput;const l : tlocation;const ref : treference);virtual;abstract;
        procedure a_load64_const_loc(list : taasmoutput;value : qword;const l : tlocation);virtual;abstract;
        procedure a_load64_reg_loc(list : taasmoutput;reg : tregister64;const l : tlocation);virtual;abstract;

        procedure a_load64high_reg_ref(list : taasmoutput;reg : tregister;const ref : treference);virtual;abstract;
        procedure a_load64low_reg_ref(list : taasmoutput;reg : tregister;const ref : treference);virtual;abstract;
        procedure a_load64high_ref_reg(list : taasmoutput;const ref : treference;reg : tregister);virtual;abstract;
        procedure a_load64low_ref_reg(list : taasmoutput;const ref : treference;reg : tregister);virtual;abstract;
        procedure a_load64high_loc_reg(list : taasmoutput;const l : tlocation;reg : tregister);virtual;abstract;
        procedure a_load64low_loc_reg(list : taasmoutput;const l : tlocation;reg : tregister);virtual;abstract;

        procedure a_op64_ref_reg(list : taasmoutput;op:TOpCG;const ref : treference;reg : tregister64);virtual;abstract;
        procedure a_op64_reg_reg(list : taasmoutput;op:TOpCG;regsrc,regdst : tregister64);virtual;abstract;
        procedure a_op64_reg_ref(list : taasmoutput;op:TOpCG;regsrc : tregister64;const ref : treference);virtual;abstract;
        procedure a_op64_const_reg(list : taasmoutput;op:TOpCG;value : qword;regdst : tregister64);virtual;abstract;
        procedure a_op64_const_ref(list : taasmoutput;op:TOpCG;value : qword;const ref : treference);virtual;abstract;
        procedure a_op64_const_loc(list : taasmoutput;op:TOpCG;value : qword;const l: tlocation);virtual;abstract;
        procedure a_op64_reg_loc(list : taasmoutput;op:TOpCG;reg : tregister64;const l : tlocation);virtual;abstract;
        procedure a_op64_loc_reg(list : taasmoutput;op:TOpCG;const l : tlocation;reg64 : tregister64);virtual;abstract;
        procedure a_op64_const_reg_reg(list: taasmoutput;op:TOpCG;value : qword;regsrc,regdst : tregister64);virtual;
        procedure a_op64_reg_reg_reg(list: taasmoutput;op:TOpCG;regsrc1,regsrc2,regdst : tregister64);virtual;

        procedure a_param64_reg(list : taasmoutput;reg64 : tregister64;const loc : tparalocation);virtual;abstract;
        procedure a_param64_const(list : taasmoutput;value : qword;const loc : tparalocation);virtual;abstract;
        procedure a_param64_ref(list : taasmoutput;const r : treference;const loc : tparalocation);virtual;abstract;
        procedure a_param64_loc(list : taasmoutput;const l : tlocation;const loc : tparalocation);virtual;abstract;

        {
             This routine tries to optimize the const_reg opcode, and should be
             called at the start of a_op64_const_reg. It returns the actual opcode
             to emit, and the constant value to emit. If this routine returns
             TRUE, @var(no) instruction should be emitted (.eg : imul reg by 1 )

             @param(op The opcode to emit, returns the opcode which must be emitted)
             @param(a  The constant which should be emitted, returns the constant which must
                    be emitted)
             @param(reg The register to emit the opcode with, returns the register with
                   which the opcode will be emitted)
        }
        function optimize64_op_const_reg(list: taasmoutput; var op: topcg; var a : qword; var reg: tregister64): boolean;virtual;abstract;


        { override to catch 64bit rangechecks }
        procedure g_rangecheck64(list: taasmoutput; const p: tnode;
          const todef: tdef);virtual;abstract;
    end;

    var
       {# Main code generator class }
       cg : tcg;
       {# Code generator class for all operations working with 64-Bit operands }
       cg64 : tcg64;

  implementation

    uses
       globals,globtype,options,systems,cgbase,
       verbose,defutil,tgobj,symdef,paramgr,
       rgobj,cutils;

    const
      max_scratch_regs = high(scratch_regs) - low(scratch_regs) + 1;

{*****************************************************************************
                            basic functionallity
******************************************************************************}

    constructor tcg.create;

      var
         i : longint;

      begin
         scratch_register_array_pointer:=1;
         for i:=low(scratch_regs) to high(scratch_regs) do
           include(unusedscratchregisters,scratch_regs[i]);
      end;

    procedure tcg.a_reg_alloc(list : taasmoutput;r : tregister);

      begin
         list.concat(tai_regalloc.alloc(r));
      end;

    procedure tcg.a_reg_dealloc(list : taasmoutput;r : tregister);

      begin
         list.concat(tai_regalloc.dealloc(r));
      end;

    procedure tcg.a_label(list : taasmoutput;l : tasmlabel);

      begin
         list.concat(tai_label.create(l));
      end;

    function tcg.get_scratch_reg_int(list : taasmoutput) : tregister;

      var
         r : tregister;
         i : longint;

      begin
         if unusedscratchregisters=[] then
           internalerror(68996);

         for i:=scratch_register_array_pointer to
                (scratch_register_array_pointer+max_scratch_regs-1) do
           if scratch_regs[(i mod max_scratch_regs)+1] in unusedscratchregisters then
             begin
                r:=scratch_regs[(i mod max_scratch_regs)+1];
                break;
             end;
         exclude(unusedscratchregisters,r);
         inc(scratch_register_array_pointer);
         if scratch_register_array_pointer>max_scratch_regs then
           scratch_register_array_pointer:=1;
         a_reg_alloc(list,r);
         get_scratch_reg_int:=r;
      end;

    { the default behavior simply returns a general purpose register }
    function tcg.get_scratch_reg_address(list : taasmoutput) : tregister;
     begin
       get_scratch_reg_address := get_scratch_reg_int(list);
     end;


    procedure tcg.free_scratch_reg(list : taasmoutput;r : tregister);

      begin
         include(unusedscratchregisters,rg.makeregsize(r,OS_INT));
         a_reg_dealloc(list,r);
      end;

{*****************************************************************************
          for better code generation these methods should be overridden
******************************************************************************}

    procedure tcg.a_param_reg(list : taasmoutput;size : tcgsize;r : tregister;const locpara : tparalocation);

      var
         ref : treference;

      begin
         case locpara.loc of
            LOC_REGISTER,LOC_CREGISTER:
              a_load_reg_reg(list,size,locpara.size,r,locpara.register);
            LOC_REFERENCE:
              begin
                 if locpara.sp_fixup<>0 then
                   a_op_const_reg(list,OP_ADD,locpara.sp_fixup,stack_pointer_reg);
                 reference_reset(ref);
                 ref.base:=locpara.reference.index;
                 ref.offset:=locpara.reference.offset;
                 a_load_reg_ref(list,size,r,ref);
              end
            else
              internalerror(2002071004);
         end;
      end;

    procedure tcg.a_param_const(list : taasmoutput;size : tcgsize;a : aword;const locpara : tparalocation);

      var
         hr : tregister;

      begin
         hr:=get_scratch_reg_int(list);
         a_load_const_reg(list,size,a,hr);
         a_param_reg(list,size,hr,locpara);
         free_scratch_reg(list,hr);
      end;

    procedure tcg.a_param_ref(list : taasmoutput;size : tcgsize;const r : treference;const locpara : tparalocation);

      var
         hr : tregister;

      begin
         hr:=get_scratch_reg_int(list);
         a_load_ref_reg(list,size,r,hr);
         a_param_reg(list,size,hr,locpara);
         free_scratch_reg(list,hr);
      end;


    procedure tcg.a_param_loc(list : taasmoutput;const l:tlocation;const locpara : tparalocation);

      begin
        case l.loc of
          LOC_REGISTER,
          LOC_CREGISTER :
            a_param_reg(list,l.size,l.register,locpara);
          LOC_CONSTANT :
            a_param_const(list,l.size,l.value,locpara);
          LOC_CREFERENCE,
          LOC_REFERENCE :
            a_param_ref(list,l.size,l.reference,locpara);
        else
          internalerror(2002032211);
        end;
      end;


    procedure tcg.a_paramaddr_ref(list : taasmoutput;const r : treference;const locpara : tparalocation);

      var
         hr : tregister;

      begin
         hr:=get_scratch_reg_address(list);
         a_loadaddr_ref_reg(list,r,hr);
         a_param_reg(list,OS_ADDR,hr,locpara);
         free_scratch_reg(list,hr);
      end;


{****************************************************************************
                       some generic implementations
****************************************************************************}

    procedure tcg.a_load_ref_ref(list : taasmoutput;size : tcgsize;const sref : treference;const dref : treference);

      var
        tmpreg: tregister;
{$ifdef i386}
        pushed_reg: tregister;
{$endif i386}

      begin
        { verify if we have the same reference }
        if references_equal(sref,dref) then
          exit;
{$ifdef i386}
        { the following is done with defines to avoid a speed penalty,  }
        { since all this is only necessary for the 80x86 (because EDI   }
        { doesn't have an 8bit component which is directly addressable) }
        pushed_reg := R_NO;
        if size in [OS_8,OS_S8] then
          if (rg.countunusedregsint = 0) then
            begin
              if (dref.base <> R_EBX) and
                 (dref.index <> R_EBX) then
                pushed_reg := R_EBX
              else if (dref.base <> R_EAX) and
                      (dref.index <> R_EAX) then
                pushed_reg := R_EAX
              else pushed_reg := R_ECX;
              tmpreg := rg.makeregsize(pushed_reg,OS_8);
              list.concat(taicpu.op_reg(A_PUSH,S_L,pushed_reg));
            end
          else
            tmpreg := rg.getregisterint(list)
        else
{$endif i386}
        tmpreg := get_scratch_reg_int(list);
        tmpreg:=rg.makeregsize(tmpreg,size);
        a_load_ref_reg(list,size,sref,tmpreg);
        a_load_reg_ref(list,size,tmpreg,dref);
{$ifdef i386}
        if size in [OS_8,OS_S8] then
          begin
            if (pushed_reg <> R_NO) then
              list.concat(taicpu.op_reg(A_POP,S_L,pushed_reg))
            else
              rg.ungetregister(list,tmpreg)
          end
        else
{$endif i386}
        free_scratch_reg(list,tmpreg);
      end;


    procedure tcg.a_load_const_ref(list : taasmoutput;size : tcgsize;a : aword;const ref : treference);

      var
        tmpreg: tregister;

      begin
        tmpreg := get_scratch_reg_int(list);
        a_load_const_reg(list,size,a,tmpreg);
        a_load_reg_ref(list,size,tmpreg,ref);
        free_scratch_reg(list,tmpreg);
      end;


    procedure tcg.a_load_const_loc(list : taasmoutput;a : aword;const loc: tlocation);
      begin
        case loc.loc of
          LOC_REFERENCE,LOC_CREFERENCE:
            a_load_const_ref(list,loc.size,a,loc.reference);
          LOC_REGISTER,LOC_CREGISTER:
            a_load_const_reg(list,loc.size,a,loc.register);
          else
            internalerror(200203272);
        end;
      end;


    procedure tcg.a_load_reg_loc(list : taasmoutput;size : tcgsize;reg : tregister;const loc: tlocation);
      begin
        case loc.loc of
          LOC_REFERENCE,LOC_CREFERENCE:
            a_load_reg_ref(list,size,reg,loc.reference);
          LOC_REGISTER,LOC_CREGISTER:
            a_load_reg_reg(list,size,loc.size,reg,loc.register);
          else
            internalerror(200203271);
        end;
      end;


    procedure tcg.a_load_loc_reg(list : taasmoutput;const loc: tlocation; reg : tregister);

      begin
        case loc.loc of
          LOC_REFERENCE,LOC_CREFERENCE:
            a_load_ref_reg(list,loc.size,loc.reference,reg);
          LOC_REGISTER,LOC_CREGISTER:
            a_load_reg_reg(list,loc.size,loc.size,loc.register,reg);
          LOC_CONSTANT:
            a_load_const_reg(list,loc.size,loc.value,reg);
          else
            begin
               writeln(ord(loc.loc));
               runerror(216);
               internalerror(200109092);
            end;
        end;
      end;


    procedure tcg.a_load_loc_ref(list : taasmoutput;const loc: tlocation; const ref : treference);

      begin
        case loc.loc of
          LOC_REFERENCE,LOC_CREFERENCE:
            a_load_ref_ref(list,loc.size,loc.reference,ref);
          LOC_REGISTER,LOC_CREGISTER:
            a_load_reg_ref(list,loc.size,loc.register,ref);
          LOC_CONSTANT:
            a_load_const_ref(list,loc.size,loc.value,ref);
          else
            internalerror(200109302);
        end;
      end;


    procedure tcg.a_call_loc(list : taasmoutput;const loc:tlocation);
      begin
        case loc.loc of
           LOC_REGISTER,LOC_CREGISTER:
             cg.a_call_reg(list,loc.register);
           LOC_REFERENCE,LOC_CREFERENCE :
             cg.a_call_ref(list,loc.reference);
           else
             internalerror(200203311);
        end;
      end;


    function tcg.optimize_op_const_reg(list: taasmoutput; var op: topcg; var a : aword; var reg:tregister): boolean;
      var
        powerval : longint;
      begin
        optimize_op_const_reg := false;
        case op of
          { or with zero returns same result }
          OP_OR : if a = 0 then optimize_op_const_reg := true;
          { and with max returns same result }
          OP_AND : if (a = high(a)) then optimize_op_const_reg := true;
          { division by 1 returns result }
          OP_DIV :
            begin
              if a = 1 then
                optimize_op_const_reg := true
              else if ispowerof2(int64(a), powerval) then
                begin
                  a := powerval;
                  op:= OP_SHR;
                end;
              exit;
            end;
          OP_IDIV:
            begin
              if a = 1 then
                optimize_op_const_reg := true
              else if ispowerof2(int64(a), powerval) then
                begin
                  a := powerval;
                  op:= OP_SAR;
                end;
               exit;
            end;
        OP_MUL,OP_IMUL:
            begin
               if a = 1 then
                  optimize_op_const_reg := true
               else if ispowerof2(int64(a), powerval) then
                 begin
                   a := powerval;
                   op:= OP_SHL;
                 end;
               exit;
            end;
        OP_SAR,OP_SHL,OP_SHR:
           begin
              if a = 0 then
                 optimize_op_const_reg := true;
              exit;
           end;
        end;
      end;

    procedure tcg.a_loadfpu_loc_reg(list: taasmoutput; const loc: tlocation; const reg: tregister);

      begin
        case loc.loc of
          LOC_REFERENCE, LOC_CREFERENCE:
            a_loadfpu_ref_reg(list,loc.size,loc.reference,reg);
          LOC_FPUREGISTER, LOC_CFPUREGISTER:
            a_loadfpu_reg_reg(list,loc.register,reg);
          else
            runerror(226);
            // internalerror(200203301);
        end;
      end;


    procedure tcg.a_loadfpu_reg_loc(list: taasmoutput; size: tcgsize; const reg: tregister; const loc: tlocation);

      begin
        case loc.loc of
          LOC_REFERENCE, LOC_CREFERENCE:
            a_loadfpu_reg_ref(list,size,reg,loc.reference);
          LOC_FPUREGISTER, LOC_CFPUREGISTER:
            a_loadfpu_reg_reg(list,reg,loc.register);
          else
            internalerror(48991);
         end;
      end;


    procedure tcg.a_op_const_ref(list : taasmoutput; Op: TOpCG; size: TCGSize; a: AWord; const ref: TReference);

      var
        tmpreg: tregister;

      begin
        tmpreg := get_scratch_reg_int(list);
        a_load_ref_reg(list,size,ref,tmpreg);
        a_op_const_reg(list,op,a,tmpreg);
        a_load_reg_ref(list,size,tmpreg,ref);
        free_scratch_reg(list,tmpreg);
      end;


    procedure tcg.a_op_const_loc(list : taasmoutput; Op: TOpCG; a: AWord; const loc: tlocation);

      begin
        case loc.loc of
          LOC_REGISTER, LOC_CREGISTER:
            a_op_const_reg(list,op,a,loc.register);
          LOC_REFERENCE, LOC_CREFERENCE:
            a_op_const_ref(list,op,loc.size,a,loc.reference);
          else
            internalerror(200109061);
        end;
      end;


    procedure tcg.a_op_reg_ref(list : taasmoutput; Op: TOpCG; size: TCGSize;reg: TRegister;  const ref: TReference);

      var
        tmpreg: tregister;

      begin
        tmpreg := get_scratch_reg_int(list);
        a_load_ref_reg(list,size,ref,tmpreg);
        a_op_reg_reg(list,op,size,reg,tmpreg);
        a_load_reg_ref(list,size,tmpreg,ref);
        free_scratch_reg(list,tmpreg);
      end;


    procedure tcg.a_op_ref_reg(list : taasmoutput; Op: TOpCG; size: TCGSize; const ref: TReference; reg: TRegister);

      var
        tmpreg: tregister;

      begin
        case op of
          OP_NOT,OP_NEG:
            { handle it as "load ref,reg; op reg" }
            begin
              a_load_ref_reg(list,size,ref,reg);
              a_op_reg_reg(list,op,size,reg,reg);
            end;
          else
            begin
              tmpreg := get_scratch_reg_int(list);
              a_load_ref_reg(list,size,ref,tmpreg);
              a_op_reg_reg(list,op,size,tmpreg,reg);
              free_scratch_reg(list,tmpreg);
            end;
        end;
      end;


    procedure tcg.a_op_reg_loc(list : taasmoutput; Op: TOpCG; reg: tregister; const loc: tlocation);

      begin
        case loc.loc of
          LOC_REGISTER, LOC_CREGISTER:
            a_op_reg_reg(list,op,loc.size,reg,loc.register);
          LOC_REFERENCE, LOC_CREFERENCE:
            a_op_reg_ref(list,op,loc.size,reg,loc.reference);
          else
            internalerror(200109061);
        end;
      end;


    procedure tcg.a_op_ref_loc(list : taasmoutput; Op: TOpCG; const ref: TReference; const loc: tlocation);

      var
        tmpreg: tregister;

      begin
        case loc.loc of
          LOC_REGISTER,LOC_CREGISTER:
            a_op_ref_reg(list,op,loc.size,ref,loc.register);
          LOC_REFERENCE,LOC_CREFERENCE:
            begin
              tmpreg := get_scratch_reg_int(list);
              tmpreg:=rg.makeregsize(tmpreg,loc.size);
              a_load_ref_reg(list,loc.size,ref,tmpreg);
              a_op_reg_ref(list,op,loc.size,tmpreg,loc.reference);
              free_scratch_reg(list,tmpreg);
            end;
          else
            internalerror(200109061);
        end;
      end;

    procedure tcg.a_op_const_reg_reg(list: taasmoutput; op: TOpCg;
        size: tcgsize; a: aword; src, dst: tregister);
      begin
        a_load_reg_reg(list,size,size,src,dst);
        a_op_const_reg(list,op,a,dst);
      end;

    procedure tcg.a_op_reg_reg_reg(list: taasmoutput; op: TOpCg;
        size: tcgsize; src1, src2, dst: tregister);
      begin
        a_load_reg_reg(list,size,size,src2,dst);
        a_op_reg_reg(list,op,size,src1,dst);
      end;



    procedure tcg.a_cmp_const_ref_label(list : taasmoutput;size : tcgsize;cmp_op : topcmp;a : aword;const ref : treference;
     l : tasmlabel);

      var
        tmpreg: tregister;

      begin
        tmpreg := get_scratch_reg_int(list);
        a_load_ref_reg(list,size,ref,tmpreg);
        a_cmp_const_reg_label(list,size,cmp_op,a,tmpreg,l);
        free_scratch_reg(list,tmpreg);
      end;

    procedure tcg.a_cmp_const_loc_label(list : taasmoutput;size : tcgsize;cmp_op : topcmp;a : aword;const loc : tlocation;
      l : tasmlabel);

      begin
        case loc.loc of
          LOC_REGISTER,LOC_CREGISTER:
            a_cmp_const_reg_label(list,size,cmp_op,a,loc.register,l);
          LOC_REFERENCE,LOC_CREFERENCE:
            a_cmp_const_ref_label(list,size,cmp_op,a,loc.reference,l);
          else
            internalerror(200109061);
        end;
      end;

    procedure tcg.a_cmp_ref_reg_label(list : taasmoutput;size : tcgsize;cmp_op : topcmp; const ref: treference; reg : tregister; l : tasmlabel);

      var
        tmpreg: tregister;

      begin
        tmpreg := get_scratch_reg_int(list);
        a_load_ref_reg(list,size,ref,tmpreg);
        a_cmp_reg_reg_label(list,size,cmp_op,tmpreg,reg,l);
        free_scratch_reg(list,tmpreg);
      end;

    procedure tcg.a_cmp_loc_reg_label(list : taasmoutput;size : tcgsize;cmp_op : topcmp; const loc: tlocation; reg : tregister; l : tasmlabel);
      begin
        case loc.loc of
          LOC_REGISTER,
          LOC_CREGISTER:
            a_cmp_reg_reg_label(list,size,cmp_op,loc.register,reg,l);
          LOC_REFERENCE,
          LOC_CREFERENCE :
            a_cmp_ref_reg_label(list,size,cmp_op,loc.reference,reg,l);
          LOC_CONSTANT:
            a_cmp_const_reg_label(list,size,cmp_op,loc.value,reg,l);
          else
            internalerror(200203231);
        end;
      end;


    procedure tcg.a_cmp_ref_loc_label(list : taasmoutput;size : tcgsize;cmp_op : topcmp;const ref: treference;const loc : tlocation;
      l : tasmlabel);

      var
        tmpreg: tregister;

      begin
        case loc.loc of
          LOC_REGISTER,LOC_CREGISTER:
            a_cmp_ref_reg_label(list,size,cmp_op,ref,loc.register,l);
          LOC_REFERENCE,LOC_CREFERENCE:
            begin
{$ifdef i386}
              { the following is done with defines to avoid a speed penalty,  }
              { since all this is only necessary for the 80x86 (because EDI   }
              { doesn't have an 8bit component which is directly addressable) }
              if size in [OS_8,OS_S8] then
                tmpreg := rg.getregisterint(list)
              else
{$endif i386}
              tmpreg := get_scratch_reg_int(list);
              tmpreg := rg.makeregsize(tmpreg,size);
              a_load_ref_reg(list,size,loc.reference,tmpreg);
              a_cmp_ref_reg_label(list,size,cmp_op,ref,tmpreg,l);
{$ifdef i386}
              if size in [OS_8,OS_S8] then
                rg.ungetregister(list,tmpreg)
              else
{$endif i386}
              free_scratch_reg(list,tmpreg);
            end
          else
            internalerror(200109061);
        end;
      end;


    class function tcg.reg_cgsize(const reg: tregister) : tcgsize;
      begin
        reg_cgsize := OS_INT;
      end;


    procedure tcg.g_copyshortstring(list : taasmoutput;const source,dest : treference;len:byte;delsource,loadref : boolean);
      begin
{$ifdef FPC}
        {$warning FIX ME!}
{$endif}
        a_paramaddr_ref(list,dest,paramanager.getintparaloc(3));
        if loadref then
          a_param_ref(list,OS_ADDR,source,paramanager.getintparaloc(2))
        else
          a_paramaddr_ref(list,source,paramanager.getintparaloc(2));
        if delsource then
         reference_release(list,source);
        a_param_const(list,OS_INT,len,paramanager.getintparaloc(1));
        a_call_name(list,'FPC_SHORTSTR_ASSIGN');
        g_maybe_loadself(list);
      end;


    procedure tcg.g_incrrefcount(list : taasmoutput;t: tdef; const ref: treference);
      var
        href : treference;
        incrfunc : string;
      begin
         { These functions should not change the registers (they use
           the saveregister proc directive }
         if is_interfacecom(t) then
          incrfunc:='FPC_INTF_INCR_REF'
         else if is_ansistring(t) then
          incrfunc:='FPC_ANSISTR_INCR_REF'
         else if is_widestring(t) then
          incrfunc:='FPC_WIDESTR_INCR_REF'
         else if is_dynamic_array(t) then
          incrfunc:='FPC_DYNARRAY_INCR_REF'
         else
          incrfunc:='';
         { call the special incr function or the generic addref }
         if incrfunc<>'' then
          begin
            a_param_ref(list,OS_ADDR,ref,paramanager.getintparaloc(1));
            a_call_name(list,incrfunc);
          end
         else
          begin
            reference_reset_symbol(href,tstoreddef(t).get_rtti_label(initrtti),0);
            a_paramaddr_ref(list,href,paramanager.getintparaloc(2));
            a_paramaddr_ref(list,ref,paramanager.getintparaloc(1));
            a_call_name(list,'FPC_ADDREF');
         end;
      end;


    procedure tcg.g_decrrefcount(list : taasmoutput;t: tdef; const ref: treference);
      var
        href : treference;
        decrfunc : string;
        needrtti : boolean;
      begin
         needrtti:=false;
         if is_interfacecom(t) then
          decrfunc:='FPC_INTF_DECR_REF'
         else if is_ansistring(t) then
          decrfunc:='FPC_ANSISTR_DECR_REF'
         else if is_widestring(t) then
          decrfunc:='FPC_WIDESTR_DECR_REF'
         else if is_dynamic_array(t) then
          begin
            decrfunc:='FPC_DYNARRAY_DECR_REF';
            needrtti:=true;
          end
         else
          decrfunc:='';
         { call the special decr function or the generic decref }
         if decrfunc<>'' then
          begin
            if needrtti then
             begin
               reference_reset_symbol(href,tstoreddef(t).get_rtti_label(initrtti),0);
               a_paramaddr_ref(list,href,paramanager.getintparaloc(2));
             end;
            a_paramaddr_ref(list,ref,paramanager.getintparaloc(1));
            a_call_name(list,decrfunc);
          end
         else
          begin
            reference_reset_symbol(href,tstoreddef(t).get_rtti_label(initrtti),0);
            a_paramaddr_ref(list,href,paramanager.getintparaloc(2));
            a_paramaddr_ref(list,ref,paramanager.getintparaloc(1));
            a_call_name(list,'FPC_DECREF');
         end;
      end;


    procedure tcg.g_initialize(list : taasmoutput;t : tdef;const ref : treference;loadref : boolean);
      var
         href : treference;
      begin
         if is_ansistring(t) or
            is_widestring(t) or
            is_interfacecom(t) then
           a_load_const_ref(list,OS_ADDR,0,ref)
         else
           begin
              reference_reset_symbol(href,tstoreddef(t).get_rtti_label(initrtti),0);
              a_paramaddr_ref(list,href,paramanager.getintparaloc(2));
              if loadref then
                a_param_ref(list,OS_ADDR,ref,paramanager.getintparaloc(1))
              else
                a_paramaddr_ref(list,ref,paramanager.getintparaloc(1));
              a_call_name(list,'FPC_INITIALIZE');
           end;
      end;


    procedure tcg.g_finalize(list : taasmoutput;t : tdef;const ref : treference;loadref : boolean);
      var
         href : treference;
      begin
         if is_ansistring(t) or
            is_widestring(t) or
            is_interfacecom(t) then
           g_decrrefcount(list,t,ref)
         else
           begin
              reference_reset_symbol(href,tstoreddef(t).get_rtti_label(initrtti),0);
              a_paramaddr_ref(list,href,paramanager.getintparaloc(2));
              if loadref then
                a_param_ref(list,OS_ADDR,ref,paramanager.getintparaloc(1))
              else
                a_paramaddr_ref(list,ref,paramanager.getintparaloc(1));
              a_call_name(list,'FPC_FINALIZE');
           end;
      end;


    procedure tcg.g_rangecheck(list: taasmoutput; const p: tnode;const todef: tdef);
    { generate range checking code for the value at location p. The type     }
    { type used is checked against todefs ranges. fromdef (p.resulttype.def) }
    { is the original type used at that location. When both defs are equal   }
    { the check is also insert (needed for succ,pref,inc,dec)                }
      const
{$ifdef ver1_0}
        awordsignedmax=high(longint);
{$else}
        awordsignedmax=high(aword) div 2;
{$endif}
      var
        neglabel : tasmlabel;
        hreg : tregister;
        fromdef : tdef;
        lto,hto,
        lfrom,hfrom : TConstExprInt;
        from_signed: boolean;
      begin
        { range checking on and range checkable value? }
        if not(cs_check_range in aktlocalswitches) or
           not(todef.deftype in [orddef,enumdef,arraydef]) then
          exit;
        if is_64bitint(p.resulttype.def) or is_64bitint(todef) then
          begin
             cg64.g_rangecheck64(list,p,todef);
             exit;
          end;
        { only check when assigning to scalar, subranges are different, }
        { when todef=fromdef then the check is always generated         }
        fromdef:=p.resulttype.def;
        getrange(p.resulttype.def,lfrom,hfrom);
        getrange(todef,lto,hto);
        { no range check if from and to are equal and are both longint/dword }
        { (if we have a 32bit processor) or int64/qword, since such          }
        { operations can at most cause overflows (JM)                        }
        { Note that these checks are mostly processor independent, they only }
        { have to be changed once we introduce 64bit subrange types          }
        if (fromdef = todef) and
           (fromdef.deftype=orddef) and
           (((sizeof(aword) = 4) and
             (((torddef(fromdef).typ = s32bit) and
               (lfrom = low(longint)) and
               (hfrom = high(longint))) or
              ((torddef(fromdef).typ = u32bit) and
               (lfrom = low(cardinal)) and
               (hfrom = high(cardinal)))))) then
          exit;
        if todef<>fromdef then
         begin
           { if the from-range falls completely in the to-range, no check }
           { is necessary                                                 }
           if (lto<=lfrom) and (hto>=hfrom) then
            exit;
         end;
        { generate the rangecheck code for the def where we are going to }
        { store the result                                               }

        { use the trick that                                                 }
        { a <= x <= b <=> 0 <= x-a <= b-a <=> unsigned(x-a) <= unsigned(b-a) }

        { To be able to do that, we have to make sure however that either    }
        { fromdef and todef are both signed or unsigned, or that we leave    }
        { the parts < 0 and > maxlongint out                                 }

        { is_signed now also works for arrays (it checks the rangetype) (JM) }
        from_signed := is_signed(fromdef);
        if from_signed xor is_signed(todef) then
          if from_signed then
            { from is signed, to is unsigned }
            begin
              { if high(from) < 0 -> always range error }
              if (hfrom < 0) or
                 { if low(to) > maxlongint also range error }
                 (lto > awordsignedmax) then
                begin
                  a_call_name(list,'FPC_RANGEERROR');
                  exit
                end;
              { from is signed and to is unsigned -> when looking at from }
              { as an unsigned value, it must be < maxlongint (otherwise  }
              { it's negative, which is invalid since "to" is unsigned)   }
              if hto > awordsignedmax then
                hto := awordsignedmax;
            end
          else
            { from is unsigned, to is signed }
            begin
              if (lfrom > awordsignedmax) or
                 (hto < 0) then
                begin
                  a_call_name(list,'FPC_RANGEERROR');
                  exit
                end;
              { from is unsigned and to is signed -> when looking at to }
              { as an unsigned value, it must be >= 0 (since negative   }
              { values are the same as values > maxlongint)             }
              if lto < 0 then
                lto := 0;
            end;

        hreg := get_scratch_reg_int(list);
        if (p.location.loc in [LOC_REGISTER,LOC_CREGISTER]) then
          a_op_const_reg_reg(list,OP_SUB,def_cgsize(p.resulttype.def),
           aword(lto),p.location.register,hreg)
        else
          begin
            a_load_ref_reg(list,def_cgsize(p.resulttype.def),
              p.location.reference,hreg);
            a_op_const_reg(list,OP_SUB,aword(lto),hreg);
          end;
        objectlibrary.getlabel(neglabel);
        a_cmp_const_reg_label(list,OS_INT,OC_BE,aword(hto-lto),hreg,neglabel);
        { !!! should happen right after the compare (JM) }
        free_scratch_reg(list,hreg);
        a_call_name(list,'FPC_RANGEERROR');
        a_label(list,neglabel);
      end;


    procedure tcg.g_stackcheck(list : taasmoutput;stackframesize : longint);

      begin
         a_param_const(list,OS_32,stackframesize,paramanager.getintparaloc(1));
         a_call_name(list,'FPC_STACKCHECK');
      end;


    procedure tcg.g_flags2ref(list: taasmoutput; size: TCgSize; const f: tresflags; const ref:TReference);

      var
        tmpreg : tregister;
      begin
        tmpreg := get_scratch_reg_int(list);
        g_flags2reg(list,size,f,tmpreg);
        a_load_reg_ref(list,size,tmpreg,ref);
        free_scratch_reg(list,tmpreg);
      end;


    procedure tcg.g_maybe_loadself(list : taasmoutput);
      var
         hp : treference;
         p : tprocinfo;
         i : longint;
      begin
         if assigned(procinfo._class) then
           begin
              list.concat(tai_regalloc.Alloc(SELF_POINTER_REG));
              if lexlevel>normal_function_level then
                begin
                   reference_reset_base(hp,procinfo.framepointer,procinfo.framepointer_offset);
                   a_load_ref_reg(list,OS_ADDR,hp,SELF_POINTER_REG);
                   p:=procinfo.parent;
                   for i:=3 to lexlevel-1 do
                     begin
                        reference_reset_base(hp,SELF_POINTER_REG,p.framepointer_offset);
                        a_load_ref_reg(list,OS_ADDR,hp,SELF_POINTER_REG);
                        p:=p.parent;
                     end;
                   reference_reset_base(hp,SELF_POINTER_REG,p.selfpointer_offset);
                   a_load_ref_reg(list,OS_ADDR,hp,SELF_POINTER_REG);
                end
              else
                begin
                   reference_reset_base(hp,procinfo.framepointer,procinfo.selfpointer_offset);
                   a_load_ref_reg(list,OS_ADDR,hp,SELF_POINTER_REG);
                end;
           end;
      end;


    procedure tcg.g_maybe_testself(list : taasmoutput);
      var
        OKLabel : tasmlabel;
        dummyloc : tparalocation;
      begin
        if (cs_check_object in aktlocalswitches) or
           (cs_check_range in aktlocalswitches) then
         begin
           objectlibrary.getlabel(oklabel);
           a_cmp_const_reg_label(list,OS_ADDR,OC_NE,0,SELF_POINTER_REG,oklabel);
           a_param_const(list,OS_INT,210,dummyloc);
           a_call_name(list,'FPC_HANDLEERROR');
           a_label(list,oklabel);
         end;
      end;


{*****************************************************************************
                            Entry/Exit Code Functions
*****************************************************************************}

    procedure tcg.g_call_constructor_helper(list : taasmoutput);
     var
      href : treference;
      hregister : tregister;
     begin
        if is_class(procinfo._class) then
          begin
            if (cs_implicit_exceptions in aktmoduleswitches) then
              procinfo.flags:=procinfo.flags or pi_needs_implicit_finally;
            { parameter 2 : self pointer / flag }
            {!! this is a terrible hack, normally the helper should get three params : }
            {    one with self register, one with flag and one with VMT pointer        }
            {reference_reset_base(href, procinfo.framepointer,procinfo.selfpointer_offset+POINTER_SIZE);}
            a_param_reg(list, OS_ADDR, SELF_POINTER_REG, paramanager.getintparaloc(2));

            { parameter 1 : vmt pointer (stored at the selfpointer address on stack)  }
            reference_reset_base(href, procinfo.framepointer,procinfo.selfpointer_offset);
            a_param_ref(list, OS_ADDR,href,paramanager.getintparaloc(1));
            a_call_name(list,'FPC_NEW_CLASS');
            a_load_reg_reg(list,OS_ADDR,OS_ADDR,accumulator,SELF_POINTER_REG);
            { save the self pointer result }
            a_load_reg_ref(list,OS_ADDR,SELF_POINTER_REG,href);
            a_cmp_const_reg_label(list,OS_ADDR,OC_EQ,0,accumulator,faillabel);
          end
        else if is_object(procinfo._class) then
          begin
            { parameter 3 :vmt_offset     }
            a_param_const(list, OS_32, procinfo._class.vmt_offset, paramanager.getintparaloc(3));
            { parameter 2 : address of pointer to vmt }
            {  this is the first(?) parameter which was pushed to the constructor }
            reference_reset_base(href, procinfo.framepointer,procinfo.selfpointer_offset-POINTER_SIZE);
            hregister:=get_scratch_reg_address(list);
            a_loadaddr_ref_reg(list, href, hregister);
            a_param_reg(list, OS_ADDR,hregister,paramanager.getintparaloc(2));
            free_scratch_reg(list, hregister);
            { parameter 1 : address of self pointer   }
            reference_reset_base(href, procinfo.framepointer,procinfo.selfpointer_offset);
            hregister:=get_scratch_reg_address(list);
            a_loadaddr_ref_reg(list, href, hregister);
            a_param_reg(list, OS_ADDR,hregister,paramanager.getintparaloc(1));
            free_scratch_reg(list, hregister);
            a_call_name(list,'FPC_HELP_CONSTRUCTOR');
            a_load_reg_reg(list,OS_ADDR,OS_ADDR,accumulator,SELF_POINTER_REG);
            a_cmp_const_reg_label(list,OS_ADDR,OC_EQ,0,accumulator,faillabel);
          end
        else
          internalerror(200006161);
     end;


    procedure tcg.g_call_destructor_helper(list : taasmoutput);
      var
        nofinal : tasmlabel;
        href : treference;
      hregister : tregister;
      begin
        if is_class(procinfo._class) then
         begin
           { 2nd parameter  : flag }
           reference_reset_base(href, procinfo.framepointer,procinfo.selfpointer_offset+POINTER_SIZE);
           a_param_ref(list, OS_ADDR,href,paramanager.getintparaloc(2));
           { 1st parameter to destructor : self }
           reference_reset_base(href, procinfo.framepointer,procinfo.selfpointer_offset);
           a_param_ref(list, OS_ADDR,href,paramanager.getintparaloc(1));
           a_call_name(list,'FPC_DISPOSE_CLASS')
         end
        else if is_object(procinfo._class) then
         begin
           { must the object be finalized ? }
           if procinfo._class.needs_inittable then
            begin
              objectlibrary.getlabel(nofinal);
              reference_reset_base(href,procinfo.framepointer,target_info.first_parm_offset);
              a_cmp_const_ref_label(list,OS_ADDR,OC_EQ,0,href,nofinal);
              reference_reset_base(href,SELF_POINTER_REG,0);
              g_finalize(list,procinfo._class,href,false);
              a_label(list,nofinal);
            end;
           { actually call destructor }
            { parameter 3 :vmt_offset     }
            a_param_const(list, OS_32, procinfo._class.vmt_offset, paramanager.getintparaloc(3));
            { parameter 2 : pointer to vmt }
            {  this is the first parameter which was pushed to the destructor }
            reference_reset_base(href, procinfo.framepointer,procinfo.selfpointer_offset-POINTER_SIZE);
            a_param_ref(list, OS_ADDR, href ,paramanager.getintparaloc(2));
            { parameter 1 : address of self pointer   }
            reference_reset_base(href, procinfo.framepointer,procinfo.selfpointer_offset);
            hregister:=get_scratch_reg_address(list);
            a_loadaddr_ref_reg(list, href, hregister);
            a_param_reg(list, OS_ADDR,hregister,paramanager.getintparaloc(1));
            free_scratch_reg(list, hregister);
            a_call_name(list,'FPC_HELP_DESTRUCTOR');
         end
        else
         internalerror(200006162);
      end;


    procedure tcg.g_call_fail_helper(list : taasmoutput);
      var
        href : treference;
        hregister : tregister;
      begin
        if is_class(procinfo._class) then
          begin
            {
              Dispose of the class then set self_pointer to nil
              both in stack and in self register.
            }
            { 2nd parameter  : flag }
            a_param_const(list,OS_32,1,paramanager.getintparaloc(2));
            { 1st parameter to destructor : self }
            reference_reset_base(href, procinfo.framepointer,procinfo.selfpointer_offset);
            a_param_ref(list, OS_ADDR,href,paramanager.getintparaloc(1));
            a_call_name(list,'FPC_DISPOSE_CLASS');
            { SET SELF TO NIL }
            a_load_const_reg(list,OS_ADDR,0,SELF_POINTER_REG);
            { set the self pointer in the stack to nil }
            a_load_reg_ref(list,OS_ADDR,SELF_POINTER_REG,href);
          end
        else if is_object(procinfo._class) then
          begin
            { parameter 3 :vmt_offset     }
            a_param_const(list, OS_32, procinfo._class.vmt_offset, paramanager.getintparaloc(3));
            { parameter 2 : address of pointer to vmt }
            {  this is the first(?) parameter which was pushed to the constructor }
            reference_reset_base(href, procinfo.framepointer,procinfo.selfpointer_offset-POINTER_SIZE);
            hregister:=get_scratch_reg_address(list);
            a_loadaddr_ref_reg(list, href, hregister);
            a_param_reg(list, OS_ADDR,hregister,paramanager.getintparaloc(2));
            free_scratch_reg(list, hregister);
            { parameter 1 : address of self pointer   }
            reference_reset_base(href, procinfo.framepointer,procinfo.selfpointer_offset);
            hregister:=get_scratch_reg_address(list);
            a_loadaddr_ref_reg(list, href, hregister);
            a_param_reg(list, OS_ADDR,hregister,paramanager.getintparaloc(1));
            free_scratch_reg(list, hregister);
            a_call_name(list,'FPC_HELP_FAIL');
            { SET SELF TO NIL }
            a_load_const_reg(list,OS_ADDR,0,SELF_POINTER_REG);
          end
        else
          internalerror(200006163);
      end;


    procedure tcg.g_interrupt_stackframe_entry(list : taasmoutput);
      begin
      end;


    procedure tcg.g_interrupt_stackframe_exit(list : taasmoutput;selfused,accused,acchiused:boolean);
      begin
      end;


    procedure tcg.g_profilecode(list : taasmoutput);
      begin
      end;


    procedure tcg.g_exception_reason_save(list : taasmoutput; const href : treference);
     begin
       a_load_reg_ref(list, OS_S32, accumulator, href);
     end;


    procedure tcg.g_exception_reason_save_const(list : taasmoutput; const href : treference; a: aword);
     begin
       a_load_const_ref(list, OS_S32, a, href);
     end;


    procedure tcg.g_exception_reason_load(list : taasmoutput; const href : treference);
     begin
       a_load_ref_reg(list, OS_S32, href, accumulator);
     end;


    procedure tcg64.a_op64_const_reg_reg(list: taasmoutput;op:TOpCG;value : qword;
       regsrc,regdst : tregister64);
      begin
        a_load64_reg_reg(list,regsrc,regdst);
        a_op64_const_reg(list,op,value,regdst);
      end;


    procedure tcg64.a_op64_reg_reg_reg(list: taasmoutput;op:TOpCG;regsrc1,regsrc2,regdst : tregister64);
      begin
        a_load64_reg_reg(list,regsrc2,regdst);
        a_op64_reg_reg(list,op,regsrc1,regdst);
      end;



initialization
    ;
finalization
  cg.free;
  cg64.free;
end.
{
  $Log$
  Revision 1.66  2002-11-25 17:43:16  peter
    * splitted defbase in defutil,symutil,defcmp
    * merged isconvertable and is_equal into compare_defs(_ext)
    * made operator search faster by walking the list only once

  Revision 1.65  2002/11/17 16:27:31  carl
    * document flags2reg

  Revision 1.64  2002/11/16 17:06:28  peter
    * return error 210 for failed self test

  Revision 1.63  2002/11/15 01:58:46  peter
    * merged changes from 1.0.7 up to 04-11
      - -V option for generating bug report tracing
      - more tracing for option parsing
      - errors for cdecl and high()
      - win32 import stabs
      - win32 records<=8 are returned in eax:edx (turned off by default)
      - heaptrc update
      - more info for temp management in .s file with EXTDEBUG

  Revision 1.62  2002/10/16 19:01:43  peter
    + $IMPLICITEXCEPTIONS switch to turn on/off generation of the
      implicit exception frames for procedures with initialized variables
      and for constructors. The default is on for compatibility

  Revision 1.61  2002/10/05 12:43:23  carl
    * fixes for Delphi 6 compilation
     (warning : Some features do not work under Delphi)

  Revision 1.60  2002/10/02 18:20:52  peter
    * Copy() is now internal syssym that calls compilerprocs

  Revision 1.59  2002/09/17 18:54:02  jonas
    * a_load_reg_reg() now has two size parameters: source and dest. This
      allows some optimizations on architectures that don't encode the
      register size in the register name.

  Revision 1.58  2002/09/09 19:29:29  peter
    * fixed dynarr_decr_ref call

  Revision 1.57  2002/09/07 15:25:01  peter
    * old logs removed and tabs fixed

  Revision 1.56  2002/09/01 21:04:47  florian
    * several powerpc related stuff fixed

  Revision 1.55  2002/09/01 17:05:43  florian
    + added abstract tcg.g_removevaluepara_openarray

  Revision 1.54  2002/09/01 12:09:27  peter
    + a_call_reg, a_call_loc added
    * removed exprasmlist references

  Revision 1.53  2002/08/19 18:17:48  carl
    + optimize64_op_const_reg implemented (optimizes 64-bit constant opcodes)
    * more fixes to m68k for 64-bit operations

  Revision 1.52  2002/08/17 22:09:43  florian
    * result type handling in tcgcal.pass_2 overhauled
    * better tnode.dowrite
    * some ppc stuff fixed

  Revision 1.51  2002/08/17 09:23:33  florian
    * first part of procinfo rewrite

  Revision 1.50  2002/08/16 14:24:57  carl
    * issameref() to test if two references are the same (then emit no opcodes)
    + ret_in_reg to replace ret_in_acc
      (fix some register allocation bugs at the same time)
    + save_std_register now has an extra parameter which is the
      usedinproc registers

  Revision 1.49  2002/08/15 08:13:54  carl
    - a_load_sym_ofs_reg removed
    * loadvmt now calls loadaddr_ref_reg instead

  Revision 1.48  2002/08/14 19:26:02  carl
    + routine to optimize opcodes with constants

  Revision 1.47  2002/08/11 14:32:26  peter
    * renamed current_library to objectlibrary

  Revision 1.46  2002/08/11 13:24:11  peter
    * saving of asmsymbols in ppu supported
    * asmsymbollist global is removed and moved into a new class
      tasmlibrarydata that will hold the info of a .a file which
      corresponds with a single module. Added librarydata to tmodule
      to keep the library info stored for the module. In the future the
      objectfiles will also be stored to the tasmlibrarydata class
    * all getlabel/newasmsymbol and friends are moved to the new class

  Revision 1.45  2002/08/10 17:15:20  jonas
    * register parameters are now LOC_CREGISTER instead of LOC_REGISTER

  Revision 1.44  2002/08/09 19:10:05  carl
    - moved new_exception and free_exception to ncgutils

  Revision 1.43  2002/08/05 18:27:48  carl
    + more more more documentation
    + first version include/exclude (can't test though, not enough scratch for i386 :()...

  Revision 1.42  2002/08/04 19:08:21  carl
    + added generic exception support (still does not work!)
    + more documentation

  Revision 1.41  2002/07/30 20:50:43  florian
    * the code generator knows now if parameters are in registers

  Revision 1.40  2002/07/29 21:16:02  florian
    * some more ppc fixes

  Revision 1.39  2002/07/28 15:56:00  jonas
    + tcg64.a_op64_const_reg_reg() and tcg64.a_op64_reg_reg_reg() methods +
      generic implementation

  Revision 1.38  2002/07/27 19:53:51  jonas
    + generic implementation of tcg.g_flags2ref()
    * tcg.flags2xxx() now also needs a size parameter

  Revision 1.37  2002/07/20 11:57:53  florian
    * types.pas renamed to defbase.pas because D6 contains a types
      unit so this would conflicts if D6 programms are compiled
    + Willamette/SSE2 instructions to assembler added

}