freepascal.compiler/compiler/aarch64/aoptcpu.pas

{
    Copyright (c) 1998-2002 by Jonas Maebe, member of the Free Pascal
    Development Team

    This unit implements the ARM64 optimizer 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.

 ****************************************************************************
}

Unit aoptcpu;

{$i fpcdefs.inc}

{ $define DEBUG_AOPTCPU}

Interface

    uses
      globtype, globals,
      cutils,
      cgbase, cpubase, aasmtai, aasmcpu, aopt, aoptcpub;

    Type
      TCpuAsmOptimizer = class(TAsmOptimizer)
        { uses the same constructor as TAopObj }
        function PeepHoleOptPass1Cpu(var p: tai): boolean; override;
        procedure PeepHoleOptPass2;override;
        function GetNextInstructionUsingReg(Current : tai; out Next : tai; reg : TRegister) : Boolean;
        function LookForPostindexedPattern(p : taicpu) : boolean;
        procedure DebugMsg(const s : string; p : tai);
      End;

Implementation

  uses
    aasmbase;

{$ifdef DEBUG_AOPTCPU}
  procedure TCpuAsmOptimizer.DebugMsg(const s: string;p : tai);
    begin
      asml.insertbefore(tai_comment.Create(strpnew(s)), p);
    end;
{$else DEBUG_AOPTCPU}
  procedure TCpuAsmOptimizer.DebugMsg(const s: string;p : tai);inline;
    begin
    end;
{$endif DEBUG_AOPTCPU}

  function CanBeCond(p : tai) : boolean;
    begin
      result:=(p.typ=ait_instruction) and (taicpu(p).condition=C_None);
    end;


  function MatchInstruction(const instr: tai; const op: TAsmOps; const postfix: TOpPostfixes): boolean;
    begin
      result :=
        (instr.typ = ait_instruction) and
        ((op = []) or (taicpu(instr).opcode in op)) and
        ((postfix = []) or (taicpu(instr).oppostfix in postfix));
    end;


  function MatchInstruction(const instr: tai; const op: TAsmOp; const postfix: TOpPostfixes): boolean;
    begin
      result :=
        (instr.typ = ait_instruction) and
        (taicpu(instr).opcode = op) and
        ((postfix = []) or (taicpu(instr).oppostfix in postfix));
    end;


  function TCpuAsmOptimizer.GetNextInstructionUsingReg(Current: tai;
    Out Next: tai; reg: TRegister): Boolean;
    begin
      Next:=Current;
      repeat
        Result:=GetNextInstruction(Next,Next);
      until not (Result) or
            not(cs_opt_level3 in current_settings.optimizerswitches) or
            (Next.typ<>ait_instruction) or
            RegInInstruction(reg,Next) or
            is_calljmp(taicpu(Next).opcode);
    end;

  {
    optimize
      ldr/str regX,[reg1]
      ...
      add/sub reg1,reg1,regY/const

      into

      ldr/str regX,[reg1], regY/const
  }
  function TCpuAsmOptimizer.LookForPostindexedPattern(p: taicpu) : boolean;
    var
      hp1 : tai;
    begin
      Result:=false;
      if (p.oper[1]^.typ = top_ref) and
        (p.oper[1]^.ref^.addressmode=AM_OFFSET) and
        (p.oper[1]^.ref^.index=NR_NO) and
        (p.oper[1]^.ref^.offset=0) and
        GetNextInstructionUsingReg(p, hp1, p.oper[1]^.ref^.base) and
        { we cannot check NR_DEFAULTFLAGS for modification yet so don't allow a condition }
        MatchInstruction(hp1, [A_ADD, A_SUB], [PF_None]) and
        (taicpu(hp1).oper[0]^.reg=p.oper[1]^.ref^.base) and
        (taicpu(hp1).oper[1]^.reg=p.oper[1]^.ref^.base) and
        (
         { valid offset? }
         (taicpu(hp1).oper[2]^.typ=top_const) and
         (taicpu(hp1).oper[2]^.val>=-256) and
         (abs(taicpu(hp1).oper[2]^.val)<256)
        ) and
        { don't apply the optimization if the base register is loaded }
        (getsupreg(p.oper[0]^.reg)<>getsupreg(p.oper[1]^.ref^.base)) and
        not(RegModifiedBetween(taicpu(hp1).oper[0]^.reg,p,hp1)) and
        not(RegModifiedBetween(taicpu(hp1).oper[2]^.reg,p,hp1)) then
        begin
          DebugMsg('Peephole Str/LdrAdd/Sub2Str/Ldr Postindex done', p);
          p.oper[1]^.ref^.addressmode:=AM_POSTINDEXED;
          if taicpu(hp1).opcode=A_ADD then
            p.oper[1]^.ref^.offset:=taicpu(hp1).oper[2]^.val
          else
            p.oper[1]^.ref^.offset:=-taicpu(hp1).oper[2]^.val;
          asml.Remove(hp1);
          hp1.Free;
          Result:=true;
        end;
    end;


  function TCpuAsmOptimizer.PeepHoleOptPass1Cpu(var p: tai): boolean;
    begin
      result := false;
      if p.typ=ait_instruction then
        begin
          case taicpu(p).opcode of
            A_LDR:
              begin
                Result:=LookForPostindexedPattern(taicpu(p));
              end;
            A_STR:
              begin
                Result:=LookForPostindexedPattern(taicpu(p));
              end;
          end;
        end;
    end;


  procedure TCpuAsmOptimizer.PeepHoleOptPass2;
    begin
    end;

begin
  casmoptimizer:=TCpuAsmOptimizer;
End.