freepascal.compiler/compiler/mips/aoptcpu.pas

{
    Copyright (c) 1998-2004 by Jonas Maebe

    This unit calls the optimization procedures to optimize the assembler
    code for sparc

    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}

  Interface

    uses
      cgbase, cpubase, aoptobj, aoptcpub, aopt, aasmtai;

    Type
      TCpuAsmOptimizer = class(TAsmOptimizer)
        function TryRemoveMov(var p: tai): boolean;
        function PeepHoleOptPass1Cpu(var p: tai): boolean; override;
      End;

  Implementation

     uses
       aasmcpu;


  function MatchInstruction(const instr: tai; const op: TAsmOp): boolean;
    begin
      result :=
        (instr.typ = ait_instruction) and
        (taicpu(instr).opcode = op);
    end;


  function MatchOperand(const oper: TOper; reg: TRegister): boolean;
    begin
      result:=(oper.typ=top_reg) and (oper.reg=reg);
    end;


  function IsSameReg(this,next: taicpu): boolean;
    begin
      result:=(next.oper[0]^.typ=top_reg) and
        (next.oper[1]^.typ=top_reg) and
        (next.oper[0]^.reg=next.oper[1]^.reg) and
        (next.oper[0]^.reg=this.oper[0]^.reg);
    end;


  function TCpuAsmOptimizer.TryRemoveMov(var p: tai): boolean;
    var
      next,hp1: tai;
      alloc,dealloc: tai_regalloc;
    begin
      { Fold
          op   $reg1,...
          move $reg2,$reg1
          dealloc $reg1
        into
          op   $reg2,...
      }
      result:=false;
      if GetNextInstruction(p,next) and
         MatchInstruction(next,A_MOVE) and
         MatchOperand(taicpu(next).oper[1]^,taicpu(p).oper[0]^.reg) then
        begin
          dealloc:=FindRegDealloc(taicpu(p).oper[0]^.reg,tai(next.Next));
          if assigned(dealloc) then
            begin
              { taicpu(p).oper[0]^.reg is not used anymore, try to find its allocation
                and remove it if possible }
              GetLastInstruction(p,hp1);

              asml.Remove(dealloc);
              alloc:=FindRegAlloc(taicpu(p).oper[0]^.reg,tai(hp1.Next));
              if assigned(alloc) then
                begin
                  asml.Remove(alloc);
                  alloc.free;
                  dealloc.free;
                end
              else
                asml.InsertAfter(dealloc,p);

              { try to move the allocation of the target register }
              GetLastInstruction(next,hp1);
              alloc:=FindRegAlloc(taicpu(next).oper[0]^.reg,tai(hp1.Next));
              if assigned(alloc) then
                begin
                  asml.Remove(alloc);
                  asml.InsertBefore(alloc,p);
                  { adjust used regs }
                  IncludeRegInUsedRegs(taicpu(next).oper[0]^.reg,UsedRegs);
                end;

              { finally get rid of the mov }
              taicpu(p).loadreg(0,taicpu(next).oper[0]^.reg);
              asml.remove(next);
              next.free;
            end;
        end;
    end;


  function TCpuAsmOptimizer.PeepHoleOptPass1Cpu(var p: tai): boolean;
    var
      next,next2: tai;
    begin
      result:=false;
      case p.typ of
        ait_instruction:
          begin
            case taicpu(p).opcode of
              A_SRL:
                begin
                  { Remove 'andi' in sequences
                      srl   Rx,Ry,16
                      andi  Rx,Rx,65535

                      srl   Rx,Ry,24
                      andi  Rx,Rx,255
                    since 'srl' clears all relevant upper bits }
                  if (taicpu(p).oper[2]^.typ=top_const) and
                    GetNextInstruction(p,next) and
                    MatchInstruction(next,A_ANDI) and
                    IsSameReg(taicpu(p),taicpu(next)) and
                    (taicpu(next).oper[2]^.typ=top_const) and
                    ((
                      (taicpu(p).oper[2]^.val>=16) and
                      (taicpu(next).oper[2]^.val=65535)
                    ) or (
                      (taicpu(p).oper[2]^.val>=24) and
                      (taicpu(next).oper[2]^.val=255)
                    )) then
                    begin
                      asml.remove(next);
                      next.free;
                    end
                  else
                    TryRemoveMov(p);
                end;

              A_ANDI:
                begin
                  { Remove sign extension after 'andi' if bit 7/15 of const operand is clear }
                  if (taicpu(p).oper[2]^.typ=top_const) and
                    GetNextInstruction(p,next) and
                    MatchInstruction(next,A_SLL) and
                    GetNextInstruction(next,next2) and
                    MatchInstruction(next2,A_SRA) and
                    IsSameReg(taicpu(p),taicpu(next)) and
                    IsSameReg(taicpu(p),taicpu(next2)) and
                    (taicpu(next).oper[2]^.typ=top_const) and
                    (taicpu(next2).oper[2]^.typ=top_const) and
                    (taicpu(next).oper[2]^.val=taicpu(next2).oper[2]^.val) and
                    ((
                      (taicpu(p).oper[2]^.val<=$7fff) and
                      (taicpu(next).oper[2]^.val=16)
                    ) or (
                      (taicpu(p).oper[2]^.val<=$7f) and
                      (taicpu(next).oper[2]^.val=24)
                    )) then
                    begin
                      asml.remove(next);
                      asml.remove(next2);
                      next.free;
                      next2.free;
                    end
                  else
                    TryRemoveMov(p);
                end;

              A_ADD,A_ADDU,
              A_ADDI,A_ADDIU,
              A_SUB,A_SUBU,
              A_SRA,A_SRAV,
              A_SRLV,
              A_SLL,A_SLLV,
              A_AND,A_OR,A_XOR,A_ORI,A_XORI:
                TryRemoveMov(p);
            end;
          end;
      end;
    end;

begin
  casmoptimizer:=TCpuAsmOptimizer;
end.