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{
Copyright (c) 1998-2002 by Jonas Maebe, member of the Free Pascal
Development Team
This unit contains the data flow analyzer object of the assembler
optimizer.
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 aoptda;
{$i fpcdefs.inc}
Interface
uses
cpubase,cgbase,
aasmtai,aasmdata,aasmcpu,
aoptcpub, aoptbase;
Type
TAOptDFA = class
{ uses the same constructor as TAoptCpu = constructor from TAoptObj }
{ How many instructions are between the current instruction and the }
{ last one that modified the register }
InstrSinceLastMod: TInstrSinceLastMod;
{ gathers the information regarding the contents of every register }
{ at the end of every instruction }
Procedure DoDFA;
{ handles the processor dependent dataflow analizing }
Procedure CpuDFA(p: PInstr); Virtual; Abstract;
{ convert a TInsChange value into the corresponding register }
//!!!!!!!!!! Function TCh2Reg(Ch: TInsChange): TRegister; Virtual;
{ returns whether the instruction P reads from register Reg }
Function RegReadByInstr(Reg: TRegister; p: tai): Boolean; Virtual; Abstract;
End;
Implementation
uses
globals;
Procedure TAOptDFA.DoDFA;
{ Analyzes the Data Flow of an assembler list. Analyses the reg contents }
{ for the instructions between blockstart and blockend. Returns the last pai }
{ which has been processed }
{
Var
CurProp: TPaiProp;
UsedRegs: TUsedRegs;
p, hp, NewBlockStart : tai;
TmpReg: TRegister;
}
Begin
(*!!!!!!!!!!
p := BlockStart;
UsedRegs.Create;
UsedRegs.Update(p);
NewBlockStart := SkipHead(p);
{ done implicitely by the constructor
FillChar(InstrSinceLastMod, SizeOf(InstrSinceLastMod), 0); }
While (P <> BlockEnd) Do
Begin
CurProp:=TPaiProp.Create;
If (p <> NewBlockStart) Then
Begin
GetLastInstruction(p, hp);
CurProp.Regs := TPaiProp(hp.OptInfo).Regs;
{ !!!!!!!!!!!! }
{$ifdef x86}
CurProp.CondRegs.Flags :=
TPaiProp(hp.OptInfo).CondRegs.Flags;
{$endif}
End;
CurProp.UsedRegs.InitWithValue(UsedRegs.GetUsedRegs);
UsedRegs.Update(tai(p.Next));
TPaiProp(p.OptInfo) := CurProp;
For TmpReg := LoGPReg To HiGPReg Do
Inc(InstrSinceLastMod[TmpReg]);
Case p^.typ Of
ait_label:
If (Pai_label(p)^.l^.is_used) Then
CurProp^.DestroyAllRegs(InstrSinceLastMod);
ait_stab, ait_force_line, ait_function_name:;
ait_instruction:
if not(PInstr(p)^.is_jmp) then
begin
If IsLoadMemReg(p) Then
Begin
CurProp^.ReadRef(PInstr(p)^.oper[LoadSrc].ref);
TmpReg := RegMaxSize(PInstr(p)^.oper[LoadDst].reg);
If RegInRef(TmpReg, PInstr(p)^.oper[LoadSrc].ref^) And
(CurProp^.GetRegContentType(TmpReg) = Con_Ref) Then
Begin
{ a load based on the value this register already }
{ contained }
With CurProp^.Regs[TmpReg] Do
Begin
CurProp^.IncWState(TmpReg);
{also store how many instructions are part of the }
{ sequence in the first instruction's PPaiProp, so }
{ it can be easily accessed from within }
{ CheckSequence }
Inc(NrOfMods, InstrSinceLastMod[TmpReg]);
PPaiProp(Pai(StartMod)^.OptInfo)^.Regs[TmpReg].NrOfMods := NrOfMods;
InstrSinceLastMod[TmpReg] := 0
End
End
Else
Begin
{ load of a register with a completely new value }
CurProp^.DestroyReg(TmpReg, InstrSinceLastMod);
If Not(RegInRef(TmpReg, PInstr(p)^.oper[LoadSrc].ref^)) Then
With CurProp^.Regs[TmpReg] Do
Begin
Typ := Con_Ref;
StartMod := p;
NrOfMods := 1;
End
End;
{$ifdef StateDebug}
hp := new(pai_asm_comment,init(strpnew(std_reg2str[TmpReg]+': '+tostr(CurProp^.Regs[TmpReg].WState))));
InsertLLItem(AsmL, p, p^.next, hp);
{$endif StateDebug}
End
Else if IsLoadConstReg(p) Then
Begin
TmpReg := RegMaxSize(PInstr(p)^.oper[LoadDst].reg);
With CurProp^.Regs[TmpReg] Do
Begin
CurProp^.DestroyReg(TmpReg, InstrSinceLastMod);
typ := Con_Const;
StartMod := Pointer(PInstr(p)^.oper[LoadSrc].val);
End
End
Else CpuDFA(Pinstr(p));
End;
Else CurProp^.DestroyAllRegs(InstrSinceLastMod);
End;
{ Inc(InstrCnt);}
GetNextInstruction(p, p);
End;
*)
End;
End.
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