{
Copyright (c) 1998-2004 by Jonas Maebe, member of the Free Pascal
Development Team
This unit contains the processor independent assembler optimizer
object, base for the dataflow analyzer, peepholeoptimizer and
common subexpression elimination objects.
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 AoptObj;
{$i fpcdefs.inc}
{ general, processor independent objects for use by the assembler optimizer }
Interface
uses
globtype,
aasmbase,aasmcpu,aasmtai,aasmdata,
cclasses,
cgbase,cgutils,
cpubase,
aoptbase,aoptcpub,aoptda;
{ ************************************************************************* }
{ ********************************* Constants ***************************** }
{ ************************************************************************* }
Const
{Possible register content types}
con_Unknown = 0;
con_ref = 1;
con_const = 2;
{***************** Types ****************}
Type
{ ************************************************************************* }
{ ************************* Some general type definitions ***************** }
{ ************************************************************************* }
TRefCompare = Function(const r1, r2: TReference): Boolean;
//!!! FIXME
TRegArray = Array[byte] of tsuperregister;
TRegSet = Set of byte;
{ possible actions on an operand: read, write or modify (= read & write) }
TOpAction = (OpAct_Read, OpAct_Write, OpAct_Modify, OpAct_Unknown);
{ ************************************************************************* }
{ * Object to hold information on which regiters are in use and which not * }
{ ************************************************************************* }
TUsedRegs = class
Constructor create;
Constructor create_regset(Const _RegSet: TRegSet);
Destructor Destroy;override;
{ update the info with the pairegalloc objects coming after }
{ p }
Procedure Update(p: Tai);
{ is Reg currently in use }
Function IsUsed(Reg: TRegister): Boolean;
{ get all the currently used registers }
Function GetUsedRegs: TRegSet;
Private
UsedRegs: TRegSet;
End;
{ ************************************************************************* }
{ ******************* Contents of the integer registers ******************* }
{ ************************************************************************* }
{ size of the integer that holds the state number of a register. Can be any }
{ integer type, so it can be changed to reduce the size of the TContent }
{ structure or to improve alignment }
TStateInt = Byte;
TContent = Record
{ start and end of block instructions that defines the }
{ content of this register. If Typ = con_const, then }
{ Longint(StartMod) = value of the constant) }
StartMod: Tai;
{ starts at 0, gets increased everytime the register is }
{ written to }
WState: TStateInt;
{ starts at 0, gets increased everytime the register is read }
{ from }
RState: TStateInt;
{ how many instructions starting with StarMod does the block }
{ consist of }
NrOfMods: Byte;
{ the type of the content of the register: unknown, memory }
{ (variable) or constant }
Typ: Byte;
End;
//!!! FIXME
TRegContent = Array[byte] Of TContent;
{ ************************************************************************** }
{ information object with the contents of every register. Every Tai object }
{ gets one of these assigned: a pointer to it is stored in the OptInfo field }
{ ************************************************************************** }
TPaiProp = class(TAoptBaseCpu)
Regs: TRegContent;
{ info about allocation of general purpose integer registers }
UsedRegs: TUsedRegs;
{ can this instruction be removed? }
CanBeRemoved: Boolean;
Constructor create; reintroduce;
{ checks the whole sequence of which (so regs[which].StartMod and and }
{ the next NrOfMods Tai objects) to see whether Reg is used somewhere, }
{ without it being loaded with something else first }
Function RegInSequence(Reg, which: TRegister): Boolean;
{ destroy the contents of a register, as well as those whose contents }
{ are based on those of that register }
Procedure DestroyReg(Reg: TRegister; var InstrSinceLastMod:
TInstrSinceLastMod);
{ if the contents of WhichReg (can be R_NO in case of a constant) are }
{ written to memory at the location Ref, the contents of the registers }
{ that depend on Ref have to be destroyed }
Procedure DestroyRefs(Const Ref: TReference; WhichReg: TRegister; var
InstrSinceLastMod: TInstrSinceLastMod);
{ an instruction reads from operand o }
Procedure ReadOp(const o:toper);
{ an instruction reads from reference Ref }
Procedure ReadRef(Ref: PReference);
{ an instruction reads from register Reg }
Procedure ReadReg(Reg: TRegister);
{ an instruction writes/modifies operand o and this has special }
{ side-effects or modifies the contents in such a way that we can't }
{ simply add this instruction to the sequence of instructions that }
{ describe the contents of the operand, so destroy it }
Procedure DestroyOp(const o:Toper; var InstrSinceLastMod:
TInstrSinceLastMod);
{ destroy the contents of all registers }
Procedure DestroyAllRegs(var InstrSinceLastMod: TInstrSinceLastMod);
{ a register's contents are modified, but not destroyed (the new value }
{ depends on the old one) }
Procedure ModifyReg(reg: TRegister; var InstrSinceLastMod:
TInstrSinceLastMod);
{ an operand's contents are modified, but not destroyed (the new value }
{ depends on the old one) }
Procedure ModifyOp(const oper: TOper; var InstrSinceLastMod:
TInstrSinceLastMod);
{ increase the write state of a register (call every time a register is }
{ written to) }
Procedure IncWState(Reg: TRegister);
{ increase the read state of a register (call every time a register is }
{ read from) }
Procedure IncRState(Reg: TRegister);
{ get the write state of a register }
Function GetWState(Reg: TRegister): TStateInt;
{ get the read state of a register }
Function GetRState(Reg: TRegister): TStateInt;
{ get the type of contents of a register }
Function GetRegContentType(Reg: TRegister): Byte;
Destructor Done;
Private
Procedure IncState(var s: TStateInt);
{ returns whether the reference Ref is used somewhere in the loading }
{ sequence Content }
Function RefInSequence(Const Ref: TReference; Content: TContent;
RefsEq: TRefCompare): Boolean;
{ returns whether the instruction P reads from and/or writes }
{ to Reg }
Function RefInInstruction(Const Ref: TReference; p: Tai;
RefsEq: TRefCompare): Boolean;
{ returns whether two references with at least one pointing to an array }
{ may point to the same memory location }
End;
{ ************************************************************************* }
{ ************************ Label information ****************************** }
{ ************************************************************************* }
TLabelTableItem = Record
PaiObj: Tai;
End;
TLabelTable = Array[0..2500000] Of TLabelTableItem;
PLabelTable = ^TLabelTable;
PLabelInfo = ^TLabelInfo;
TLabelInfo = Record
{ the highest and lowest label number occurring in the current code }
{ fragment }
LowLabel, HighLabel: AWord;
LabelDif: AWord;
{ table that contains the addresses of the Pai_Label objects associated
with each label number }
LabelTable: PLabelTable;
End;
{ ************************************************************************* }
{ ********** General optimizer object, used to derive others from ********* }
{ ************************************************************************* }
TAOptObj = class(TAoptBaseCpu)
{ the PAasmOutput list this optimizer instance works on }
AsmL: TAsmList;
{ The labelinfo record contains the addresses of the Tai objects }
{ that are labels, how many labels there are and the min and max }
{ label numbers }
LabelInfo: PLabelInfo;
{ Start and end of the block that is currently being optimized }
BlockStart, BlockEnd: Tai;
DFA: TAOptDFA;
{ _AsmL is the PAasmOutpout list that has to be optimized, }
{ _BlockStart and _BlockEnd the start and the end of the block }
{ that has to be optimized and _LabelInfo a pointer to a }
{ TLabelInfo record }
Constructor create(_AsmL: TAsmList; _BlockStart, _BlockEnd: Tai;
_LabelInfo: PLabelInfo); virtual; reintroduce;
{ processor independent methods }
{ returns true if the label L is found between hp and the next }
{ instruction }
Function FindLabel(L: TasmLabel; Var hp: Tai): Boolean;
{ inserts new_one between prev and foll in AsmL }
Procedure InsertLLItem(prev, foll, new_one: TLinkedListItem);
{ If P is a Tai object releveant to the optimizer, P is returned
If it is not relevant tot he optimizer, the first object after P
that is relevant is returned }
Function SkipHead(P: Tai): Tai;
{ returns true if the operands o1 and o2 are completely equal }
Function OpsEqual(const o1,o2:toper): Boolean;
{ Returns true if a ait_alloc object for Reg is found in the block
of Tai's starting with StartPai and ending with the next "real"
instruction }
Function FindRegAlloc(Reg: TRegister; StartPai: Tai): Boolean;
{ traces sucessive jumps to their final destination and sets it, e.g.
je l1 je l3
<code> <code>
l1: becomes l1:
je l2 je l3
<code> <code>
l2: l2:
jmp l3 jmp l3
the level parameter denotes how deeep we have already followed the jump,
to avoid endless loops with constructs such as "l5: ; jmp l5" }
function GetFinalDestination(hp: taicpu; level: longint): boolean;
function getlabelwithsym(sym: tasmlabel): tai;
{ peephole optimizer }
procedure PrePeepHoleOpts;
procedure PeepHoleOptPass1;
procedure PeepHoleOptPass2; virtual;
procedure PostPeepHoleOpts;
{ processor dependent methods }
// if it returns true, perform a "continue"
function PeepHoleOptPass1Cpu(var p: tai): boolean; virtual;
function PostPeepHoleOptsCpu(var p: tai): boolean; virtual;
End;
Function ArrayRefsEq(const r1, r2: TReference): Boolean;
{ ***************************** Implementation **************************** }
Implementation
uses
globals,
verbose,
procinfo;
{ ************************************************************************* }
{ ******************************** TUsedRegs ****************************** }
{ ************************************************************************* }
Constructor TUsedRegs.create;
Begin
UsedRegs := [];
End;
Constructor TUsedRegs.create_regset(Const _RegSet: TRegSet);
Begin
UsedRegs := _RegSet;
End;
Procedure TUsedRegs.Update(p: Tai);
{updates UsedRegs with the RegAlloc Information coming after P}
Begin
Repeat
While Assigned(p) And
((p.typ in (SkipInstr - [ait_RegAlloc])) or
((p.typ = ait_label) And
Not(Tai_Label(p).labsym.is_used))) Do
p := Tai(p.next);
While Assigned(p) And
(p.typ=ait_RegAlloc) Do
Begin
{!!!!!!!! FIXME
if tai_regalloc(p).ratype=ra_alloc then
UsedRegs := UsedRegs + [tai_regalloc(p).Reg]
else
UsedRegs := UsedRegs - [tai_regalloc(p).Reg];
p := Tai(p.next);
}
End;
Until Not(Assigned(p)) Or
(Not(p.typ in SkipInstr) And
Not((p.typ = ait_label) And
Not(Tai_Label(p).labsym.is_used)));
End;
Function TUsedRegs.IsUsed(Reg: TRegister): Boolean;
Begin
//!!!!!!!!!!! IsUsed := Reg in UsedRegs
End;
Function TUsedRegs.GetUsedRegs: TRegSet;
Begin
GetUsedRegs := UsedRegs;
End;
Destructor TUsedRegs.Destroy;
Begin
inherited destroy;
end;
{ ************************************************************************* }
{ **************************** TPaiProp *********************************** }
{ ************************************************************************* }
Constructor TPaiProp.Create;
Begin
{!!!!!!
UsedRegs.Init;
CondRegs.init;
}
{ DirFlag: TFlagContents; I386 specific}
End;
Function TPaiProp.RegInSequence(Reg, which: TRegister): Boolean;
Var p: Tai;
RegsChecked: TRegSet;
content: TContent;
Counter: Byte;
TmpResult: Boolean;
Begin
{!!!!!!!!!!1
RegsChecked := [];
content := regs[which];
p := content.StartMod;
TmpResult := False;
Counter := 1;
While Not(TmpResult) And
(Counter <= Content.NrOfMods) Do
Begin
If IsLoadMemReg(p) Then
With PInstr(p)^.oper[LoadSrc]^.ref^ Do
If (Base = ProcInfo.FramePointer)
{$ifdef RefsHaveIndexReg}
And (Index = R_NO)
{$endif RefsHaveIndexReg} Then
Begin
RegsChecked := RegsChecked +
[RegMaxSize(PInstr(p)^.oper[LoadDst]^.reg)];
If Reg = RegMaxSize(PInstr(p)^.oper[LoadDst]^.reg) Then
Break;
End
Else
Begin
If (Base = Reg) And
Not(Base In RegsChecked)
Then TmpResult := True;
{$ifdef RefsHaveIndexReg}
If Not(TmpResult) And
(Index = Reg) And
Not(Index In RegsChecked)
Then TmpResult := True;
{$Endif RefsHaveIndexReg}
End
Else TmpResult := RegInInstruction(Reg, p);
Inc(Counter);
GetNextInstruction(p,p)
End;
RegInSequence := TmpResult
}
End;
Procedure TPaiProp.DestroyReg(Reg: TRegister; var InstrSinceLastMod:
TInstrSinceLastMod);
{ Destroys the contents of the register Reg in the PPaiProp p1, as well as }
{ the contents of registers are loaded with a memory location based on Reg }
Var TmpWState, TmpRState: Byte;
Counter: TRegister;
Begin
{!!!!!!!
Reg := RegMaxSize(Reg);
If (Reg in [LoGPReg..HiGPReg]) Then
For Counter := LoGPReg to HiGPReg Do
With Regs[Counter] Do
If (Counter = reg) Or
((Typ = Con_Ref) And
RegInSequence(Reg, Counter)) Then
Begin
InstrSinceLastMod[Counter] := 0;
IncWState(Counter);
TmpWState := GetWState(Counter);
TmpRState := GetRState(Counter);
FillChar(Regs[Counter], SizeOf(TContent), 0);
WState := TmpWState;
RState := TmpRState
End
}
End;
Function ArrayRefsEq(const r1, r2: TReference): Boolean;
Begin
{!!!!!!!!!!
ArrayRefsEq := (R1.Offset+R1.OffsetFixup = R2.Offset+R2.OffsetFixup) And
{$ifdef refsHaveSegmentReg}
(R1.Segment = R2.Segment) And
{$endif}
(R1.Base = R2.Base) And
(R1.Symbol=R2.Symbol);
}
End;
Procedure TPaiProp.DestroyRefs(Const Ref: TReference; WhichReg: TRegister;
var InstrSinceLastMod: TInstrSinceLastMod);
{ destroys all registers which possibly contain a reference to Ref, WhichReg }
{ is the register whose contents are being written to memory (if this proc }
{ is called because of a "mov?? %reg, (mem)" instruction) }
Var RefsEq: TRefCompare;
Counter: TRegister;
Begin
{!!!!!!!!!!!
WhichReg := RegMaxSize(WhichReg);
If (Ref.base = procinfo.FramePointer) or
Assigned(Ref.Symbol) Then
Begin
If
{$ifdef refsHaveIndexReg}
(Ref.Index = R_NO) And
{$endif refsHaveIndexReg}
(Not(Assigned(Ref.Symbol)) or
(Ref.base = R_NO)) Then
{ local variable which is not an array }
RefsEq := @RefsEqual
Else
{ local variable which is an array }
RefsEq := @ArrayRefsEq;
{write something to a parameter, a local or global variable, so
* with uncertain optimizations on:
- destroy the contents of registers whose contents have somewhere a
"mov?? (Ref), %reg". WhichReg (this is the register whose contents
are being written to memory) is not destroyed if it's StartMod is
of that form and NrOfMods = 1 (so if it holds ref, but is not a
pointer or value based on Ref)
* with uncertain optimizations off:
- also destroy registers that contain any pointer}
For Counter := LoGPReg to HiGPReg Do
With Regs[Counter] Do
Begin
If (typ = Con_Ref) And
((Not(cs_opt_size in current_settings.optimizerswitches) And
(NrOfMods <> 1)
) Or
(RefInSequence(Ref,Regs[Counter], RefsEq) And
((Counter <> WhichReg) Or
((NrOfMods <> 1) And
{StarMod is always of the type ait_instruction}
(PInstr(StartMod)^.oper[0].typ = top_ref) And
RefsEq(PInstr(StartMod)^.oper[0].ref^, Ref)
)
)
)
)
Then
DestroyReg(Counter, InstrSinceLastMod)
End
End
Else
{write something to a pointer location, so
* with uncertain optimzations on:
- do not destroy registers which contain a local/global variable or a
parameter, except if DestroyRefs is called because of a "movsl"
* with uncertain optimzations off:
- destroy every register which contains a memory location
}
For Counter := LoGPReg to HiGPReg Do
With Regs[Counter] Do
If (typ = Con_Ref) And
(Not(cs_opt_size in current_settings.optimizerswitches) Or
{$ifdef x86}
{for movsl}
(Ref.Base = R_EDI) Or
{$endif}
{don't destroy if reg contains a parameter, local or global variable}
Not((NrOfMods = 1) And
(PInstr(StartMod)^.oper[0].typ = top_ref) And
((PInstr(StartMod)^.oper[0].ref^.base = ProcInfo.FramePointer) Or
Assigned(PInstr(StartMod)^.oper[0].ref^.Symbol)
)
)
)
Then DestroyReg(Counter, InstrSinceLastMod)
}
End;
Procedure TPaiProp.DestroyAllRegs(var InstrSinceLastMod: TInstrSinceLastMod);
Var Counter: TRegister;
Begin {initializes/desrtoys all registers}
{!!!!!!!!!
For Counter := LoGPReg To HiGPReg Do
Begin
ReadReg(Counter);
DestroyReg(Counter, InstrSinceLastMod);
End;
CondRegs.Init;
{ FPURegs.Init; }
}
End;
Procedure TPaiProp.DestroyOp(const o:Toper; var InstrSinceLastMod:
TInstrSinceLastMod);
Begin
{!!!!!!!
Case o.typ Of
top_reg: DestroyReg(o.reg, InstrSinceLastMod);
top_ref:
Begin
ReadRef(o.ref);
DestroyRefs(o.ref^, R_NO, InstrSinceLastMod);
End;
top_symbol:;
End;
}
End;
Procedure TPaiProp.ReadReg(Reg: TRegister);
Begin
{!!!!!!!
Reg := RegMaxSize(Reg);
If Reg in General_Registers Then
IncRState(RegMaxSize(Reg))
}
End;
Procedure TPaiProp.ReadRef(Ref: PReference);
Begin
{!!!!!!!
If Ref^.Base <> R_NO Then
ReadReg(Ref^.Base);
{$ifdef refsHaveIndexReg}
If Ref^.Index <> R_NO Then
ReadReg(Ref^.Index);
{$endif}
}
End;
Procedure TPaiProp.ReadOp(const o:toper);
Begin
Case o.typ Of
top_reg: ReadReg(o.reg);
top_ref: ReadRef(o.ref);
else
internalerror(200410241);
End;
End;
Procedure TPaiProp.ModifyReg(reg: TRegister; Var InstrSinceLastMod:
TInstrSinceLastMod);
Begin
{!!!!!!!
With Regs[reg] Do
If (Typ = Con_Ref)
Then
Begin
IncState(WState);
{also store how many instructions are part of the sequence in the first
instructions PPaiProp, so it can be easily accessed from within
CheckSequence}
Inc(NrOfMods, InstrSinceLastMod[Reg]);
PPaiProp(StartMod.OptInfo)^.Regs[Reg].NrOfMods := NrOfMods;
InstrSinceLastMod[Reg] := 0;
End
Else
DestroyReg(Reg, InstrSinceLastMod);
}
End;
Procedure TPaiProp.ModifyOp(const oper: TOper; var InstrSinceLastMod:
TInstrSinceLastMod);
Begin
If oper.typ = top_reg Then
ModifyReg(RegMaxSize(oper.reg),InstrSinceLastMod)
Else
Begin
ReadOp(oper);
DestroyOp(oper, InstrSinceLastMod);
End
End;
Procedure TPaiProp.IncWState(Reg: TRegister);{$ifdef inl} inline;{$endif inl}
Begin
//!!!! IncState(Regs[Reg].WState);
End;
Procedure TPaiProp.IncRState(Reg: TRegister);{$ifdef inl} inline;{$endif inl}
Begin
//!!!! IncState(Regs[Reg].RState);
End;
Function TPaiProp.GetWState(Reg: TRegister): TStateInt; {$ifdef inl} inline;{$endif inl}
Begin
//!!!! GetWState := Regs[Reg].WState
End;
Function TPaiProp.GetRState(Reg: TRegister): TStateInt; {$ifdef inl} inline;{$endif inl}
Begin
//!!!! GetRState := Regs[Reg].RState
End;
Function TPaiProp.GetRegContentType(Reg: TRegister): Byte; {$ifdef inl} inline;{$endif inl}
Begin
//!!!! GetRegContentType := Regs[Reg].typ
End;
Destructor TPaiProp.Done;
Begin
//!!!! UsedRegs.Done;
//!!!! CondRegs.Done;
{ DirFlag: TFlagContents; I386 specific}
End;
{ ************************ private TPaiProp stuff ************************* }
Procedure TPaiProp.IncState(Var s: TStateInt); {$ifdef inl} inline;{$endif inl}
Begin
If s <> High(TStateInt) Then Inc(s)
Else s := 0
End;
Function TPaiProp.RefInInstruction(Const Ref: TReference; p: Tai;
RefsEq: TRefCompare): Boolean;
Var Count: AWord;
TmpResult: Boolean;
Begin
TmpResult := False;
If (p.typ = ait_instruction) Then
Begin
Count := 0;
Repeat
If (TInstr(p).oper[Count]^.typ = Top_Ref) Then
TmpResult := RefsEq(Ref, PInstr(p)^.oper[Count]^.ref^);
Inc(Count);
Until (Count = MaxOps) or TmpResult;
End;
RefInInstruction := TmpResult;
End;
Function TPaiProp.RefInSequence(Const Ref: TReference; Content: TContent;
RefsEq: TRefCompare): Boolean;
Var p: Tai;
Counter: Byte;
TmpResult: Boolean;
Begin
p := Content.StartMod;
TmpResult := False;
Counter := 1;
While Not(TmpResult) And
(Counter <= Content.NrOfMods) Do
Begin
If (p.typ = ait_instruction) And
RefInInstruction(Ref, p, @references_equal)
Then TmpResult := True;
Inc(Counter);
GetNextInstruction(p,p)
End;
RefInSequence := TmpResult
End;
{ ************************************************************************* }
{ ***************************** TAoptObj ********************************** }
{ ************************************************************************* }
Constructor TAoptObj.create(_AsmL: TAsmList; _BlockStart, _BlockEnd: Tai;
_LabelInfo: PLabelInfo);
Begin
AsmL := _AsmL;
BlockStart := _BlockStart;
BlockEnd := _BlockEnd;
LabelInfo := _LabelInfo
End;
Function TAOptObj.FindLabel(L: TasmLabel; Var hp: Tai): Boolean;
Var TempP: Tai;
Begin
TempP := hp;
While Assigned(TempP) and
(TempP.typ In SkipInstr + [ait_label]) Do
If (TempP.typ <> ait_Label) Or
(Tai_label(TempP).labsym <> L)
Then GetNextInstruction(TempP, TempP)
Else
Begin
hp := TempP;
FindLabel := True;
exit
End;
FindLabel := False;
End;
Procedure TAOptObj.InsertLLItem(prev, foll, new_one : TLinkedListItem);
Begin
If Assigned(prev) Then
If Assigned(foll) Then
Begin
If Assigned(new_one) Then
Begin
new_one.previous := prev;
new_one.next := foll;
prev.next := new_one;
foll.previous := new_one;
{ should we update line information? }
if (not (tai(new_one).typ in SkipLineInfo)) and
(not (tai(foll).typ in SkipLineInfo)) then
Tailineinfo(new_one).fileinfo := Tailineinfo(foll).fileinfo
End
End
Else AsmL.Concat(new_one)
Else If Assigned(Foll) Then AsmL.Insert(new_one)
End;
Function TAOptObj.SkipHead(P: Tai): Tai;
Var OldP: Tai;
Begin
Repeat
OldP := P;
If (P.typ in SkipInstr) Or
((P.typ = ait_marker) And
(Tai_Marker(P).Kind = mark_AsmBlockEnd)) Then
GetNextInstruction(P, P)
Else If ((P.Typ = Ait_Marker) And
(Tai_Marker(P).Kind = mark_NoPropInfoStart)) Then
{ a marker of the type mark_NoPropInfoStart can't be the first instruction of a }
{ paasmoutput list }
GetNextInstruction(Tai(P.Previous),P);
If (P.Typ = Ait_Marker) And
(Tai_Marker(P).Kind = mark_AsmBlockStart) Then
Begin
P := Tai(P.Next);
While (P.typ <> Ait_Marker) Or
(Tai_Marker(P).Kind <> mark_AsmBlockEnd) Do
P := Tai(P.Next)
End;
Until P = OldP;
SkipHead := P;
End;
Function TAOptObj.OpsEqual(const o1,o2:toper): Boolean;
Begin
if o1.typ=o2.typ then
Case o1.typ Of
Top_Reg :
OpsEqual:=o1.reg=o2.reg;
Top_Ref :
OpsEqual := references_equal(o1.ref^, o2.ref^);
Top_Const :
OpsEqual:=o1.val=o2.val;
Top_None :
OpsEqual := True
else OpsEqual := False
End;
End;
Function TAOptObj.FindRegAlloc(Reg: TRegister; StartPai: Tai): Boolean;
Begin
FindRegAlloc:=False;
Repeat
While Assigned(StartPai) And
((StartPai.typ in (SkipInstr - [ait_regAlloc])) Or
((StartPai.typ = ait_label) and
Not(Tai_Label(StartPai).labsym.Is_Used))) Do
StartPai := Tai(StartPai.Next);
If Assigned(StartPai) And
(StartPai.typ = ait_regAlloc) and (tai_regalloc(StartPai).ratype=ra_alloc) Then
Begin
if tai_regalloc(StartPai).Reg = Reg then
begin
FindRegAlloc:=true;
exit;
end;
StartPai := Tai(StartPai.Next);
End
else
exit;
Until false;
End;
function SkipLabels(hp: tai; var hp2: tai): boolean;
{skips all labels and returns the next "real" instruction}
begin
while assigned(hp.next) and
(tai(hp.next).typ in SkipInstr + [ait_label,ait_align]) Do
hp := tai(hp.next);
if assigned(hp.next) then
begin
SkipLabels := True;
hp2 := tai(hp.next)
end
else
begin
hp2 := hp;
SkipLabels := False
end;
end;
function FindAnyLabel(hp: tai; var l: tasmlabel): Boolean;
begin
FindAnyLabel := false;
while assigned(hp.next) and
(tai(hp.next).typ in (SkipInstr+[ait_align])) Do
hp := tai(hp.next);
if assigned(hp.next) and
(tai(hp.next).typ = ait_label) then
begin
FindAnyLabel := true;
l := tai_label(hp.next).labsym;
end
end;
{$ifopt r+}
{$define rangewason}
{$r-}
{$endif}
function tAOptObj.getlabelwithsym(sym: tasmlabel): tai;
begin
if (sym.labelnr >= labelinfo^.lowlabel) and
(sym.labelnr <= labelinfo^.highlabel) then { range check, a jump can go past an assembler block! }
getlabelwithsym := labelinfo^.labeltable^[sym.labelnr-labelinfo^.lowlabel].paiobj
else
getlabelwithsym := nil;
end;
{$ifdef rangewason}
{$r+}
{$undef rangewason}
{$endif}
function TAOptObj.GetFinalDestination(hp: taicpu; level: longint): boolean;
{traces sucessive jumps to their final destination and sets it, e.g.
je l1 je l3
<code> <code>
l1: becomes l1:
je l2 je l3
<code> <code>
l2: l2:
jmp l3 jmp l3
the level parameter denotes how deeep we have already followed the jump,
to avoid endless loops with constructs such as "l5: ; jmp l5" }
var p1, p2: tai;
l: tasmlabel;
begin
GetfinalDestination := false;
if level > 20 then
exit;
p1 := getlabelwithsym(tasmlabel(hp.oper[0]^.ref^.symbol));
if assigned(p1) then
begin
SkipLabels(p1,p1);
if (tai(p1).typ = ait_instruction) and
(taicpu(p1).is_jmp) then
if { the next instruction after the label where the jump hp arrives}
{ is unconditional or of the same type as hp, so continue }
(((taicpu(p1).opcode = aopt_uncondjmp) and
{$ifdef arm}
(taicpu(p1).condition = C_None) and
{$endif arm}
(taicpu(p1).oper[0]^.typ = top_ref) and
(assigned(taicpu(p1).oper[0]^.ref^.symbol)) and
(taicpu(p1).oper[0]^.ref^.symbol is TAsmLabel)) or
conditions_equal(taicpu(p1).condition,hp.condition)) or
{ the next instruction after the label where the jump hp arrives}
{ is the opposite of hp (so this one is never taken), but after }
{ that one there is a branch that will be taken, so perform a }
{ little hack: set p1 equal to this instruction (that's what the}
{ last SkipLabels is for, only works with short bool evaluation)}
(conditions_equal(taicpu(p1).condition,inverse_cond(hp.condition)) and
SkipLabels(p1,p2) and
(p2.typ = ait_instruction) and
(taicpu(p2).is_jmp) and
(((taicpu(p2).opcode = aopt_uncondjmp) and
{$ifdef arm}
(taicpu(p1).condition = C_None) and
{$endif arm}
(taicpu(p2).oper[0]^.typ = top_ref) and
(assigned(taicpu(p2).oper[0]^.ref^.symbol)) and
(taicpu(p2).oper[0]^.ref^.symbol is TAsmLabel)) or
(conditions_equal(taicpu(p2).condition,hp.condition))) and
SkipLabels(p1,p1)) then
begin
{ quick check for loops of the form "l5: ; jmp l5 }
if (tasmlabel(taicpu(p1).oper[0]^.ref^.symbol).labelnr =
tasmlabel(hp.oper[0]^.ref^.symbol).labelnr) then
exit;
if not GetFinalDestination(taicpu(p1),succ(level)) then
exit;
tasmlabel(hp.oper[0]^.ref^.symbol).decrefs;
hp.oper[0]^.ref^.symbol:=taicpu(p1).oper[0]^.ref^.symbol;
tasmlabel(hp.oper[0]^.ref^.symbol).increfs;
end
else
if conditions_equal(taicpu(p1).condition,inverse_cond(hp.condition)) then
if not FindAnyLabel(p1,l) then
begin
{$ifdef finaldestdebug}
insertllitem(asml,p1,p1.next,tai_comment.Create(
strpnew('previous label inserted'))));
{$endif finaldestdebug}
current_asmdata.getjumplabel(l);
insertllitem(p1,p1.next,tai_label.Create(l));
tasmlabel(taicpu(hp).oper[0]^.ref^.symbol).decrefs;
hp.oper[0]^.ref^.symbol := l;
l.increfs;
{ this won't work, since the new label isn't in the labeltable }
{ so it will fail the rangecheck. Labeltable should become a }
{ hashtable to support this: }
{ GetFinalDestination(asml, hp); }
end
else
begin
{$ifdef finaldestdebug}
insertllitem(asml,p1,p1.next,tai_comment.Create(
strpnew('next label reused'))));
{$endif finaldestdebug}
l.increfs;
hp.oper[0]^.ref^.symbol := l;
if not GetFinalDestination(hp,succ(level)) then
exit;
end;
end;
GetFinalDestination := true;
end;
procedure TAOptObj.PrePeepHoleOpts;
begin
end;
procedure TAOptObj.PeepHoleOptPass1;
var
p,hp1,hp2 : tai;
begin
p := BlockStart;
//!!!! UsedRegs := [];
while (p <> BlockEnd) Do
begin
//!!!! UpDateUsedRegs(UsedRegs, tai(p.next));
if PeepHoleOptPass1Cpu(p) then
continue;
case p.Typ Of
ait_instruction:
begin
{ Handle Jmp Optimizations }
if taicpu(p).is_jmp then
begin
{ the following if-block removes all code between a jmp and the next label,
because it can never be executed
}
if (taicpu(p).opcode = aopt_uncondjmp) and
{$ifdef arm}
(taicpu(p).condition = C_None) and
{$endif arm}
(taicpu(p).oper[0]^.typ = top_ref) and
(assigned(taicpu(p).oper[0]^.ref^.symbol)) and
(taicpu(p).oper[0]^.ref^.symbol is TAsmLabel) then
begin
while GetNextInstruction(p, hp1) and
(hp1.typ <> ait_label) do
if not(hp1.typ in ([ait_label,ait_align]+skipinstr)) then
begin
asml.remove(hp1);
hp1.free;
end
else break;
end;
{ remove jumps to a label coming right after them }
if GetNextInstruction(p, hp1) then
begin
if FindLabel(tasmlabel(taicpu(p).oper[0]^.ref^.symbol), hp1) and
{$warning FIXME removing the first instruction fails}
(p<>blockstart) then
begin
hp2:=tai(hp1.next);
asml.remove(p);
p.free;
p:=hp2;
continue;
end
else
begin
if hp1.typ = ait_label then
SkipLabels(hp1,hp1);
if (tai(hp1).typ=ait_instruction) and
(taicpu(hp1).opcode=aopt_uncondjmp) and
{$ifdef arm}
(taicpu(hp1).condition=C_None) and
{$endif arm}
(taicpu(hp1).oper[0]^.typ = top_ref) and
(assigned(taicpu(hp1).oper[0]^.ref^.symbol)) and
(taicpu(hp1).oper[0]^.ref^.symbol is TAsmLabel) and
GetNextInstruction(hp1, hp2) and
FindLabel(tasmlabel(taicpu(p).oper[0]^.ref^.symbol), hp2) then
begin
if (taicpu(p).opcode=aopt_condjmp)
{$ifdef arm}
and (taicpu(p).condition<>C_None)
{$endif arm}
then
begin
taicpu(p).condition:=inverse_cond(taicpu(p).condition);
tai_label(hp2).labsym.decrefs;
taicpu(p).oper[0]^.ref^.symbol:=taicpu(hp1).oper[0]^.ref^.symbol;
{ when freeing hp1, the reference count
isn't decreased, so don't increase
taicpu(p).oper[0]^.ref^.symbol.increfs;
}
{$ifdef SPARC}
hp2:=tai(hp1.next);
asml.remove(hp2);
hp2.free;
{$endif SPARC}
asml.remove(hp1);
hp1.free;
GetFinalDestination(taicpu(p),0);
end
else
begin
GetFinalDestination(taicpu(p),0);
p:=tai(p.next);
continue;
end;
end
else
GetFinalDestination(taicpu(p),0);
end;
end;
end
else
{ All other optimizes }
begin
end; { if is_jmp }
end;
end;
//!!!!!!!! updateUsedRegs(UsedRegs,p);
p:=tai(p.next);
end;
end;
procedure TAOptObj.PeepHoleOptPass2;
begin
end;
procedure TAOptObj.PostPeepHoleOpts;
var
p: tai;
begin
p := BlockStart;
//!!!! UsedRegs := [];
while (p <> BlockEnd) Do
begin
//!!!! UpDateUsedRegs(UsedRegs, tai(p.next));
if PostPeepHoleOptsCpu(p) then
continue;
//!!!!!!!! updateUsedRegs(UsedRegs,p);
p:=tai(p.next);
end;
end;
function TAOptObj.PeepHoleOptPass1Cpu(var p: tai): boolean;
begin
result := false;
end;
function TAOptObj.PostPeepHoleOptsCpu(var p: tai): boolean;
begin
result := false;
end;
End.
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