{
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;
{ $define DEBUG_AOPTOBJ}
{ $define DEBUG_JUMP}
{$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 = tcpuregisterset;
{ 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 }
TUsedRegs = class
Constructor create(aTyp : TRegisterType);
Constructor create_regset(aTyp : TRegisterType;Const _RegSet: TRegSet);
Destructor Destroy;override;
Procedure Clear;
{ update the info with the pairegalloc objects coming after
p }
procedure Update(p: Tai; IgnoreNewAllocs: Boolean=false);
{ is Reg currently in use }
Function IsUsed(Reg: TRegister): Boolean;
{ get all the currently used registers }
Function GetUsedRegs: TRegSet;
{ outputs the current set }
Procedure Dump(var t : text);
Private
Typ : TRegisterType;
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 }
TPaiProp = class(TAoptBaseCpu)
Regs: TRegContent;
{ 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 }
class function RefInSequence(Const Ref: TReference; Content: TContent;
RefsEq: TRefCompare): Boolean; static;
{ returns whether the instruction P reads from and/or writes }
{ to Reg }
class function RefInInstruction(Const Ref: TReference; p: Tai;
RefsEq: TRefCompare): Boolean; static;
{ 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: longint;
LabelDif: cardinal;
{ 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 ********* }
{ ************************************************************************* }
TAllUsedRegs = array[TRegisterType] of TUsedRegs;
{ TAOptObj }
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, and
a selected start point after the start of the block }
BlockStart, BlockEnd, StartPoint: Tai;
DFA: TAOptDFA;
UsedRegs: TAllUsedRegs;
{ _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;
Destructor Destroy;override;
{ processor independent methods }
Procedure CreateUsedRegs(var regs: TAllUsedRegs);
Procedure ClearUsedRegs;
Procedure UpdateUsedRegs(p : Tai);
class procedure UpdateUsedRegs(var Regs: TAllUsedRegs; p: Tai); static;
{ If UpdateUsedRegsAndOptimize has read ahead, the result is one before
the next valid entry (so "p.Next" returns what's expected). If no
reading ahead happened, then the result is equal to p. }
function UpdateUsedRegsAndOptimize(p : Tai): Tai;
Function CopyUsedRegs(var dest : TAllUsedRegs) : boolean;
procedure RestoreUsedRegs(const Regs : TAllUsedRegs);
procedure TransferUsedRegs(var dest: TAllUsedRegs);
class procedure ReleaseUsedRegs(const regs : TAllUsedRegs); static;
class function RegInUsedRegs(reg : TRegister;regs : TAllUsedRegs) : boolean; static;
class procedure IncludeRegInUsedRegs(reg : TRegister;var regs : TAllUsedRegs); static;
class procedure ExcludeRegFromUsedRegs(reg: TRegister;var regs : TAllUsedRegs); static;
class function GetAllocationString(const regs : TAllUsedRegs) : string; static;
{ returns true if the label L is found between hp and the next }
{ instruction }
class function FindLabel(L: TasmLabel; Var hp: Tai): Boolean; static;
{ 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 }
class function SkipHead(P: Tai): Tai; static;
{ returns true if the operands o1 and o2 are completely equal }
class function OpsEqual(const o1,o2:toper): Boolean; static;
{ Returns the next ait_alloc object with ratype ra_alloc for
Reg is found in the block
of Tai's starting with StartPai and ending with the next "real"
instruction. If none is found, it returns
nil
}
class function FindRegAlloc(Reg: TRegister; StartPai: Tai): tai_regalloc; static;
{ Returns the last ait_alloc object with ratype ra_alloc for
Reg is found in the block
of Tai's starting with StartPai and ending with the next "real"
instruction. If none is found, it returns
nil
}
class function FindRegAllocBackward(Reg : TRegister; StartPai : Tai) : tai_regalloc; static;
{ Returns the next ait_alloc object with ratype ra_dealloc
for Reg which is found in the block of Tai's starting with StartPai
and ending with the next "real" instruction. If none is found, it returns
nil }
class function FindRegDeAlloc(Reg: TRegister; StartPai: Tai): tai_regalloc; static;
{ allocates register reg between (and including) instructions p1 and p2
the type of p1 and p2 must not be in SkipInstr }
procedure AllocRegBetween(reg : tregister; p1,p2 : tai; var initialusedregs : TAllUsedRegs);
{ reg used after p? }
function RegUsedAfterInstruction(reg: Tregister; p: tai; var AllUsedRegs: TAllUsedRegs): Boolean;
{ returns true if reg reaches it's end of life at p, this means it is either
reloaded with a new value or it is deallocated afterwards }
function RegEndOfLife(reg: TRegister;p: taicpu): boolean;
{ removes p from asml, updates registers and replaces it by a valid value, if this is the case true is returned }
function RemoveCurrentP(var p : tai): boolean;
{ removes p from asml, updates registers and replaces p with hp1 (if the next instruction was known beforehand) }
procedure RemoveCurrentP(var p: tai; const hp1: tai); inline;
{ removes hp from asml then frees it }
procedure RemoveInstruction(const hp: tai); inline;
{ 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;
{ Removes an instruction following hp1 (possibly with reg.deallocations in between),
if its opcode is A_NOP. }
procedure RemoveDelaySlot(hp1: tai);
{ peephole optimizer }
procedure PrePeepHoleOpts; virtual;
procedure PeepHoleOptPass1; virtual;
procedure PeepHoleOptPass2; virtual;
procedure PostPeepHoleOpts; virtual;
{ processor dependent methods }
// if it returns true, perform a "continue"
function PrePeepHoleOptsCpu(var p: tai): boolean; virtual;
function PeepHoleOptPass1Cpu(var p: tai): boolean; virtual;
function PeepHoleOptPass2Cpu(var p: tai): boolean; virtual;
function PostPeepHoleOptsCpu(var p: tai): boolean; virtual;
{ Output debug message to console - null function if EXTDEBUG is not defined }
class procedure DebugWrite(Message: string); static; inline;
{ Converts a conditional jump into an unconditional jump. Only call this
procedure on an instruction that you already know is a conditional jump }
procedure MakeUnconditional(p: taicpu); virtual;
{ Removes all instructions between an unconditional jump and the next label.
Returns True if a jump in between was removed (as it may open up new
optimisations if the label appeared earlier in the stream) }
function RemoveDeadCodeAfterJump(p: tai): Boolean;
{ If hp is a label, strip it if its reference count is zero. Repeat until
a non-label is found, or a label with a non-zero reference count.
True is returned if something was stripped }
function StripDeadLabels(hp: tai; var NextValid: tai): Boolean;
{ Strips a label and any aligns that appear before it (if hp points to
them rather than the label). Only call this procedure on a label that
you already know is no longer referenced }
procedure StripLabelFast(hp: tai); {$ifdef USEINLINE}inline;{$endif USEINLINE}
{ Checks and removes "jmp @@lbl; @lbl". Returns True if the jump was removed }
function CollapseZeroDistJump(var p: tai; ThisLabel: TAsmLabel): Boolean;
{ If a group of labels are clustered, change the jump to point to the last one that is still referenced }
function CollapseLabelCluster(jump: tai; var lbltai: tai): TAsmLabel;
{$ifndef JVM}
function OptimizeConditionalJump(CJLabel: TAsmLabel; var p: tai; hp1: tai; var stoploop: Boolean): Boolean;
{$endif JVM}
{ Function to determine if the jump optimisations can be performed }
function CanDoJumpOpts: Boolean; virtual;
{ Jump/label optimisation entry method }
function DoJumpOptimizations(var p: tai; var stoploop: Boolean): Boolean;
{ insert debug comments about which registers are read and written by
each instruction. Useful for debugging the InstructionLoadsFromReg and
other similar functions. }
procedure Debug_InsertInstrRegisterDependencyInfo; virtual;
private
procedure DebugMsg(const s: string; p: tai);
End;
Function ArrayRefsEq(const r1, r2: TReference): Boolean;
{ Returns a pointer to the operand that contains the destination label }
function JumpTargetOp(ai: taicpu): poper;
{ Returns True if hp is any jump to a label }
function IsJumpToLabel(hp: taicpu): boolean;
{ Returns True if hp is an unconditional jump to a label }
function IsJumpToLabelUncond(hp: taicpu): boolean;
{ ***************************** Implementation **************************** }
Implementation
uses
cutils,
globals,
verbose,
aoptutils,
aasmcfi,
{$if defined(ARM)}
cpuinfo,
{$endif defined(ARM)}
procinfo;
{$ifdef DEBUG_AOPTOBJ}
const
SPeepholeOptimization: shortstring = 'Peephole Optimization: ';
{$else DEBUG_AOPTOBJ}
{ Empty strings help the optimizer to remove string concatenations that won't
ever appear to the user on release builds. [Kit] }
const
SPeepholeOptimization = '';
{$endif DEBUG_AOPTOBJ}
function JumpTargetOp(ai: taicpu): poper; inline;
begin
{$if defined(MIPS) or defined(riscv64) or defined(riscv32) or defined(xtensa)}
{ MIPS, Xtensa or RiscV branches can have 1,2 or 3 operands, target label is the last one. }
result:=ai.oper[ai.ops-1];
{$elseif defined(SPARC64)}
if ai.ops=2 then
result:=ai.oper[1]
else
result:=ai.oper[0];
{$else MIPS}
result:=ai.oper[0];
{$endif}
end;
{ ************************************************************************* }
{ ******************************** TUsedRegs ****************************** }
{ ************************************************************************* }
Constructor TUsedRegs.create(aTyp : TRegisterType);
Begin
Typ:=aTyp;
UsedRegs := [];
End;
Constructor TUsedRegs.create_regset(aTyp : TRegisterType;Const _RegSet: TRegSet);
Begin
Typ:=aTyp;
UsedRegs := _RegSet;
End;
{
updates UsedRegs with the RegAlloc Information coming after P
}
Procedure TUsedRegs.Update(p: Tai;IgnoreNewAllocs : Boolean = false);
Begin
{ this code is normally not used because updating the register allocation information is done in
TAOptObj.UpdateUsedRegs for speed reasons }
repeat
while assigned(p) and
((p.typ in (SkipInstr - [ait_RegAlloc])) or
(p.typ = ait_label) or
((p.typ = ait_marker) and
(tai_Marker(p).Kind in [mark_AsmBlockEnd,mark_NoLineInfoStart,mark_NoLineInfoEnd]))) do
p := tai(p.next);
while assigned(p) and
(p.typ=ait_RegAlloc) Do
begin
if (getregtype(tai_regalloc(p).reg) = typ) then
begin
case tai_regalloc(p).ratype of
ra_alloc :
if not(IgnoreNewAllocs) then
Include(UsedRegs, getsupreg(tai_regalloc(p).reg));
ra_dealloc :
Exclude(UsedRegs, getsupreg(tai_regalloc(p).reg));
else
;
end;
end;
p := tai(p.next);
end;
until not(assigned(p)) or
(not(p.typ in SkipInstr) and
not((p.typ = ait_label) and
labelCanBeSkipped(tai_label(p))));
End;
Function TUsedRegs.IsUsed(Reg: TRegister): Boolean;
Begin
IsUsed := (getregtype(Reg)=Typ) and (getsupreg(Reg) in UsedRegs);
End;
Function TUsedRegs.GetUsedRegs: TRegSet; inline;
Begin
GetUsedRegs := UsedRegs;
End;
procedure TUsedRegs.Dump(var t: text);
var
i: dword;
begin
write(t,Typ,' ');
for i:=low(TRegSet) to high(TRegSet) do
if i in UsedRegs then
write(t,i,' ');
writeln(t);
end;
Destructor TUsedRegs.Destroy;
Begin
inherited destroy;
end;
procedure TUsedRegs.Clear;
begin
UsedRegs := [];
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
Result:=False; { unimplemented }
(*!!!!!!!!!!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 cpurefshaveindexreg}
And (Index = R_NO)
{$endif cpurefshaveindexreg} Then
Begin
RegsChecked := RegsChecked +
[RegMaxSize(PInstr(p)^.oper[LoadDst]^.reg)];
If Reg = RegMaxSize(PInstr(p)^.oper[LoadDst]^.reg) Then
Break;
End
Else
Begin
If (Base = Reg) And
Not(Base In RegsChecked)
Then TmpResult := True;
{$ifdef cpurefshaveindexreg}
If Not(TmpResult) And
(Index = Reg) And
Not(Index In RegsChecked)
Then TmpResult := True;
{$Endif cpurefshaveindexreg}
End
Else TmpResult := RegInInstruction(Reg, p);
Inc(Counter);
GetNextInstruction(p,p)
End;
RegInSequence := TmpResult
*)
End;
Procedure TPaiProp.DestroyReg(Reg: TRegister; var InstrSinceLastMod:
TInstrSinceLastMod);
{ Destroys the contents of the register Reg in the PPaiProp p1, as well as }
{ the contents of registers are loaded with a memory location based on Reg }
{
Var TmpWState, TmpRState: Byte;
Counter: TRegister;
}
Begin
{!!!!!!!
Reg := RegMaxSize(Reg);
If (Reg in [LoGPReg..HiGPReg]) Then
For Counter := LoGPReg to HiGPReg Do
With Regs[Counter] Do
If (Counter = reg) Or
((Typ = Con_Ref) And
RegInSequence(Reg, Counter)) Then
Begin
InstrSinceLastMod[Counter] := 0;
IncWState(Counter);
TmpWState := GetWState(Counter);
TmpRState := GetRState(Counter);
FillChar(Regs[Counter], SizeOf(TContent), 0);
WState := TmpWState;
RState := TmpRState
End
}
End;
Function ArrayRefsEq(const r1, r2: TReference): Boolean;
Begin
Result:=False; { unimplemented }
(*!!!!!!!!!!
ArrayRefsEq := (R1.Offset+R1.OffsetFixup = R2.Offset+R2.OffsetFixup) And
{$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 cpurefshaveindexreg}
(Ref.Index = R_NO) And
{$endif cpurefshaveindexreg}
(Not(Assigned(Ref.Symbol)) or
(Ref.base = R_NO)) Then
{ local variable which is not an array }
RefsEq := @RefsEqual
Else
{ local variable which is an array }
RefsEq := @ArrayRefsEq;
{write something to a parameter, a local or global variable, so
* with uncertain optimizations on:
- destroy the contents of registers whose contents have somewhere a
"mov?? (Ref), %reg". WhichReg (this is the register whose contents
are being written to memory) is not destroyed if it's StartMod is
of that form and NrOfMods = 1 (so if it holds ref, but is not a
pointer or value based on Ref)
* with uncertain optimizations off:
- also destroy registers that contain any pointer}
For Counter := LoGPReg to HiGPReg Do
With Regs[Counter] Do
Begin
If (typ = Con_Ref) And
((Not(cs_opt_size in current_settings.optimizerswitches) And
(NrOfMods <> 1)
) Or
(RefInSequence(Ref,Regs[Counter], RefsEq) And
((Counter <> WhichReg) Or
((NrOfMods <> 1) And
{StarMod is always of the type ait_instruction}
(PInstr(StartMod)^.oper[0].typ = top_ref) And
RefsEq(PInstr(StartMod)^.oper[0].ref^, Ref)
)
)
)
)
Then
DestroyReg(Counter, InstrSinceLastMod)
End
End
Else
{write something to a pointer location, so
* with uncertain optimzations on:
- do not destroy registers which contain a local/global variable or a
parameter, except if DestroyRefs is called because of a "movsl"
* with uncertain optimzations off:
- destroy every register which contains a memory location
}
For Counter := LoGPReg to HiGPReg Do
With Regs[Counter] Do
If (typ = Con_Ref) And
(Not(cs_opt_size in current_settings.optimizerswitches) Or
{$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 cpurefshaveindexreg}
If Ref^.Index <> R_NO Then
ReadReg(Ref^.Index);
{$endif cpurefshaveindexreg}
*)
End;
Procedure TPaiProp.ReadOp(const o:toper);
Begin
Case o.typ Of
top_reg: ReadReg(o.reg);
top_ref: ReadRef(o.ref);
else
internalerror(200410241);
End;
End;
Procedure TPaiProp.ModifyReg(reg: TRegister; Var InstrSinceLastMod:
TInstrSinceLastMod);
Begin
(*!!!!!!!
With Regs[reg] Do
If (Typ = Con_Ref)
Then
Begin
IncState(WState);
{also store how many instructions are part of the sequence in the first
instructions PPaiProp, so it can be easily accessed from within
CheckSequence}
Inc(NrOfMods, InstrSinceLastMod[Reg]);
PPaiProp(StartMod.OptInfo)^.Regs[Reg].NrOfMods := NrOfMods;
InstrSinceLastMod[Reg] := 0;
End
Else
DestroyReg(Reg, InstrSinceLastMod);
*)
End;
Procedure TPaiProp.ModifyOp(const oper: TOper; var InstrSinceLastMod:
TInstrSinceLastMod);
Begin
If oper.typ = top_reg Then
ModifyReg(RegMaxSize(oper.reg),InstrSinceLastMod)
Else
Begin
ReadOp(oper);
DestroyOp(oper, InstrSinceLastMod);
End
End;
Procedure TPaiProp.IncWState(Reg: TRegister);{$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;{$endif inl}
Begin
Result:=0; { unimplemented }
//!!!! GetWState := Regs[Reg].WState
End;
Function TPaiProp.GetRState(Reg: TRegister): TStateInt; {$ifdef inl} inline;{$endif inl}
Begin
Result:=0; { unimplemented }
//!!!! GetRState := Regs[Reg].RState
End;
Function TPaiProp.GetRegContentType(Reg: TRegister): Byte; {$ifdef inl} inline;{$endif inl}
Begin
Result:=0; { unimplemented }
//!!!! GetRegContentType := Regs[Reg].typ
End;
Destructor TPaiProp.Done;
Begin
//!!!! UsedRegs.Done;
//!!!! CondRegs.Done;
{ DirFlag: TFlagContents; I386 specific}
End;
{ ************************ private TPaiProp stuff ************************* }
Procedure TPaiProp.IncState(Var s: TStateInt); {$ifdef inl} inline;{$endif inl}
Begin
If s <> High(TStateInt) Then Inc(s)
Else s := 0
End;
class Function TPaiProp.RefInInstruction(Const Ref: TReference; p: Tai;
RefsEq: TRefCompare): Boolean;
Var Count: AWord;
TmpResult: Boolean;
Begin
TmpResult := False;
If (p.typ = ait_instruction) Then
Begin
Count := 0;
Repeat
If (TInstr(p).oper[Count]^.typ = Top_Ref) Then
TmpResult := RefsEq(Ref, PInstr(p)^.oper[Count]^.ref^);
Inc(Count);
Until (Count = max_operands) or TmpResult;
End;
RefInInstruction := TmpResult;
End;
class function TPaiProp.RefInSequence(Const Ref: TReference; Content: TContent;
RefsEq: TRefCompare): Boolean;
Var p: Tai;
Counter: Byte;
TmpResult: Boolean;
Begin
p := Content.StartMod;
TmpResult := False;
Counter := 1;
While Not(TmpResult) And
(Counter <= Content.NrOfMods) Do
Begin
If (p.typ = ait_instruction) And
RefInInstruction(Ref, p, @references_equal)
Then TmpResult := True;
Inc(Counter);
GetNextInstruction(p,p)
End;
RefInSequence := TmpResult
End;
{ ************************************************************************* }
{ ***************************** TAoptObj ********************************** }
{ ************************************************************************* }
Constructor TAoptObj.create(_AsmL: TAsmList; _BlockStart, _BlockEnd: Tai;
_LabelInfo: PLabelInfo);
Begin
AsmL := _AsmL;
BlockStart := _BlockStart;
BlockEnd := _BlockEnd;
LabelInfo := _LabelInfo;
CreateUsedRegs(UsedRegs);
End;
destructor TAOptObj.Destroy;
var
i : TRegisterType;
begin
for i:=low(TRegisterType) to high(TRegisterType) do
UsedRegs[i].Destroy;
inherited Destroy;
end;
{$ifdef DEBUG_AOPTOBJ}
procedure TAOptObj.DebugMsg(const s: string;p : tai);
begin
asml.insertbefore(tai_comment.Create(strpnew(s)), p);
end;
{$else DEBUG_AOPTOBJ}
procedure TAOptObj.DebugMsg(const s: string;p : tai);inline;
begin
end;
{$endif DEBUG_AOPTOBJ}
procedure TAOptObj.CreateUsedRegs(var regs: TAllUsedRegs);
var
i : TRegisterType;
begin
for i:=low(TRegisterType) to high(TRegisterType) do
Regs[i]:=TUsedRegs.Create(i);
end;
procedure TAOptObj.ClearUsedRegs;
var
i : TRegisterType;
begin
for i:=low(TRegisterType) to high(TRegisterType) do
UsedRegs[i].Clear;
end;
{ If UpdateUsedRegsAndOptimize has read ahead, the result is one before
the next valid entry (so "p.Next" returns what's expected). If no
reading ahead happened, then the result is equal to p. }
function TAOptObj.UpdateUsedRegsAndOptimize(p : Tai): Tai;
var
NotFirst: Boolean;
begin
{ this code is based on TUsedRegs.Update to avoid multiple passes through the asmlist,
the code is duplicated here }
Result := p;
if (p.typ in [ait_instruction, ait_label]) then
begin
if (p.next <> BlockEnd) and (tai(p.next).typ <> ait_instruction) then
begin
{ Advance one, otherwise the routine exits immediately and wastes time }
p := tai(p.Next);
NotFirst := True;
end
else
{ If the next entry is an instruction, nothing will be updated or
optimised here, so exit now to save time }
Exit;
end
else
NotFirst := False;
repeat
while assigned(p) and
((p.typ in (SkipInstr + [ait_align, ait_label] - [ait_RegAlloc])) or
((p.typ = ait_marker) and
(tai_Marker(p).Kind in [mark_AsmBlockEnd,mark_NoLineInfoStart,mark_NoLineInfoEnd]))) do
begin
prefetch(pointer(p.Next)^);
{ Here's the optimise part }
if (p.typ in [ait_align, ait_label]) then
begin
if StripDeadLabels(p, p) then
begin
{ Note, if the first instruction is stripped and is
the only one that gets removed, Result will now
contain a dangling pointer, so compensate for this. }
if not NotFirst then
Result := tai(p.Previous);
Continue;
end;
if ((p.typ = ait_label) and not labelCanBeSkipped(tai_label(p))) then
Break;
end;
Result := p;
p := tai(p.next);
end;
while assigned(p) and
(p.typ=ait_RegAlloc) Do
begin
prefetch(pointer(p.Next)^);
case tai_regalloc(p).ratype of
ra_alloc :
Include(UsedRegs[getregtype(tai_regalloc(p).reg)].UsedRegs, getsupreg(tai_regalloc(p).reg));
ra_dealloc :
Exclude(UsedRegs[getregtype(tai_regalloc(p).reg)].UsedRegs, getsupreg(tai_regalloc(p).reg));
else
{ Do nothing };
end;
Result := p;
p := tai(p.next);
end;
NotFirst := True;
until not(assigned(p)) or
(not(p.typ in SkipInstr + [ait_align]) and
not((p.typ = ait_label) and
labelCanBeSkipped(tai_label(p))));
end;
procedure TAOptObj.UpdateUsedRegs(p : Tai);
begin
{ this code is based on TUsedRegs.Update to avoid multiple passes through the asmlist,
the code is duplicated here }
repeat
while assigned(p) and
((p.typ in (SkipInstr - [ait_RegAlloc])) or
((p.typ = ait_label) and
labelCanBeSkipped(tai_label(p))) or
((p.typ = ait_marker) and
(tai_Marker(p).Kind in [mark_AsmBlockEnd,mark_NoLineInfoStart,mark_NoLineInfoEnd]))) do
p := tai(p.next);
while assigned(p) and
(p.typ=ait_RegAlloc) Do
begin
prefetch(pointer(p.Next)^);
case tai_regalloc(p).ratype of
ra_alloc :
Include(UsedRegs[getregtype(tai_regalloc(p).reg)].UsedRegs, getsupreg(tai_regalloc(p).reg));
ra_dealloc :
Exclude(UsedRegs[getregtype(tai_regalloc(p).reg)].UsedRegs, getsupreg(tai_regalloc(p).reg));
else
;
end;
p := tai(p.next);
end;
until not(assigned(p)) or
(not(p.typ in SkipInstr) and
not((p.typ = ait_label) and
labelCanBeSkipped(tai_label(p))));
end;
class procedure TAOptObj.UpdateUsedRegs(var Regs : TAllUsedRegs;p : Tai);
var
i : TRegisterType;
begin
for i:=low(TRegisterType) to high(TRegisterType) do
Regs[i].Update(p);
end;
function TAOptObj.CopyUsedRegs(var dest: TAllUsedRegs): boolean;
var
i : TRegisterType;
begin
Result:=true;
for i:=low(TRegisterType) to high(TRegisterType) do
dest[i]:=TUsedRegs.Create_Regset(i,UsedRegs[i].GetUsedRegs);
end;
procedure TAOptObj.RestoreUsedRegs(const Regs: TAllUsedRegs);
var
i : TRegisterType;
begin
{ Note that the constructor Create_Regset is being called as a regular
method - it is not instantiating a new object. This is because it is
the only published means to modify the internal state en-masse. [Kit] }
for i:=low(TRegisterType) to high(TRegisterType) do
UsedRegs[i].Create_Regset(i,Regs[i].GetUsedRegs);
end;
procedure TAOptObj.TransferUsedRegs(var dest: TAllUsedRegs);
var
i : TRegisterType;
begin
{ Note that the constructor Create_Regset is being called as a regular
method - it is not instantiating a new object. This is because it is
the only published means to modify the internal state en-masse. [Kit] }
for i:=low(TRegisterType) to high(TRegisterType) do
dest[i].Create_Regset(i, UsedRegs[i].GetUsedRegs);
end;
class procedure TAOptObj.ReleaseUsedRegs(const regs: TAllUsedRegs);
var
i : TRegisterType;
begin
for i:=low(TRegisterType) to high(TRegisterType) do
regs[i].Free;
end;
class Function TAOptObj.RegInUsedRegs(reg : TRegister;regs : TAllUsedRegs) : boolean;
begin
result:=regs[getregtype(reg)].IsUsed(reg);
end;
class procedure TAOptObj.IncludeRegInUsedRegs(reg: TRegister;
var regs: TAllUsedRegs);
begin
include(regs[getregtype(reg)].UsedRegs,getsupreg(Reg));
end;
class procedure TAOptObj.ExcludeRegFromUsedRegs(reg: TRegister;
var regs: TAllUsedRegs);
begin
exclude(regs[getregtype(reg)].UsedRegs,getsupreg(Reg));
end;
class function TAOptObj.GetAllocationString(const regs: TAllUsedRegs): string;
var
i : TRegisterType;
j : TSuperRegister;
begin
Result:='';
for i:=low(TRegisterType) to high(TRegisterType) do
for j in regs[i].UsedRegs do
Result:=Result+std_regname(newreg(i,j,R_SUBWHOLE))+' ';
end;
class 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,ait_align]) 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;
class 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;
class 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^) and
(o1.ref^.volatility=[]) and
(o2.ref^.volatility=[]);
Top_Const :
OpsEqual:=o1.val=o2.val;
Top_None :
OpsEqual := True
else OpsEqual := False
End
else
OpsEqual := False;
End;
class function TAOptObj.FindRegAlloc(Reg: TRegister; StartPai: Tai): tai_regalloc;
Begin
Result:=nil;
Repeat
While Assigned(StartPai) And
((StartPai.typ in (SkipInstr - [ait_regAlloc])) Or
{$ifdef cpudelayslot}
((startpai.typ=ait_instruction) and (taicpu(startpai).opcode=A_NOP)) or
{$endif cpudelayslot}
((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) Then
Begin
if (tai_regalloc(StartPai).ratype=ra_alloc) and
(getregtype(tai_regalloc(StartPai).Reg) = getregtype(Reg)) and
(getsupreg(tai_regalloc(StartPai).Reg) = getsupreg(Reg)) then
begin
Result:=tai_regalloc(StartPai);
exit;
end;
StartPai := Tai(StartPai.Next);
End
else
exit;
Until false;
End;
class function TAOptObj.FindRegAllocBackward(Reg: TRegister; StartPai: Tai): tai_regalloc;
Begin
Result:=nil;
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.Previous);
If Assigned(StartPai) And
(StartPai.typ = ait_regAlloc) Then
Begin
if (tai_regalloc(StartPai).ratype=ra_alloc) and
SuperRegistersEqual(tai_regalloc(StartPai).Reg,Reg) then
begin
Result:=tai_regalloc(StartPai);
exit;
end;
StartPai := Tai(StartPai.Previous);
End
else
exit;
Until false;
End;
class function TAOptObj.FindRegDeAlloc(Reg: TRegister; StartPai: Tai): tai_regalloc;
Begin
Result:=nil;
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) Then
Begin
if (tai_regalloc(StartPai).ratype=ra_dealloc) and
(getregtype(tai_regalloc(StartPai).Reg) = getregtype(Reg)) and
(getsupreg(tai_regalloc(StartPai).Reg) = getsupreg(Reg)) then
begin
Result:=tai_regalloc(StartPai);
exit;
end;
StartPai := Tai(StartPai.Next);
End
else
exit;
Until false;
End;
{ allocates register reg between (and including) instructions p1 and p2
the type of p1 and p2 must not be in SkipInstr }
procedure TAOptObj.AllocRegBetween(reg: tregister; p1, p2: tai; var initialusedregs: TAllUsedRegs);
var
hp, start: tai;
removedsomething,
firstRemovedWasAlloc,
lastRemovedWasDealloc: boolean;
begin
{$ifdef EXTDEBUG}
{ if assigned(p1.optinfo) and
(ptaiprop(p1.optinfo)^.usedregs <> initialusedregs) then
internalerror(2004101010); }
{$endif EXTDEBUG}
if not Assigned(p2) then
{ We need a valid final instruction }
InternalError(2022010401);
start := p1;
if (reg = NR_STACK_POINTER_REG) or
(reg = current_procinfo.framepointer) or
not(assigned(p1)) then
{ this happens with registers which are loaded implicitely, outside the }
{ current block (e.g. esi with self) }
exit;
{$ifdef allocregdebug}
insertllitem(p1.previous,p1,tai_comment.Create(strpnew('allocating '+std_regname(reg)+' from here...')));
insertllitem(p2,p2.next,tai_comment.Create(strpnew('allocated '+std_regname(reg)+' till here...')));
{$endif allocregdebug}
{ make sure we allocate it for this instruction }
getnextinstruction(p2,p2);
lastRemovedWasDealloc := false;
removedSomething := false;
firstRemovedWasAlloc := false;
{ do it the safe way: always allocate the full super register,
as we do no register re-allocation in the peephole optimizer,
this does not hurt
}
case getregtype(reg) of
R_MMREGISTER:
reg:=newreg(R_MMREGISTER,getsupreg(reg),R_SUBMMWHOLE);
R_INTREGISTER:
reg:=newreg(R_INTREGISTER,getsupreg(reg),R_SUBWHOLE);
R_FPUREGISTER:
reg:=newreg(R_FPUREGISTER,getsupreg(reg),R_SUBWHOLE);
R_ADDRESSREGISTER:
reg:=newreg(R_ADDRESSREGISTER,getsupreg(reg),R_SUBWHOLE);
R_SPECIALREGISTER:
reg:=newreg(R_SPECIALREGISTER,getsupreg(reg),R_SUBWHOLE);
else
Internalerror(2018030701);
end;
if not(RegInUsedRegs(reg,initialusedregs)) then
begin
hp := tai_regalloc.alloc(reg,nil);
insertllItem(p1.previous,p1,hp);
IncludeRegInUsedRegs(reg,initialusedregs);
lastRemovedWasDealloc := True; { If no tai_regallocs are found at all, treat as if the last one was a deallocation }
end;
while assigned(p1) and
(p1 <> p2) do
begin
if assigned(p1.optinfo) then
internalerror(2014022301); // IncludeRegInUsedRegs(reg,ptaiprop(p1.optinfo)^.usedregs);
p1 := tai(p1.next);
repeat
while assigned(p1) and
(p1.typ in (SkipInstr-[ait_regalloc])) Do
p1 := tai(p1.next);
{ remove all allocation/deallocation info about the register in between }
if assigned(p1) and
(p1.typ = ait_regalloc) then
begin
{ same super register, different sub register? }
if SuperRegistersEqual(reg,tai_regalloc(p1).reg) and (tai_regalloc(p1).reg<>reg) then
begin
if (getsubreg(reg)<>R_SUBMMWHOLE) and { R_SUBMMWHOLE is below R_SUBMMX, R_SUBMMY and R_SUBMMZ }
((getsubreg(tai_regalloc(p1).reg)>getsubreg(reg)) or (getsubreg(reg)=R_SUBH)) then
internalerror(2016101501);
tai_regalloc(p1).reg:=reg;
end;
if tai_regalloc(p1).reg=reg then
begin
if not removedSomething then
begin
firstRemovedWasAlloc := tai_regalloc(p1).ratype=ra_alloc;
removedSomething := true;
end;
lastRemovedWasDealloc := (tai_regalloc(p1).ratype=ra_dealloc);
hp := tai(p1.Next);
asml.Remove(p1);
p1.free;
p1 := hp;
end
else
p1 := tai(p1.next);
end;
until not(assigned(p1)) or
not(p1.typ in SkipInstr);
end;
if assigned(p1) then
begin
if firstRemovedWasAlloc then
begin
hp := tai_regalloc.Alloc(reg,nil);
insertLLItem(start.previous,start,hp);
end;
if lastRemovedWasDealloc then
begin
hp := tai_regalloc.DeAlloc(reg,nil);
insertLLItem(p1.previous,p1,hp);
end;
end;
end;
function TAOptObj.RegUsedAfterInstruction(reg: Tregister; p: tai;var AllUsedRegs: TAllUsedRegs): Boolean;
begin
AllUsedRegs[getregtype(reg)].Update(tai(p.Next),true);
RegUsedAfterInstruction :=
AllUsedRegs[getregtype(reg)].IsUsed(reg) and
not(regLoadedWithNewValue(reg,p)) and
(
not(GetNextInstruction(p,p)) or
InstructionLoadsFromReg(reg,p) or
not(regLoadedWithNewValue(reg,p))
);
end;
function TAOptObj.RegEndOfLife(reg : TRegister;p : taicpu) : boolean;
begin
Result:=assigned(FindRegDealloc(reg,tai(p.Next))) or
RegLoadedWithNewValue(reg,p);
end;
function TAOptObj.RemoveCurrentP(var p : tai) : boolean;
var
hp1 : tai;
begin
result:=GetNextInstruction(p,hp1);
{ p will be removed, update used register as we continue
with the next instruction after p }
UpdateUsedRegs(tai(p.Next));
AsmL.Remove(p);
p.Free;
p:=hp1;
end;
procedure TAOptObj.RemoveCurrentP(var p: tai; const hp1: tai); inline;
begin
if (p=hp1) then
internalerror(2020120501);
UpdateUsedRegs(tai(p.Next));
AsmL.Remove(p);
p.Free;
p := hp1;
end;
procedure TAOptObj.RemoveInstruction(const hp: tai); inline;
begin
AsmL.Remove(hp);
hp.Free;
end;
function FindLiveLabel(hp: tai; var l: tasmlabel): Boolean;
var
next: tai;
begin
FindLiveLabel := false;
while True do
begin
while assigned(hp.next) and
(tai(hp.next).typ in (SkipInstr+[ait_align])) Do
hp := tai(hp.next);
next := tai(hp.next);
if assigned(next) and
(tai(next).typ = ait_label) then
begin
l := tai_label(next).labsym;
if not l.is_used then
begin
{ Unsafe label }
hp := next;
Continue;
end;
FindLiveLabel := true;
end;
Exit;
end;
end;
{$push}
{$r-}
function TAOptObj.getlabelwithsym(sym: tasmlabel): tai;
begin
if (int64(sym.labelnr) >= int64(labelinfo^.lowlabel)) and
(int64(sym.labelnr) <= int64(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;
{$pop}
{ Returns True if hp is an unconditional jump to a label }
function IsJumpToLabelUncond(hp: taicpu): boolean;
begin
{$if defined(avr) or defined(z80)}
result:=(hp.opcode in aopt_uncondjmp) and
{$else}
result:=(hp.opcode=aopt_uncondjmp) and
{$endif}
{$if defined(arm) or defined(aarch64) or defined(z80)}
(hp.condition=c_None) and
{$endif arm or aarch64 or z80}
(hp.ops>0) and
{$if defined(riscv32) or defined(riscv64)}
(hp.oper[0]^.reg=NR_X0) and
{$endif riscv}
(JumpTargetOp(hp)^.typ = top_ref) and
(JumpTargetOp(hp)^.ref^.symbol is TAsmLabel);
end;
{ Returns True if hp is any jump to a label }
function IsJumpToLabel(hp: taicpu): boolean;
begin
result:=hp.is_jmp and
(hp.ops>0) and
(JumpTargetOp(hp)^.typ = top_ref) and
(JumpTargetOp(hp)^.ref^.symbol is TAsmLabel);
end;
procedure TAOptObj.RemoveDelaySlot(hp1:tai);
var
hp2: tai;
begin
hp2:=tai(hp1.next);
while assigned(hp2) and (hp2.typ in SkipInstr) do
hp2:=tai(hp2.next);
if assigned(hp2) and (hp2.typ=ait_instruction) and
(taicpu(hp2).opcode=A_NOP) then
begin
asml.remove(hp2);
hp2.free;
end;
{ Anything except A_NOP must be left in place: these instructions
execute before branch, so code stays correct if branch is removed. }
end;
{ Output debug message to console - null function if EXTDEBUG is not defined }
class procedure TAOptObj.DebugWrite(Message: string); inline;
begin
{$ifdef DEBUG_JUMP}
WriteLn(Message);
{$else DEBUG_JUMP}
{ Do nothing }
{$endif DEBUG_JUMP}
end;
{ Converts a conditional jump into an unconditional jump. Only call this
procedure on an instruction that you already know is a conditional jump }
procedure TAOptObj.MakeUnconditional(p: taicpu);
begin
{ TODO: If anyone can improve this particular optimisation to work on
AVR, please do (it's currently not called at all). [Kit] }
{$if not defined(avr)}
{$if defined(powerpc) or defined(powerpc64)}
p.condition.cond := C_None;
p.condition.simple := True;
{$else powerpc}
p.condition := C_None;
{$endif powerpc}
{$ifndef z80}
p.opcode := aopt_uncondjmp;
{$endif not z80}
{$ifdef RISCV}
p.loadoper(1, p.oper[p.ops-1]^);
p.loadreg(0, NR_X0);
p.ops:=2;
{$endif}
{$ifdef xtensa}
p.opcode := aopt_uncondjmp;
p.loadoper(0, p.oper[p.ops-1]^);
p.ops:=1;
{$endif}
{$endif not avr}
{$ifdef mips}
{ MIPS conditional jump instructions also conntain register
operands. A proper implementation is needed here. }
internalerror(2020071301);
{$endif}
end;
{ Removes all instructions between an unconditional jump and the next label.
Returns True if a jump in between was removed (as it may open up new
optimisations if the label appeared earlier in the stream) }
function TAOptObj.RemoveDeadCodeAfterJump(p: tai): Boolean;
const
{$ifdef JVM}
TaiFence = SkipInstr + [ait_const, ait_realconst, ait_typedconst, ait_label, ait_jcatch];
{$else JVM}
{ Stop if it reaches SEH directive information in the form of
consts, which may occur if RemoveDeadCodeAfterJump is called on
the final RET instruction on x86, for example }
TaiFence = SkipInstr + [ait_const, ait_realconst, ait_typedconst, ait_label];
{$endif JVM}
var
hp1, hp2: tai;
begin
{ the following code removes all code between a jmp and the next label,
because it can never be executed
}
Result := False;
while GetNextInstruction(p, hp1) and
(hp1 <> BlockEnd) and
not (hp1.typ in TaiFence) do
begin
if (hp1.typ = ait_instruction) and
taicpu(hp1).is_jmp and
(JumpTargetOp(taicpu(hp1))^.typ = top_ref) and
(JumpTargetOp(taicpu(hp1))^.ref^.symbol is TAsmLabel) then
begin
{ If the destination label appears earlier, it may permit
further optimisations, so signal this in the Result }
Result := True;
TAsmLabel(JumpTargetOp(taicpu(hp1))^.ref^.symbol).decrefs;
end;
{ don't kill start/end of assembler block,
no-line-info-start/end etc }
if (hp1.typ<>ait_marker) and
((hp1.typ<>ait_cfi) or
(tai_cfi_base(hp1).cfityp<>cfi_endproc)) then
begin
{$ifdef cpudelayslot}
if (hp1.typ=ait_instruction) and (taicpu(hp1).is_jmp) then
RemoveDelaySlot(hp1);
{$endif cpudelayslot}
hp2 := hp1;
while (hp2.typ = ait_align) do
begin
{ Only remove the align if a label doesn't immediately follow }
if GetNextInstruction(hp2, hp2) and (hp2.typ = ait_label) then
{ The label is unskippable }
Exit;
{ Check again in case there's more than one adjacent alignment entry
(a frequent construct under x86, for example). [Kit] }
end;
asml.remove(hp1);
hp1.free;
end
else
p:=hp1;
end;
end;
{ If hp is a label, strip it if its reference count is zero. Repeat until
a non-label is found, or a label with a non-zero reference count.
True is returned if something was stripped }
function TAOptObj.StripDeadLabels(hp: tai; var NextValid: tai): Boolean;
var
tmp, tmpNext: tai;
hp1: tai;
CurrentAlign: tai;
begin
CurrentAlign := nil;
Result := False;
hp1 := hp;
NextValid := hp;
{ Stop if hp is an instruction, for example }
while (hp1 <> BlockEnd) and (hp1.typ in [ait_label,ait_align]) do
begin
prefetch(pointer(hp1.Next)^);
case hp1.typ of
ait_label:
begin
with tai_label(hp1).labsym do
if is_used or (bind <> AB_LOCAL) or (labeltype <> alt_jump) then
begin
{ Valid label }
if Result then
NextValid := hp1;
DebugWrite('JUMP DEBUG: Last label in cluster:' + tostr(labelnr));
Exit;
end;
DebugWrite('JUMP DEBUG: Removed label ' + tostr(TAsmLabel(tai_label(hp1).labsym).labelnr));
{ Set tmp to the next valid entry }
tmp := tai(hp1.Next);
{ Remove label }
AsmL.Remove(hp1);
hp1.Free;
hp1 := tmp;
Result := True;
Continue;
end;
{ Also remove the align if it comes before an unused label }
ait_align:
begin
tmp := tai(hp1.Next);
if tmp = BlockEnd then
{ End of block }
Exit;
repeat
case tmp.typ of
ait_align: { Merge the aligns if permissible }
begin
{ Check the maxbytes field though, since this may result in the
alignment being ignored }
if ((tai_align_abstract(hp1).maxbytes = 0) and (tai_align_abstract(tmp).maxbytes = 0)) or
{ If a maxbytes field is present, only merge if the aligns have the same granularity }
((tai_align_abstract(hp1).aligntype = tai_align_abstract(tmp).aligntype)) then
begin
with tai_align_abstract(hp1) do
begin
aligntype := max(aligntype, tai_align_abstract(tmp).aligntype);
maxbytes := max(maxbytes, tai_align_abstract(tmp).maxbytes);
fillsize := max(fillsize, tai_align_abstract(tmp).fillsize);
use_op := use_op or tai_align_abstract(tmp).use_op;
if use_op and (tai_align_abstract(tmp).fillop <> 0) then
fillop := tai_align_abstract(tmp).fillop;
end;
tmpNext := tai(tmp.Next);
AsmL.Remove(tmp);
tmp.Free;
Result := True;
tmp := tmpNext;
end
else
tmp := tai(tmp.Next);
Continue;
end;
ait_label:
begin
{ Signal that we can possibly delete this align entry }
CurrentAlign := hp1;
repeat
with tai_label(tmp).labsym do
if is_used or (bind <> AB_LOCAL) or (labeltype <> alt_jump) then
begin
{ Valid label }
if Result then
NextValid := tmp;
DebugWrite('JUMP DEBUG: Last label in cluster:' + tostr(labelnr));
Exit;
end;
DebugWrite('JUMP DEBUG: Removed label ' + tostr(TAsmLabel(tai_label(tmp).labsym).labelnr));
{ Remove label }
tmpNext := tai(tmp.Next);
AsmL.Remove(tmp);
tmp.Free;
Result := True;
tmp := tmpNext;
{ Loop here for a minor performance gain }
until (tmp = BlockEnd) or (tmp.typ <> ait_label);
{ Re-evaluate the align and see what follows }
Continue;
end
else
begin
{ Set hp1 to the instruction after the align, because the
align might get deleted later and hence set NextValid
to a dangling pointer. [Kit] }
hp1 := tmp;
Break;
end;
end;
until (tmp = BlockEnd);
{ Break out of the outer loop if the above Break is called }
if (hp1 = tmp) then
Break;
end
else
Break;
end;
hp1 := tai(hp1.Next);
end;
{ hp1 will be the next valid entry }
NextValid := hp1;
{ Remove the alignment field (but only if the next valid entry is not a live label) }
while Assigned(CurrentAlign) and (CurrentAlign.typ = ait_align) do
begin
DebugWrite('JUMP DEBUG: Alignment field removed');
tmp := tai(CurrentAlign.next);
AsmL.Remove(CurrentAlign);
CurrentAlign.Free;
CurrentAlign := tmp;
end;
end;
{ Strips a label and any aligns that appear before it (if hp points to
them rather than the label). Only call this procedure on a label that
you already know is no longer referenced }
procedure TAOptObj.StripLabelFast(hp: tai); {$ifdef USEINLINE}inline;{$endif USEINLINE}
var
tmp: tai;
begin
repeat
case hp.typ of
ait_align:
begin
tmp := tai(hp.Next);
asml.Remove(hp);
hp.Free;
hp := tmp;
{ Control flow will now return to 'repeat' }
end;
ait_label:
begin
{$ifdef EXTDEBUG}
{ When not in debug mode, deleting a live label will cause an
access violation later on. [Kit] }
if tai_label(hp).labsym.getrefs <> 0 then
InternalError(2019110802);
{$endif EXTDEBUG}
asml.Remove(hp);
hp.Free;
Exit;
end;
else
begin
{ Might be a comment or temporary allocation entry }
if not (hp.typ in SkipInstr) then
InternalError(2019110801);
hp := tai(hp.Next);
end;
end;
until False;
end;
{ If a group of labels are clustered, change the jump to point to the last one
that is still referenced }
function TAOptObj.CollapseLabelCluster(jump: tai; var lbltai: tai): TAsmLabel;
var
LastLabel: TAsmLabel;
hp2: tai;
begin
Result := tai_label(lbltai).labsym;
LastLabel := Result;
hp2 := tai(lbltai.next);
while (hp2 <> BlockEnd) and (hp2.typ in SkipInstr + [ait_align, ait_label]) do
begin
if (hp2.typ = ait_label) and
(tai_label(hp2).labsym.is_used) and
(tai_label(hp2).labsym.labeltype = alt_jump) then
LastLabel := tai_label(hp2).labsym;
hp2 := tai(hp2.next);
end;
if (Result <> LastLabel) then
begin
Result.decrefs;
JumpTargetOp(taicpu(jump))^.ref^.symbol := LastLabel;
LastLabel.increfs;
Result := LastLabel;
lbltai := hp2;
end;
end;
{$ifndef JVM}
function TAOptObj.OptimizeConditionalJump(CJLabel: TAsmLabel; var p: tai; hp1: tai; var stoploop: Boolean): Boolean;
var
hp2: tai;
NCJLabel: TAsmLabel;
begin
Result := False;
while (hp1 <> BlockEnd) do
begin
StripDeadLabels(hp1, hp1);
if (hp1 <> BlockEnd) and
(tai(hp1).typ=ait_instruction) and
IsJumpToLabel(taicpu(hp1)) then
begin
NCJLabel := TAsmLabel(JumpTargetOp(taicpu(hp1))^.ref^.symbol);
if IsJumpToLabelUncond(taicpu(hp1)) then
begin
{ Do it now to get it out of the way and to aid optimisations
later on in this method }
if RemoveDeadCodeAfterJump(taicpu(hp1)) then
stoploop := False;
hp2 := getlabelwithsym(NCJLabel);
if Assigned(hp2) then
{ Collapse the cluster now to aid optimisation and potentially
cut down on the number of iterations required }
NCJLabel := CollapseLabelCluster(hp1, hp2);
{ GetNextInstruction could be factored out, but hp2 might be
different after "RemoveDeadCodeAfterJump" }
GetNextInstruction(hp1, hp2);
{ Check for:
jmp<cond> @Lbl
jmp @Lbl
}
if (CJLabel = NCJLabel) then
begin
DebugMsg(SPeepholeOptimization+'Short-circuited conditional jump',p);
{ Both jumps go to the same label }
CJLabel.decrefs;
{$ifdef cpudelayslot}
RemoveDelaySlot(p);
{$endif cpudelayslot}
RemoveCurrentP(p, hp1);
Result := True;
Exit;
end;
if FindLabel(CJLabel, hp2) then
begin
{ change the following jumps:
jmp<cond> CJLabel jmp<inv_cond> NCJLabel
jmp NCJLabel >>> <code>
CJLabel: NCJLabel:
<code>
NCJLabel:
}
{$if defined(arm) or defined(aarch64)}
if (taicpu(p).condition<>C_None)
{$if defined(aarch64)}
{ can't have conditional branches to
global labels on AArch64, because the
offset may become too big }
and (NCJLabel.bind=AB_LOCAL)
{$endif aarch64}
then
begin
{$endif arm or aarch64}
DebugMsg(SPeepholeOptimization+'Conditional jump inversion',p);
taicpu(p).condition:=inverse_cond(taicpu(p).condition);
CJLabel.decrefs;
JumpTargetOp(taicpu(p))^.ref^.symbol := NCJLabel;
{ when freeing hp1, the reference count
isn't decreased, so don't increase }
{$ifdef cpudelayslot}
RemoveDelaySlot(hp1);
{$endif cpudelayslot}
RemoveInstruction(hp1);
stoploop := False;
if not CJLabel.is_used then
begin
CJLabel := NCJLabel;
StripDeadLabels(tai(p.Next), hp1);
if (hp1 = BlockEnd) then
Exit;
{ Attempt another iteration in case more jumps follow }
if (hp1.typ in SkipInstr) then
GetNextInstruction(hp1, hp1);
Continue;
end;
{$if defined(arm) or defined(aarch64)}
end;
{$endif arm or aarch64}
end
else if CollapseZeroDistJump(hp1, NCJLabel) then
begin
if (hp1 = BlockEnd) then
Exit;
{ Attempt another iteration in case more jumps follow }
if (hp1.typ in SkipInstr) then
GetNextInstruction(hp1, hp1);
Continue;
end;
end
else
begin
{ Do not try to optimize if the test generating the condition
is the same instruction, like 'bne $v0,$zero,.Lj3' for MIPS }
if (taicpu(p).ops>1) or (taicpu(hp1).ops>1) then
exit;
{ Check for:
jmp<cond1> @Lbl1
jmp<cond2> @Lbl2
Remove 2nd jump if conditions are equal or cond2 is a subset of cond1
(as if the first jump didn't branch, then neither will the 2nd)
}
if condition_in(taicpu(hp1).condition, taicpu(p).condition) then
begin
DebugMsg(SPeepholeOptimization+'Dominated conditional jump',p);
NCJLabel.decrefs;
GetNextInstruction(hp1, hp2);
{$ifdef cpudelayslot}
RemoveDelaySlot(hp1);
{$endif cpudelayslot}
RemoveInstruction(hp1);
hp1 := hp2;
{ Flag another pass in case @Lbl2 appeared earlier in the procedure and is now a dead label }
stoploop := False;
{ Attempt another iteration in case more jumps follow }
Continue;
end;
{ Check for:
jmp<cond1> @Lbl1
jmp<cond2> @Lbl2
And inv(cond1) is a subset of cond2 (e.g. je followed by jne, or jae followed by jbe) )
}
if condition_in(inverse_cond(taicpu(p).condition), taicpu(hp1).condition) then
begin
GetNextInstruction(hp1, hp2);
{ If @lbl1 immediately follows jmp<cond2>, we can remove
the first jump completely }
if FindLabel(CJLabel, hp2) then
begin
{ However, to be absolutely correct, cond2 must be changed to inv(cond1) }
taicpu(hp1).condition := inverse_cond(taicpu(p).condition);
DebugMsg(SPeepholeOptimization+'jmp<cond> before jmp<inv_cond> - removed first jump',p);
CJLabel.decrefs;
{$ifdef cpudelayslot}
RemoveDelaySlot(p);
{$endif cpudelayslot}
RemoveCurrentP(p, hp1);
Result := True;
Exit;
{$if not defined(avr)}
end
else
{ NOTE: There is currently no watertight, cross-platform way to create
an unconditional jump without access to the cg object. If anyone can
improve this particular optimisation to work on AVR,
please do. [Kit] }
begin
{ Since inv(cond1) is a subset of cond2, jmp<cond2> will always branch if
jmp<cond1> does not, so change jmp<cond2> to an unconditional jump. }
DebugMsg(SPeepholeOptimization+'jmp<cond> before jmp<inv_cond> - made second jump unconditional',p);
MakeUnconditional(taicpu(hp1));
{ NOTE: Changing the jump to unconditional won't open up new opportunities
for GetFinalDestination on earlier jumps because there's no live label
between the two jump instructions, so setting 'stoploop' to False only
wastes time. [Kit] }
{ See if more optimisations are possible }
Continue;
{$endif}
end;
end;
end;
end;
if GetFinalDestination(taicpu(p),0) then
stoploop := False;
Exit;
end;
end;
{$endif JVM}
function TAOptObj.CollapseZeroDistJump(var p: tai; ThisLabel: TAsmLabel): Boolean;
var
tmp, hp1: tai;
begin
Result := False;
if not GetNextInstruction(p,hp1) then
exit;
if (hp1 = BlockEnd) then
Exit;
{ remove jumps to labels coming right after them }
if FindLabel(ThisLabel, hp1) and
{ Cannot remove the first instruction }
(p<>StartPoint) then
begin
ThisLabel.decrefs;
{$ifdef cpudelayslot}
RemoveDelaySlot(p);
{$endif cpudelayslot}
tmp := tai(p.Next); { Might be an align before the label, so keep a note of it }
asml.remove(p);
p.free;
StripDeadLabels(tmp, p);
if p.typ <> ait_instruction then
GetNextInstruction(UpdateUsedRegsAndOptimize(p), p);
Result := True;
end;
end;
function TAOptObj.CanDoJumpOpts: Boolean;
begin
{ Always allow by default }
Result := True;
end;
function TAOptObj.DoJumpOptimizations(var p: tai; var stoploop: Boolean): Boolean;
var
hp1, hp2: tai;
ThisLabel: TAsmLabel;
ThisPassResult: Boolean;
begin
Result := False;
if (p.typ <> ait_instruction) or not IsJumpToLabel(taicpu(p)) then
Exit;
repeat
ThisPassResult := False;
if GetNextInstruction(p, hp1) and (hp1 <> BlockEnd) then
begin
SkipEntryExitMarker(hp1,hp1);
if (hp1 = BlockEnd) then
Exit;
ThisLabel := TAsmLabel(JumpTargetOp(taicpu(p))^.ref^.symbol);
hp2 := getlabelwithsym(ThisLabel);
{ getlabelwithsym returning nil occurs if a label is in a
different block (e.g. on the other side of an asm...end pair). }
if Assigned(hp2) then
begin
{ If there are multiple labels in a row, change the destination to the last one
in order to aid optimisation later }
ThisLabel := CollapseLabelCluster(p, hp2);
if CollapseZeroDistJump(p, ThisLabel) then
begin
stoploop := False;
Result := True;
Exit;
end;
if IsJumpToLabelUncond(taicpu(p)) then
begin
{ Remove unreachable code between the jump and the next label }
ThisPassResult := RemoveDeadCodeAfterJump(taicpu(p));
if GetFinalDestination(taicpu(p), 0) or ThisPassResult then
{ Might have caused some earlier labels to become dead }
stoploop := False;
end
{$ifndef JVM}
else if (taicpu(p).opcode {$ifdef z80}in{$else}={$endif} aopt_condjmp) then
ThisPassResult := OptimizeConditionalJump(ThisLabel, p, hp1, stoploop)
{$endif JVM}
;
end;
end;
Result := Result or ThisPassResult;
until not (ThisPassResult and (p.typ = ait_instruction) and IsJumpToLabel(taicpu(p)));
end;
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 deep we have already followed the jump,
to avoid endless loops with constructs such as "l5: ; jmp l5" }
var p1: tai;
p2: tai;
{$if not defined(MIPS) and not defined(riscv64) and not defined(riscv32) and not defined(JVM)}
p3: tai;
{$endif}
ThisLabel, l: tasmlabel;
begin
GetFinalDestination := false;
if level > 20 then
exit;
ThisLabel := TAsmLabel(JumpTargetOp(hp)^.ref^.symbol);
p1 := getlabelwithsym(ThisLabel);
if assigned(p1) then
begin
SkipLabels(p1,p1);
if (p1.typ = ait_instruction) and
(taicpu(p1).is_jmp) then
begin
p2 := tai(p1.Next);
if p2 = BlockEnd then
Exit;
{ Collapse any zero distance jumps we stumble across }
while (p1<>StartPoint) and CollapseZeroDistJump(p1, TAsmLabel(JumpTargetOp(taicpu(p1))^.ref^.symbol)) do
begin
{ Note: Cannot remove the first instruction }
if (p1.typ = ait_label) then
SkipLabels(p1, p1);
if not Assigned(p1) then
{ No more valid commands }
Exit;
{ Check to see that we are actually still at a jump }
if not ((tai(p1).typ = ait_instruction) and (taicpu(p1).is_jmp)) then
begin
{ Required to ensure recursion works properly, but to also
return false if a jump isn't modified. [Kit] }
if level > 0 then GetFinalDestination := True;
Exit;
end;
p2 := tai(p1.Next);
if p2 = BlockEnd then
Exit;
end;
{$if not defined(MIPS) and not defined(riscv64) and not defined(riscv32) and not defined(JVM)}
p3 := p2;
{$endif not MIPS and not RV64 and not RV32 and not JVM}
if { the next instruction after the label where the jump hp arrives}
{ is unconditional or of the same type as hp, so continue }
IsJumpToLabelUncond(taicpu(p1))
{ TODO: For anyone with experience with MIPS or RISC-V, please add support for tracing
conditional jumps. [Kit] }
{$if not defined(MIPS) and not defined(riscv64) and not defined(riscv32) and not defined(JVM)}
{ for MIPS, it isn't enough to check the condition; first operands must be same, too. }
or
condition_in(hp.condition, taicpu(p1).condition) or
{ the next instruction after the label where the jump hp arrives
is the opposite of hp (so this one is never taken), but after
that one there is a branch that will be taken, so perform a
little hack: set p1 equal to this instruction }
(condition_in(hp.condition, inverse_cond(taicpu(p1).condition)) and
SkipLabels(p3,p2) and
(p2.typ = ait_instruction) and
(taicpu(p2).is_jmp) and
(IsJumpToLabelUncond(taicpu(p2)) or
(condition_in(hp.condition, taicpu(p2).condition))
) and
SetAndTest(p2,p1)
)
{$endif not MIPS and not RV64 and not RV32 and not JVM}
then
begin
{ quick check for loops of the form "l5: ; jmp l5" }
if (TAsmLabel(JumpTargetOp(taicpu(p1))^.ref^.symbol).labelnr = ThisLabel.labelnr) then
exit;
if not GetFinalDestination(taicpu(p1),succ(level)) then
exit;
{ NOTE: Do not move this before the "l5: ; jmp l5" check,
because GetFinalDestination may change the destination
label of p1. [Kit] }
l := tasmlabel(JumpTargetOp(taicpu(p1))^.ref^.symbol);
{$if defined(aarch64)}
{ can't have conditional branches to
global labels on AArch64, because the
offset may become too big }
if not(taicpu(hp).condition in [C_None,C_AL,C_NV]) and
(l.bind<>AB_LOCAL) then
exit;
{$endif aarch64}
ThisLabel.decrefs;
JumpTargetOp(hp)^.ref^.symbol:=l;
l.increfs;
GetFinalDestination := True;
Exit;
end
{$if not defined(MIPS) and not defined(riscv64) and not defined(riscv32) and not defined(JVM)}
else
if condition_in(inverse_cond(hp.condition), taicpu(p1).condition) then
begin
if not FindLiveLabel(p1,l) then
begin
{$ifdef finaldestdebug}
insertllitem(asml,p1,p1.next,tai_comment.Create(
strpnew('previous label inserted'))));
{$endif finaldestdebug}
current_asmdata.getjumplabel(l);
insertllitem(p1,p1.next,tai_label.Create(l));
ThisLabel.decrefs;
JumpTargetOp(hp)^.ref^.symbol := l;
l.increfs;
GetFinalDestination := True;
{ this won't work, since the new label isn't in the labeltable }
{ so it will fail the rangecheck. Labeltable should become a }
{ hashtable to support this: }
{ GetFinalDestination(asml, hp); }
end
else
begin
{$ifdef finaldestdebug}
insertllitem(asml,p1,p1.next,tai_comment.Create(
strpnew('next label reused'))));
{$endif finaldestdebug}
l.increfs;
ThisLabel.decrefs;
JumpTargetOp(hp)^.ref^.symbol := l;
if not GetFinalDestination(hp,succ(level)) then
exit;
end;
GetFinalDestination := True;
Exit;
end;
{$endif not MIPS and not RV64 and not RV32 and not JVM}
end;
end;
{ Required to ensure recursion works properly, but to also
return false if a jump isn't modified. [Kit] }
if level > 0 then GetFinalDestination := True;
end;
procedure TAOptObj.PrePeepHoleOpts;
var
p: tai;
begin
p := BlockStart;
ClearUsedRegs;
while (p <> BlockEnd) Do
begin
prefetch(pointer(p.Next)^);
if PrePeepHoleOptsCpu(p) then
continue;
if assigned(p) then
begin
p:=tai(p.next);
UpdateUsedRegs(p);
end;
end;
end;
procedure TAOptObj.PeepHoleOptPass1;
const
MaxPasses: array[1..3] of Cardinal = (1, 2, 8);
var
p : tai;
stoploop, FirstInstruction, JumpOptsAvailable: boolean;
PassCount, MaxCount: Cardinal;
begin
JumpOptsAvailable := CanDoJumpOpts();
StartPoint := BlockStart;
PassCount := 0;
{ Determine the maximum number of passes allowed based on the compiler switches }
if (cs_opt_level3 in current_settings.optimizerswitches) then
{ it should never take more than 8 passes, but the limit is finite to protect against faulty optimisations }
MaxCount := MaxPasses[3]
else if (cs_opt_level2 in current_settings.optimizerswitches) then
MaxCount := MaxPasses[2] { The original double run of Pass 1 }
else
MaxCount := MaxPasses[1];
repeat
stoploop:=true;
p := StartPoint;
FirstInstruction := True;
ClearUsedRegs;
while Assigned(p) and (p <> BlockEnd) Do
begin
prefetch(pointer(p.Next)^);
{ I'am not sure why this is done, UsedRegs should reflect the register usage before the instruction
If an instruction needs the information of this, it can easily create a TempUsedRegs (FK)
UpdateUsedRegs(tai(p.next));
}
{$ifdef DEBUG_OPTALLOC}
if p.Typ=ait_instruction then
InsertLLItem(tai(p.Previous),p,tai_comment.create(strpnew(GetAllocationString(UsedRegs))));
{$endif DEBUG_OPTALLOC}
{ Handle jump optimizations first }
if JumpOptsAvailable and DoJumpOptimizations(p, stoploop) then
begin
if FirstInstruction then
{ Update StartPoint, since the old p was removed;
don't set FirstInstruction to False though, as
the new p might get removed too. }
StartPoint := p;
if (p.typ = ait_instruction) and IsJumpToLabel(taicpu(p)) then
Continue;
end;
if PeepHoleOptPass1Cpu(p) then
begin
stoploop:=false;
UpdateUsedRegs(p);
if FirstInstruction then
{ Update StartPoint, since the old p was modified;
don't set FirstInstruction to False though, as
the new p might get modified too. }
StartPoint := p;
continue;
end;
FirstInstruction := False;
if assigned(p) then
p := tai(UpdateUsedRegsAndOptimize(p).Next);
end;
Inc(PassCount);
until stoploop or (PassCount >= MaxCount);
end;
procedure TAOptObj.PeepHoleOptPass2;
var
p: tai;
begin
p := BlockStart;
ClearUsedRegs;
while (p <> BlockEnd) Do
begin
prefetch(pointer(p.Next)^);
if PeepHoleOptPass2Cpu(p) then
continue;
if assigned(p) then
p := tai(UpdateUsedRegsAndOptimize(p).Next);
end;
end;
procedure TAOptObj.PostPeepHoleOpts;
var
p: tai;
begin
p := BlockStart;
ClearUsedRegs;
while (p <> BlockEnd) Do
begin
prefetch(pointer(p.Next)^);
if PostPeepHoleOptsCpu(p) then
continue;
if assigned(p) then
begin
p:=tai(p.next);
UpdateUsedRegs(p);
end;
end;
end;
function TAOptObj.PrePeepHoleOptsCpu(var p : tai) : boolean;
begin
result := false;
end;
function TAOptObj.PeepHoleOptPass1Cpu(var p: tai): boolean;
begin
result := false;
end;
function TAOptObj.PeepHoleOptPass2Cpu(var p : tai) : boolean;
begin
result := false;
end;
function TAOptObj.PostPeepHoleOptsCpu(var p: tai): boolean;
begin
result := false;
end;
procedure TAOptObj.Debug_InsertInstrRegisterDependencyInfo;
var
p: tai;
ri: tregisterindex;
reg: TRegister;
commentstr: AnsiString;
registers_found: Boolean;
begin
p:=tai(AsmL.First);
while (p<>AsmL.Last) Do
begin
if p.typ=ait_instruction then
begin
{$ifdef x86}
taicpu(p).SetOperandOrder(op_att);
{$endif x86}
commentstr:='Instruction reads';
registers_found:=false;
for ri in tregisterindex do
begin
reg:=regnumber_table[ri];
if (reg<>NR_NO) and InstructionLoadsFromReg(reg,p) then
begin
commentstr:=commentstr+' '+std_regname(reg);
registers_found:=true;
end;
end;
if not registers_found then
commentstr:=commentstr+' no registers';
commentstr:=commentstr+' and writes new values in';
registers_found:=false;
for ri in tregisterindex do
begin
reg:=regnumber_table[ri];
if (reg<>NR_NO) and RegLoadedWithNewValue(reg,p) then
begin
commentstr:=commentstr+' '+std_regname(reg);
registers_found:=true;
end;
end;
if not registers_found then
commentstr:=commentstr+' no registers';
AsmL.InsertAfter(tai_comment.Create(strpnew(commentstr)),p);
end;
p:=tai(p.next);
end;
end;
End.