{ $Id$ Copyright (c) 1998-2000 by Jonas Maebe, member of the Free Pascal development team This unit contains the common subexpression elimination procedure. 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 CSOpt386; Interface Uses aasm; {Procedure CSOpt386(First, Last: Pai);} Procedure CSE(AsmL: PAasmOutput; First, Last: Pai); Implementation Uses CObjects, verbose, hcodegen, globals,cpubase,cpuasm,DAOpt386, tgeni386; { Function PaiInSequence(P: Pai; Const Seq: TContent): Boolean; Var P1: Pai; Counter: Byte; TmpResult: Boolean; Begin TmpResult := False; P1 := Seq.StartMod; Counter := 1; While Not(TmpResult) And (Counter <= Seq.NrOfMods) Do Begin If (P = P1) Then TmpResult := True; Inc(Counter); p1 := Pai(p1^.Next); End; PaiInSequence := TmpResult; End; } Function CheckSequence(p: Pai; Reg: TRegister; Var Found: Longint; Var RegInfo: TRegInfo): Boolean; {checks whether the current instruction sequence (starting with p) and the one between StartMod and EndMod of Reg are the same. If so, the number of instructions that match is stored in Found and true is returned, otherwise Found holds the number of instructions between StartMod and EndMod and false is returned} Var hp2, hp3{, EndMod}: Pai; PrevNonRemovablePai: Pai; {Cnt,} OldNrOfMods: Longint; OrgRegInfo, HighRegInfo: TRegInfo; HighFound, OrgRegFound: Byte; RegCounter, regCounter2: TRegister; OrgRegResult: Boolean; TmpResult: Boolean; {TmpState: Byte;} Begin {CheckSequence} Reg := Reg32(Reg); TmpResult := False; FillChar(OrgRegInfo, SizeOf(OrgRegInfo), 0); OrgRegFound := 0; HighFound := 0; OrgRegResult := False; RegCounter := R_EAX; GetLastInstruction(p, PrevNonRemovablePai); While (RegCounter <= R_EDI) And not(ppaiprop(prevNonRemovablePai^.optInfo)^.regs[regCounter].typ in [con_ref,con_noRemoveRef]) do Inc(RegCounter); While (RegCounter <= R_EDI) Do Begin FillChar(RegInfo, SizeOf(RegInfo), 0); RegInfo.NewRegsEncountered := [procinfo^.FramePointer, R_ESP]; RegInfo.OldRegsEncountered := RegInfo.NewRegsEncountered; RegInfo.New2OldReg[procinfo^.FramePointer] := procinfo^.FramePointer; RegInfo.New2OldReg[R_ESP] := R_ESP; Found := 0; hp2 := PPaiProp(PrevNonRemovablePai^.OptInfo)^.Regs[RegCounter].StartMod; If (PrevNonRemovablePai <> PPaiProp(PrevNonRemovablePai^.OptInfo)^.Regs[RegCounter].StartMod) Then OldNrOfMods := PPaiProp(PrevNonRemovablePai^.OptInfo)^.Regs[RegCounter].NrOfMods Else OldNrOfMods := 1; hp3 := p; While (Found <> OldNrOfMods) And { old new } InstructionsEquivalent(hp2, hp3, RegInfo) Do Begin if (hp3^.typ = ait_instruction) and ((paicpu(hp3)^.opcode = A_MOV) or (paicpu(hp3)^.opcode = A_MOVZX) or (paicpu(hp3)^.opcode = A_MOVSX)) and (paicpu(hp3)^.oper[0].typ in [top_const,top_ref,top_symbol]) and (paicpu(hp3)^.oper[1].typ = top_reg) then regInfo.lastReload [reg32(paicpu(hp3)^.oper[1].reg)] := hp3; GetNextInstruction(hp2, hp2); GetNextInstruction(hp3, hp3); Inc(Found) End; for regCounter2 := R_EAX to R_EDX do if (regInfo.new2OldReg[regCounter2] <> R_NO) and (reg in PPaiProp(hp3^.optInfo)^.usedRegs) and not regLoadedWithNewValue(reg,false,hp3) then include(regInfo.regsStillUsedAfterSeq,regCounter); If (Found <> OldNrOfMods) or { the following is to avoid problems with rangecheck code (see testcse2) } (assigned(hp3) and ((reg in regInfo.regsLoadedForRef) and (reg in PPaiProp(hp3^.optInfo)^.usedRegs) and not regLoadedWithNewValue(reg,false,hp3))) then Begin TmpResult := False; If (found > 0) then {this is correct because we only need to turn off the CanBeRemoved flag when an instruction has already been processed by CheckSequence (otherwise CanBeRemoved can't be true and thus can't have to be turned off). If it has already been processed by CheckSequence and flagged to be removed, it means that it has been checked against a previous sequence and that it was equal (otherwise CheckSequence would have returned false and the instruction wouldn't have been removed). If this "If found > 0" check is left out, incorrect optimizations are performed.} Found := PPaiProp(Pai(p)^.OptInfo)^.Regs[Reg].NrOfMods End Else TmpResult := True; If TmpResult And (Found > HighFound) Then Begin HighFound := Found; HighRegInfo := RegInfo; End; If (RegCounter = Reg) Then Begin OrgRegFound := Found; OrgRegResult := TmpResult; OrgRegInfo := RegInfo End; Repeat Inc(RegCounter); Until (RegCounter > R_EDI) or ((ppaiprop(prevNonRemovablePai^.optInfo)^.regs[regCounter].typ in [con_ref,con_noRemoveRef]) {And ((Regcounter = Reg) Or Not(PaiInSequence(p, PPaiProp(PrevNonRemovablePai^.OptInfo)^.Regs[RegCounter]))) } ); End; If (HighFound > 0) And (Not(OrgRegResult) Or (HighFound > OrgRegFound)) Then Begin {$ifndef fpc} TmpResult := True; {$else fpc} CheckSequence := True; {$endif fpc} RegInfo := HighRegInfo; Found := HighFound End Else Begin {$ifndef fpc} TmpResult := OrgRegResult; {$else fpc} CheckSequence := OrgRegResult; {$endif fpc} Found := OrgRegFound; RegInfo := OrgRegInfo; End; {$ifndef fpc} CheckSequence := TmpResult; {$endif fpc} End; {CheckSequence} Procedure SetAlignReg(p: Pai); Const alignSearch = 12; var regsUsable: TRegSet; prevInstrCount, nextInstrCount: Longint; prevState, nextWState,nextRState: Array[R_EAX..R_EDI] of byte; regCounter, lastRemoved: TRegister; prev, next: Pai; {$ifdef alignregdebug} temp: Pai; {$endif alignregdebug} begin regsUsable := [R_EAX,R_ECX,R_EDX,R_EBX,{R_ESP,R_EBP,}R_ESI,R_EDI]; for regCounter := R_EAX to R_EDI do begin prevState[regCounter] := PPaiProp(p^.optInfo)^.Regs[regCounter].wState; nextWState[regCounter] := PPaiProp(p^.optInfo)^.Regs[regCounter].wState; nextRState[regCounter] := PPaiProp(p^.optInfo)^.Regs[regCounter].rState; end; getLastInstruction(p,prev); getNextInstruction(p,next); lastRemoved := pai_align(p)^.reg; nextInstrCount := 0; prevInstrCount := 0; while ((assigned(prev) and assigned(prev^.optInfo) and (prevInstrCount < alignSearch)) or (assigned(next) and assigned(next^.optInfo) and (nextInstrCount < alignSearch))) And (regsUsable <> []) do begin {$ifdef alignregdebug} if assigned(prev) then begin temp := new(pai_asm_comment,init(strpnew('got here'))); temp^.next := prev^.next; temp^.previous := prev; prev^.next := temp; if assigned(temp^.next) then temp^.next^.previous := temp; end; {$endif alignregdebug} if assigned(prev) and assigned(prev^.optinfo) and (prevInstrCount < alignSearch) then begin if (prev^.typ = ait_instruction) And (insProp[PaiCpu(prev)^.opcode].ch[1] <> Ch_ALL) and (PaiCpu(prev)^.opcode <> A_JMP) then begin inc(prevInstrCount); for regCounter := R_EAX to R_EDI do begin if (regCounter in regsUsable) And (PPaiProp(prev^.optInfo)^.Regs[regCounter].wState <> prevState[regCounter]) then begin lastRemoved := regCounter; exclude(regsUsable,regCounter); {$ifdef alignregdebug} temp := new(pai_asm_comment,init(strpnew( att_reg2str[regCounter]+' removed'))); temp^.next := prev^.next; temp^.previous := prev; prev^.next := temp; if assigned(temp^.next) then temp^.next^.previous := temp; if regsUsable = [] then begin temp := new(pai_asm_comment,init(strpnew( 'regsUsable empty here'))); temp^.next := prev^.next; temp^.previous := prev; prev^.next := temp; if assigned(temp^.next) then temp^.next^.previous := temp; end; {$endif alignregdebug} end; prevState[regCounter] := PPaiProp(prev^.optInfo)^.Regs[regCounter].wState; end; getLastInstruction(prev,prev); end else If GetLastInstruction(prev,prev) and assigned(prev^.optinfo) then for regCounter := R_EAX to R_EDI do prevState[regCounter] := PPaiProp(prev^.optInfo)^.Regs[regCounter].wState end; if assigned(next) and assigned(next^.optInfo) and (nextInstrCount < alignSearch) then begin if (next^.typ = ait_instruction) and (insProp[PaiCpu(next)^.opcode].ch[1] <> Ch_ALL) and (PaiCpu(next)^.opcode <> A_JMP) then begin inc(nextInstrCount); for regCounter := R_EAX to R_EDI do begin if (regCounter in regsUsable) And ((PPaiProp(next^.optInfo)^.Regs[regCounter].wState <> nextWState[regCounter]) or (PPaiProp(next^.optInfo)^.Regs[regCounter].rState <> nextRState[regCounter])) Then begin lastRemoved := regCounter; exclude(regsUsable,regCounter); {$ifdef alignregdebug} temp := new(pai_asm_comment,init(strpnew( att_reg2str[regCounter]+' removed'))); temp^.next := next^.next; temp^.previous := next; next^.next := temp; if assigned(temp^.next) then temp^.next^.previous := temp; if regsUsable = [] then begin temp := new(pai_asm_comment,init(strpnew( 'regsUsable empty here'))); temp^.next := next^.next; temp^.previous := next; next^.next := temp; if assigned(temp^.next) then temp^.next^.previous := temp; end; {$endif alignregdebug} end; nextWState[regCounter] := PPaiProp(next^.optInfo)^.Regs[regCounter].wState; nextRState[regCounter] := PPaiProp(next^.optInfo)^.Regs[regCounter].rState; end end else for regCounter := R_EAX to R_EDI do begin nextWState[regCounter] := PPaiProp(next^.optInfo)^.Regs[regCounter].wState; nextRState[regCounter] := PPaiProp(next^.optInfo)^.Regs[regCounter].rState; end; getNextInstruction(next,next); end; end; if regsUsable <> [] then for regCounter := R_EAX to R_EDI do if regCounter in regsUsable then begin lastRemoved := regCounter; break end; {$ifdef alignregdebug} next := new(pai_asm_comment,init(strpnew(att_reg2str[lastRemoved]+ ' chosen as alignment register'))); next^.next := p^.next; next^.previous := p; p^.next := next; if assigned(next^.next) then next^.next^.previous := next; {$endif alignregdebug} pai_align(p)^.reg := lastRemoved; End; Procedure RestoreRegContentsTo(reg: TRegister; const c: TContent; p, endP: pai); var {$ifdef replaceregdebug} hp: pai; {$endif replaceregdebug} tmpState: byte; begin {$ifdef replaceregdebug} hp := new(pai_asm_comment,init(strpnew( 'restored '+att_reg2str[reg]+' with data from here...'))); hp^.next := p; hp^.previous := p^.previous; p^.previous := hp; if assigned(hp^.previous) then hp^.previous^.next := hp; {$endif replaceregdebug} { PPaiProp(p^.optInfo)^.Regs[reg] := c;} While (p <> endP) Do Begin PPaiProp(p^.optInfo)^.Regs[reg] := c; getNextInstruction(p,p); end; tmpState := PPaiProp(p^.optInfo)^.Regs[reg].wState; repeat PPaiProp(p^.optInfo)^.Regs[reg] := c; until not getNextInstruction(p,p) or (PPaiProp(p^.optInfo)^.Regs[reg].wState <> tmpState); {$ifdef replaceregdebug} if assigned(p) then begin hp := new(pai_asm_comment,init(strpnew( 'restored '+att_reg2str[reg]+' till here...'))); hp^.next := p; hp^.previous := p^.previous; p^.previous := hp; if assigned(hp^.previous) then hp^.previous^.next := hp; end; {$endif replaceregdebug} end; function FindRegDealloc(reg: tregister; p: pai): boolean; { assumes reg is a 32bit register } var hp: pai; first: boolean; begin findregdealloc := false; first := true; while assigned(p^.previous) and ((Pai(p^.previous)^.typ in (skipinstr+[ait_align])) or ((Pai(p^.previous)^.typ = ait_label) and labelCanBeSkipped(pai_label(p^.previous)))) do begin p := pai(p^.previous); if (p^.typ = ait_regalloc) and (pairegalloc(p)^.reg = reg) then if not(pairegalloc(p)^.allocation) then if first then begin findregdealloc := true; break; end else begin findRegDealloc := getNextInstruction(p,hp) and regLoadedWithNewValue(reg,false,hp); break end else first := false; end end; Procedure ClearRegContentsFrom(reg: TRegister; p, endP: pai); { first clears the contents of reg from p till endP. Then the contents are } { cleared until the first instruction that changes reg } var {$ifdef replaceregdebug} hp: pai; {$endif replaceregdebug} tmpState: byte; begin PPaiProp(p^.optInfo)^.Regs[reg].typ := con_unknown; While (p <> endP) Do Begin PPaiProp(p^.optInfo)^.Regs[reg].typ := con_unknown; getNextInstruction(p,p); end; tmpState := PPaiProp(p^.optInfo)^.Regs[reg].wState; repeat PPaiProp(p^.optInfo)^.Regs[reg].typ := con_unknown; until not getNextInstruction(p,p) or (PPaiProp(p^.optInfo)^.Regs[reg].wState <> tmpState); {$ifdef replaceregdebug} if assigned(p) then begin hp := new(pai_asm_comment,init(strpnew( 'cleared '+att_reg2str[reg]+' till here...'))); hp^.next := p; hp^.previous := p^.previous; p^.previous := hp; if assigned(hp^.previous) then hp^.previous^.next := hp; end; {$endif replaceregdebug} end; function NoHardCodedRegs(p: paicpu; orgReg, newReg: tRegister): boolean; var chCount: byte; begin case p^.opcode of A_IMUL: noHardCodedRegs := p^.ops <> 1; A_SHL,A_SHR,A_SHLD,A_SHRD: noHardCodedRegs := (p^.oper[0].typ <> top_reg) or ((orgReg <> R_ECX) and (newReg <> R_ECX)); else begin NoHardCodedRegs := true; with InsProp[p^.opcode] do for chCount := 1 to MaxCh do if Ch[chCount] in ([Ch_REAX..Ch_MEDI,Ch_WMemEDI,Ch_All]-[Ch_RESP,Ch_WESP,Ch_RWESP]) then begin NoHardCodedRegs := false; break end; end; end; end; Procedure ChangeReg(var Reg: TRegister; orgReg, newReg: TRegister); begin if reg = newReg then reg := orgReg else if reg = regtoreg8(newReg) then reg := regtoreg8(orgReg) else if reg = regtoreg16(newReg) then reg := regtoreg16(orgReg); end; procedure changeOp(var o: toper; orgReg, newReg: tregister); begin case o.typ of top_reg: changeReg(o.reg,orgReg,newReg); top_ref: begin changeReg(o.ref^.base,orgReg,newReg); changeReg(o.ref^.index,orgReg,newReg); end; end; end; Procedure DoReplaceReg(orgReg,newReg: tregister; hp: paicpu); var opCount: byte; begin for opCount := 0 to 2 do changeOp(hp^.oper[opCount],orgReg,newReg) end; function RegSizesOK(oldReg,newReg: TRegister; p: paicpu): boolean; { oldreg and newreg must be 32bit components } var opCount: byte; begin RegSizesOK := true; { if only one of them is a general purpose register ... } if (IsGP32reg(oldReg) xor IsGP32Reg(newReg)) then begin for opCount := 0 to 2 do if (p^.oper[opCount].typ = top_reg) and (p^.oper[opCount].reg in [R_AL..R_DH]) then begin RegSizesOK := false; break end end; end; procedure DoReplaceReadReg(orgReg,newReg: tregister; p: paicpu); var opCount: byte; begin { handle special case } case p^.opcode of A_IMUL: begin case p^.ops of 1: internalerror(1301001); 2,3: begin changeOp(p^.oper[0],orgReg,newReg); if p^.ops = 3 then changeOp(p^.oper[1],orgReg,newReg); end; end; end; A_DIV,A_IDIV,A_MUL: internalerror(1301002); else begin for opCount := 0 to 2 do if p^.oper[opCount].typ = top_ref then changeOp(p^.oper[opCount],orgReg,newReg); for opCount := 1 to MaxCh do case InsProp[p^.opcode].Ch[opCount] of Ch_ROp1: if p^.oper[0].typ = top_reg then ChangeReg(p^.oper[0].reg,orgReg,newReg); Ch_ROp2: if p^.oper[1].typ = top_reg then ChangeReg(p^.oper[1].reg,orgReg,newReg); Ch_ROp3: if p^.oper[2].typ = top_reg then ChangeReg(p^.oper[2].reg,orgReg,newReg); end; end; end; end; function ReplaceReg(asmL: PaasmOutput; orgReg, newReg: TRegister; p: pai; const c: TContent; orgRegCanBeModified: Boolean; var returnEndP: pai): Boolean; { Tries to replace orgreg with newreg in all instructions coming after p } { until orgreg gets loaded with a new value. Returns true if successful, } { false otherwise. If successful, the contents of newReg are set to c, } { which should hold the contents of newReg before the current sequence } { started } { if the function returns true, returnEndP holds the last instruction } { where newReg was replaced by orgReg } var endP, hp: Pai; removeLast, sequenceEnd, tmpResult, newRegModified, orgRegRead: Boolean; function storeBack(p1: pai): boolean; { returns true if p1 contains an instruction that stores the contents } { of newReg back to orgReg } begin storeBack := (p1^.typ = ait_instruction) and (paicpu(p1)^.opcode = A_MOV) and (paicpu(p1)^.oper[0].typ = top_reg) and (paicpu(p1)^.oper[0].reg = newReg) and (paicpu(p1)^.oper[1].typ = top_reg) and (paicpu(p1)^.oper[1].reg = orgReg); end; begin ReplaceReg := false; tmpResult := true; sequenceEnd := false; newRegModified := false; orgRegRead := false; removeLast := false; endP := p; while tmpResult and not sequenceEnd do begin tmpResult := getNextInstruction(endP,endP) and (endP^.typ = ait_instruction); if tmpresult and not assigned(endP^.optInfo) then begin { hp := new(pai_asm_comment,init(strpnew('next no optinfo'))); hp^.next := endp; hp^.previous := endp^.previous; endp^.previous := hp; if assigned(hp^.previous) then hp^.previous^.next := hp;} exit; end; If tmpResult and { don't take into account instructions that will be removed } Not (PPaiProp(endP^.optInfo)^.canBeRemoved) then begin { if the newReg gets stored back to the oldReg, we can change } { "mov %oldReg,%newReg; ; mov %newReg, } { %oldReg" to "" } removeLast := storeBack(endP); sequenceEnd := { no support for (i)div, mul and imul with hardcoded operands } (noHardCodedRegs(paicpu(endP),orgReg,newReg) and { if newReg gets loaded with a new value, we can stop } { replacing newReg with oldReg here (possibly keeping } { the original contents of oldReg so we still know them } { afterwards) } RegLoadedWithNewValue(newReg,true,paicpu(endP)) or { we can also stop if we reached the end of the use of } { newReg's current contents } (GetNextInstruction(endp,hp) and FindRegDealloc(newReg,hp))); { to be able to remove the first and last instruction of } { movl %reg1, %reg2 } { (replacing reg2 with reg1 here) } { movl %reg2, %reg1 } { %reg2 must not be use afterwards (it can be as the } { result of a peepholeoptimization) } removeLast := removeLast and sequenceEnd; newRegModified := newRegModified or (not(regLoadedWithNewValue(newReg,true,paicpu(endP))) and RegModifiedByInstruction(newReg,endP)); orgRegRead := newRegModified and RegReadByInstruction(orgReg,endP); sequenceEnd := SequenceEnd and (removeLast or { since newReg will be replaced by orgReg, we can't allow that newReg } { gets modified if orgReg is still read afterwards (since after } { replacing, this would mean that orgReg first gets modified and then } { gets read in the assumption it still contains the unmodified value) } not(newRegModified and orgRegRead)) (* and { since newReg will be replaced by orgReg, we can't allow that newReg } { gets modified if orgRegCanBeModified = false } (orgRegCanBeModified or not(newRegModified)) *); tmpResult := not(removeLast) and not(newRegModified and orgRegRead) and (* (orgRegCanBeModified or not(newRegModified)) and *) (endP^.typ = ait_instruction) and not(paicpu(endP)^.is_jmp) and NoHardCodedRegs(paicpu(endP),orgReg,newReg) and RegSizesOk(orgReg,newReg,paicpu(endP)) and not RegModifiedByInstruction(orgReg,endP); end; end; sequenceEnd := sequenceEnd and (removeLast or (orgRegCanBeModified or not(newRegModified))) and (not(assigned(endp)) or not(endp^.typ = ait_instruction) or (noHardCodedRegs(paicpu(endP),orgReg,newReg) and RegSizesOk(orgReg,newReg,paicpu(endP)) and not(newRegModified and (orgReg in PPaiProp(endP^.optInfo)^.usedRegs) and not(RegLoadedWithNewValue(orgReg,true,paicpu(endP)))))); if SequenceEnd then begin {$ifdef replaceregdebug} hp := new(pai_asm_comment,init(strpnew( 'replacing '+att_reg2str[newreg]+' with '+att_reg2str[orgreg]+ ' from here...'))); hp^.next := p; hp^.previous := p^.previous; p^.previous := hp; if assigned(hp^.previous) then hp^.previous^.next := hp; hp := new(pai_asm_comment,init(strpnew( 'replaced '+att_reg2str[newreg]+' with '+att_reg2str[orgreg]+ ' till here'))); hp^.next := endp^.next; hp^.previous := endp; endp^.next := hp; if assigned(hp^.next) then hp^.next^.previous := hp; {$endif replaceregdebug} replaceReg := true; returnEndP := endP; getNextInstruction(p,hp); while hp <> endP do begin if not(PPaiProp(hp^.optInfo)^.canBeRemoved) and (hp^.typ = ait_instruction) then DoReplaceReg(orgReg,newReg,paicpu(hp)); GetNextInstruction(hp,hp) end; if assigned(endp) and (endp^.typ = ait_instruction) then DoReplaceReadReg(orgReg,newReg,paicpu(endP)); { the replacing stops either at the moment that } { a) the newreg gets loaded with a new value (one not depending on the } { current value of newreg) } { b) newreg is completely replaced in this sequence and it's current value } { isn't used anymore } { In case b, the newreg was completely replaced by oldreg, so it's contents } { are unchanged compared the start of this sequence, so restore them } If removeLast or RegLoadedWithNewValue(newReg,true,endP) then GetLastInstruction(endP,hp) else hp := endP; if removeLast or (p <> endp) or not RegLoadedWithNewValue(newReg,true,endP) then RestoreRegContentsTo(newReg, c ,p, hp); { In both case a and b, it is possible that the new register was modified } { (e.g. an add/sub), so if it was replaced by oldreg in that instruction, } { oldreg's contents have been changed. To take this into account, we simply } { set the contents of orgreg to "unknown" after this sequence } if newRegModified then ClearRegContentsFrom(orgReg,p,hp); if removeLast then ppaiprop(endP^.optinfo)^.canBeRemoved := true; allocRegBetween(asml,orgReg,p,endP); end {$ifdef replaceregdebug} else begin hp := new(pai_asm_comment,init(strpnew( 'replacing '+att_reg2str[newreg]+' with '+att_reg2str[orgreg]+ ' from here...'))); hp^.previous := p^.previous; hp^.next := p; p^.previous := hp; if assigned(hp^.previous) then hp^.previous^.next := hp; hp := new(pai_asm_comment,init(strpnew( 'replacing '+att_reg2str[newreg]+' with '+att_reg2str[orgreg]+ ' failed here'))); hp^.next := endp^.next; hp^.previous := endp; endp^.next := hp; if assigned(hp^.next) then hp^.next^.previous := hp; end; {$endif replaceregdebug} End; Function FindRegWithConst(p: Pai; size: topsize; l: longint; Var Res: TRegister): Boolean; {Finds a register which contains the constant l} Var Counter: TRegister; {$ifdef testing} hp: pai; {$endif testing} tmpresult: boolean; Begin Counter := R_NO; repeat inc(counter); tmpresult := (ppaiprop(p^.optInfo)^.regs[counter].typ in [con_const,con_noRemoveConst]) and (paicpu(PPaiProp(p^.OptInfo)^.Regs[Counter].StartMod)^.opsize = size) and (paicpu(PPaiProp(p^.OptInfo)^.Regs[Counter].StartMod)^.oper[0].typ = top_const) and (paicpu(PPaiProp(p^.OptInfo)^.Regs[Counter].StartMod)^.oper[0].val = l); {$ifdef testing} if (ppaiprop(p^.optInfo)^.regs[counter].typ in [con_const,con_noRemoveConst]) then begin hp := new(pai_asm_comment,init(strpnew( 'checking const load of '+tostr(l)+' here...'))); hp^.next := PPaiProp(p^.OptInfo)^.Regs[Counter].StartMod; hp^.previous := PPaiProp(p^.OptInfo)^.Regs[Counter].StartMod^.previous; PPaiProp(p^.OptInfo)^.Regs[Counter].StartMod^.previous := hp; if assigned(hp^.previous) then hp^.previous^.next := hp; end; {$endif testing} until tmpresult or (Counter = R_EDI); res := counter; FindRegWithConst := tmpResult; End; procedure removePrevNotUsedLoad(p: pai; reg: tRegister; check: boolean); { If check = true, it means the procedure has to check whether it isn't } { possible that the contents are still used after p (used when removing } { instructions because of a "call"), otherwise this is not necessary } { (e.g. when you have a "mov 8(%ebp),%eax", you can be sure the previous } { value of %eax isn't used anymore later on) } var hp1: pai; begin if getLastInstruction(p,hp1) then with ppaiprop(hp1^.optInfo)^.regs[reg] do if (typ in [con_ref,con_invalid]) and (nrOfMods = 1) and (rState = ppaiprop(startmod^.optInfo)^.regs[reg].rState) and (not(check) or (not(regInInstruction(reg,p)) and (not(reg in usableregs) and (startmod^.typ = ait_instruction) and ((paicpu(startmod)^.opcode = A_MOV) or (paicpu(startmod)^.opcode = A_MOVZX) or (paicpu(startmod)^.opcode = A_MOVSX)) and (paicpu(startmod)^.oper[0].typ = top_ref) and (paicpu(startmod)^.oper[0].ref^.base = stack_pointer)) or not(reg in ppaiprop(hp1^.optInfo)^.usedRegs) or findRegDealloc(reg,p))) then ppaiprop(startMod^.optInfo)^.canBeRemoved := true; end; Procedure DoCSE(AsmL: PAasmOutput; First, Last: Pai); {marks the instructions that can be removed by RemoveInstructs. They're not removed immediately because sometimes an instruction needs to be checked in two different sequences} Var Cnt, Cnt2: Longint; p, hp1, hp2: Pai; hp3, hp4: pai; hp5 : pai; RegInfo: TRegInfo; RegCounter: TRegister; Begin p := First; SkipHead(p); First := p; While (p <> Last) Do Begin Case p^.typ Of ait_align: if not(pai_align(p)^.use_op) then SetAlignReg(p); ait_instruction: Begin Case Paicpu(p)^.opcode Of A_CALL: for regCounter := R_EAX to R_EBX do removePrevNotUsedLoad(p,regCounter,true); A_CLD: If GetLastInstruction(p, hp1) And (PPaiProp(hp1^.OptInfo)^.DirFlag = F_NotSet) Then PPaiProp(Pai(p)^.OptInfo)^.CanBeRemoved := True; A_MOV, A_MOVZX, A_MOVSX: Begin Case Paicpu(p)^.oper[0].typ Of Top_Ref: Begin {destination is always a register in this case} With PPaiProp(p^.OptInfo)^.Regs[Reg32(Paicpu(p)^.oper[1].reg)] Do Begin If (p = StartMod) And GetLastInstruction (p, hp1) And (hp1^.typ <> ait_marker) Then {so we don't try to check a sequence when p is the first instruction of the block} begin {$ifdef csdebug} hp5 := new(pai_asm_comment,init(strpnew( 'cse checking '+att_reg2str[Reg32(Paicpu(p)^.oper[1].reg)]))); insertLLItem(asml,p,p^.next,hp5); {$endif csdebug} If CheckSequence(p, Paicpu(p)^.oper[1].reg, Cnt, RegInfo) And (Cnt > 0) Then Begin hp1 := nil; { although it's perfectly ok to remove an instruction which doesn't contain } { the register that we've just checked (CheckSequence takes care of that), } { the sequence containing this other register should also be completely } { checked and removed, otherwise we may get situations like this: } { } { movl 12(%ebp), %edx movl 12(%ebp), %edx } { movl 16(%ebp), %eax movl 16(%ebp), %eax } { movl 8(%edx), %edx movl 8(%edx), %edx } { movl (%eax), eax movl (%eax), eax } { cmpl %eax, %edx cmpl %eax, %edx } { jnz l123 getting converted to jnz l123 } { movl 12(%ebp), %edx movl 4(%eax), eax } { movl 16(%ebp), %eax } { movl 8(%edx), %edx } { movl 4(%eax), eax } hp2 := p; Cnt2 := 1; While Cnt2 <= Cnt Do Begin If Not(RegInInstruction(reg32(Paicpu(hp2)^.oper[1].reg), p)) then begin if ((p^.typ = ait_instruction) And ((paicpu(p)^.OpCode = A_MOV) or (paicpu(p)^.opcode = A_MOVZX) or (paicpu(p)^.opcode = A_MOVSX)) And (paicpu(p)^.Oper[0].typ in [top_const,top_ref,top_symbol])) and (paicpu(p)^.oper[1].typ = top_reg) then begin regCounter := reg32(paicpu(p)^.oper[1].reg); if (regCounter in reginfo.regsStillUsedAfterSeq) then begin if (hp1 = nil) then hp1 := reginfo.lastReload[regCounter]; end {$ifndef noremove} else PPaiProp(p^.OptInfo)^.CanBeRemoved := True; {$endif noremove} end end {$ifndef noremove} else if regInInstruction(Paicpu(hp2)^.oper[1].reg,p) then PPaiProp(p^.OptInfo)^.CanBeRemoved := True {$endif noremove} ; Inc(Cnt2); GetNextInstruction(p, p); End; hp3 := New(Pai_Marker,Init(NoPropInfoStart)); InsertLLItem(AsmL, Pai(hp2^.Previous), hp2, hp3); {hp4 is used to get the contents of the registers before the sequence} GetLastInstruction(hp2, hp4); {$IfDef CSDebug} For RegCounter := R_EAX To R_EDI Do If (RegCounter in RegInfo.RegsLoadedForRef) Then Begin hp5 := new(pai_asm_comment,init(strpnew('New: '+att_reg2str[RegCounter]+', Old: '+ att_reg2str[RegInfo.New2OldReg[RegCounter]]))); InsertLLItem(AsmL, Pai(hp2^.previous), hp2, hp5); End; {$EndIf CSDebug} { If some registers were different in the old and the new sequence, move } { the contents of those old registers to the new ones } For RegCounter := R_EAX To R_EDI Do If Not(RegCounter in [R_ESP,procinfo^.framepointer]) And (RegInfo.New2OldReg[RegCounter] <> R_NO) Then Begin AllocRegBetween(AsmL,RegInfo.New2OldReg[RegCounter], PPaiProp(hp4^.OptInfo)^.Regs[RegInfo.New2OldReg[RegCounter]].StartMod,hp2); If Not(RegCounter In RegInfo.RegsLoadedForRef) And {old reg new reg} (RegInfo.New2OldReg[RegCounter] <> RegCounter) Then Begin getLastInstruction(p,hp3); If not(regCounter in usableRegs + [R_EDI,R_ESI]) or not ReplaceReg(asmL,RegInfo.New2OldReg[RegCounter], regCounter,hp3, PPaiProp(hp4^.optInfo)^.Regs[regCounter],true,hp5) then begin hp3 := New(Paicpu,Op_Reg_Reg(A_MOV, S_L, {old reg new reg} RegInfo.New2OldReg[RegCounter], RegCounter)); InsertLLItem(AsmL, Pai(hp2^.previous), hp2, hp3); end End Else { imagine the following code: } { normal wrong optimized } { movl 8(%ebp), %eax movl 8(%ebp), %eax } { movl (%eax), %eax movl (%eax), %eax } { cmpl 8(%ebp), %eax cmpl 8(%ebp), %eax } { jne l1 jne l1 } { movl 8(%ebp), %eax } { movl (%eax), %edi movl %eax, %edi } { movl %edi, -4(%ebp) movl %edi, -4(%ebp) } { movl 8(%ebp), %eax } { pushl 70(%eax) pushl 70(%eax) } { } { The error is that at the moment that the last instruction is executed, } { %eax doesn't contain 8(%ebp) anymore. Solution: the contents of } { registers that are completely removed from a sequence (= registers in } { RegLoadedForRef, have to be changed to their contents from before the } { sequence. } If RegCounter in RegInfo.RegsLoadedForRef Then Begin hp3 := hp2; { cnt still holds the number of instructions } { of the sequence, so go to the end of it } for cnt2 := 1 to pred(cnt) Do getNextInstruction(hp3,hp3); { hp4 = instruction prior to start of sequence } restoreRegContentsTo(regCounter, PPaiProp(hp4^.OptInfo)^.Regs[RegCounter], hp2,hp3); End; End; hp3 := New(Pai_Marker,Init(NoPropInfoEnd)); InsertLLItem(AsmL, Pai(hp2^.Previous), hp2, hp3); If hp1 <> nil Then p := hp1; Continue; End Else If (PPaiProp(p^.OptInfo)^. regs[reg32(paicpu(p)^.oper[1].reg)].typ in [con_ref,con_noRemoveRef]) and (PPaiProp(p^.OptInfo)^.CanBeRemoved) Then if (cnt > 0) then begin hp2 := p; Cnt2 := 1; While Cnt2 <= Cnt Do Begin If RegInInstruction(Paicpu(hp2)^.oper[1].reg, p) Then PPaiProp(p^.OptInfo)^.CanBeRemoved := False; Inc(Cnt2); GetNextInstruction(p, p); End; Continue; End else begin { Fix for web bug 972 } regCounter := Reg32(Paicpu(p)^.oper[1].reg); cnt := PPaiProp(p^.optInfo)^.Regs[regCounter].nrOfMods; hp3 := p; for cnt2 := 1 to cnt do if not(regModifiedByInstruction(regCounter,hp3) and not(PPaiProp(hp3^.optInfo)^.canBeRemoved)) then getNextInstruction(hp3,hp3) else break; getLastInstruction(p,hp4); RestoreRegContentsTo(regCounter, PPaiProp(hp4^.optInfo)^.Regs[regCounter], p,hp3); end; End; End; if not ppaiprop(p^.optinfo)^.canBeRemoved and not regInRef(reg32(paicpu(p)^.oper[1].reg), paicpu(p)^.oper[0].ref^) then removePrevNotUsedLoad(p,reg32(paicpu(p)^.oper[1].reg),false); End; top_Reg: { try to replace the new reg with the old reg } if not(PPaiProp(p^.optInfo)^.canBeRemoved) and { only remove if we're not storing something in a regvar } (paicpu(p)^.oper[1].reg in (usableregs+[R_EDI])) and (paicpu(p)^.opcode = A_MOV) and getLastInstruction(p,hp4) then begin case paicpu(p)^.oper[1].typ of top_Reg: { we only have to start replacing from the instruction after the mov, } { but replacereg only starts with getnextinstruction(p,p) } if ReplaceReg(asmL,paicpu(p)^.oper[0].reg, paicpu(p)^.oper[1].reg,p, PPaiProp(hp4^.optInfo)^.Regs[paicpu(p)^.oper[1].reg],false,hp1) then begin PPaiProp(p^.optInfo)^.canBeRemoved := true; allocRegBetween(asmL,paicpu(p)^.oper[0].reg, PPaiProp(p^.optInfo)^.regs[paicpu(p)^.oper[0].reg].startMod, hp1); end; end end; top_symbol,Top_Const: Begin Case Paicpu(p)^.oper[1].typ Of Top_Reg: Begin regCounter := Reg32(Paicpu(p)^.oper[1].reg); If GetLastInstruction(p, hp1) Then With PPaiProp(hp1^.OptInfo)^.Regs[regCounter] Do if (typ in [con_const,con_noRemoveConst]) and (paicpu(startMod)^.opsize >= paicpu(p)^.opsize) and opsequal(paicpu(StartMod)^.oper[0],paicpu(p)^.oper[0]) Then begin PPaiProp(p^.OptInfo)^.CanBeRemoved := True; allocRegBetween(asmL,regCounter,startMod,p); end; End; Top_Ref: if (paicpu(p)^.oper[0].typ = top_const) and getLastInstruction(p,hp1) and findRegWithConst(hp1,paicpu(p)^.opsize,paicpu(p)^.oper[0].val,regCounter) then begin paicpu(p)^.loadreg(0,regCounter); allocRegBetween(AsmL,reg32(regCounter), PPaiProp(hp1^.optinfo)^.regs[regCounter].startMod,p); end; End; End; End; End; A_STD: If GetLastInstruction(p, hp1) And (PPaiProp(hp1^.OptInfo)^.DirFlag = F_Set) Then PPaiProp(Pai(p)^.OptInfo)^.CanBeRemoved := True; End End; End; GetNextInstruction(p, p); End; End; Procedure RemoveInstructs(AsmL: PAasmOutput; First, Last: Pai); { Removes the marked instructions and disposes the PPaiProps of the other } { instructions } Var p, hp1: Pai; begin p := First; While (p <> Last) Do Begin If (p^.typ = ait_marker) and (pai_marker(p)^.kind in [noPropInfoStart,noPropInfoEnd]) then begin hp1 := pai(p^.next); asmL^.remove(p); dispose(p,done); p := hp1 end else {$ifndef noinstremove} if assigned(p^.optInfo) and PPaiProp(p^.optInfo)^.canBeRemoved then begin {$IfDef TP} Dispose(PPaiProp(p^.OptInfo)); {$EndIf} hp1 := pai(p^.next); AsmL^.Remove(p); Dispose(p, Done); p := hp1; End Else {$endif noinstremove} Begin {$IfDef TP} if assigned(p^.optInfo) then Dispose(PPaiProp(p^.OptInfo)); {$EndIf TP} p^.OptInfo := nil; p := pai(p^.next);; End; End; {$IfNDef TP} FreeMem(PaiPropBlock, NrOfPaiObjs*(((SizeOf(TPaiProp)+3)div 4)*4)) {$EndIf TP} End; Procedure CSE(AsmL: PAasmOutput; First, Last: Pai); Begin DoCSE(AsmL, First, Last); RemoveInstructs(AsmL, First, Last); End; End. { $Log$ Revision 1.6 2000-08-23 12:55:10 jonas * fix for web bug 1112 and a bit of clean up in csopt386 (merged from fixes branch) Revision 1.5 2000/08/04 20:08:03 jonas * improved detection of range of instructions which use a register (merged from fixes branch) Revision 1.4 2000/07/21 15:19:54 jonas * daopt386: changes to getnextinstruction/getlastinstruction so they ignore labels who have is_addr set + daopt386/csopt386: remove loads of registers which are overwritten before their contents are used (especially usefull for removing superfluous maybe_loadesi outputs and push/pops transformed by below optimization + popt386: transform pop/pop/pop/.../push/push/push to sequences of 'movl x(%esp),%reg' (only active when compiling a go32v2 compiler currently because I don't know whether it's safe to do this under Win32/ Linux (because of problems we had when using esp as frame pointer on those os'es) Revision 1.3 2000/07/14 05:11:48 michael + Patch to 1.1 Revision 1.2 2000/07/13 11:32:39 michael + removed logs }