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Improved JccMov1JmpMov0Jmp -> SETcc optimisation
This commit is contained in:
J. Gareth "Curious Kit" Moreton
FPK
parent
89e0282856
commit
c4ea01cf3d
@ -138,6 +138,7 @@ unit aoptx86;
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function DoSubAddOpt(var p : tai) : Boolean;
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function DoSubAddOpt(var p : tai) : Boolean;
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function DoMovCmpMemOpt(var p : tai; const hp1: tai; UpdateTmpUsedRegs: Boolean) : Boolean;
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function DoMovCmpMemOpt(var p : tai; const hp1: tai; UpdateTmpUsedRegs: Boolean) : Boolean;
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function DoSETccLblRETOpt(var p: tai; const hp_label: tai_label) : Boolean;
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function PrePeepholeOptSxx(var p : tai) : boolean;
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function PrePeepholeOptSxx(var p : tai) : boolean;
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function PrePeepholeOptIMUL(var p : tai) : boolean;
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function PrePeepholeOptIMUL(var p : tai) : boolean;
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@ -5406,6 +5407,214 @@ unit aoptx86;
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end;
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end;
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function TX86AsmOptimizer.DoSETccLblRETOpt(var p: tai; const hp_label: tai_label) : Boolean;
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var
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hp2, hp3, hp4, hp5, hp6: tai;
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ThisReg: TRegister;
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JumpLoc: TAsmLabel;
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begin
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Result := False;
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{
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Convert:
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j<c> .L1
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.L2:
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mov 1,reg
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jmp .L3 (or ret, although it might not be a RET yet)
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.L1:
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mov 0,reg
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jmp .L3 (or ret)
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( As long as .L3 <> .L1 or .L2)
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To:
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mov 0,reg
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set<not(c)> reg
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jmp .L3 (or ret)
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.L2:
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mov 1,reg
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jmp .L3 (or ret)
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.L1:
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mov 0,reg
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jmp .L3 (or ret)
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}
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if JumpTargetOp(taicpu(p))^.ref^.refaddr<>addr_full then
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Exit;
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JumpLoc := TAsmLabel(JumpTargetOp(taicpu(p))^.ref^.symbol);
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if GetNextInstruction(hp_label, hp2) and
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MatchInstruction(hp2,A_MOV,[]) and
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(taicpu(hp2).oper[0]^.typ = top_const) and
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(
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(
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(taicpu(hp2).oper[1]^.typ = top_reg)
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{$ifdef i386}
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{ Under i386, ESI, EDI, EBP and ESP
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don't have an 8-bit representation }
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and not (getsupreg(taicpu(hp2).oper[1]^.reg) in [RS_ESI, RS_EDI, RS_EBP, RS_ESP])
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{$endif i386}
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) or (
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{$ifdef i386}
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(taicpu(hp2).oper[1]^.typ <> top_reg) and
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{$endif i386}
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(taicpu(hp2).opsize = S_B)
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)
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) and
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GetNextInstruction(hp2, hp3) and
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MatchInstruction(hp3, A_JMP, A_RET, []) and
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(
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(taicpu(hp3).opcode=A_RET) or
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(
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(taicpu(hp3).oper[0]^.ref^.refaddr=addr_full) and
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(tasmlabel(taicpu(hp3).oper[0]^.ref^.symbol)<>tai_label(hp_label).labsym)
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)
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) and
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GetNextInstruction(hp3, hp4) and
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SkipAligns(hp4, hp4) and
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(hp4.typ=ait_label) and
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(tai_label(hp4).labsym=JumpLoc) and
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(
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not (cs_opt_size in current_settings.optimizerswitches) or
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{ If the initial jump is the label's only reference, then it will
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become a dead label if the other conditions are met and hence
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remove at least 2 instructions, including a jump }
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(JumpLoc.getrefs = 1)
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) and
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{ Don't check if hp3 jumps to hp4 because this is a zero-distance jump
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that will be optimised out }
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GetNextInstruction(hp4, hp5) and
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MatchInstruction(hp5,A_MOV,[taicpu(hp2).opsize]) and
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(taicpu(hp5).oper[0]^.typ = top_const) and
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(
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((taicpu(hp2).oper[0]^.val = 0) and (taicpu(hp5).oper[0]^.val = 1)) or
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((taicpu(hp2).oper[0]^.val = 1) and (taicpu(hp5).oper[0]^.val = 0))
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) and
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MatchOperand(taicpu(hp2).oper[1]^,taicpu(hp5).oper[1]^) and
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GetNextInstruction(hp5,hp6) and
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(
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(hp6.typ<>ait_label) or
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SkipLabels(hp6, hp6)
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) and
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(hp6.typ=ait_instruction) then
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begin
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{ First, let's look at the two jumps that are hp3 and hp6 }
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if not
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(
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(taicpu(hp6).opcode=taicpu(hp3).opcode) and { Both RET or both JMP to the same label }
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(
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(taicpu(hp6).opcode=A_RET) or
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MatchOperand(taicpu(hp6).oper[0]^, taicpu(hp3).oper[0]^)
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)
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) then
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{ If condition is False, then the JMP/RET instructions matched conventionally }
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begin
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{ See if one of the jumps can be instantly converted into a RET }
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if (taicpu(hp3).opcode=A_JMP) then
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begin
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{ Reuse hp5 }
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hp5 := getlabelwithsym(TAsmLabel(JumpTargetOp(taicpu(hp3))^.ref^.symbol));
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{ Make sure hp5 doesn't jump back to .L2 (infinite loop) }
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if not Assigned(hp5) or (hp5=hp4) or not GetNextInstruction(hp5, hp5) then
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Exit;
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if MatchInstruction(hp5, A_RET, []) then
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begin
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DebugMsg(SPeepholeOptimization + 'Converted JMP to RET as part of SETcc optimisation (1st jump)', hp3);
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ConvertJumpToRET(hp3, hp5);
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Result := True;
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end
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else
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Exit;
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end;
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if (taicpu(hp6).opcode=A_JMP) then
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begin
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{ Reuse hp5 }
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hp5 := getlabelwithsym(TAsmLabel(JumpTargetOp(taicpu(hp6))^.ref^.symbol));
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if not Assigned(hp5) or not GetNextInstruction(hp5, hp5) then
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Exit;
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if MatchInstruction(hp5, A_RET, []) then
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begin
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DebugMsg(SPeepholeOptimization + 'Converted JMP to RET as part of SETcc optimisation (2nd jump)', hp6);
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ConvertJumpToRET(hp6, hp5);
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Result := True;
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end
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else
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Exit;
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end;
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if not
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(
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(taicpu(hp6).opcode=taicpu(hp3).opcode) and { Both RET or both JMP to the same label }
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(
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(taicpu(hp6).opcode=A_RET) or
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MatchOperand(taicpu(hp6).oper[0]^, taicpu(hp3).oper[0]^)
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)
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) then
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{ Still doesn't match }
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Exit;
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end;
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if (taicpu(hp2).oper[0]^.val = 1) then
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begin
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taicpu(p).condition := inverse_cond(taicpu(p).condition);
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DebugMsg(SPeepholeOptimization + 'J(c)Mov1Jmp/RetMov0Jmp/Ret -> Set(~c)Jmp/Ret',p)
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end
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else
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DebugMsg(SPeepholeOptimization + 'J(c)Mov0Jmp/RetMov1Jmp/Ret -> Set(c)Jmp/Ret',p);
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if taicpu(hp2).opsize=S_B then
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begin
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if taicpu(hp2).oper[1]^.typ = top_reg then
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hp4:=taicpu.op_reg(A_SETcc, S_B, taicpu(hp2).oper[1]^.reg)
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else
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hp4:=taicpu.op_ref(A_SETcc, S_B, taicpu(hp2).oper[1]^.ref^);
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hp2 := p;
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end
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else
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begin
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{ Will be a register because the size can't be S_B otherwise }
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ThisReg:=newreg(R_INTREGISTER,getsupreg(taicpu(hp2).oper[1]^.reg), R_SUBL);
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hp4:=taicpu.op_reg(A_SETcc, S_B, ThisReg);
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hp2:=taicpu.op_const_reg(A_MOV, taicpu(hp2).opsize, 0, taicpu(hp2).oper[1]^.reg);
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{ Inserting it right before p will guarantee that the flags are also tracked }
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Asml.InsertBefore(hp2, p);
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end;
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taicpu(hp4).condition:=taicpu(p).condition;
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asml.InsertBefore(hp4, hp2);
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JumpLoc.decrefs;
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if taicpu(hp3).opcode = A_JMP then
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begin
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MakeUnconditional(taicpu(p));
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taicpu(p).loadref(0, JumpTargetOp(taicpu(hp3))^.ref^);
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TAsmLabel(JumpTargetOp(taicpu(hp3))^.ref^.symbol).increfs;
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end
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else
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begin
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taicpu(p).condition := C_None;
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taicpu(p).opcode := A_RET;
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taicpu(p).clearop(0);
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taicpu(p).ops := 0;
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end;
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if (JumpLoc.getrefs = 0) then
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RemoveDeadCodeAfterJump(hp3);
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Result:=true;
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exit;
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end;
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end;
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function TX86AsmOptimizer.OptPass1Sub(var p : tai) : boolean;
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function TX86AsmOptimizer.OptPass1Sub(var p : tai) : boolean;
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var
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var
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hp1, hp2: tai;
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hp1, hp2: tai;
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@ -6805,11 +7014,11 @@ unit aoptx86;
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function TX86AsmOptimizer.OptPass1Jcc(var p : tai) : boolean;
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function TX86AsmOptimizer.OptPass1Jcc(var p : tai) : boolean;
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var
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var
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hp1, hp2, hp3, hp4, hp5: tai;
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hp1, hp2, hp3, hp4, hp5, hp6: tai;
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ThisReg: TRegister;
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ThisReg: TRegister;
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begin
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begin
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Result := False;
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Result := False;
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if not GetNextInstruction(p,hp1) or (hp1.typ <> ait_instruction) then
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if not GetNextInstruction(p,hp1) then
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Exit;
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Exit;
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{
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{
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@ -6966,6 +7175,8 @@ unit aoptx86;
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Result:=true;
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Result:=true;
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exit;
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exit;
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end
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end
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else if (hp1.typ = ait_label) then
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Result := DoSETccLblRETOpt(p, tai_label(hp1));
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end;
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end;
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@ -9847,8 +10058,16 @@ unit aoptx86;
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increg, tmpreg: TRegister;
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increg, tmpreg: TRegister;
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begin
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begin
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result:=false;
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result:=false;
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if GetNextInstruction(p,hp1) and (hp1.typ=ait_instruction) then
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if GetNextInstruction(p,hp1) then
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begin
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begin
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if (hp1.typ=ait_label) then
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begin
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Result := DoSETccLblRETOpt(p, tai_label(hp1));
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Exit;
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end
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else if (hp1.typ<>ait_instruction) then
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Exit;
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symbol := TAsmLabel(taicpu(p).oper[0]^.ref^.symbol);
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symbol := TAsmLabel(taicpu(p).oper[0]^.ref^.symbol);
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if (
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if (
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(
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(
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