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* x86: Separated out Jcc; STC/CLC optimisation and added additional peephole optimisations
This commit is contained in:
J. Gareth "Curious Kit" Moreton
FPK
parent
3e06242fd8
commit
698d432cce
@ -222,6 +222,7 @@ unit aoptx86;
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function TrySwapMovOp(var p, hp1: tai): Boolean;
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function TrySwapMovCmp(var p, hp1: tai): Boolean;
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function TryCmpCMovOpts(var p, hp1: tai) : Boolean;
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function TryJccStcClcOpt(var p, hp1: tai): Boolean;
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{ Processor-dependent reference optimisation }
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class procedure OptimizeRefs(var p: taicpu); static;
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@ -8629,7 +8630,6 @@ unit aoptx86;
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var
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hp1, hp2, hp3, hp4, hp5: tai;
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ThisReg: TRegister;
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TempBool: Boolean;
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begin
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Result := False;
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if not GetNextInstruction(p,hp1) then
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@ -8788,55 +8788,7 @@ unit aoptx86;
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exit;
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end
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else if MatchInstruction(hp1, A_CLC, A_STC, []) then
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begin
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{
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j(c) .L1
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stc/clc
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.L1:
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jc/jnc .L2
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(Flags deallocated)
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Change to:
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j)c) .L1
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jmp .L2
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.L1:
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jc/jnc .L2
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Then call DoJumpOptimizations to convert to:
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j(nc) .L2
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.L1: (may become a dead label)
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jc/jnc .L2
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}
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if GetNextInstruction(hp1, hp2) and
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(hp2.typ = ait_label) and
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(tai_label(hp2).labsym = TAsmLabel(taicpu(p).oper[0]^.ref^.symbol)) and
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GetNextInstruction(hp2, hp3) and
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MatchInstruction(hp3, A_Jcc, []) and
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(
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(
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(taicpu(hp3).condition = C_C) and
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(taicpu(hp1).opcode = A_STC)
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) or (
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(taicpu(hp3).condition = C_NC) and
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(taicpu(hp1).opcode = A_CLC)
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)
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) and
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{ Make sure the flags aren't used again }
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Assigned(FindRegDealloc(NR_DEFAULTFLAGS, tai(hp3.Next))) then
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begin
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taicpu(hp1).allocate_oper(1);
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taicpu(hp1).ops := 1;
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taicpu(hp1).loadsymbol(0, TAsmLabel(taicpu(hp3).oper[0]^.ref^.symbol), 0);
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taicpu(hp1).opcode := A_JMP;
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taicpu(hp1).is_jmp := True;
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TempBool := True; { Prevent compiler warnings }
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if DoJumpOptimizations(p, TempBool) then
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Result := True
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else
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Include(OptsToCheck, aoc_ForceNewIteration);
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end;
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end
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Result := TryJccStcClcOpt(p, hp1)
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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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@ -9462,7 +9414,7 @@ unit aoptx86;
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var
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hp1, hp2, p_dist, hp1_dist: tai;
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JumpLabel: TAsmLabel;
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Tmp: string;
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begin
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Result := False;
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{ Look for:
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@ -9484,55 +9436,155 @@ unit aoptx86;
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if (hp1.typ = ait_instruction) and
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IsJumpToLabel(taicpu(hp1)) then
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begin
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{ Optimise the J(c); stc/clc optimisation first since this will
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get missed if the main optimisation takes place }
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if (taicpu(hp1).opcode = A_JCC) and
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GetNextInstruction(hp1, hp2) and
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MatchInstruction(hp2, A_CLC, A_STC, []) and
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TryJccStcClcOpt(hp1, hp2) then
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begin
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Result := True;
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Exit;
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end;
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hp2 := nil; { Suppress compiler warning }
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JumpLabel := TAsmLabel(taicpu(hp1).oper[0]^.ref^.symbol);
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if Assigned(JumpLabel) and
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SetAndTest(getlabelwithsym(JumpLabel), hp2) and
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GetNextInstruction(hp2, p_dist) and
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MatchInstruction(p_dist, A_SETcc, []) and
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(taicpu(p_dist).condition in [C_C, C_NC]) and
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{ Make sure the flags aren't used again }
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SetAndTest(FindRegDealloc(NR_DEFAULTFLAGS, tai(p_dist.Next)), hp2) and
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GetNextInstruction(hp2, hp1_dist) and
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IsJumpToLabel(taicpu(hp1_dist)) and
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{ Make sure the carry flag doesn't appear in the jump conditions }
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not (taicpu(hp1).condition in [C_AE, C_NB, C_NC, C_B, C_C, C_NAE, C_BE, C_NA]) and
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not (taicpu(hp1_dist).condition in [C_AE, C_NB, C_NC, C_B, C_C, C_NAE, C_BE, C_NA]) and
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{ This works if hp1_dist or both are regular JMP instructions }
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condition_in(taicpu(hp1).condition, taicpu(hp1_dist).condition) then
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MatchInstruction(p_dist, A_Jcc, A_SETcc, []) and
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(taicpu(p_dist).condition in [C_C, C_NC]) then
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begin
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taicpu(p).allocate_oper(2);
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taicpu(p).ops := 2;
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case taicpu(p_dist).opcode of
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A_Jcc:
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{ clc + jc = False; clc + jnc = True; stc + jc = True; stc + jnc = False }
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if ((taicpu(p).opcode = A_STC) xor (taicpu(p_dist).condition = C_NC)) then
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begin
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DebugMsg(SPeepholeOptimization + 'STC/CLC; JMP/Jcc; ... J(N)C -> JMP/Jcc (StcClcJ(c)2Jmp)', p);
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{ clc + setc = 0; clc + setnc = 1; stc + setc = 1; stc + setnc = 0 }
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taicpu(p).loadconst(0, TCGInt((taicpu(p).opcode = A_STC) xor (taicpu(p_dist).condition = C_NC)));
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taicpu(p).loadoper(1, taicpu(p_dist).oper[0]^);
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taicpu(p).opcode := A_MOV;
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taicpu(p).opsize := S_B;
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JumpLabel.decrefs;
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taicpu(hp1).loadsymbol(0, taicpu(p_dist).oper[0]^.ref^.symbol, 0);
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if (taicpu(p_dist).oper[0]^.typ = top_reg) then
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AllocRegBetween(taicpu(p_dist).oper[0]^.reg, p, hp1, UsedRegs);
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RemoveCurrentP(p, hp1);
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Result := True;
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Exit;
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end
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else if GetNextInstruction(p_dist, hp1_dist) and
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(hp1_dist.typ = ait_label) then
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begin
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DebugMsg(SPeepholeOptimization + 'STC/CLC; JMP/Jcc; ... J(N)C; .Lbl -> JMP/Jcc .Lbl (StcClcJ(~c)Lbl2Jmp)', p);
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DebugMsg(SPeepholeOptimization + 'STC/CLC; JMP; ... SET(N)C; JMP -> MOV; JMP (StcClc2Mov)', p);
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JumpLabel.decrefs;
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taicpu(hp1).loadsymbol(0, tai_label(hp1_dist).labsym, 0);
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JumpLabel.decrefs;
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taicpu(hp1).loadsymbol(0, taicpu(hp1_dist).oper[0]^.ref^.symbol, 0);
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RemoveCurrentP(p, hp1);
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Result := True;
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Exit;
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end;
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{ If a flag allocation is found, try to move it to after the MOV so "mov $0,%reg" gets optimised to "xor %reg,%reg" }
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if SetAndTest(FindRegAlloc(NR_DEFAULTFLAGS, p), hp1) and
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(tai_regalloc(hp1).ratype = ra_alloc) then
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begin
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Asml.Remove(hp1);
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Asml.InsertAfter(hp1, p);
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end;
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A_SETcc:
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if { Make sure the flags aren't used again }
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SetAndTest(FindRegDealloc(NR_DEFAULTFLAGS, tai(p_dist.Next)), hp2) and
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GetNextInstruction(hp2, hp1_dist) and
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IsJumpToLabel(taicpu(hp1_dist)) and
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{ Make sure the carry flag doesn't appear in the jump conditions }
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not (taicpu(hp1).condition in [C_AE, C_NB, C_NC, C_B, C_C, C_NAE, C_BE, C_NA]) and
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not (taicpu(hp1_dist).condition in [C_AE, C_NB, C_NC, C_B, C_C, C_NAE, C_BE, C_NA]) and
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{ This works if hp1_dist or both are regular JMP instructions }
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condition_in(taicpu(hp1).condition, taicpu(hp1_dist).condition) then
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begin
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taicpu(p).allocate_oper(2);
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taicpu(p).ops := 2;
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Result := True;
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Exit;
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{ clc + setc = 0; clc + setnc = 1; stc + setc = 1; stc + setnc = 0 }
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taicpu(p).loadconst(0, TCGInt((taicpu(p).opcode = A_STC) xor (taicpu(p_dist).condition = C_NC)));
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taicpu(p).loadoper(1, taicpu(p_dist).oper[0]^);
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taicpu(p).opcode := A_MOV;
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taicpu(p).opsize := S_B;
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if (taicpu(p_dist).oper[0]^.typ = top_reg) then
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AllocRegBetween(taicpu(p_dist).oper[0]^.reg, p, hp1, UsedRegs);
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DebugMsg(SPeepholeOptimization + 'STC/CLC; JMP; ... SET(N)C; JMP -> MOV; JMP (StcClcSet(c)2Mov)', p);
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JumpLabel.decrefs;
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taicpu(hp1).loadsymbol(0, taicpu(hp1_dist).oper[0]^.ref^.symbol, 0);
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{ If a flag allocation is found, try to move it to after the MOV so "mov $0,%reg" gets optimised to "xor %reg,%reg" }
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if SetAndTest(FindRegAllocBackward(NR_DEFAULTFLAGS, tai(p.Previous)), hp1) and
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(tai_regalloc(hp1).ratype = ra_alloc) then
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begin
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Asml.Remove(hp1);
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Asml.InsertAfter(hp1, p);
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end;
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Result := True;
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Exit;
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end;
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else
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;
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end;
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end;
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end;
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end;
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function TX86AsmOptimizer.TryJccStcClcOpt(var p, hp1: tai): Boolean;
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var
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hp2, hp3: tai;
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TempBool: Boolean;
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begin
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Result := False;
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{
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j(c) .L1
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stc/clc
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.L1:
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jc/jnc .L2
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(Flags deallocated)
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Change to:
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j)c) .L1
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jmp .L2
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.L1:
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jc/jnc .L2
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Then call DoJumpOptimizations to convert to:
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j(nc) .L2
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.L1: (may become a dead label)
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jc/jnc .L2
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}
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if GetNextInstruction(hp1, hp2) and
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(hp2.typ = ait_label) and
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(tai_label(hp2).labsym = TAsmLabel(taicpu(p).oper[0]^.ref^.symbol)) and
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GetNextInstruction(hp2, hp3) and
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MatchInstruction(hp3, A_Jcc, []) and
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(
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(
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(taicpu(hp3).condition = C_C) and
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(taicpu(hp1).opcode = A_STC)
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) or (
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(taicpu(hp3).condition = C_NC) and
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(taicpu(hp1).opcode = A_CLC)
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)
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) and
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{ Make sure the flags aren't used again }
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Assigned(FindRegDealloc(NR_DEFAULTFLAGS, tai(hp3.Next))) then
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begin
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tai_label(hp2).labsym.DecRefs;
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taicpu(hp1).allocate_oper(1);
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taicpu(hp1).ops := 1;
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taicpu(hp1).loadsymbol(0, TAsmLabel(taicpu(hp3).oper[0]^.ref^.symbol), 0);
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taicpu(hp1).opcode := A_JMP;
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taicpu(hp1).is_jmp := True;
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TempBool := True; { Prevent compiler warnings }
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if DoJumpOptimizations(p, TempBool) then
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Result := True
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else
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Include(OptsToCheck, aoc_ForceNewIteration);
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end;
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end;
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function TX86AsmOptimizer.OptPass2MOV(var p : tai) : boolean;
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