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https://gitlab.com/freepascal.org/fpc/source.git
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Improved handling of signed sequences in OptPass2Movx
This commit is contained in:
J. Gareth "Curious Kit" Moreton
FPK
parent
01e5f4855a
commit
d255ffba8b
@ -7942,7 +7942,7 @@ unit aoptx86;
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movzx_cascade;
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var
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ThisReg: TRegister;
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MinSize, MaxSize, TrySmaller, TargetSize: TOpSize;
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MinSize, MaxSize, TryShiftDown, TargetSize: TOpSize;
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TargetSubReg: TSubRegister;
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hp1, hp2: tai;
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RegInUse, RegChanged, p_removed: Boolean;
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@ -7951,13 +7951,17 @@ unit aoptx86;
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GetNextInstructionUsingReg multiple times }
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InstrList: array of taicpu;
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InstrMax, Index: Integer;
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UpperLimit, TrySmallerLimit: TCgInt;
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UpperLimit, SignedUpperLimit, SignedLowerLimitBottom,
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LowerLimit, SignedLowerLimit, SignedLowerLimitBottom,
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TryShiftDownLimit, TryShiftDownSignedLimit, TryShiftDownSignedLimitLower,
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WorkingValue: TCgInt;
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PreMessage: string;
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{ Data flow analysis }
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TestValMin, TestValMax: TCgInt;
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SmallerOverflow, BitwiseOnly, OrXorUsed: Boolean;
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TestValMin, TestValMax, TestValSignedMax: TCgInt;
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BitwiseOnly, OrXorUsed,
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ShiftDownOverflow, SignedOverflow, UnsignedOverflow, LowerSignedOverflow, UpperSignedOverflow: Boolean;
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begin
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Result := False;
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@ -8074,15 +8078,29 @@ unit aoptx86;
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{$endif i386 or i8086}
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UpperLimit := $FF;
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SignedLowerLimit := $7F;
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SignedLowerLimitBottom := -128;
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MinSize := S_B;
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if taicpu(p).opsize = S_BW then
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MaxSize := S_W
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begin
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MaxSize := S_W;
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SignedUpperLimit := $7F;
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SignedLowerLimitBottom := -32768;
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end
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else
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MaxSize := S_L;
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begin
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MaxSize := S_L;
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SignedUpperLimit := $7FFFFFFF;
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SignedUpperLimitBottom := -2147483648;
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end;
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end;
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S_WL:
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begin
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UpperLimit := $FFFF;
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SignedUpperLimit := $7FFF;
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SignedLowerLimitBottom := -32768;
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SignedUpperLimit := $7FFFFFFF;
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SignedUpperLimitBottom := -2147483648;
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MinSize := S_W;
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MaxSize := S_L;
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end
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@ -8092,12 +8110,17 @@ unit aoptx86;
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TestValMin := 0;
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TestValMax := UpperLimit;
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TrySmallerLimit := UpperLimit;
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TrySmaller := S_NO;
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SmallerOverflow := False;
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TestValSignedMax := SignedUpperLimit;
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TryShiftDownLimit := UpperLimit;
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TryShiftDown := S_NO;
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ShiftDownOverflow := False;
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RegChanged := False;
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BitwiseOnly := True;
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OrXorUsed := False;
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SignedOverflow := False;
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LowerSignedOverflow := False;
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UnsignedOverflow := False;
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LowerUnsignedOverflow := False;
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hp1 := p;
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@ -8122,19 +8145,35 @@ unit aoptx86;
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begin
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Inc(TestValMin);
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Inc(TestValMax);
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Inc(TestValSignedMax);
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end
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else
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begin
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Dec(TestValMin);
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Dec(TestValMax);
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Dec(TestValSignedMax);
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end;
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end;
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A_CMP:
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A_TEST, A_CMP:
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begin
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if (taicpu(hp1).oper[1]^.typ <> top_reg) or
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if (
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{ Too high a risk of non-linear behaviour that breaks DFA
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here, unless it's cmp $0,%reg, which is equivalent to
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test %reg,%reg }
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OrXorUsed and
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(taicpu(hp1).opcode = A_CMP) and
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not Matchoperand(taicpu(hp1).oper[0]^, 0)
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) or
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(taicpu(hp1).oper[1]^.typ <> top_reg) or
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{ Has to be an exact match on the register }
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(taicpu(hp1).oper[1]^.reg <> ThisReg) or
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(
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{ Permit "test %reg,%reg" }
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(taicpu(hp1).opcode = A_TEST) and
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(taicpu(hp1).oper[0]^.typ = top_reg) and
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(taicpu(hp1).oper[0]^.reg <> ThisReg)
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) or
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(taicpu(hp1).oper[0]^.typ <> top_const) or
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{ Make sure the comparison value is not smaller than the
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smallest allowed signed value for the minimum size (e.g.
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@ -8142,17 +8181,45 @@ unit aoptx86;
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not (
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((taicpu(hp1).oper[0]^.val and UpperLimit) = taicpu(hp1).oper[0]^.val) or
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{ Is it in the negative range? }
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(((not taicpu(hp1).oper[0]^.val) and (UpperLimit shr 1)) = (not taicpu(hp1).oper[0]^.val))
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(taicpu(hp1).oper[0]^.val >= SignedLowerLimitBottom)
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) then
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Break;
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TestValMin := TestValMin - taicpu(hp1).oper[0]^.val;
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TestValMax := TestValMax - taicpu(hp1).oper[0]^.val;
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{ ANDing can't increase the value past the limit or decrease
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it below 0, so we can skip the checks, plus the test value
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won't change afterwards }
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if (taicpu(hp1).opcode = A_CMP) and
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{ cmp $0,$reg is equivalent to test %reg,%reg, plus the
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test values aren't being modified anyway }
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(taicpu(hp1).oper[0]^.val <> 0) then
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begin
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WorkingValue := taicpu(hp1).oper[0]^.val;
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if (TestValMin < TrySmallerLimit) or (TestValMax < TrySmallerLimit) or
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(TestValMin > UpperLimit) or (TestValMax > UpperLimit) then
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{ Overflow }
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Break;
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TestValMin := TestValMin - WorkingValue;
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TestValMax := TestValMax - WorkingValue;
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TestValSignedMax := TestValSignedMax - WorkingValue;
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if (TestValSignedMax > SignedUpperLimit) then
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SignedOverflow := True;
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if (TestValMin > UpperLimit) or (TestValMax > UpperLimit) then
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{ Absolute overflow }
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Break
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else if not ShiftDownOverflow and (TryShiftDown <> S_NO) and
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((TestValMin > TryShiftDownLimit) or (TestValMax > TryShiftDownLimit)) then
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ShiftDownOverflow := True
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else if (TestValMin < SignedLowerLimitBottom) or (TestValMax < SignedLowerLimitBottom) then
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{ Absolute overflow }
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Break
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else if (TestValMin < 0) or (TestValMax < 0) then
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UnsignedOverflow := True;
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{ Because the register isn't actually adjusted, we can
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restore the test values to what they were previously }
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TestValMin := TestValMin + WorkingValue;
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TestValMax := TestValMax + WorkingValue;
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TestValSignedMax := TestValSignedMax + WorkingValue;
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end;
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{ Check to see if the active register is used afterwards }
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TransferUsedRegs(TmpUsedRegs);
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@ -8216,7 +8283,7 @@ unit aoptx86;
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end;
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end;
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A_ADD,A_SUB,A_AND,A_OR,A_XOR,A_SHL,A_SHR:
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A_ADD,A_SUB,A_AND,A_OR,A_XOR,A_SHL,A_SHR,A_SAR:
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begin
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if
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(taicpu(hp1).oper[1]^.typ <> top_reg) or
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@ -8266,11 +8333,13 @@ unit aoptx86;
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begin
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TestValMin := TestValMin * 2;
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TestValMax := TestValMax * 2;
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TestValSignedMax := TestValSignedMax * 2;
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end
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else
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begin
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TestValMin := TestValMin + taicpu(hp1).oper[0]^.val;
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TestValMax := TestValMax + taicpu(hp1).oper[0]^.val;
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TestValSignedMax := TestValSignedMax + taicpu(hp1).oper[0]^.val;
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end;
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end;
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A_SUB:
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@ -8285,11 +8354,13 @@ unit aoptx86;
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begin
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TestValMin := 0;
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TestValMax := 0;
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TestValSignedMax := 0;
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end
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else
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begin
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TestValMin := TestValMin - taicpu(hp1).oper[0]^.val;
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TestValMax := TestValMax - taicpu(hp1).oper[0]^.val;
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TestValSignedMax := TestValSignedMax - taicpu(hp1).oper[0]^.val;
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end;
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end;
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A_AND:
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@ -8304,21 +8375,21 @@ unit aoptx86;
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if ((taicpu(hp1).oper[0]^.val and $FF) = taicpu(hp1).oper[0]^.val) or
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((not(taicpu(hp1).oper[0]^.val) and $7F) = (not taicpu(hp1).oper[0]^.val)) then
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begin
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TrySmaller := S_B;
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TrySmallerLimit := $FF;
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TryShiftDown := S_B;
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TryShiftDownLimit := $FF;
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end;
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S_L:
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if ((taicpu(hp1).oper[0]^.val and $FF) = taicpu(hp1).oper[0]^.val) or
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((not(taicpu(hp1).oper[0]^.val) and $7F) = (not taicpu(hp1).oper[0]^.val)) then
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begin
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TrySmaller := S_B;
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TrySmallerLimit := $FF;
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TryShiftDown := S_B;
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TryShiftDownLimit := $FF;
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end
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else if ((taicpu(hp1).oper[0]^.val and $FFFF) = taicpu(hp1).oper[0]^.val) or
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((not(taicpu(hp1).oper[0]^.val) and $7FFF) = (not taicpu(hp1).oper[0]^.val)) then
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begin
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TrySmaller := S_W;
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TrySmallerLimit := $FFFF;
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TryShiftDown := S_W;
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TryShiftDownLimit := $FFFF;
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end;
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else
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InternalError(2020112320);
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@ -8326,6 +8397,7 @@ unit aoptx86;
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TestValMin := TestValMin and taicpu(hp1).oper[0]^.val;
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TestValMax := TestValMax and taicpu(hp1).oper[0]^.val;
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TestValSignedMax := TestValSignedMax and taicpu(hp1).oper[0]^.val;
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end;
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A_OR:
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begin
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@ -8336,6 +8408,7 @@ unit aoptx86;
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TestValMin := TestValMin or taicpu(hp1).oper[0]^.val;
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TestValMax := TestValMax or taicpu(hp1).oper[0]^.val;
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TestValSignedMax := TestValSignedMax or taicpu(hp1).oper[0]^.val;
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end;
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A_XOR:
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begin
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@ -8346,13 +8419,17 @@ unit aoptx86;
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TestValMin := TestValMin xor taicpu(hp1).oper[0]^.val;
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TestValMax := TestValMax xor taicpu(hp1).oper[0]^.val;
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TestValSignedMax := TestValSignedMax xor taicpu(hp1).oper[0]^.val;
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end;
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A_SHL:
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begin
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TestValMin := TestValMin shl taicpu(hp1).oper[0]^.val;
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TestValMax := TestValMax shl taicpu(hp1).oper[0]^.val;
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TestValSignedMax := TestValSignedMax shl taicpu(hp1).oper[0]^.val;
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end;
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A_SHR:
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A_SHR,
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{ The first instruction was MOVZX, so the value won't be negative }
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A_SAR:
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begin
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{ we might be able to go smaller if SHR appears first }
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if InstrMax = -1 then
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@ -8362,26 +8439,42 @@ unit aoptx86;
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S_W:
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if (taicpu(hp1).oper[0]^.val >= 8) then
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begin
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TrySmaller := S_B;
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TrySmallerLimit := $FF;
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TryShiftDown := S_B;
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TryShiftDownLimit := $FF;
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TryShiftDownSignedLimit := $7F;
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TrySmallerSignedLowerLimit := -128;
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end;
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S_L:
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if (taicpu(hp1).oper[0]^.val >= 24) then
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begin
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TrySmaller := S_B;
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TrySmallerLimit := $FF;
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TryShiftDown := S_B;
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TryShiftDownLimit := $FF;
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TryShiftDownSignedLimit := $7F;
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TrySmallerSignedLowerLimit := -128;
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end
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else if (taicpu(hp1).oper[0]^.val >= 16) then
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begin
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TrySmaller := S_W;
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TrySmallerLimit := $FFFF;
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TryShiftDown := S_W;
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TryShiftDownLimit := $FFFF;
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TryShiftDownSignedLimit := $7FFF;
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TrySmallerSignedLowerLimit := -32768;
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end;
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else
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InternalError(2020112321);
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end;
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TestValMin := TestValMin shr taicpu(hp1).oper[0]^.val;
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TestValMax := TestValMax shr taicpu(hp1).oper[0]^.val;
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if taicpu(hp1).opcode = A_SAR then
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begin
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TestValMin := SarInt64(TestValMin, taicpu(hp1).oper[0]^.val);
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TestValMax := SarInt64(TestValMax, taicpu(hp1).oper[0]^.val);
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TestValSignedMax := SarInt64(TestValSignedMax, taicpu(hp1).oper[0]^.val);
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end
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else
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begin
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TestValMin := TestValMin shr taicpu(hp1).oper[0]^.val;
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TestValMax := TestValMax shr taicpu(hp1).oper[0]^.val;
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TestValSignedMax := TestValSignedMax shr taicpu(hp1).oper[0]^.val;
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end;
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end;
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else
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InternalError(2020112303);
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@ -8400,6 +8493,7 @@ unit aoptx86;
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TestValMin := TestValMin * TestValMin;
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TestValMax := TestValMax * TestValMax;
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TestValSignedMax := TestValSignedMax * TestValMax;
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end;
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3:
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begin
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@ -8414,6 +8508,7 @@ unit aoptx86;
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TestValMin := TestValMin * taicpu(hp1).oper[0]^.val;
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TestValMax := TestValMax * taicpu(hp1).oper[0]^.val;
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TestValSignedMax := TestValSignedMax * taicpu(hp1).oper[0]^.val;
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end;
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else
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Break;
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@ -8434,6 +8529,7 @@ unit aoptx86;
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TestValMin := TestValMin div taicpu(hp1).oper[0]^.val;
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TestValMax := TestValMax div taicpu(hp1).oper[0]^.val;
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TestValSignedMax := TestValSignedMax div taicpu(hp1).oper[0]^.val;
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end;
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else
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Break;
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@ -8442,7 +8538,7 @@ unit aoptx86;
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A_MOVSX{$ifdef x86_64}, A_MOVSXD{$endif x86_64}:
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begin
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{ If there are no instructions in between, then we might be able to make a saving }
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if (InstrMax <> -1) or (taicpu(hp1).oper[0]^.typ <> top_reg) or (taicpu(hp1).oper[0]^.reg <> ThisReg) then
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if SignedOverflow or (taicpu(hp1).oper[0]^.typ <> top_reg) or (taicpu(hp1).oper[0]^.reg <> ThisReg) then
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Break;
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{ We have something like:
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@ -8481,7 +8577,7 @@ unit aoptx86;
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A_MOVZX:
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begin
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if not MatchOpType(taicpu(hp1), top_reg, top_reg) then
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if UnsignedOverflow or (taicpu(hp1).oper[0]^.typ <> top_reg) then
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Break;
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if not SuperRegistersEqual(taicpu(hp1).oper[0]^.reg, ThisReg) then
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@ -8513,10 +8609,10 @@ movzx_cascade:
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TargetSize := S_L;
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TargetSubReg := R_SUBD;
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end
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else if ((TrySmaller in [S_B, S_W]) and not SmallerOverflow) then
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else if ((TryShiftDown in [S_B, S_W]) and not ShiftDownOverflow) then
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begin
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TargetSize := TrySmaller;
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if TrySmaller = S_B then
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TargetSize := TryShiftDown;
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if TryShiftDown = S_B then
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TargetSubReg := R_SUBL
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else
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TargetSubReg := R_SUBW;
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@ -8530,7 +8626,7 @@ movzx_cascade:
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TargetSize := S_W;
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TargetSubReg := R_SUBW;
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end
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else if ((TrySmaller = S_B) and not SmallerOverflow) then
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else if ((TryShiftDown = S_B) and not ShiftDownOverflow) then
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begin
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TargetSize := S_B;
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TargetSubReg := R_SUBL;
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@ -8544,7 +8640,7 @@ movzx_cascade:
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TargetSize := S_L;
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TargetSubReg := R_SUBD;
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end
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else if ((TrySmaller = S_B) and not SmallerOverflow) then
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else if ((TryShiftDown = S_B) and not ShiftDownOverflow) then
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begin
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TargetSize := S_B;
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TargetSubReg := R_SUBL;
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@ -8752,13 +8848,18 @@ movzx_cascade:
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Break;
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end;
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if (TestValMin < 0) or (TestValMax < 0) or
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(TestValMin > UpperLimit) or (TestValMax > UpperLimit) then
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{ Overflow }
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if (TestValSignedMax > SignedLowerLimit) or (TestValSignedMax < SignedLowerLimitBottom) then
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SignedOverflow := True;
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if (TestValMin > UpperLimit) or (TestValMax > UpperLimit) or (TestValSignedMax > UpperLimit) or
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(TestValMin < SignedLowerLimitBottom) or (TestValMax < SignedLowerLimitBottom) or (TestValSignedMax > SignedLowerLimitBottom) then
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{ Absolute overflow }
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Break
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else if not SmallerOverflow and (TrySmaller <> S_NO) and
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((TestValMin > TrySmallerLimit) or (TestValMax > TrySmallerLimit)) then
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SmallerOverflow := True;
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else if not ShiftDownOverflow and (TryShiftDown <> S_NO) and
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((TestValMin > TryShiftDownLimit) or (TestValMax > TryShiftDownLimit)) then
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ShiftDownOverflow := True
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else if (TestValMin < 0) or (TestValMax < 0) then
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UnsignedOverflow := True;
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{ Contains highest index (so instruction count - 1) }
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Inc(InstrMax);
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