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Modulo operators replaced with steppers, where possible.

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mlemanczyk committed 2025-12-08 20:57:47 +01:00
1 parent 475507ce0c
commit f7dbc017a9
15 files changed
+531 -151
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PerfectNumbers.Core/HeuristicPrimeTester.cs
+89 -70
View File
@@ -30,6 +30,23 @@ public sealed class HeuristicPrimeTester
private static readonly ulong[] HeuristicSmallCycleSnapshot = MersenneDivisorCycles.Shared.ExportSmallCyclesSnapshot();
[ThreadStatic]
private static BidirectionalCycleRemainderStepper _mod10Stepper;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static byte GetMod10Remainder(ulong value)
{
if (_mod10Stepper.Modulus != 10UL)
{
_mod10Stepper = new BidirectionalCycleRemainderStepper(10UL);
_mod10Stepper.Initialize(value);
return (byte)_mod10Stepper.Step(value);
}
// Caller must initialize once per thread before first use.
return (byte)_mod10Stepper.Step(value);
}
internal enum HeuristicDivisorGroup : byte
{
None = 0,
@@ -70,7 +87,7 @@ public sealed class HeuristicPrimeTester
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static bool IsPrimeCpu(ulong n)
{
byte nMod10 = (byte)n.Mod10();
byte nMod10 = GetMod10Remainder(n);
ulong maxDivisorSquare = ComputeHeuristicDivisorSquareLimit(n);
if (maxDivisorSquare < 9UL)
@@ -85,7 +102,7 @@ public sealed class HeuristicPrimeTester
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static bool IsPrimeGpu(PrimeOrderCalculatorAccelerator gpu, ulong n)
{
byte nMod10 = (byte)n.Mod10();
byte nMod10 = GetMod10Remainder(n);
ulong maxDivisorSquare = ComputeHeuristicDivisorSquareLimit(n);
return IsPrimeGpu(gpu, n, maxDivisorSquare, nMod10);
}
@@ -132,11 +149,11 @@ public sealed class HeuristicPrimeTester
break;
}
ulong divisor = groupADivisors[groupAIndex];
if (n % divisor == 0UL)
{
return false;
}
ulong divisor = groupADivisors[groupAIndex];
if (n.ReduceCycleRemainder(divisor) == 0UL)
{
return false;
}
groupAIndex++;
processed++;
@@ -186,10 +203,10 @@ public sealed class HeuristicPrimeTester
}
ulong divisor = groupADivisors[groupAIndex];
if (n % divisor == 0UL)
{
return false;
}
if (n.ReduceCycleRemainder(divisor) == 0UL)
{
return false;
}
groupAIndex++;
processed++;
@@ -220,7 +237,7 @@ public sealed class HeuristicPrimeTester
break;
}
if (n % divisor == 0UL)
if (n.ReduceCycleRemainder(divisor) == 0UL)
{
return false;
}
@@ -241,7 +258,6 @@ public sealed class HeuristicPrimeTester
private static bool HeuristicTrialDivisionGpuDetectsDivisor(PrimeOrderCalculatorAccelerator gpu, ulong n, ulong maxDivisorSquare, byte nMod10)
{
// GpuPrimeWorkLimiter.Acquire();
int acceleratorIndex = gpu.AcceleratorIndex;
var kernelLauncher = gpu.HeuristicCombinedTrialDivisionKernelLauncher;
bool compositeDetected;
@@ -252,13 +268,6 @@ public sealed class HeuristicPrimeTester
var stream = AcceleratorStreamPool.Rent(acceleratorIndex);
flagView1DView.CopyFromCPU(stream, ref compositeFlag, 1);
// Index1D index,
// ArrayView<int> resultFlag,
// ulong n,
// ulong maxDivisorSquare,
// HeuristicGpuDivisorTableKind tableKind,
// HeuristicGpuDivisorTables tables)
kernelLauncher(
stream,
1,
@@ -271,48 +280,9 @@ public sealed class HeuristicPrimeTester
flagView1DView.CopyToCPU(stream, ref compositeFlag, 1);
stream.Synchronize();
compositeDetected = compositeFlag != 0;
// compositeDetected = compositeFlag != 0;
// if (!compositeDetected)
// {
// ReadOnlySpan<byte> endingOrder = GetGroupBEndingOrder(nMod10);
// for (int i = 0; i < endingOrder.Length && !compositeDetected; i++)
// {
// byte ending = endingOrder[i];
// HeuristicGpuDivisorTableKind tableKind = ending switch
// {
// 1 => HeuristicGpuDivisorTableKind.GroupBEnding1,
// 7 => HeuristicGpuDivisorTableKind.GroupBEnding7,
// 9 => HeuristicGpuDivisorTableKind.GroupBEnding9,
// _ => HeuristicGpuDivisorTableKind.GroupA,
// };
// if (tableKind == HeuristicGpuDivisorTableKind.GroupA)
// {
// continue;
// }
// int divisorLength = GetGroupBDivisors(ending).Length;
// compositeFlag = 0;
// flagView1D.CopyFromCPU(stream, ref compositeFlag, 1);
// kernelLauncher(
// stream,
// 1,
// flagView1D,
// n,
// maxDivisorSquare,
// tableKind,
// gpu.HeuristicGpuTables);
// flagView1D.CopyToCPU(stream, ref compositeFlag, 1);
// stream.Synchronize();
// compositeDetected = compositeFlag != 0;
// }
// }
AcceleratorStreamPool.Return(acceleratorIndex, stream);
// GpuPrimeWorkLimiter.Release();
compositeDetected = compositeFlag != 0;
return compositeDetected;
}
@@ -556,6 +526,10 @@ public sealed class HeuristicPrimeTester
private readonly ReadOnlySpan<ulong> groupADivisorSquares;
private int groupAIndex;
private Span<HeuristicGroupBSequenceState> groupBStates;
private CycleRemainderStepper endingStepper;
private CycleRemainderStepper wheelStepper;
private bool hasRemainders;
private ulong lastDivisor;
public HeuristicDivisorEnumerator(ulong maxDivisorSquare, byte nMod10, Span<HeuristicGroupBSequenceState> groupBBuffer)
{
@@ -566,6 +540,10 @@ public sealed class HeuristicPrimeTester
int count = InitializeGroupBStates(nMod10, groupBBuffer);
groupBStates = count == 0 ? Span<HeuristicGroupBSequenceState>.Empty : groupBBuffer[..count];
endingStepper = new CycleRemainderStepper(10UL);
wheelStepper = new CycleRemainderStepper(Wheel210);
hasRemainders = false;
lastDivisor = 0UL;
}
public bool TryGetNext(out HeuristicDivisorCandidate candidate)
@@ -586,13 +564,14 @@ public sealed class HeuristicPrimeTester
HeuristicDivisorGroup group = currentIndex < GroupAConstantCount
? HeuristicDivisorGroup.GroupAConstant
: HeuristicDivisorGroup.GroupAWheel;
(byte ending, ushort wheelResidue) = UpdateRemainders(divisor);
candidate = new HeuristicDivisorCandidate(
divisor,
group,
(byte)(divisor % 10UL),
ending,
0,
(ushort)(divisor % Wheel210));
wheelResidue);
return true;
}
@@ -623,14 +602,35 @@ public sealed class HeuristicPrimeTester
ref HeuristicGroupBSequenceState bestState = ref groupBStates[bestIndex];
bestState.Advance();
(byte candidateEnding, ushort wheelResidueBest) = UpdateRemainders(bestCandidate);
candidate = new HeuristicDivisorCandidate(
bestCandidate,
HeuristicDivisorGroup.GroupB,
bestState.Ending,
candidateEnding,
bestState.PriorityIndex,
(ushort)(bestCandidate % Wheel210));
wheelResidueBest);
return true;
}
private (byte ending, ushort wheelResidue) UpdateRemainders(ulong divisor)
{
byte ending;
ushort wheelResidue;
if (!hasRemainders)
{
ending = (byte)endingStepper.Initialize(divisor);
wheelResidue = (ushort)wheelStepper.Initialize(divisor);
hasRemainders = true;
}
else
{
ending = (byte)endingStepper.ComputeNext(divisor);
wheelResidue = (ushort)wheelStepper.ComputeNext(divisor);
}
lastDivisor = divisor;
return (ending, wheelResidue);
}
}
@@ -684,6 +684,10 @@ public sealed class HeuristicPrimeTester
private readonly GpuUInt128 step;
private readonly GpuUInt128 limit;
private GpuUInt128 current;
private CycleRemainderStepper endingStepper;
private CycleRemainderStepper wheelStepper;
private byte currentEnding;
private ushort currentWheelResidue;
private MersenneDivisorResidueStepper residueStepper;
private bool active;
private ulong processedCount;
@@ -705,6 +709,21 @@ public sealed class HeuristicPrimeTester
current = hasCandidates ? firstDivisor : GpuUInt128.Zero;
residueStepper = hasCandidates ? new MersenneDivisorResidueStepper(exponent, stepLocal, firstDivisor) : default;
if (hasCandidates)
{
endingStepper = new CycleRemainderStepper(10UL);
currentEnding = (byte)endingStepper.Initialize(firstDivisor.Low);
wheelStepper = new CycleRemainderStepper(Wheel210);
currentWheelResidue = (ushort)wheelStepper.Initialize(firstDivisor.Low);
}
else
{
endingStepper = default;
wheelStepper = default;
currentEnding = 0;
currentWheelResidue = 0;
}
active = hasCandidates;
processedCount = 0UL;
lastDivisor = 0UL;
@@ -724,7 +743,7 @@ public sealed class HeuristicPrimeTester
if (admissible)
{
candidate = CreateCandidate(value);
candidate = CreateCandidate(value, currentEnding, currentWheelResidue);
return true;
}
}
@@ -746,6 +765,8 @@ public sealed class HeuristicPrimeTester
current = next;
residueStepper.Advance();
currentEnding = (byte)endingStepper.ComputeNext(next.Low);
currentWheelResidue = (ushort)wheelStepper.ComputeNext(next.Low);
}
public readonly ulong ProcessedCount => processedCount;
@@ -754,9 +775,8 @@ public sealed class HeuristicPrimeTester
public readonly bool Exhausted => !active;
private static HeuristicDivisorCandidate CreateCandidate(ulong value)
private static HeuristicDivisorCandidate CreateCandidate(ulong value, byte ending, ushort wheelResidue)
{
byte ending = (byte)(value % 10UL);
HeuristicDivisorGroup group;
if (value == 3UL || value == 7UL || value == 11UL || value == 13UL)
@@ -772,8 +792,7 @@ public sealed class HeuristicPrimeTester
group = HeuristicDivisorGroup.GroupB;
}
ushort residue = (ushort)(value % Wheel210);
return new HeuristicDivisorCandidate(value, group, ending, 0, residue);
return new HeuristicDivisorCandidate(value, group, ending, 0, wheelResidue);
}
}
}