Use divisor squares to bound heuristic combined trial division

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Marek Lemańczyk committed 2025-10-29 15:13:54 +01:00
1 parent 4ab77ba170
commit b0158a844a
4 files changed
+351 -235

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@@ -17,29 +17,33 @@ public sealed class HeuristicCombinedPrimeTester
{
HeuristicPrimeSieves.EnsureInitialized();
CombinedDivisorsEnding1TwoAOneB = BuildCombinedDivisors(1, CombinedDivisorPattern.TwoAOneB);
CombinedDivisorsEnding3TwoAOneB = BuildCombinedDivisors(3, CombinedDivisorPattern.TwoAOneB);
CombinedDivisorsEnding7TwoAOneB = BuildCombinedDivisors(7, CombinedDivisorPattern.TwoAOneB);
CombinedDivisorsEnding9TwoAOneB = BuildCombinedDivisors(9, CombinedDivisorPattern.TwoAOneB);
CombinedDivisorsEnding1TwoAOneB = BuildCombinedDivisors(1, CombinedDivisorPattern.TwoAOneB, out CombinedDivisorsEnding1TwoAOneBSquares);
CombinedDivisorsEnding3TwoAOneB = BuildCombinedDivisors(3, CombinedDivisorPattern.TwoAOneB, out CombinedDivisorsEnding3TwoAOneBSquares);
CombinedDivisorsEnding7TwoAOneB = BuildCombinedDivisors(7, CombinedDivisorPattern.TwoAOneB, out CombinedDivisorsEnding7TwoAOneBSquares);
CombinedDivisorsEnding9TwoAOneB = BuildCombinedDivisors(9, CombinedDivisorPattern.TwoAOneB, out CombinedDivisorsEnding9TwoAOneBSquares);
CombinedDivisorsEnding1OneAOneB = BuildCombinedDivisors(1, CombinedDivisorPattern.OneAOneB);
CombinedDivisorsEnding3OneAOneB = BuildCombinedDivisors(3, CombinedDivisorPattern.OneAOneB);
CombinedDivisorsEnding7OneAOneB = BuildCombinedDivisors(7, CombinedDivisorPattern.OneAOneB);
CombinedDivisorsEnding9OneAOneB = BuildCombinedDivisors(9, CombinedDivisorPattern.OneAOneB);
CombinedDivisorsEnding1OneAOneB = BuildCombinedDivisors(1, CombinedDivisorPattern.OneAOneB, out CombinedDivisorsEnding1OneAOneBSquares);
CombinedDivisorsEnding3OneAOneB = BuildCombinedDivisors(3, CombinedDivisorPattern.OneAOneB, out CombinedDivisorsEnding3OneAOneBSquares);
CombinedDivisorsEnding7OneAOneB = BuildCombinedDivisors(7, CombinedDivisorPattern.OneAOneB, out CombinedDivisorsEnding7OneAOneBSquares);
CombinedDivisorsEnding9OneAOneB = BuildCombinedDivisors(9, CombinedDivisorPattern.OneAOneB, out CombinedDivisorsEnding9OneAOneBSquares);
CombinedDivisorsEnding1ThreeAOneB = BuildCombinedDivisors(1, CombinedDivisorPattern.ThreeAOneB);
CombinedDivisorsEnding3ThreeAOneB = BuildCombinedDivisors(3, CombinedDivisorPattern.ThreeAOneB);
CombinedDivisorsEnding7ThreeAOneB = BuildCombinedDivisors(7, CombinedDivisorPattern.ThreeAOneB);
CombinedDivisorsEnding9ThreeAOneB = BuildCombinedDivisors(9, CombinedDivisorPattern.ThreeAOneB);
CombinedDivisorsEnding1ThreeAOneB = BuildCombinedDivisors(1, CombinedDivisorPattern.ThreeAOneB, out CombinedDivisorsEnding1ThreeAOneBSquares);
CombinedDivisorsEnding3ThreeAOneB = BuildCombinedDivisors(3, CombinedDivisorPattern.ThreeAOneB, out CombinedDivisorsEnding3ThreeAOneBSquares);
CombinedDivisorsEnding7ThreeAOneB = BuildCombinedDivisors(7, CombinedDivisorPattern.ThreeAOneB, out CombinedDivisorsEnding7ThreeAOneBSquares);
CombinedDivisorsEnding9ThreeAOneB = BuildCombinedDivisors(9, CombinedDivisorPattern.ThreeAOneB, out CombinedDivisorsEnding9ThreeAOneBSquares);
CombinedDivisorsEnding1ThreeATwoB = BuildCombinedDivisors(1, CombinedDivisorPattern.ThreeATwoB);
CombinedDivisorsEnding3ThreeATwoB = BuildCombinedDivisors(3, CombinedDivisorPattern.ThreeATwoB);
CombinedDivisorsEnding7ThreeATwoB = BuildCombinedDivisors(7, CombinedDivisorPattern.ThreeATwoB);
CombinedDivisorsEnding9ThreeATwoB = BuildCombinedDivisors(9, CombinedDivisorPattern.ThreeATwoB);
CombinedDivisorsEnding1ThreeATwoB = BuildCombinedDivisors(1, CombinedDivisorPattern.ThreeATwoB, out CombinedDivisorsEnding1ThreeATwoBSquares);
CombinedDivisorsEnding3ThreeATwoB = BuildCombinedDivisors(3, CombinedDivisorPattern.ThreeATwoB, out CombinedDivisorsEnding3ThreeATwoBSquares);
CombinedDivisorsEnding7ThreeATwoB = BuildCombinedDivisors(7, CombinedDivisorPattern.ThreeATwoB, out CombinedDivisorsEnding7ThreeATwoBSquares);
CombinedDivisorsEnding9ThreeATwoB = BuildCombinedDivisors(9, CombinedDivisorPattern.ThreeATwoB, out CombinedDivisorsEnding9ThreeATwoBSquares);
CombinedDivisorsEnding1 = CombinedDivisorsEnding1OneAOneB;
CombinedDivisorsEnding3 = CombinedDivisorsEnding3OneAOneB;
CombinedDivisorsEnding7 = CombinedDivisorsEnding7OneAOneB;
CombinedDivisorsEnding9 = CombinedDivisorsEnding9OneAOneB;
CombinedDivisorsEnding1Squares = CombinedDivisorsEnding1OneAOneBSquares;
CombinedDivisorsEnding3Squares = CombinedDivisorsEnding3OneAOneBSquares;
CombinedDivisorsEnding7Squares = CombinedDivisorsEnding7OneAOneBSquares;
CombinedDivisorsEnding9Squares = CombinedDivisorsEnding9OneAOneBSquares;
}
private const ulong Wheel210 = 210UL;
@@ -71,6 +75,31 @@ public sealed class HeuristicCombinedPrimeTester
private static readonly uint[] CombinedDivisorsEnding7;
private static readonly uint[] CombinedDivisorsEnding9;
private static readonly ulong[] CombinedDivisorsEnding1TwoAOneBSquares;
private static readonly ulong[] CombinedDivisorsEnding3TwoAOneBSquares;
private static readonly ulong[] CombinedDivisorsEnding7TwoAOneBSquares;
private static readonly ulong[] CombinedDivisorsEnding9TwoAOneBSquares;
private static readonly ulong[] CombinedDivisorsEnding1OneAOneBSquares;
private static readonly ulong[] CombinedDivisorsEnding3OneAOneBSquares;
private static readonly ulong[] CombinedDivisorsEnding7OneAOneBSquares;
private static readonly ulong[] CombinedDivisorsEnding9OneAOneBSquares;
private static readonly ulong[] CombinedDivisorsEnding1ThreeAOneBSquares;
private static readonly ulong[] CombinedDivisorsEnding3ThreeAOneBSquares;
private static readonly ulong[] CombinedDivisorsEnding7ThreeAOneBSquares;
private static readonly ulong[] CombinedDivisorsEnding9ThreeAOneBSquares;
private static readonly ulong[] CombinedDivisorsEnding1ThreeATwoBSquares;
private static readonly ulong[] CombinedDivisorsEnding3ThreeATwoBSquares;
private static readonly ulong[] CombinedDivisorsEnding7ThreeATwoBSquares;
private static readonly ulong[] CombinedDivisorsEnding9ThreeATwoBSquares;
private static readonly ulong[] CombinedDivisorsEnding1Squares;
private static readonly ulong[] CombinedDivisorsEnding3Squares;
private static readonly ulong[] CombinedDivisorsEnding7Squares;
private static readonly ulong[] CombinedDivisorsEnding9Squares;
private static readonly ulong[] HeuristicSmallCycleSnapshot = MersenneDivisorCycles.Shared.ExportSmallCyclesSnapshot();
internal enum CombinedDivisorPattern : byte
@@ -155,21 +184,28 @@ public sealed class HeuristicCombinedPrimeTester
private static bool HeuristicTrialDivisionCpu(ulong n, ulong sqrtLimit, byte nMod10)
{
ReadOnlySpan<uint> combinedDivisors = GetCombinedDivisors(nMod10);
if (combinedDivisors.IsEmpty)
ReadOnlySpan<ulong> combinedDivisorSquares = GetCombinedDivisorSquares(nMod10);
if (combinedDivisors.IsEmpty || combinedDivisorSquares.IsEmpty)
{
return EvaluateWithOpenNumericFallback(n);
}
int length = combinedDivisors.Length;
int squaresLength = combinedDivisorSquares.Length;
if (squaresLength < length)
{
length = squaresLength;
}
for (int i = 0; i < length; i++)
{
uint entry = combinedDivisors[i];
if (entry > sqrtLimit)
ulong divisorSquare = combinedDivisorSquares[i];
if (divisorSquare > n)
{
break;
}
if (n % entry == 0UL)
if (n % combinedDivisors[i] == 0UL)
{
return false;
}
@@ -180,98 +216,88 @@ public sealed class HeuristicCombinedPrimeTester
private static bool HeuristicTrialDivisionGpuDetectsDivisor(ulong n, ulong sqrtLimit, byte nMod10)
{
int batchCapacity = HeuristicGpuDivisorBatchSize;
var divisorPool = ThreadStaticPools.UlongPool;
var hitPool = ThreadStaticPools.BytePool;
int batchCapacity = HeuristicGpuDivisorBatchSize;
var divisorPool = ThreadStaticPools.UlongPool;
ulong[] divisorArray = divisorPool.Rent(batchCapacity);
byte[] hitFlags = hitPool.Rent(batchCapacity);
ulong[] divisorArray = divisorPool.Rent(batchCapacity);
var limiter = GpuPrimeWorkLimiter.Acquire();
var gpu = PrimeTester.PrimeTesterGpuContextPool.Rent();
var accelerator = gpu.Accelerator;
var state = PrimeTester.GpuKernelState.GetOrCreate(accelerator);
var scratch = state.RentScratch(batchCapacity, accelerator);
var limiter = GpuPrimeWorkLimiter.Acquire();
var gpu = PrimeTester.PrimeTesterGpuContextPool.Rent(batchCapacity, 1);
var accelerator = gpu.Accelerator;
var state = gpu.State;
var scratch = gpu.Scratch;
bool compositeDetected = false;
int count = 0;
bool compositeDetected = false;
int count = 0;
var input = scratch.Input;
var output = scratch.Output;
var inputView = scratch.Input.View;
var outputView = scratch.Output.View;
bool ProcessBatch(int length)
{
input.View.CopyFromCPU(ref divisorArray[0], length);
state.HeuristicTrialDivisionKernel(length, input.View, n, output.View);
accelerator.Synchronize();
output.View.CopyToCPU(ref hitFlags[0], length);
bool ProcessBatch(int length)
{
inputView.CopyFromCPU(ref divisorArray[0], length);
byte compositeFlag = 0;
outputView.CopyFromCPU(ref compositeFlag, 1);
state.HeuristicTrialDivisionKernel(length, inputView, n, outputView);
accelerator.Synchronize();
outputView.CopyToCPU(ref compositeFlag, 1);
for (int i = 0; i < length; i++)
{
if (hitFlags[i] == 0)
{
continue;
}
return compositeFlag != 0;
}
return true;
// ulong divisor = divisorArray[i];
// if (divisor > 1UL && n % divisor == 0UL)
// {
// return true;
// }
}
ReadOnlySpan<uint> combinedDivisors = GetCombinedDivisors(nMod10);
ReadOnlySpan<ulong> combinedDivisorSquares = GetCombinedDivisorSquares(nMod10);
return false;
}
if (combinedDivisors.IsEmpty || combinedDivisorSquares.IsEmpty)
{
goto Cleanup;
}
ReadOnlySpan<uint> combinedDivisors = GetCombinedDivisors(nMod10);
if (combinedDivisors.IsEmpty)
{
goto Cleanup;
}
int length = combinedDivisors.Length;
int squaresLength = combinedDivisorSquares.Length;
if (squaresLength < length)
{
length = squaresLength;
}
int length = combinedDivisors.Length;
for (int i = 0; i < length; i++)
{
uint entry = combinedDivisors[i];
if (entry > sqrtLimit)
{
break;
}
for (int i = 0; i < length; i++)
{
ulong divisorSquare = combinedDivisorSquares[i];
if (divisorSquare > n)
{
break;
}
divisorArray[count] = entry;
count++;
divisorArray[count] = combinedDivisors[i];
count++;
if (count == batchCapacity)
{
if (ProcessBatch(count))
{
compositeDetected = true;
goto Cleanup;
}
if (count == batchCapacity)
{
if (ProcessBatch(count))
{
compositeDetected = true;
goto Cleanup;
}
count = 0;
}
}
count = 0;
}
}
if (!compositeDetected && count > 0)
{
if (ProcessBatch(count))
{
compositeDetected = true;
goto Cleanup;
}
}
if (count > 0 && ProcessBatch(count))
{
compositeDetected = true;
goto Cleanup;
}
Cleanup:
state.ReturnScratch(scratch);
divisorPool.Return(divisorArray);
hitPool.Return(hitFlags);
gpu.Dispose();
limiter.Dispose();
return compositeDetected;
Cleanup:
divisorPool.Return(divisorArray);
gpu.Dispose();
limiter.Dispose();
return compositeDetected;
}
private static bool EvaluateWithOpenNumericFallback(ulong n)
{
return Prime.Numbers.IsPrime(n);
@@ -312,6 +338,18 @@ public sealed class HeuristicCombinedPrimeTester
};
}
private static ReadOnlySpan<ulong> GetCombinedDivisorSquares(byte nMod10)
{
return nMod10 switch
{
1 => CombinedDivisorsEnding1Squares,
3 => CombinedDivisorsEnding3Squares,
7 => CombinedDivisorsEnding7Squares,
9 => CombinedDivisorsEnding9Squares,
_ => ReadOnlySpan<ulong>.Empty,
};
}
internal static ReadOnlySpan<uint> GetCombinedDivisors(byte nMod10, CombinedDivisorPattern pattern)
{
return pattern switch
@@ -352,7 +390,47 @@ public sealed class HeuristicCombinedPrimeTester
};
}
private static uint[] BuildCombinedDivisors(byte nMod10, CombinedDivisorPattern pattern)
internal static ReadOnlySpan<ulong> GetCombinedDivisorSquares(byte nMod10, CombinedDivisorPattern pattern)
{
return pattern switch
{
CombinedDivisorPattern.TwoAOneB => nMod10 switch
{
1 => CombinedDivisorsEnding1TwoAOneBSquares,
3 => CombinedDivisorsEnding3TwoAOneBSquares,
7 => CombinedDivisorsEnding7TwoAOneBSquares,
9 => CombinedDivisorsEnding9TwoAOneBSquares,
_ => ReadOnlySpan<ulong>.Empty,
},
CombinedDivisorPattern.OneAOneB => nMod10 switch
{
1 => CombinedDivisorsEnding1OneAOneBSquares,
3 => CombinedDivisorsEnding3OneAOneBSquares,
7 => CombinedDivisorsEnding7OneAOneBSquares,
9 => CombinedDivisorsEnding9OneAOneBSquares,
_ => ReadOnlySpan<ulong>.Empty,
},
CombinedDivisorPattern.ThreeAOneB => nMod10 switch
{
1 => CombinedDivisorsEnding1ThreeAOneBSquares,
3 => CombinedDivisorsEnding3ThreeAOneBSquares,
7 => CombinedDivisorsEnding7ThreeAOneBSquares,
9 => CombinedDivisorsEnding9ThreeAOneBSquares,
_ => ReadOnlySpan<ulong>.Empty,
},
CombinedDivisorPattern.ThreeATwoB => nMod10 switch
{
1 => CombinedDivisorsEnding1ThreeATwoBSquares,
3 => CombinedDivisorsEnding3ThreeATwoBSquares,
7 => CombinedDivisorsEnding7ThreeATwoBSquares,
9 => CombinedDivisorsEnding9ThreeATwoBSquares,
_ => ReadOnlySpan<ulong>.Empty,
},
_ => ReadOnlySpan<ulong>.Empty,
};
}
private static uint[] BuildCombinedDivisors(byte nMod10, CombinedDivisorPattern pattern, out ulong[] squares)
{
ReadOnlySpan<int> groupA = HeuristicPrimeSieves.GroupADivisors;
ReadOnlySpan<uint> groupB = GetGroupBDivisors(nMod10);
@@ -412,7 +490,16 @@ public sealed class HeuristicCombinedPrimeTester
}
}
return combined.ToArray();
uint[] result = combined.ToArray();
ulong[] resultSquares = new ulong[result.Length];
for (int i = 0; i < result.Length; i++)
{
ulong divisor = result[i];
resultSquares[i] = divisor * divisor;
}
squares = resultSquares;
return result;
}