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Merge pull request #238 from mlemanczyk/codex/optimize-evenperfectbitscanner-loops-kit1so

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Hoist prime order thresholds in CPU heuristics
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Marek Lemańczyk authored and GitHub committed 2025-10-27 21:31:23 +01:00
2 parents d381abe0cc 968dd89d0d
commit bd0727131f
11 files changed
+635 -351
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PerfectNumbers.Core/MersenneDivisorCycles.cs
+24 -36
View File
@@ -4,6 +4,7 @@ using System.Numerics;
using System.Runtime.CompilerServices;
using System.Security.Cryptography;
using System.Text;
using System.Runtime.InteropServices;
using PerfectNumbers.Core.Gpu;
using ILGPU;
using ILGPU.Runtime;
@@ -379,7 +380,8 @@ public class MersenneDivisorCycles
for (int i = 0; i < smallLength; i++)
{
ulong prime = smallPrimes[i];
if (smallPrimesSquared[i] > remaining)
ulong primeSquared = smallPrimesSquared[i];
if (primeSquared > remaining)
{
break;
}
@@ -439,26 +441,14 @@ public class MersenneDivisorCycles
private static void AddFactor(Dictionary<ulong, int> counts, ulong factor)
{
if (counts.TryGetValue(factor, out int existing))
{
counts[factor] = existing + 1;
}
else
{
counts[factor] = 1;
}
ref int entry = ref CollectionsMarshal.GetValueRefOrAddDefault(counts, factor, out bool exists);
entry = exists ? entry + 1 : 1;
}
private static void AddFactor(Dictionary<ulong, int> counts, ulong factor, int multiplicity)
{
if (counts.TryGetValue(factor, out int existing))
{
counts[factor] = existing + multiplicity;
}
else
{
counts[factor] = multiplicity;
}
ref int entry = ref CollectionsMarshal.GetValueRefOrAddDefault(counts, factor, out bool exists);
entry = exists ? entry + multiplicity : multiplicity;
}
private static ulong ReduceOrder(in MontgomeryDivisorData divisorData, ulong initialOrder, Dictionary<ulong, int> factorCounts)
@@ -536,8 +526,8 @@ public class MersenneDivisorCycles
private static void ProcessReduceOrderPrime(Span<ulong> candidateBuffer, Span<bool> evaluationBuffer, ref ulong order, ulong prime, int multiplicity, ref ExponentRemainderStepperCpu stepper)
{
ulong working = order;
int actual = 0;
while (actual < multiplicity)
int writeIndex = multiplicity;
while (writeIndex > 0)
{
if (working < prime)
{
@@ -550,26 +540,20 @@ public class MersenneDivisorCycles
break;
}
candidateBuffer[actual] = reduced;
writeIndex--;
candidateBuffer[writeIndex] = reduced;
working = reduced;
actual++;
}
int actual = multiplicity - writeIndex;
if (actual == 0)
{
return;
}
Span<ulong> candidates = candidateBuffer.Slice(0, actual);
Span<ulong> candidates = candidateBuffer.Slice(writeIndex, actual);
Span<bool> evaluations = evaluationBuffer.Slice(0, actual);
for (int left = 0, right = actual - 1; left < right; left++, right--)
{
ulong tmp = candidates[left];
candidates[left] = candidates[right];
candidates[right] = tmp;
}
stepper.Reset();
evaluations[0] = stepper.InitializeCpuIsUnity(candidates[0]);
@@ -599,24 +583,28 @@ public class MersenneDivisorCycles
// return 2UL;
// }
ulong modulus = n;
ulong nMinus1 = modulus - 1UL;
ulong nMinus2 = modulus - 2UL;
while (true)
{
ulong c = (NextRandomUInt64() % (n - 1UL)) + 1UL;
ulong x = (NextRandomUInt64() % (n - 2UL)) + 2UL;
ulong c = (NextRandomUInt64() % nMinus1) + 1UL;
ulong x = (NextRandomUInt64() % nMinus2) + 2UL;
ulong y = x;
ulong d = 1UL;
while (d == 1UL)
{
x = AdvancePolynomial(x, c, n);
y = AdvancePolynomial(y, c, n);
y = AdvancePolynomial(y, c, n);
x = AdvancePolynomial(x, c, modulus);
y = AdvancePolynomial(y, c, modulus);
y = AdvancePolynomial(y, c, modulus);
ulong diff = x > y ? x - y : y - x;
d = BinaryGcd(diff, n);
d = BinaryGcd(diff, modulus);
}
if (d != n)
if (d != modulus)
{
return d;
}