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Smaller optimizations. Division by zero fixed?

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mlemanczyk committed 2025-10-17 14:18:49 +02:00
1 parent 5fcd082fff
commit 43cf4a978f
3 files changed
+33 -24
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PerfectNumbers.Core/PrimeOrderCalculator.Cpu.cs
+26 -20
View File
@@ -77,11 +77,17 @@ internal static partial class PrimeOrderCalculator
private static bool TrySpecialMaxCpu(ulong phi, ulong prime, PartialFactorResult factors, in MontgomeryDivisorData divisorData)
{
ReadOnlySpan<FactorEntry> factorSpan = factors.Factors;
int length = factors.Count;
ReadOnlySpan<FactorEntry> factorSpan = new(factors.Factors, 0, length);
for (int i = 0; i < length; i++)
{
ulong factor = factorSpan[i].Value;
// Don't uncomment this. If there is division by zero, that means something wrong.
// if (factor == 0UL)
// {
// continue;
// }
ulong reduced = phi / factor;
if (Pow2EqualsOneCpu(reduced, prime, divisorData))
{
@@ -638,7 +644,7 @@ internal static partial class PrimeOrderCalculator
private static bool Pow2EqualsOneCpu(ulong exponent, ulong prime, in MontgomeryDivisorData divisorData)
{
// if (IsGpuPow2Allowed)
if (IsGpuPow2Allowed)
{
ulong remainder = exponent.Pow2MontgomeryModWindowedGpu(divisorData, false);
// GpuPow2ModStatus status = PrimeOrderGpuHeuristics.TryPow2Mod(exponent, prime, out ulong remainder, divisorData);
@@ -741,26 +747,26 @@ internal static partial class PrimeOrderCalculator
remaining = PopulateSmallPrimeFactorsCpu(value, limit, counts);
// }
// int dictionaryCount = counts.Count;
// if (dictionaryCount <= FactorSlotCount)
// {
// int copyIndex = 0;
// foreach (KeyValuePair<ulong, int> entry in counts)
// {
// primeSlots[copyIndex] = entry.Key;
// exponentSlots[copyIndex] = entry.Value;
// copyIndex++;
// }
int dictionaryCount = counts.Count;
if (dictionaryCount <= FactorSlotCount)
{
int copyIndex = 0;
foreach (KeyValuePair<ulong, int> entry in counts)
{
primeSlots[copyIndex] = entry.Key;
exponentSlots[copyIndex] = entry.Value;
copyIndex++;
}
// factorCount = copyIndex;
// ThreadStaticPools.ReturnUlongIntDictionary(counts);
// counts = null;
// }
// else
// {
factorCount = copyIndex;
ThreadStaticPools.ReturnUlongIntDictionary(counts);
counts = null;
}
else
{
useDictionary = true;
// factorCount = dictionaryCount;
// }
factorCount = dictionaryCount;
}
}
PerfectNumbers.Core/ULongExtensions.cs
+5 -4
View File
@@ -331,10 +331,11 @@ public static class ULongExtensions
public static ulong Pow2MontgomeryModWindowedCpu(this ulong exponent, in MontgomeryDivisorData divisor, bool keepMontgomery)
{
ulong modulus = divisor.Modulus;
if (exponent == 0UL)
{
return keepMontgomery ? divisor.MontgomeryOne : 1UL % modulus;
}
// This should never happen in production code. If it does, we need to fix it.
// if (exponent == 0UL)
// {
// return keepMontgomery ? divisor.MontgomeryOne : 1UL % modulus;
// }
if (exponent <= Pow2WindowFallbackThreshold)
{
PerfectNumbers.Core/UnboundedTaskScheduler.cs
+2
View File
@@ -9,6 +9,8 @@ public sealed class UnboundedTaskScheduler : TaskScheduler
private UnboundedTaskScheduler()
{
ThreadPool.SetMaxThreads(100_000, 100_000);
ThreadPool.SetMinThreads(10_300, 100);
}
public override int MaximumConcurrencyLevel => int.MaxValue;