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Remove Montgomery divisor cache

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Marek Lemańczyk committed 2025-10-11 20:50:13 +02:00
1 parent fca650b285
commit cd69c08fb4
3 files changed
+26 -31
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PerfectNumbers.Core/Cpu/MersenneNumberDivisorByDivisorCpuTester.cs
+26 -2
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@@ -192,6 +192,10 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
Dictionary<ulong, MersenneDivisorCycles.FactorCacheEntry>? factorCache = null;
DivisorCycleCache cycleCache = DivisorCycleCache.Shared;
ulong cachedModulus = 0UL;
MontgomeryDivisorData cachedDivisorData = default;
bool hasCachedDivisorData = false;
byte step10 = (byte)(step % 10UL);
byte step8 = (byte)(step % 8UL);
byte step5 = (byte)(step % 5UL);
@@ -222,7 +226,14 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
if (admissible && (remainder8 == 1 || remainder8 == 7) && remainder3 != 0 && remainder5 != 0 && remainder7 != 0 && remainder11 != 0)
{
MontgomeryDivisorData divisorData = MontgomeryDivisorDataCache.Get(candidate);
if (!hasCachedDivisorData || cachedModulus != candidate)
{
cachedDivisorData = MontgomeryDivisorData.FromModulus(candidate);
cachedModulus = candidate;
hasCachedDivisorData = true;
}
MontgomeryDivisorData divisorData = cachedDivisorData;
ulong divisorCycle;
if (candidate <= PerfectNumberConstants.MaxQForDivisorCycles)
@@ -340,6 +351,9 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
{
private readonly MersenneNumberDivisorByDivisorCpuTester _owner;
private bool _disposed;
private bool _hasCachedDivisorData;
private ulong _cachedDivisor;
private MontgomeryDivisorData _cachedDivisorData;
internal DivisorScanSession(MersenneNumberDivisorByDivisorCpuTester owner)
{
@@ -349,6 +363,9 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
internal void Reset()
{
_disposed = false;
_hasCachedDivisorData = false;
_cachedDivisor = 0UL;
_cachedDivisorData = default;
}
public void CheckDivisor(ulong divisor, in MontgomeryDivisorData divisorData, ulong divisorCycle, ReadOnlySpan<ulong> primes, Span<byte> hits)
@@ -367,7 +384,14 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
MontgomeryDivisorData cachedData = divisorData;
if (cachedData.Modulus != divisor)
{
cachedData = MontgomeryDivisorDataCache.Get(divisor);
if (!_hasCachedDivisorData || _cachedDivisor != divisor)
{
_cachedDivisorData = MontgomeryDivisorData.FromModulus(divisor);
_cachedDivisor = divisor;
_hasCachedDivisorData = true;
}
cachedData = _cachedDivisorData;
}
if (divisorCycle == 0UL)
PerfectNumbers.Core/Gpu/MersenneNumberDivisorByDivisorGpuTester.cs
-1
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@@ -7,7 +7,6 @@ using System.Numerics;
using ILGPU;
using ILGPU.Runtime;
using MontgomeryDivisorData = PerfectNumbers.Core.MontgomeryDivisorData;
using MontgomeryDivisorDataCache = PerfectNumbers.Core.MontgomeryDivisorDataCache;
using CycleRemainderStepper = PerfectNumbers.Core.CycleRemainderStepper;
namespace PerfectNumbers.Core.Gpu;
PerfectNumbers.Core/MontgomeryDivisorData.cs
-28
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@@ -45,32 +45,4 @@ public readonly struct MontgomeryDivisorData(ulong modulus, ulong nPrime, ulong
montgomeryTwo,
montgomeryTwoSquared);
}
}
internal static class MontgomeryDivisorDataCache
{
[ThreadStatic]
private static bool s_hasCachedValue;
[ThreadStatic]
private static ulong s_cachedModulus;
[ThreadStatic]
private static MontgomeryDivisorData s_cachedData;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static MontgomeryDivisorData Get(ulong modulus)
{
if (s_hasCachedValue && s_cachedModulus == modulus)
{
return s_cachedData;
}
MontgomeryDivisorData computed = MontgomeryDivisorData.FromModulus(modulus);
s_cachedModulus = modulus;
s_cachedData = computed;
s_hasCachedValue = true;
return computed;
}
}