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Refine GPU residue utilities and add positive divisor tests

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Marek Lemańczyk committed 2025-09-13 16:47:38 +02:00
1 parent 515a1bb342
commit 58eb65ca9e
7 files changed
+224 -121
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PerfectNumbers.Core/Gpu/MersenneNumberIncrementalGpuTester.cs
+43 -19
View File
@@ -1,5 +1,6 @@
using System.Buffers;
using System.Runtime.InteropServices;
using ILGPU;
using ILGPU.Runtime;
namespace PerfectNumbers.Core.Gpu;
@@ -18,9 +19,20 @@ public class MersenneNumberIncrementalGpuTester(GpuKernelType kernelType, bool u
ulong divMul = (ulong)((((UInt128)1 << 64) - UInt128.One) / exponent) + 1UL;
byte last = lastIsSeven ? (byte)1 : (byte)0; // ILGPU kernels do not support bool parameters
var kernel = (_kernelType == GpuKernelType.Pow2Mod)
? gpuLease.Pow2ModKernel
: gpuLease.IncrementalKernel;
var pow2Kernel = gpuLease.Pow2ModKernel;
var incKernel = gpuLease.IncrementalKernel;
ulong step10 = ((exponent % 10UL) << 1) % 10UL;
ulong step8 = ((exponent & 7UL) << 1) & 7UL;
ulong step3 = ((exponent % 3UL) << 1) % 3UL;
ulong step5 = ((exponent % 5UL) << 1) % 5UL;
GpuUInt128 twoPGpu = (GpuUInt128)twoP;
var smallCyclesView = GpuKernelPool.EnsureSmallCyclesOnDevice(accelerator);
ArrayView1D<uint, Stride1D.Dense> smallPrimesView = default;
ArrayView1D<ulong, Stride1D.Dense> smallPrimesPow2View = default;
if (_kernelType == GpuKernelType.Pow2Mod)
{
(smallPrimesView, smallPrimesPow2View) = GpuKernelPool.EnsureSmallPrimesOnDevice(accelerator);
}
var orderBuffer = accelerator.Allocate1D<ulong>(batchSize);
// Avoid giant stack allocations that can trigger StackOverflow when batchSize is large.
@@ -39,27 +51,39 @@ public class MersenneNumberIncrementalGpuTester(GpuKernelType kernelType, bool u
Span<ulong> orders = orderArray.AsSpan(0, currentSize);
// Precompute residue automaton bases for this batch
UInt128 q0 = twoP * kStart + UInt128.One;
ulong q0m10 = q0.Mod10();
ulong q0m8 = q0.Mod8();
ulong q0m3 = q0.Mod3();
ulong q0m5 = q0.Mod5();
ulong step10 = ((exponent % 10UL) << 1) % 10UL;
ulong step8 = ((exponent & 7UL) << 1) & 7UL;
ulong step3 = ((exponent % 3UL) << 1) % 3UL;
ulong step5 = ((exponent % 5UL) << 1) % 5UL;
var smallCyclesView = GpuKernelPool.EnsureSmallCyclesOnDevice(accelerator);
kernel(currentSize, exponent, (GpuUInt128)twoP, (GpuUInt128)kStart, last, divMul,
q0m10, q0m8, q0m3, q0m5, orderBuffer.View, smallCyclesView);
if (_kernelType == GpuKernelType.Pow2Mod)
{
q0.Mod10_8_5_3(out ulong q0m10, out ulong q0m8, out ulong q0m5, out ulong q0m3);
var ra = new ResidueAutomatonArgs(q0m10, step10, q0m8, step8, q0m3, step3, q0m5, step5);
pow2Kernel(currentSize, exponent, twoPGpu, (GpuUInt128)kStart, last, divMul,
ra, orderBuffer.View, smallCyclesView, smallPrimesView, smallPrimesPow2View);
}
else
{
q0.Mod10_8_5_3(out ulong q0m10, out ulong q0m8, out ulong q0m5, out ulong q0m3);
incKernel(currentSize, exponent, twoPGpu, (GpuUInt128)kStart, last, divMul,
q0m10, q0m8, q0m3, q0m5, orderBuffer.View, smallCyclesView);
}
accelerator.Synchronize();
orderBuffer.View.CopyToCPU(ref MemoryMarshal.GetReference(orders), currentSize);
q = twoP * kStart + UInt128.One;
for (i = 0; i < currentSize && Volatile.Read(ref isPrime); i++, q += twoP)
if (_kernelType == GpuKernelType.Pow2Mod)
{
if (orders[i] != 0UL)
for (i = 0; i < currentSize; i++)
{
if (q.IsPrimeCandidate())
if (orders[i] != 0UL)
{
Volatile.Write(ref isPrime, false);
break;
}
}
}
else
{
q = twoP * kStart + UInt128.One;
for (i = 0; i < currentSize && Volatile.Read(ref isPrime); i++, q += twoP)
{
if (orders[i] != 0UL && q.IsPrimeCandidate())
{
Volatile.Write(ref isPrime, false);
}