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even-perfect-numbers-scanner/PerfectNumbers.Core/Gpu/GpuKernelLease.cs
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using System.Collections.Concurrent;
using System.Runtime.CompilerServices;
using ILGPU;
using ILGPU.Runtime;
using static PerfectNumbers.Core.Gpu.GpuContextPool;
namespace PerfectNumbers.Core.Gpu;
public sealed class GpuKernelLease
{
private static readonly ConcurrentQueue<GpuKernelLease> Pool = new();
private IDisposable? _limiter;
private GpuContextLease? _gpu;
private KernelContainer? _kernels;
private AcceleratorStream? _stream;
private object? _executionLock;
private bool _disposed;
private GpuKernelLease()
{
}
internal static GpuKernelLease Rent(IDisposable limiter, GpuContextLease gpu, KernelContainer kernels)
{
if (!Pool.TryDequeue(out var lease))
{
lease = new GpuKernelLease();
}
lease._limiter = limiter;
lease._gpu = gpu;
lease._kernels = kernels;
lease._stream = null;
lease._executionLock = gpu.ExecutionLock;
lease._disposed = false;
return lease;
}
public Accelerator Accelerator => _gpu?.Accelerator ?? throw new NullReferenceException("GPU context is already released");
public AcceleratorStream Stream
{
get
{
if (_stream is { } stream)
{
return stream;
}
// It feels that we can combine these into 1 return statement, but that increases the max stack frame size to 3 from 2
stream = Accelerator.CreateStream();
_stream = stream;
return stream;
}
}
public ExecutionScope EnterExecutionScope() => new ExecutionScope(_executionLock);
public Action<AcceleratorStream, Index1D, ulong, ulong, ArrayView<GpuUInt128>, ArrayView<ulong>> OrderKernel
{
get
{
var accel = Accelerator; // avoid capturing 'this' in lambda
lock (_gpu!.Value.KernelInitLock)
{
return KernelContainer.InitOnce(ref _kernels!.Order, () =>
{
var loaded = accel.LoadAutoGroupedStreamKernel<Index1D, ulong, ulong, ArrayView<GpuUInt128>, ArrayView<ulong>>(OrderKernelScan);
var kernel = KernelUtil.GetKernel(loaded);
return kernel.CreateLauncherDelegate<Action<AcceleratorStream, Index1D, ulong, ulong, ArrayView<GpuUInt128>, ArrayView<ulong>>>();
});
}
}
}
public Action<AcceleratorStream, Index1D, ulong, GpuUInt128, GpuUInt128, byte, ulong, ResidueAutomatonArgs, ArrayView<ulong>, ArrayView1D<ulong, Stride1D.Dense>, ArrayView1D<uint, Stride1D.Dense>, ArrayView1D<uint, Stride1D.Dense>, ArrayView1D<ulong, Stride1D.Dense>, ArrayView1D<ulong, Stride1D.Dense>> Pow2ModKernel
{
get
{
var accel = Accelerator;
lock (_gpu!.Value.KernelInitLock)
{
return KernelContainer.InitOnce(ref _kernels!.Pow2Mod, () =>
{
var loaded = accel.LoadAutoGroupedStreamKernel<Index1D, ulong, GpuUInt128, GpuUInt128, byte, ulong, ResidueAutomatonArgs, ArrayView<ulong>, ArrayView1D<ulong, Stride1D.Dense>, ArrayView1D<uint, Stride1D.Dense>, ArrayView1D<uint, Stride1D.Dense>, ArrayView1D<ulong, Stride1D.Dense>, ArrayView1D<ulong, Stride1D.Dense>>(Pow2ModKernelScan);
var kernel = KernelUtil.GetKernel(loaded);
return kernel.CreateLauncherDelegate<Action<AcceleratorStream, Index1D, ulong, GpuUInt128, GpuUInt128, byte, ulong, ResidueAutomatonArgs, ArrayView<ulong>, ArrayView1D<ulong, Stride1D.Dense>, ArrayView1D<uint, Stride1D.Dense>, ArrayView1D<uint, Stride1D.Dense>, ArrayView1D<ulong, Stride1D.Dense>, ArrayView1D<ulong, Stride1D.Dense>>>();
});
}
}
}
public Action<AcceleratorStream, Index1D, ulong, GpuUInt128, GpuUInt128, byte, ulong, ulong, ulong, ulong, ulong, ArrayView<ulong>, ArrayView1D<ulong, Stride1D.Dense>> IncrementalKernel
{
get
{
var accel = Accelerator;
lock (_gpu!.Value.KernelInitLock)
{
return KernelContainer.InitOnce(ref _kernels!.Incremental, () =>
{
var loaded = accel.LoadAutoGroupedStreamKernel<Index1D, ulong, GpuUInt128, GpuUInt128, byte, ulong, ulong, ulong, ulong, ulong, ArrayView<ulong>, ArrayView1D<ulong, Stride1D.Dense>>(IncrementalKernelScan);
var kernel = KernelUtil.GetKernel(loaded);
return kernel.CreateLauncherDelegate<Action<AcceleratorStream, Index1D, ulong, GpuUInt128, GpuUInt128, byte, ulong, ulong, ulong, ulong, ulong, ArrayView<ulong>, ArrayView1D<ulong, Stride1D.Dense>>>();
});
}
}
}
public Action<AcceleratorStream, Index1D, ulong, GpuUInt128, GpuUInt128, byte, ulong, ResidueAutomatonArgs, ArrayView<int>, ArrayView1D<ulong, Stride1D.Dense>> IncrementalOrderKernel
{
get
{
var accel = Accelerator;
lock (_gpu!.Value.KernelInitLock)
{
return KernelContainer.InitOnce(ref _kernels!.IncrementalOrder, () =>
{
var loaded = accel.LoadAutoGroupedStreamKernel<Index1D, ulong, GpuUInt128, GpuUInt128, byte, ulong, ResidueAutomatonArgs, ArrayView<int>, ArrayView1D<ulong, Stride1D.Dense>>(IncrementalOrderKernelScan);
var kernel = KernelUtil.GetKernel(loaded);
return kernel.CreateLauncherDelegate<Action<AcceleratorStream, Index1D, ulong, GpuUInt128, GpuUInt128, byte, ulong, ResidueAutomatonArgs, ArrayView<int>, ArrayView1D<ulong, Stride1D.Dense>>>();
});
}
}
}
public Action<AcceleratorStream, Index1D, ulong, GpuUInt128, GpuUInt128, byte, ulong, ResidueAutomatonArgs, ArrayView<int>, ArrayView1D<ulong, Stride1D.Dense>> Pow2ModOrderKernel
{
get
{
var accel = Accelerator;
lock (_gpu!.Value.KernelInitLock)
{
return KernelContainer.InitOnce(ref _kernels!.Pow2ModOrder, () =>
{
var loaded = accel.LoadAutoGroupedStreamKernel<Index1D, ulong, GpuUInt128, GpuUInt128, byte, ulong, ResidueAutomatonArgs, ArrayView<int>, ArrayView1D<ulong, Stride1D.Dense>>(Pow2ModOrderKernelScan);
var kernel = KernelUtil.GetKernel(loaded);
return kernel.CreateLauncherDelegate<Action<AcceleratorStream, Index1D, ulong, GpuUInt128, GpuUInt128, byte, ulong, ResidueAutomatonArgs, ArrayView<int>, ArrayView1D<ulong, Stride1D.Dense>>>();
});
}
}
}
public Action<AcceleratorStream, Index1D, ulong, uint, ArrayView1D<uint, Stride1D.Dense>, ArrayView1D<ulong, Stride1D.Dense>, int, ArrayView1D<ulong, Stride1D.Dense>, ArrayView1D<int, Stride1D.Dense>, ArrayView1D<int, Stride1D.Dense>, ArrayView1D<ulong, Stride1D.Dense>> SmallPrimeFactorKernel
{
get
{
var accel = Accelerator;
lock (_gpu!.Value.KernelInitLock)
{
return KernelContainer.InitOnce(ref _kernels!.SmallPrimeFactor, () =>
{
var loaded = accel.LoadAutoGroupedStreamKernel<Index1D, ulong, uint, ArrayView1D<uint, Stride1D.Dense>, ArrayView1D<ulong, Stride1D.Dense>, int, ArrayView1D<ulong, Stride1D.Dense>, ArrayView1D<int, Stride1D.Dense>, ArrayView1D<int, Stride1D.Dense>, ArrayView1D<ulong, Stride1D.Dense>>(SmallPrimeFactorKernelScan);
var kernel = KernelUtil.GetKernel(loaded);
return kernel.CreateLauncherDelegate<Action<AcceleratorStream, Index1D, ulong, uint, ArrayView1D<uint, Stride1D.Dense>, ArrayView1D<ulong, Stride1D.Dense>, int, ArrayView1D<ulong, Stride1D.Dense>, ArrayView1D<int, Stride1D.Dense>, ArrayView1D<int, Stride1D.Dense>, ArrayView1D<ulong, Stride1D.Dense>>>();
});
}
}
}
private static void SmallPrimeFactorKernelScan(
Index1D index,
ulong value,
uint limit,
ArrayView1D<uint, Stride1D.Dense> primes,
ArrayView1D<ulong, Stride1D.Dense> squares,
int primeCount,
ArrayView1D<ulong, Stride1D.Dense> primeSlots,
ArrayView1D<int, Stride1D.Dense> exponentSlots,
ArrayView1D<int, Stride1D.Dense> countSlot,
ArrayView1D<ulong, Stride1D.Dense> remainingSlot)
{
if (index != 0)
{
return;
}
uint effectiveLimit = limit == 0 ? uint.MaxValue : limit;
ulong remaining = value;
int count = 0;
int capacity = (int)primeSlots.Length;
for (int i = 0; i < primeCount && remaining > 1UL && count < capacity; i++)
{
uint primeCandidate = primes[i];
if (primeCandidate == 0U || primeCandidate > effectiveLimit)
{
break;
}
ulong primeSquare = squares[i];
if (primeSquare != 0UL && primeSquare > remaining)
{
break;
}
ulong primeValue = primeCandidate;
if ((remaining % primeValue) != 0UL)
{
continue;
}
int exponent = 0;
do
{
remaining /= primeValue;
exponent++;
}
while ((remaining % primeValue) == 0UL);
primeSlots[count] = primeValue;
exponentSlots[count] = exponent;
count++;
}
countSlot[0] = count;
remainingSlot[0] = remaining;
}
// TODO: Plumb the small-cycles device buffer into all kernels that can benefit
// (some already accept it). Consider a compact type (byte/ushort) for memory footprint.
private static void IncrementalKernelScan(Index1D index, ulong exponent, GpuUInt128 twoP, GpuUInt128 kStart, byte lastIsSeven, ulong divMul,
ulong q0m10, ulong q0m8, ulong q0m3, ulong q0m5, ArrayView<ulong> orders,
ArrayView1D<ulong, Stride1D.Dense> smallCycles)
{
ulong idx = (ulong)index.X;
// TODO: Replace these `%` computations with the precomputed Mod3/Mod5 tables so GPU kernels reuse cached residues
// instead of performing modulo operations that the benchmarks showed slower on wide sweeps.
ulong idxMod3 = idx % 3UL;
ulong idxMod5 = idx % 5UL;
// residue automaton
ulong step10 = (exponent.Mod10() << 1).Mod10();
ulong r10 = q0m10 + (step10 * idx).Mod10();
r10 -= (r10 >= 10UL) ? 10UL : 0UL;
bool shouldCheck = r10 != 5UL; // skip q ≡ 5 (mod 10); other residues handled by r8/r3/r5
if (shouldCheck)
{
ulong step8 = ((exponent & 7UL) << 1) & 7UL;
ulong r8 = (q0m8 + ((step8 * idx) & 7UL)) & 7UL;
if (r8 != 1UL && r8 != 7UL)
{
shouldCheck = false;
}
else
{
// TODO: Swap these `%` filters to the shared Mod helpers so the residue automaton matches the benchmarked
// bitmask-based implementation for GPU workloads.
ulong step3 = ((exponent % 3UL) << 1) % 3UL;
ulong r3 = q0m3 + (step3 * idxMod3); r3 -= (r3 >= 3UL) ? 3UL : 0UL;
if (r3 == 0UL)
{
shouldCheck = false;
}
else
{
ulong step5Loc = ((exponent % 5UL) << 1) % 5UL;
ulong r5 = q0m5 + (step5Loc * idxMod5); if (r5 >= 5UL) r5 -= 5UL;
if (r5 == 0UL)
{
shouldCheck = false;
}
}
}
}
if (!shouldCheck)
{
orders[index] = 0UL;
return;
}
// TODO: Is this expected that the value of kStart is modified?
GpuUInt128 k = kStart + (GpuUInt128)idx;
GpuUInt128 q = twoP;
q.Mul64(k);
q.Add(GpuUInt128.One);
ReadOnlyGpuUInt128 readOnlyQ = q.AsReadOnly();
// Small-cycles in-kernel early rejection from device table
if (q.High == 0UL && q.Low < (ulong)smallCycles.Length)
{
ulong cycle = smallCycles[(int)q.Low];
if (cycle != 0UL && cycle <= exponent && (exponent % cycle) != 0UL)
{
orders[index] = 0UL;
return;
}
}
// TODO: q will be lowered by GpuUInt128.One here. Is this expected? Maybe that's why we have issues with the incremental kernel? Review other places where we use GpuUInt128 operators.
GpuUInt128 phi = q - GpuUInt128.One;
// TODO: Do we have the check here because we don't support high values or this is expected result?
if (phi.High != 0UL)
{
orders[index] = 0UL;
return;
}
ulong phi64 = phi.Low;
// TODO: Replace these Pow2Mod calls with the ProcessEightBitWindows helper when the shared windowed
// scalar implementation lands; benchmarks showed the windowed kernel trimming per-divisor runtime by ~2.4×.
if (GpuUInt128.Pow2Mod(phi64, in readOnlyQ) != GpuUInt128.One)
{
orders[index] = 0UL;
return;
}
GpuUInt128 halfPow = GpuUInt128.Pow2Mod(phi64 >> 1, in readOnlyQ) - GpuUInt128.One;
if (GpuUInt128.BinaryGcd(halfPow, q) != GpuUInt128.One)
{
orders[index] = 0UL;
return;
}
ulong div = FastDiv64Gpu(phi64, exponent, divMul);
GpuUInt128 divPow = GpuUInt128.Pow2Mod(div, in readOnlyQ) - GpuUInt128.One;
if (GpuUInt128.BinaryGcd(divPow, q) != GpuUInt128.One)
{
orders[index] = 0UL;
return;
}
orders[index] = 1UL;
}
private static void OrderKernelScan(Index1D index, ulong exponent, ulong divMul, ArrayView<GpuUInt128> qs, ArrayView<ulong> orders)
{
GpuUInt128 q = qs[index];
ReadOnlyGpuUInt128 readOnlyQ = q.AsReadOnly();
GpuUInt128 phi = q - GpuUInt128.One;
if (phi.High != 0UL)
{
orders[index] = 0UL;
return;
}
ulong phi64 = phi.Low;
// TODO: Once the ProcessEightBitWindows helper is available, switch this order kernel to that faster
// Pow2Mod variant so cycle checks inherit the same gains observed in GpuPow2ModBenchmarks.
GpuUInt128 pow = GpuUInt128.Pow2Mod(phi64, in readOnlyQ);
if (pow != GpuUInt128.One)
{
orders[index] = 0UL;
return;
}
GpuUInt128 halfPow = GpuUInt128.Pow2Mod(phi64 >> 1, in readOnlyQ) - GpuUInt128.One;
if (GpuUInt128.BinaryGcd(halfPow, q) != GpuUInt128.One)
{
orders[index] = 0UL;
return;
}
ulong div = FastDiv64Gpu(phi64, exponent, divMul);
GpuUInt128 divPow = GpuUInt128.Pow2Mod(div, in readOnlyQ) - GpuUInt128.One;
if (GpuUInt128.BinaryGcd(divPow, q) != GpuUInt128.One)
{
orders[index] = 0UL;
return;
}
orders[index] = exponent;
}
private void Dispose(bool disposing)
{
if (_disposed)
{
return;
}
if (disposing)
{
_stream?.Dispose();
_stream = null;
_gpu?.Dispose();
_gpu = null;
_executionLock = null;
_limiter?.Dispose();
_limiter = null;
}
_kernels = null;
_disposed = true;
Pool.Enqueue(this);
}
private static void Pow2ModKernelScan(Index1D index, ulong exponent, GpuUInt128 twoP, GpuUInt128 kStart, byte lastIsSeven, ulong _,
ResidueAutomatonArgs ra, ArrayView<ulong> orders,
ArrayView1D<ulong, Stride1D.Dense> smallCycles,
ArrayView1D<uint, Stride1D.Dense> smallPrimesLastOne,
ArrayView1D<uint, Stride1D.Dense> smallPrimesLastSeven,
ArrayView1D<ulong, Stride1D.Dense> smallPrimesPow2LastOne,
ArrayView1D<ulong, Stride1D.Dense> smallPrimesPow2LastSeven)
{
ulong idx = (ulong)index.X;
ulong idxMod3 = idx % 3UL;
ulong idxMod5 = idx % 5UL;
ulong r10 = ra.Q0M10 + (ra.Step10 * idx).Mod10(); r10 -= (r10 >= 10UL) ? 10UL : 0UL;
bool shouldCheck = r10 != 5UL;
if (shouldCheck)
{
ulong r8 = (ra.Q0M8 + ((ra.Step8 * idx) & 7UL)) & 7UL;
if (r8 != 1UL && r8 != 7UL)
{
shouldCheck = false;
}
else
{
ulong r3 = ra.Q0M3 + (ra.Step3 * idxMod3);
if (r3 >= 6UL) r3 -= 6UL;
if (r3 >= 3UL) r3 -= 3UL;
if (r3 == 0UL)
{
shouldCheck = false;
}
else
{
ulong r5 = ra.Q0M5 + (ra.Step5 * idxMod5);
if (r5 >= 15UL) r5 -= 15UL;
if (r5 >= 10UL) r5 -= 10UL;
if (r5 >= 5UL) r5 -= 5UL;
if (r5 == 0UL)
{
shouldCheck = false;
}
}
}
}
if (!shouldCheck)
{
orders[index] = 0UL;
return;
}
// TODO: kStart is modified after this. Is this expected?
kStart.Add(idx);
GpuUInt128 q = twoP;
q.Mul64(kStart);
q.Add(GpuUInt128.One);
ReadOnlyGpuUInt128 readOnlyQ = q.AsReadOnly();
if (q.High == 0UL && q.Low < (ulong)smallCycles.Length)
{
ulong cycle = smallCycles[(int)q.Low];
// cycle should always be initialized if we're within array limit in production code
if (cycle != 0UL && cycle <= exponent && (exponent % cycle) != 0UL)
{
orders[index] = 0UL;
return;
}
}
// TODO: Swap Pow2Minus1Mod for the eight-bit window helper once the scalar version switches;
// benchmarks show the windowed variant cuts large-divisor scans from ~51 µs to ~21 µs.
if (GpuUInt128.Pow2Minus1Mod(exponent, in readOnlyQ) != GpuUInt128.Zero)
{
orders[index] = 0UL;
return;
}
ArrayView1D<uint, Stride1D.Dense> primes = lastIsSeven != 0 ? smallPrimesLastSeven : smallPrimesLastOne;
ArrayView1D<ulong, Stride1D.Dense> primesPow2 = lastIsSeven != 0 ? smallPrimesPow2LastSeven : smallPrimesPow2LastOne;
int primesLen = (int)primes.Length;
for (int i = 0; i < primesLen; i++)
{
ulong square = primesPow2[i];
if (new GpuUInt128(0UL, square) > q)
{
break;
}
ulong prime = primes[i];
if (Mod128By64(q, prime) == 0UL)
{
orders[index] = 0UL;
return;
}
}
orders[index] = exponent;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static ulong FastDiv64Gpu(ulong value, ulong divisor, ulong mul)
{
ulong quotient = GpuUInt128.MulHigh(value, mul);
GpuUInt128 remainder = new(0UL, value);
GpuUInt128 product = new(GpuUInt128.MulHigh(quotient, divisor), quotient * divisor);
remainder.Sub(product);
if (remainder.High != 0UL || remainder.Low >= divisor)
{
quotient++;
}
return quotient;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static ulong Mod128By64(GpuUInt128 value, ulong modulus)
{
ulong rem = 0UL;
ulong part = value.High;
for (int i = 0; i < 64; i++)
{
rem = (rem << 1) | (part >> 63);
if (rem >= modulus)
{
rem -= modulus;
}
part <<= 1;
}
part = value.Low;
for (int i = 0; i < 64; i++)
{
rem = (rem << 1) | (part >> 63);
if (rem >= modulus)
{
rem -= modulus;
}
part <<= 1;
}
return rem;
}
// Device-friendly small cycle length for 2 mod divisor
private static ulong CalculateCycleLengthSmall(ulong divisor)
{
if ((divisor & (divisor - 1UL)) == 0UL)
return 1UL;
ulong order = 1UL, pow = 2UL;
while (pow != 1UL)
{
pow <<= 1;
if (pow > divisor)
pow -= divisor;
order++;
}
return order;
}
private static void IncrementalOrderKernelScan(Index1D index, ulong exponent, GpuUInt128 twoP, GpuUInt128 kStart, byte lastIsSeven, ulong divMul,
ResidueAutomatonArgs ra, ArrayView<int> found, ArrayView1D<ulong, Stride1D.Dense> smallCycles)
{
ulong idx = (ulong)index.X;
ulong idxMod3 = idx % 3UL;
ulong idxMod5 = idx % 5UL;
ulong r10 = ra.Q0M10 + (ra.Step10 * idx).Mod10(); r10 -= (r10 >= 10UL) ? 10UL : 0UL;
bool shouldCheck = r10 != 5UL;
if (shouldCheck)
{
ulong r8 = (ra.Q0M8 + ((ra.Step8 * idx) & 7UL)) & 7UL;
if (r8 != 1UL && r8 != 7UL)
{
shouldCheck = false;
}
else
{
ulong r3 = ra.Q0M3 + (ra.Step3 * idxMod3);
if (r3 >= 6UL) r3 -= 6UL;
if (r3 >= 3UL) r3 -= 3UL;
if (r3 == 0UL)
{
shouldCheck = false;
}
else
{
ulong r5 = ra.Q0M5 + (ra.Step5 * idxMod5);
if (r5 >= 15UL) r5 -= 15UL;
if (r5 >= 10UL) r5 -= 10UL;
if (r5 >= 5UL) r5 -= 5UL;
if (r5 == 0UL)
{
shouldCheck = false;
}
}
}
}
if (!shouldCheck)
{
return;
}
GpuUInt128 k = kStart + (GpuUInt128)idx;
GpuUInt128 q = twoP;
q.Mul64(k);
q.Add(GpuUInt128.One);
ReadOnlyGpuUInt128 readOnlyQ = q.AsReadOnly();
// Small-cycles in-kernel early rejection from device table
if (q.High == 0UL && q.Low < (ulong)smallCycles.Length)
{
ulong cycle = smallCycles[(int)q.Low];
if (cycle != 0UL && cycle <= exponent && (exponent % cycle) != 0UL)
{
return;
}
}
GpuUInt128 phi = q - GpuUInt128.One;
if (phi.High != 0UL)
{
return;
}
ulong phi64 = phi.Low;
// TODO: Upgrade this pow2mod order kernel to the ProcessEightBitWindows helper once available so GPU residue
// scans avoid the single-bit ladder that benchmarks found to be 2.3× slower on large exponents.
if (GpuUInt128.Pow2Mod(phi64, in readOnlyQ) != GpuUInt128.One)
{
return;
}
GpuUInt128 halfPow = GpuUInt128.Pow2Mod(phi64 >> 1, in readOnlyQ) - GpuUInt128.One;
if (GpuUInt128.BinaryGcd(halfPow, q) != GpuUInt128.One)
{
return;
}
ulong div = FastDiv64Gpu(phi64, exponent, divMul);
GpuUInt128 divPow = GpuUInt128.Pow2Mod(div, in readOnlyQ) - GpuUInt128.One;
if (GpuUInt128.BinaryGcd(divPow, q) != GpuUInt128.One)
{
return;
}
Atomic.Or(ref found[0], 1);
}
private static void Pow2ModOrderKernelScan(Index1D index, ulong exponent, GpuUInt128 twoP, GpuUInt128 kStart, byte lastIsSeven, ulong _,
ResidueAutomatonArgs ra, ArrayView<int> found, ArrayView1D<ulong, Stride1D.Dense> smallCycles)
{
ulong idx = (ulong)index.X;
ulong idxMod3 = idx % 3UL;
ulong idxMod5 = idx % 5UL;
ulong r10 = ra.Q0M10 + (ra.Step10 * idx).Mod10(); r10 -= (r10 >= 10UL) ? 10UL : 0UL;
bool shouldCheck = r10 != 5UL;
if (shouldCheck)
{
ulong r8 = (ra.Q0M8 + ((ra.Step8 * idx) & 7UL)) & 7UL;
if (r8 != 1UL && r8 != 7UL)
{
shouldCheck = false;
}
else
{
ulong r3 = ra.Q0M3 + (ra.Step3 * idxMod3);
if (r3 >= 6UL) r3 -= 6UL;
if (r3 >= 3UL) r3 -= 3UL;
if (r3 == 0UL)
{
shouldCheck = false;
}
else
{
ulong r5 = ra.Q0M5 + (ra.Step5 * idxMod5);
if (r5 >= 15UL) r5 -= 15UL;
if (r5 >= 10UL) r5 -= 10UL;
if (r5 >= 5UL) r5 -= 5UL;
if (r5 == 0UL)
{
shouldCheck = false;
}
}
}
}
if (!shouldCheck)
{
return;
}
GpuUInt128 k = kStart + (GpuUInt128)idx;
GpuUInt128 q = twoP;
q.Mul64(k);
q.Add(GpuUInt128.One);
ReadOnlyGpuUInt128 readOnlyQ = q.AsReadOnly();
// Small-cycles in-kernel early rejection from device table
if (q.High == 0UL && q.Low < (ulong)smallCycles.Length)
{
ulong cycle = smallCycles[(int)q.Low];
if (cycle != 0UL && cycle <= exponent && (exponent % cycle) != 0UL)
{
return;
}
}
// TODO: Replace this Pow2Mod check with the ProcessEightBitWindows helper once Pow2Minus1Mod adopts it;
// residue order scans will then benefit from the same 2× speedup the benchmarked windowed kernel delivered.
if (GpuUInt128.Pow2Mod(exponent, in readOnlyQ) != GpuUInt128.One)
{
return;
}
Atomic.Or(ref found[0], 1);
}
public void Dispose()
{
Dispose(disposing: false);
}
public readonly struct ExecutionScope
{
private readonly object? _lock;
public ExecutionScope(object? sync)
{
_lock = sync;
if (_lock is not null)
{
Monitor.Enter(_lock);
}
}
public void Dispose()
{
if (_lock is not null)
{
Monitor.Exit(_lock);
}
}
}
}