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Clarify cycle stepper reset inlining

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Marek Lemańczyk committed 2025-10-02 13:30:56 +02:00
1 parent 8b467c27f3
commit b8aa845c5c
53 files changed
+1736 -1131
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PerfectNumbers.Core/Cpu/MersenneNumberIncrementalCpuTester.cs
+89 -82
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@@ -2,94 +2,101 @@ namespace PerfectNumbers.Core.Cpu;
public class MersenneNumberIncrementalCpuTester(GpuKernelType kernelType)
{
private static readonly MersenneDivisorCycles _cycles = MersenneDivisorCycles.Shared;
private readonly GpuKernelType _kernelType = kernelType;
private static readonly MersenneDivisorCycles _cycles = MersenneDivisorCycles.Shared;
private readonly GpuKernelType _kernelType = kernelType;
public void Scan(ulong exponent, UInt128 twoP, bool lastIsSeven, UInt128 maxK, ref bool isPrime)
{
UInt128 k, one = k = UInt128.One;
ulong divMul = (ulong)((((UInt128)1 << 64) - UInt128.One) / exponent) + 1UL;
// Use residue automaton always on CPU
var auto = new MersenneResidueAutomaton(exponent);
public void Scan(ulong exponent, UInt128 twoP, bool lastIsSeven, UInt128 maxK, ref bool isPrime)
{
UInt128 k = UInt128.One;
UInt128 one = k;
ulong divMul = (ulong)((((UInt128)1 << 64) - UInt128.One) / exponent) + 1UL;
// Use residue automaton always on CPU
var auto = new MersenneResidueAutomaton(exponent);
bool reject, shouldCheck;
UInt128 q = auto.CurrentQ(),
divPow, halfPow, phi, qCycle;
bool reject;
bool shouldCheck;
UInt128 q = auto.CurrentQ();
UInt128 divPow;
UInt128 halfPow;
UInt128 phi;
UInt128 qCycle;
ulong div, mod8, phi64;
ulong div;
ulong mod8;
ulong phi64;
while (k <= maxK && Volatile.Read(ref isPrime))
{
qCycle = MersenneDivisorCycles.GetCycle(q);
shouldCheck = lastIsSeven
? (auto.Mod10R != 5UL)
: (auto.Mod10R != 5UL);
if (shouldCheck)
{
mod8 = auto.Mod8R;
if (mod8 != 1UL && mod8 != 7UL)
{
shouldCheck = false;
}
else if (auto.Mod3R == 0UL || auto.Mod5R == 0UL)
{
shouldCheck = false;
}
}
while (k <= maxK && Volatile.Read(ref isPrime))
{
// TODO: Replace this direct GetCycle call with DivisorCycleCache.Lookup so we reuse the single snapshot block
// and compute missing cycles on the configured device without queuing additional block generation.
qCycle = MersenneDivisorCycles.GetCycle(q);
shouldCheck = auto.Mod10R != 5UL;
if (shouldCheck)
{
mod8 = auto.Mod8R;
if (mod8 != 1UL && mod8 != 7UL)
{
shouldCheck = false;
}
else if (auto.Mod3R == 0UL || auto.Mod5R == 0UL)
{
// TODO: Swap these Mod3/Mod5 zero checks to the cached residue tables once the automaton exposes
// the benchmarked lookup-based helpers so CPU scans avoid runtime modulo instructions.
shouldCheck = false;
}
}
if (shouldCheck)
{
if (_kernelType == GpuKernelType.Pow2Mod)
if (shouldCheck)
{
if (_kernelType == GpuKernelType.Pow2Mod)
{
// TODO: Swap this PowModWithCycle call for the ProcessEightBitWindows helper once
// the scalar implementation lands so CPU pow2mod scans match the GPU speedups
// captured in GpuPow2ModBenchmarks.
reject = exponent.PowModWithCycle(q, qCycle) == UInt128.One;
}
else
{
phi = q - one;
reject = false;
if (phi <= ulong.MaxValue)
{
phi64 = (ulong)phi;
// TODO: Route the phi-based powmods through the upcoming windowed helper to
// avoid the current square-and-multiply cost highlighted in the Pow2 bench
// suite when scanning large divisors.
if (phi64.PowModWithCycle(q, qCycle) == one)
{
// TODO: Once the windowed pow2 helper is available expose a version
// that reuses cached windows here instead of recomputing via the slow
// bit ladder for every divisor.
halfPow = (phi64 >> 1).PowModWithCycle(q, qCycle) - one;
if (halfPow.BinaryGcd(q) == one)
{
div = phi64.FastDiv64(exponent, divMul);
// TODO: Replace this divisor powmod with the shared windowed
// implementation so each candidate uses the benchmarked fast
// path instead of the current per-bit multiply chain.
divPow = div.PowModWithCycle(q, qCycle) - one;
if (divPow.BinaryGcd(q) == one)
{
// TODO: Swap this PowModWithCycle call for the ProcessEightBitWindows helper once
// the scalar implementation lands so CPU pow2mod scans match the GPU speedups
// captured in GpuPow2ModBenchmarks.
reject = exponent.PowModWithCycle(q, qCycle) == UInt128.One;
reject = true;
}
else
{
phi = q - one;
reject = false;
if (phi <= ulong.MaxValue)
{
phi64 = (ulong)phi;
// TODO: Route the phi-based powmods through the upcoming windowed helper to
// avoid the current square-and-multiply cost highlighted in the Pow2 bench
// suite when scanning large divisors.
if (phi64.PowModWithCycle(q, qCycle) == one)
{
// TODO: Once the windowed pow2 helper is available expose a version
// that reuses cached windows here instead of recomputing via the slow
// bit ladder for every divisor.
halfPow = (phi64 >> 1).PowModWithCycle(q, qCycle) - one;
if (halfPow.BinaryGcd(q) == one)
{
div = phi64.FastDiv64(exponent, divMul);
// TODO: Replace this divisor powmod with the shared windowed
// implementation so each candidate uses the benchmarked fast
// path instead of the current per-bit multiply chain.
divPow = div.PowModWithCycle(q, qCycle) - one;
if (divPow.BinaryGcd(q) == one)
{
reject = true;
}
}
}
}
}
}
}
}
}
if (reject && q.IsPrimeCandidate())
{
Volatile.Write(ref isPrime, false);
break;
}
}
if (reject && q.IsPrimeCandidate())
{
Volatile.Write(ref isPrime, false);
break;
}
}
k += 1UL;
auto.Next();
q = auto.CurrentQ();
}
return;
}
}
k += 1UL;
auto.Next();
q = auto.CurrentQ();
}
}
}