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PrimeOrderCalculatorAccelerator.Rent is now created outside of the loops and re-used for all calculations.

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mlemanczyk committed 2025-11-24 22:51:53 +01:00
1 parent 57a50e2a37
commit b9ca95bf8c
53 files changed
+4639 -4229
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PerfectNumbers.Core/Cpu/MersenneNumberLucasLehmerCpuTester.cs
+37 -35
View File
@@ -1,44 +1,46 @@
using PerfectNumbers.Core.Gpu.Accelerators;
namespace PerfectNumbers.Core;
public class MersenneNumberLucasLehmerCpuTester
{
public bool IsPrime(ulong exponent)
{
// Early rejections aligned with incremental/order sieves, but safe for small p:
// - If 3 | p and p != 3, then 7 | M_p -> composite.
// - If p ≡ 1 (mod 4) and p shares a factor with (p-1), reject fast.
// - If p is divisible by divisors specific to numbers ending with 1 or 7, reject fast.
// TODO: Replace these `%` checks with Mod3/Mod5/Mod7/Mod11 helpers once Lucas–Lehmer CPU filtering
// shares the benchmarked bitmask implementations and avoids slow modulo instructions in the hot path.
if (
((exponent % 3UL) == 0UL && exponent != 3UL) ||
((exponent % 5UL) == 0UL && exponent != 5UL) ||
((exponent % 7UL) == 0UL && exponent != 7UL) ||
((exponent % 11UL) == 0UL && exponent != 11UL)
)
{
return false;
}
public bool IsPrime(PrimeOrderCalculatorAccelerator gpu, ulong exponent)
{
// Early rejections aligned with incremental/order sieves, but safe for small p:
// - If 3 | p and p != 3, then 7 | M_p -> composite.
// - If p ≡ 1 (mod 4) and p shares a factor with (p-1), reject fast.
// - If p is divisible by divisors specific to numbers ending with 1 or 7, reject fast.
// TODO: Replace these `%` checks with Mod3/Mod5/Mod7/Mod11 helpers once Lucas–Lehmer CPU filtering
// shares the benchmarked bitmask implementations and avoids slow modulo instructions in the hot path.
if (
((exponent % 3UL) == 0UL && exponent != 3UL) ||
((exponent % 5UL) == 0UL && exponent != 5UL) ||
((exponent % 7UL) == 0UL && exponent != 7UL) ||
((exponent % 11UL) == 0UL && exponent != 11UL)
)
{
return false;
}
if ((exponent & 3UL) == 1UL && exponent.SharesFactorWithExponentMinusOne())
{
return false;
}
if ((exponent & 3UL) == 1UL && exponent.SharesFactorWithExponentMinusOne(gpu))
{
return false;
}
UInt128 s = UInt128Numbers.Four, two = UInt128Numbers.Two,
m = (UInt128.One << (int)exponent) - UInt128.One;
UInt128 s = UInt128Numbers.Four, two = UInt128Numbers.Two,
m = (UInt128.One << (int)exponent) - UInt128.One;
UInt128 limit = exponent - UInt128Numbers.Two;
for (UInt128 i = UInt128.Zero; i < limit; i++)
{
// Lucas–Lehmer squares the evolving residue, so we stay on the Montgomery powmod path rather than the pow2-specific helper.
s = s.PowModWithCycle(two, MersenneDivisorCycles.GetCycle(m)) - two;
if (s < UInt128.Zero)
{
s += m;
}
}
UInt128 limit = exponent - UInt128Numbers.Two;
for (UInt128 i = UInt128.Zero; i < limit; i++)
{
// Lucas–Lehmer squares the evolving residue, so we stay on the Montgomery powmod path rather than the pow2-specific helper.
s = s.PowModWithCycle(two, MersenneDivisorCycles.GetCycle(gpu, m)) - two;
if (s < UInt128.Zero)
{
s += m;
}
}
return s == UInt128.Zero;
}
return s == UInt128.Zero;
}
}