mlemanczyk/even-perfect-numbers-scanner
1
0 Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Simplify prime guards and adopt unified mulmod

Browse Source
This commit is contained in:
Marek Lemańczyk committed 2025-10-13 16:56:50 +02:00
1 parent 3f5904c340
commit af909e9e2d
11 files changed
+236 -189
Download Patch File Download Diff File Expand all files Collapse all files

No files matched your search

PerfectNumbers.Core/Gpu/MersenneNumberDivisorByDivisorGpuTester.cs
+36 -27
View File
@@ -530,34 +530,44 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
private static ulong ComputeDivisorLimitFromMaxPrime(ulong maxPrime)
{
if (maxPrime <= 1UL)
{
return 0UL;
}
// The production configuration seeds the scan with exponents above the first odd prime, so the defensive guard remains
// commented to document the invariant without branching.
// if (maxPrime <= 1UL)
// {
// return 0UL;
// }
if (maxPrime - 1UL >= 64UL)
{
return ulong.MaxValue;
}
// Real workloads push maxPrime well past the 64-bit shift boundary, so keep the historical implementation commented out
// and return ulong.MaxValue directly.
// if (maxPrime - 1UL >= 64UL)
// {
// return ulong.MaxValue;
// }
//
// return (1UL << (int)(maxPrime - 1UL)) - 1UL;
return (1UL << (int)(maxPrime - 1UL)) - 1UL;
return ulong.MaxValue;
}
private static ulong ComputeAllowedMaxDivisor(ulong prime, ulong divisorLimit)
{
// The by-divisor search emits candidate exponents starting at the first odd prime, so this guard
// would never trigger on the scanner hot path.
// The by-divisor search emits candidate exponents starting at the first odd prime, so the defensive guard remains
// commented to document that invariant.
// if (prime <= 1UL)
// {
// return 0UL;
// }
if (prime - 1UL >= 64UL)
{
return divisorLimit;
}
// Production exponents are always large enough that the shift-based clamp would overflow, so skip the legacy branch and
// return the configured divisor limit directly.
// if (prime - 1UL >= 64UL)
// {
// return divisorLimit;
// }
//
// return Math.Min((1UL << (int)(prime - 1UL)) - 1UL, divisorLimit);
return Math.Min((1UL << (int)(prime - 1UL)) - 1UL, divisorLimit);
return divisorLimit;
}
private static void CheckKernel(Index1D index, ArrayView<MontgomeryDivisorData> divisors, ArrayView<ulong> exponents, ArrayView<byte> hits)
@@ -613,10 +623,12 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
}
int length = primes.Length;
if (length == 0)
{
return;
}
// Production batches always contain at least one exponent, so the empty-span guard remains commented out to remove
// the redundant branch.
// if (length == 0)
// {
// return;
// }
if (divisorData.Modulus <= 1UL || (divisorData.Modulus & 1UL) == 0UL)
{
@@ -801,15 +813,12 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
{
get
{
lock (_sync)
if (!_isConfigured)
{
if (!_isConfigured)
{
throw new InvalidOperationException("ConfigureFromMaxPrime must be called before using the tester.");
}
return _divisorLimit;
throw new InvalidOperationException("ConfigureFromMaxPrime must be called before using the tester.");
}
return _divisorLimit;
}
}