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Simplify prime guards and adopt unified mulmod

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Marek Lemańczyk committed 2025-10-13 16:56:50 +02:00
1 parent 3f5904c340
commit af909e9e2d
11 files changed
+236 -189
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PerfectNumbers.Core/Gpu/PrimeOrderGpuHeuristics.cs
+49 -36
View File
@@ -850,10 +850,11 @@ internal static partial class PrimeOrderGpuHeuristics
{
ulong primeFactor = factors[i];
int exponent = exponents[i];
if (primeFactor <= 1UL)
{
continue;
}
// Factorization never yields unity on the scanning path, so skip the redundant guard.
// if (primeFactor <= 1UL)
// {
// continue;
// }
for (int iteration = 0; iteration < exponent; iteration++)
{
@@ -889,10 +890,12 @@ internal static partial class PrimeOrderGpuHeuristics
ArrayView1D<ulong, Stride1D.Dense> compositeStack,
ArrayView1D<byte, Stride1D.Dense> statusOut)
{
if (order == 0UL)
{
return false;
}
// Order values handed to the kernel are strictly positive on the production path, so the zero guard stays commented
// out to remove the redundant branch.
// if (order == 0UL)
// {
// return false;
// }
if ((order).Pow2ModWindowedGpu(divisor.Modulus) != 1UL)
{
@@ -924,10 +927,11 @@ internal static partial class PrimeOrderGpuHeuristics
{
ulong primeFactor = factors[i];
int exponent = exponents[i];
if (primeFactor <= 1UL)
{
continue;
}
// Factorization never yields one on the by-divisor path, so the defensive continue stays commented out.
// if (primeFactor <= 1UL)
// {
// continue;
// }
ulong reduced = order;
for (int iteration = 0; iteration < exponent; iteration++)
@@ -1008,20 +1012,22 @@ internal static partial class PrimeOrderGpuHeuristics
SortCandidatesKernel(prime, previousOrder, hasPreviousOrder != 0, candidates, candidateCount);
int powBudget = maxPowChecks <= 0 ? candidateCount : maxPowChecks;
if (powBudget <= 0)
{
powBudget = candidateCount;
}
// The heuristics always reserve at least one check, so the zero-budget fallback remains commented out.
// if (powBudget <= 0)
// {
// powBudget = candidateCount;
// }
int powUsed = 0;
for (int i = 0; i < candidateCount && powUsed < powBudget; i++)
{
ulong candidate = candidates[i];
if (candidate <= 1UL)
{
continue;
}
// Candidate generation skips 1 by construction, so the defensive continue stays commented out.
// if (candidate <= 1UL)
// {
// continue;
// }
if (powUsed >= powBudget)
{
@@ -1309,10 +1315,11 @@ internal static partial class PrimeOrderGpuHeuristics
{
ulong primeFactor = factors[i];
int exponent = exponents[i];
if (primeFactor <= 1UL)
{
continue;
}
// Factorization never yields one for candidate orders, so keep the guard commented out to avoid re-checking inputs.
// if (primeFactor <= 1UL)
// {
// continue;
// }
ulong reduced = candidate;
for (int iteration = 0; iteration < exponent; iteration++)
@@ -1351,10 +1358,12 @@ internal static partial class PrimeOrderGpuHeuristics
ArrayView1D<ulong, Stride1D.Dense> compositeStack,
ArrayView1D<byte, Stride1D.Dense> statusOut)
{
if (initial <= 1UL)
{
return true;
}
// Composite candidates sent here are always greater than one during production scans, so the trivial-return branch stays
// commented out.
// if (initial <= 1UL)
// {
// return true;
// }
int stackCapacity = (int)compositeStack.Length;
if (stackCapacity <= 0)
@@ -1616,10 +1625,11 @@ internal static partial class PrimeOrderGpuHeuristics
private static GpuPow2ModStatus TryPow2ModBatchInternal(ReadOnlySpan<UInt128> exponents, UInt128 prime, Span<UInt128> remainders)
{
if (exponents.Length == 0)
{
return GpuPow2ModStatus.Success;
}
// Residue batches are never empty on production workloads, so skip the zero-length success shortcut.
// if (exponents.Length == 0)
// {
// return GpuPow2ModStatus.Success;
// }
if (remainders.Length < exponents.Length)
{
@@ -1706,10 +1716,11 @@ internal static partial class PrimeOrderGpuHeuristics
private static bool TryComputeOnGpuWide(ReadOnlySpan<UInt128> exponents, UInt128 prime, Span<UInt128> results)
{
int length = exponents.Length;
if (length == 0)
{
return true;
}
// Production launches always carry work, so keep the empty-batch shortcut commented out.
// if (length == 0)
// {
// return true;
// }
GpuUInt128[]? rentedExponents = null;
GpuUInt128[]? rentedResults = null;
@@ -1763,6 +1774,8 @@ internal static partial class PrimeOrderGpuHeuristics
}
finally
{
// Small batches use the stack-allocated fast path, leaving the rented arrays null. Retain the guards so pooled
// buffers are only returned when they were actually leased.
if (rentedExponents is not null)
{
ArrayPool<GpuUInt128>.Shared.Return(rentedExponents, clearArray: false);