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Simplify GPU by-divisor configuration guards

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Marek Lemańczyk committed 2025-10-22 03:49:04 +02:00
1 parent 43cd067e09
commit 00341fbb8c
3 files changed
+390 -364
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PerfectNumbers.Core/Gpu/Kernels/DivisorByDivisorKernels.cs
+25 -70
View File
@@ -10,14 +10,11 @@ internal static class DivisorByDivisorKernels
{
MontgomeryDivisorData divisor = divisors[index];
ulong modulus = divisor.Modulus;
if (modulus <= 1UL || (modulus & 1UL) == 0UL)
{
hits[index] = 0;
return;
}
// The GPU by-divisor pipeline only materializes odd moduli greater than one (q = 2kp + 1),
// so the defensive guard for invalid values stays disabled here to keep the kernel branch-free.
ulong exponent = exponents[index];
hits[index] = ULongExtensions.Pow2MontgomeryModWindowedGpuConvertToStandard(divisor, exponent) == 1UL ? (byte)1 : (byte)0;
ulong montgomeryResult = ULongExtensions.Pow2MontgomeryModWindowedGpuConvertToStandard(divisor, exponent);
hits[index] = montgomeryResult == 1UL ? (byte)1 : (byte)0;
}
public static void ComputeRemainderDeltasKernel(Index1D index, ArrayView<ulong> gaps, ArrayView<byte> deltas, byte modulus)
@@ -50,42 +47,25 @@ internal static class DivisorByDivisorKernels
int mod = modulus;
while (offset < groupSize)
{
int addend = 0;
if (localIndex >= offset)
{
addend = shared[localIndex - offset];
}
bool apply = localIndex >= offset;
int addend = apply ? shared[localIndex - offset] : 0;
Group.Barrier();
if (localIndex >= offset)
{
int sum = shared[localIndex] + addend;
if (sum >= mod)
{
sum %= mod;
}
shared[localIndex] = sum;
}
int current = shared[localIndex];
int sum = apply ? current + addend : current;
int wrap = sum >= mod ? 1 : 0;
sum -= wrap * mod;
shared[localIndex] = apply ? sum : current;
Group.Barrier();
offset <<= 1;
}
if (globalIndex == 0)
{
remainders[0] = baseRemainder;
return;
}
int remainder = baseRemainder + shared[localIndex];
if (remainder >= mod)
{
remainder %= mod;
}
int remainderWrap = remainder >= mod ? 1 : 0;
remainder -= remainderWrap * mod;
remainders[globalIndex] = (byte)remainder;
}
@@ -106,49 +86,24 @@ internal static class DivisorByDivisorKernels
}
byte value10 = remainder10[globalIndex];
bool accept10;
if (lastIsSevenFlag != 0)
{
accept10 = value10 == 3 || value10 == 7 || value10 == 9;
}
else
{
accept10 = value10 == 1 || value10 == 3 || value10 == 7 || value10 == 9;
}
if (!accept10)
{
mask[globalIndex] = 0;
return;
}
bool lastIsSeven = lastIsSevenFlag != 0;
bool acceptSeven = value10 == 3 || value10 == 7 || value10 == 9;
bool acceptNonSeven = value10 == 1 || value10 == 3 || value10 == 7 || value10 == 9;
bool accept10 = lastIsSeven ? acceptSeven : acceptNonSeven;
byte value8 = remainder8[globalIndex];
if (value8 != 1 && value8 != 7)
{
mask[globalIndex] = 0;
return;
}
if (remainder3[globalIndex] == 0 || remainder5[globalIndex] == 0)
{
mask[globalIndex] = 0;
return;
}
mask[globalIndex] = 1;
bool accept8 = value8 == 1 || value8 == 7;
bool accept5 = remainder5[globalIndex] != 0;
bool accept3 = remainder3[globalIndex] != 0;
byte accepted = (byte)((accept10 && accept8 && accept3 && accept5) ? 1 : 0);
mask[globalIndex] = accepted;
}
public static void ComputeMontgomeryExponentKernel(Index1D index, MontgomeryDivisorData divisor, ArrayView<ulong> exponents, ArrayView<ulong> results)
{
ulong modulus = divisor.Modulus;
if (modulus <= 1UL || (modulus & 1UL) == 0UL)
{
results[index] = 0UL;
return;
}
// Each divisor flowing through this kernel follows q = 2kp + 1 with k >= 1, so modulus is always odd and exceeds one.
ulong exponent = exponents[index];
results[index] = ULongExtensions.Pow2MontgomeryModWindowedGpuKeepMontgomery(divisor, exponent);
ulong montgomeryResult = ULongExtensions.Pow2MontgomeryModWindowedGpuKeepMontgomery(divisor, exponent);
results[index] = montgomeryResult;
}
}