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Document hot-path guards in GPU mask compaction helpers

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Marek Lemańczyk committed 2025-10-22 18:48:03 +02:00
1 parent add62df697
commit 586eb8d303
1 file changed
+17 -17
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PerfectNumbers.Core/Gpu/MersenneNumberDivisorByDivisorGpuTester.cs
+17 -17
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@@ -344,10 +344,10 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
BuildCandidateMaskOnGpu(effectiveCount, remainder10View, remainder8View, remainder5View, remainder3View, lastIsSevenFlag, maskView, candidateMaskKernel); BuildCandidateMaskOnGpu(effectiveCount, remainder10View, remainder8View, remainder5View, remainder3View, lastIsSevenFlag, maskView, candidateMaskKernel);
byte lastRemainder10 = FetchLastRemainder(remainder10View, effectiveCount); byte lastRemainder10 = effectiveCount > 0 ? FetchLastRemainder(remainder10View, effectiveCount) : (byte)0;
byte lastRemainder8 = FetchLastRemainder(remainder8View, effectiveCount); byte lastRemainder8 = effectiveCount > 0 ? FetchLastRemainder(remainder8View, effectiveCount) : (byte)0;
byte lastRemainder5 = FetchLastRemainder(remainder5View, effectiveCount); byte lastRemainder5 = effectiveCount > 0 ? FetchLastRemainder(remainder5View, effectiveCount) : (byte)0;
byte lastRemainder3 = FetchLastRemainder(remainder3View, effectiveCount); byte lastRemainder3 = effectiveCount > 0 ? FetchLastRemainder(remainder3View, effectiveCount) : (byte)0;
remainder10 = AddModGpu(lastRemainder10, step10, 10); remainder10 = AddModGpu(lastRemainder10, step10, 10);
remainder8 = AddModGpu(lastRemainder8, step8, 8); remainder8 = AddModGpu(lastRemainder8, step8, 8);
@@ -563,10 +563,12 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
ArrayView1D<byte, Stride1D.Dense> maskView, ArrayView1D<byte, Stride1D.Dense> maskView,
Action<Index1D, ArrayView<byte>, ArrayView<byte>, ArrayView<byte>, ArrayView<byte>, byte, ArrayView<byte>> maskKernel) Action<Index1D, ArrayView<byte>, ArrayView<byte>, ArrayView<byte>, ArrayView<byte>, byte, ArrayView<byte>> maskKernel)
{ {
if (count <= 0) // EvenPerfectBitScanner always supplies a positive count here,
{ // so the guard stays commented out to keep the hot path branch-free.
return; // if (count <= 0)
} // {
// return;
// }
maskKernel(count, remainder10View, remainder8View, remainder5View, remainder3View, lastIsSevenFlag, maskView); maskKernel(count, remainder10View, remainder8View, remainder5View, remainder3View, lastIsSevenFlag, maskView);
} }
@@ -579,10 +581,12 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
ArrayView1D<int, Stride1D.Dense> countView, ArrayView1D<int, Stride1D.Dense> countView,
Action<KernelConfig, Index1D, ArrayView<byte>, ArrayView<ulong>, ArrayView<ulong>, ArrayView<int>> compactionKernel) Action<KernelConfig, Index1D, ArrayView<byte>, ArrayView<ulong>, ArrayView<ulong>, ArrayView<int>> compactionKernel)
{ {
if (count <= 0) // EvenPerfectBitScanner always compacts with a positive count,
{ // so the guard stays commented out to keep the hot path branch-free.
return 0; // if (count <= 0)
} // {
// return 0;
// }
SharedMemoryConfig sharedMemoryConfig = SharedMemoryConfig.RequestDynamic<int>(count); SharedMemoryConfig sharedMemoryConfig = SharedMemoryConfig.RequestDynamic<int>(count);
Index1D gridDim = new Index1D(1); Index1D gridDim = new Index1D(1);
@@ -598,11 +602,7 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
private static byte FetchLastRemainder(ArrayView1D<byte, Stride1D.Dense> remainderView, int count) private static byte FetchLastRemainder(ArrayView1D<byte, Stride1D.Dense> remainderView, int count)
{ {
if (count <= 0) // Callers guard against zero counts before invoking this helper to keep the hot path branch-free.
{
return 0;
}
byte value = 0; byte value = 0;
remainderView.SubView(count - 1, 1).CopyToCPU(ref value, 1); remainderView.SubView(count - 1, 1).CopyToCPU(ref value, 1);
return value; return value;