Avoid redundant compaction buffer clearing on GPU

PerfectNumbers.Core/Gpu/Kernels/DivisorByDivisorKernels.cs

@@ -232,8 +232,10 @@ internal static class DivisorByDivisorKernels
 
         int lastLaneMask = globalIndex == length - 1 ? 1 : 0;
         int countValue = shared[prefixBase + localIndex];
-        int storedCount = lastLaneMask != 0 ? countValue : 0;
-        Atomic.Max(ref compactedCount[0], storedCount);
+        if (lastLaneMask != 0)
+        {
+            compactedCount[0] = countValue;
+        }
     }
 
     public static void PublishFirstHitKernel(

PerfectNumbers.Core/Gpu/MersenneNumberDivisorByDivisorGpuTester.cs

@@ -600,7 +600,6 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
         //     return 0;
         // }
 
-        countView.MemSetToZero();
         SharedMemoryConfig sharedMemoryConfig = SharedMemoryConfig.RequestDynamic<int>(count * 3);
         Index1D gridDim = new Index1D(1);
         Index1D groupDim = new Index1D(count);