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Refine Mul64 benchmarks with GPU-friendly variant

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Marek Lemańczyk committed 2025-09-30 04:24:40 +02:00
1 parent daab18504b
commit ebe3b306b9
4 files changed
+133 -6
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PerfectNumbers.Core/UInt128Extensions.cs
+17 -6
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@@ -251,12 +251,23 @@ public static class UInt128Extensions
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static UInt128 Mul64(this UInt128 a, UInt128 b)
{
ulong aLow = (ulong)a;
ulong bLow = (ulong)b;
return ((UInt128)(aLow * (ulong)(b >> 64) + aLow.MulHigh(bLow)) << 64) | (aLow * bLow);
}
public static UInt128 Mul64(this UInt128 a, UInt128 b)
{
ulong aLow = (ulong)a;
ulong bLow = (ulong)b;
ulong bHigh = (ulong)(b >> 64);
ulong low = aLow * bLow;
// Keep the high-word accumulation in locals so the JIT does not rebuild the
// expression tree around the shift. Mirroring the MulHigh layout lets RyuJIT
// keep the intermediate sum in registers instead of reloading the partial
// product from the stack.
ulong high = aLow.MulHigh(bLow);
high += aLow * bHigh;
return ((UInt128)high << 64) | low;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static UInt128 MulMod(this UInt128 a, UInt128 b, UInt128 modulus)