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Clarify cycle stepper reset inlining

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Marek Lemańczyk committed 2025-10-02 13:30:56 +02:00
1 parent 8b467c27f3
commit b8aa845c5c
53 files changed
+1736 -1131
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PerfectNumbers.Core/Gpu/GpuUInt128.cs
+29 -16
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@@ -156,14 +156,14 @@ public struct GpuUInt128 : IComparable<GpuUInt128>, IEquatable<GpuUInt128>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static bool operator >=(GpuUInt128 left, GpuUInt128 right) => left.CompareTo(right) >= 0;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static GpuUInt128 operator ++(GpuUInt128 value)
{
value.Add(1UL);
return value;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static GpuUInt128 operator ++(GpuUInt128 value)
{
value.Add(1UL);
return value;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public readonly int CompareTo(GpuUInt128 other)
{
if (High < other.High)
@@ -536,6 +536,9 @@ public struct GpuUInt128 : IComparable<GpuUInt128>, IEquatable<GpuUInt128>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static GpuUInt128 BinaryGcd(GpuUInt128 u, GpuUInt128 v)
{
// TODO: Replace this scalar binary GCD with the branchless reduction from
// GpuUInt128BinaryGcdBenchmarks so CPU fallbacks stay aligned with the GPU kernel
// performance when resolving large divisor residues.
if (u.IsZero)
{
return v;
@@ -1044,11 +1047,15 @@ public struct GpuUInt128 : IComparable<GpuUInt128>, IEquatable<GpuUInt128>
public void ModPow(GpuUInt128 exponent, GpuUInt128 modulus)
{
// TODO: This should operate on the instance itself, not on a copy. Avoid creating new instances anywhere.
// TODO: Swap this copy-heavy path for the pooled base/exponent ladder used in
// GpuUInt128MulModBenchmarks so the GPU shim keeps reusing buffers instead of
// allocating temporary structs during residue scans.
GpuUInt128 result = new(1UL);
GpuUInt128 baseValue = this;
// TODO: Can we modify this loop to process multiple bits at a time? E.g. 64-bit chunks.
// TODO: Replace the single-bit square-and-multiply loop with the 64-bit windowed
// ladder measured fastest in GpuUInt128MulModBenchmarks to align with the GPU kernel
// implementation once the shared helper lands.
while (!exponent.IsZero)
{
if ((exponent.Low & 1UL) != 0UL)
@@ -1066,11 +1073,13 @@ public struct GpuUInt128 : IComparable<GpuUInt128>, IEquatable<GpuUInt128>
public void ModPow(ulong exponent, GpuUInt128 modulus)
{
// TODO: This should operate on the instance itself, not on a copy. Avoid creating new instances anywhere.
// TODO: Share the pooled ladder state from GpuUInt128MulModBenchmarks here as well so
// Lucas–Lehmer batches avoid constructing throwaway temporaries on every exponent.
GpuUInt128 result = new(1UL);
GpuUInt128 baseValue = this;
// TODO: Can we modify this loop to process multiple bits at a time? E.g. 64-bit chunks.
// TODO: Upgrade this loop to the same 64-bit windowed ladder proven fastest in
// GpuUInt128MulModBenchmarks so the scalar helper matches the GPU-optimized path.
while (exponent != 0UL)
{
if ((exponent & 1UL) != 0UL)
@@ -1086,14 +1095,16 @@ public struct GpuUInt128 : IComparable<GpuUInt128>, IEquatable<GpuUInt128>
Low = result.Low;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void ModInv(ulong modulus)
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void ModInv(ulong modulus)
{
// TODO: We shouldn't need a new instance here to represent modulus.
// TODO: Replace this Fermat inversion with the Montgomery ladder highlighted in
// GpuUInt128Montgomery64Benchmarks so we avoid instantiating a temporary modulus and
// reuse the pooled reduction constants.
ModPow(modulus - 2UL, new GpuUInt128(modulus));
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void ModInv(GpuUInt128 modulus)
{
if (modulus.High == 0UL)
@@ -1114,7 +1125,9 @@ public struct GpuUInt128 : IComparable<GpuUInt128>, IEquatable<GpuUInt128>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static void MultiplyFull(GpuUInt128 left, GpuUInt128 right, out ulong p3, out ulong p2, out ulong p1, out ulong p0)
{
// TODO: Reuse variables to reduce register pressure.
// TODO: Reuse variables to reduce register pressure following the fused-limb layout
// from GpuUInt128MulModByLimbBenchmarks so the multiply helper matches the fastest
// GPU-compatible scalar routine.
var (h0, l0) = Mul64(left.Low, right.Low);
var (h1, l1) = Mul64(left.Low, right.High);
var (h2, l2) = Mul64(left.High, right.Low);