Clean up resolved windowed pow2 TODOs on CPU paths

PerfectNumbers.Core/ExponentRemainderStepper.cs

@@ -44,9 +44,6 @@ internal struct ExponentRemainderStepper
 
         if (!_hasState || exponent <= _previousExponent)
         {
-            // TODO: Route these state resets through the ProcessEightBitWindows helper once the scalar
-            // Pow2MontgomeryMod implementation adopts it so delta stepping inherits the benchmarked
-            // 2× gains for large exponents.
             _currentMontgomery = exponent.Pow2MontgomeryModWindowedCpu(_divisor, keepMontgomery: true);
             _previousExponent = exponent;
             _hasState = true;
@@ -57,8 +54,6 @@ internal struct ExponentRemainderStepper
         // TODO: Once divisor cycle lengths are mandatory, pull the delta multiplier from the
         // single-block divisor-cycle snapshot so we can skip the powmod entirely and reuse the
         // cached Montgomery residue ladder highlighted in MersenneDivisorCycleLengthGpuBenchmarks.
-        // TODO: Replace this per-delta powmod with the upcoming windowed ladder so incremental
-        // updates stop paying the single-bit cost highlighted in GpuPow2ModBenchmarks.
         ulong multiplier = delta.Pow2MontgomeryModWindowedCpu(_divisor, keepMontgomery: true);
         _currentMontgomery = _currentMontgomery.MontgomeryMultiply(multiplier, _modulus, _nPrime);
         _previousExponent = exponent;
@@ -75,8 +70,6 @@ internal struct ExponentRemainderStepper
 
         if (!_hasState || exponent <= _previousExponent)
         {
-            // TODO: Switch this reload to the shared windowed pow2 helper once available so CPU
-            // residue checks align with the optimized ProcessEightBitWindows timings.
             _currentMontgomery = exponent.Pow2MontgomeryModWindowedCpu(_divisor, keepMontgomery: true);
             _previousExponent = exponent;
             _hasState = true;
@@ -86,8 +79,6 @@ internal struct ExponentRemainderStepper
         ulong delta = exponent - _previousExponent;
         // TODO: Reuse the divisor-cycle derived Montgomery delta once the cache exposes single-cycle
         // lookups so this branch also avoids recomputing powmods when the snapshot lacks the divisor.
-        // TODO: Use the windowed delta pow2 helper here as well to avoid the single-bit ladder that
-        // currently lags behind the benchmarked implementation for huge divisor cycles.
         ulong multiplier = delta.Pow2MontgomeryModWindowedCpu(_divisor, keepMontgomery: true);
         _currentMontgomery = _currentMontgomery.MontgomeryMultiply(multiplier, _modulus, _nPrime);
         _previousExponent = exponent;
@@ -121,8 +112,6 @@ internal struct ExponentRemainderStepper
 
         if (!_hasState || exponent <= _previousExponent)
         {
-            // TODO: Replace this fallback path with the upcoming ProcessEightBitWindows helper so
-            // fresh Montgomery states also benefit from the faster pow2 ladder measured on CPUs.
             _currentMontgomery = exponent.Pow2MontgomeryModWindowedCpu(_divisor, keepMontgomery: true);
             _previousExponent = exponent;
             _hasState = true;