The sampler's last "unknown" LOD0 bucket (~13.8%) was ucrtbase.dll!_finite: FMath::IsFinite is an
out-of-line CRT call on the MSVC game path, hit from the innermost tunnel, passage, density,
spatial-index and meshing loops.
- VoxelMath::IsFiniteFast(float/double) in VoxelTypes.h: memcpy to uint32/uint64,
(Bits & ExpMask) != ExpMask. It is the same predicate for every bit pattern, with no FP
comparison for fast-math to fold. The disassembly shows it inlined (movd/movq, mask, compare).
- VoxelMath::IsFinite routes through a plain global, voxel.FastIsFinite (default 1), for the A/B.
The CRT call remains only on the switch-off branch. Hot generation-path uses are replaced; no
_finite / std::isfinite remains in Source/VoxelForge. Tool/editor/test code keeps FMath.
- A test that can fail: VoxelForge.Math.IsFiniteExact compares against FMath::IsFinite over 22
explicit float/double patterns (+-0, denormals, min/max normal, +-Inf, quiet and signalling NaN
payloads) plus 2,000,000 hashed patterns each: 0 mismatches. The explicit NaNs make a NaN-wrong
helper fail.
Field exact: 841/841 keyed tiles identical to NextHeadStaticTrace_20260913 (verdict/empty/
triangles), export OBJ unchanged (b3e5f4c3..9b377), capability 20,830 / 10,909.
Within-round A/B, game path, two interleaved runs each, sampler off (off -> on):
static LOD0 request p50 95.5 -> 84.8 ms generation p50/p95 70.3/114.1 -> 62.3/100.6 ms
worker 35.4 -> 31.6 s (-10.5%)
moving LOD0 request p50/p95 70.8/144.2 -> 62.0/126.1 ms
generation p50/p95 62.6/113.4 -> 55.1/101.0 ms
worker 102.6 -> 91.3 s (-11.0%)
Sampler-on moving: the _finite/CRT cluster is gone.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TaFdXhTdYMkW1xrV6ApT6Y
Fr0zkaandClaude Opus 5
5489b5e311