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perf(generation): inline exact IsFinite -- LOD0 ~11-12% faster, field-exact

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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
This commit is contained in:
Fr0zkaandClaude Opus 5 committed 2026-09-13 23:50:30 +02:00
1 parent 22186473f9
commit 5489b5e311
11 files changed
+816 -558
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Source/VoxelForge/Private/VoxelGenerator.cpp
+55 -24
View File
@@ -29,8 +29,37 @@
#include <atomic>
namespace VoxelMath
{
VOXELFORGE_API int32 GFastIsFinite = 1;
}
namespace
{
// The default-on branch uses VoxelMath::IsFiniteFast, while 0 retains the original
// FMath::IsFinite call for a real within-round A/B and sampler comparison.
FAutoConsoleVariableRef CVarVoxelForgeFastIsFinite(
TEXT("voxel.FastIsFinite"),
VoxelMath::GFastIsFinite,
TEXT("Use the exact inline IEEE-754 bit test instead of the CRT-backed FMath::IsFinite."));
bool GVoxelForgeFastIsFiniteSwitchParsed = false;
void VF_ParseFastIsFiniteSwitch()
{
if (GVoxelForgeFastIsFiniteSwitchParsed)
{
return;
}
GVoxelForgeFastIsFiniteSwitchParsed = true;
int32 CommandLineValue = VoxelMath::GFastIsFinite;
if (FParse::Value(
FCommandLine::Get(), TEXT("voxel.FastIsFinite="), CommandLineValue))
{
VoxelMath::GFastIsFinite = CommandLineValue;
}
VoxelMath::GFastIsFinite = VoxelMath::GFastIsFinite != 0 ? 1 : 0;
}
// The canonical native TunnelNetwork/Underwater graph has a hand-lowered evaluator. Keep a
// command-line switch so every change can be A/B'd against the existing interpreted/block
// path without changing the authored graph or rebuilding a different world definition.
@@ -861,7 +890,7 @@ static FORCEINLINE bool VF_DisturbanceBandTouchesBox(
{
const float InnerTop = D.StrateTopWorldZ - D.BoundarySealThickness;
const float InnerBot = D.StrateBottomWorldZ + D.BoundarySealThickness;
if (!FMath::IsFinite(InnerTop) || !FMath::IsFinite(InnerBot))
if (!VoxelMath::IsFinite(InnerTop) || !VoxelMath::IsFinite(InnerBot))
{
return true; // Unknown boundary placement must not discharge a proof.
}
@@ -929,16 +958,16 @@ static bool VF_AnyChasmCanTouchLattice(
{
return false;
}
if (!FMath::IsFinite(D.ChasmDensity) || D.ChasmDensity < 0.0f
|| D.ChasmDensity > 1.0f || !FMath::IsFinite(D.ChasmSpacing)
|| !FMath::IsFinite(D.ChasmRadius) || D.ChasmSpacing <= 0.0f
if (!VoxelMath::IsFinite(D.ChasmDensity) || D.ChasmDensity < 0.0f
|| D.ChasmDensity > 1.0f || !VoxelMath::IsFinite(D.ChasmSpacing)
|| !VoxelMath::IsFinite(D.ChasmRadius) || D.ChasmSpacing <= 0.0f
|| D.ChasmRadius < 0.0f)
{
return true;
}
const float InnerTop = D.StrateTopWorldZ - D.BoundarySealThickness;
const float InnerBot = D.StrateBottomWorldZ + D.BoundarySealThickness;
if (!FMath::IsFinite(InnerTop) || !FMath::IsFinite(InnerBot))
if (!VoxelMath::IsFinite(InnerTop) || !VoxelMath::IsFinite(InnerBot))
{
return true;
}
@@ -987,16 +1016,16 @@ static bool VF_AnyBridgeCanTouchLattice(
{
return false;
}
if (!FMath::IsFinite(D.BridgeDensity) || D.BridgeDensity < 0.0f
|| D.BridgeDensity > 1.0f || !FMath::IsFinite(D.BridgeSpacing)
|| !FMath::IsFinite(D.BridgeRadius) || D.BridgeSpacing <= 0.0f
if (!VoxelMath::IsFinite(D.BridgeDensity) || D.BridgeDensity < 0.0f
|| D.BridgeDensity > 1.0f || !VoxelMath::IsFinite(D.BridgeSpacing)
|| !VoxelMath::IsFinite(D.BridgeRadius) || D.BridgeSpacing <= 0.0f
|| D.BridgeRadius < 0.0f)
{
return true;
}
const float InnerTop = D.StrateTopWorldZ - D.BoundarySealThickness;
const float InnerBot = D.StrateBottomWorldZ + D.BoundarySealThickness;
if (!FMath::IsFinite(InnerTop) || !FMath::IsFinite(InnerBot))
if (!VoxelMath::IsFinite(InnerTop) || !VoxelMath::IsFinite(InnerBot))
{
return true;
}
@@ -1055,16 +1084,16 @@ static bool VF_AnyRidgeCanTouchLattice(
{
return false;
}
if (!FMath::IsFinite(D.RidgeDensity) || D.RidgeDensity < 0.0f
|| D.RidgeDensity > 1.0f || !FMath::IsFinite(D.RidgeSpacing)
|| !FMath::IsFinite(D.RidgeHeight) || !FMath::IsFinite(D.RidgeThickness)
if (!VoxelMath::IsFinite(D.RidgeDensity) || D.RidgeDensity < 0.0f
|| D.RidgeDensity > 1.0f || !VoxelMath::IsFinite(D.RidgeSpacing)
|| !VoxelMath::IsFinite(D.RidgeHeight) || !VoxelMath::IsFinite(D.RidgeThickness)
|| D.RidgeSpacing <= 0.0f || D.RidgeHeight <= 0.0f || D.RidgeThickness < 0.0f)
{
return true;
}
const float InnerTop = D.StrateTopWorldZ - D.BoundarySealThickness;
const float InnerBot = D.StrateBottomWorldZ + D.BoundarySealThickness;
if (!FMath::IsFinite(InnerTop) || !FMath::IsFinite(InnerBot))
if (!VoxelMath::IsFinite(InnerTop) || !VoxelMath::IsFinite(InnerBot))
{
return true;
}
@@ -1124,9 +1153,9 @@ static bool VF_AnyChasmCanTouchBox(
{
return false;
}
if (!FMath::IsFinite(D.ChasmDensity) || D.ChasmDensity < 0.0f
|| D.ChasmDensity > 1.0f || !FMath::IsFinite(D.ChasmSpacing)
|| !FMath::IsFinite(D.ChasmRadius) || D.ChasmSpacing <= 0.0f
if (!VoxelMath::IsFinite(D.ChasmDensity) || D.ChasmDensity < 0.0f
|| D.ChasmDensity > 1.0f || !VoxelMath::IsFinite(D.ChasmSpacing)
|| !VoxelMath::IsFinite(D.ChasmRadius) || D.ChasmSpacing <= 0.0f
|| D.ChasmRadius < 0.0f)
{
return true;
@@ -1171,9 +1200,9 @@ static bool VF_AnyBridgeCanTouchBox(
{
return false;
}
if (!FMath::IsFinite(D.BridgeDensity) || D.BridgeDensity < 0.0f
|| D.BridgeDensity > 1.0f || !FMath::IsFinite(D.BridgeSpacing)
|| !FMath::IsFinite(D.BridgeRadius) || D.BridgeSpacing <= 0.0f
if (!VoxelMath::IsFinite(D.BridgeDensity) || D.BridgeDensity < 0.0f
|| D.BridgeDensity > 1.0f || !VoxelMath::IsFinite(D.BridgeSpacing)
|| !VoxelMath::IsFinite(D.BridgeRadius) || D.BridgeSpacing <= 0.0f
|| D.BridgeRadius < 0.0f)
{
return true;
@@ -1224,9 +1253,9 @@ static bool VF_AnyRidgeCanTouchBox(
{
return false;
}
if (!FMath::IsFinite(D.RidgeDensity) || D.RidgeDensity < 0.0f
|| D.RidgeDensity > 1.0f || !FMath::IsFinite(D.RidgeSpacing)
|| !FMath::IsFinite(D.RidgeHeight) || !FMath::IsFinite(D.RidgeThickness)
if (!VoxelMath::IsFinite(D.RidgeDensity) || D.RidgeDensity < 0.0f
|| D.RidgeDensity > 1.0f || !VoxelMath::IsFinite(D.RidgeSpacing)
|| !VoxelMath::IsFinite(D.RidgeHeight) || !VoxelMath::IsFinite(D.RidgeThickness)
|| D.RidgeSpacing <= 0.0f || D.RidgeHeight <= 0.0f || D.RidgeThickness < 0.0f)
{
return true;
@@ -1758,6 +1787,7 @@ UVoxelGenerator::UVoxelGenerator()
void UVoxelGenerator::InitializeSettings(const UVoxelSettings* Settings)
{
VF_ParseFastIsFiniteSwitch();
// Les paramètres globaux sont copiés ici une seule fois : le chemin voxel ne doit pas
// déréférencer l'asset de settings.
Seed = Settings ? Settings->GetEffectiveWorldSeed() : 0;
@@ -1780,6 +1810,7 @@ void UVoxelGenerator::EndDensityBlock() const
float UVoxelGenerator::GetDensityAt(float WorldX, float WorldY, float WorldZ) const
{
TRACE_CPUPROFILER_EVENT_SCOPE(VoxelForge_GetDensityAt);
VF_ParseFastIsFiniteSwitch();
VF_ParseFusedEvaluatorSwitch();
VoxelDensityProfile::FScopedTimer DensityProfileTimer(
VoxelDensityProfile::EBucket::GetDensityAt);
@@ -5009,7 +5040,7 @@ static EVoxelTileClass VF_ClassifyBoxRefined(const FVoxelOpStack& Stack,
for (const int32 IX : Xs)
{
const float Density = EvaluateExactLatticeValue(IX, IY, IZ, bUseFinalField);
if (!FMath::IsFinite(Density) || Density == 0.0f)
if (!VoxelMath::IsFinite(Density) || Density == 0.0f)
{
return false;
}
@@ -5053,7 +5084,7 @@ static EVoxelTileClass VF_ClassifyBoxRefined(const FVoxelOpStack& Stack,
for (int32 IX = IX0; IX <= IX1; ++IX)
{
const float Density = EvaluateExactLatticeValue(IX, IY, IZ, bUseFinalField);
if (!FMath::IsFinite(Density) || Density == 0.0f)
if (!VoxelMath::IsFinite(Density) || Density == 0.0f)
{
++ZeroOrInvalidCount;
IZ = IZ1;