unchecked-hulls (off by default): elides bounds checks on hull-topology
indexing in the three SAT hot loops via a cfg'd accessor. Safety contract
= hull connectivity invariants validated at construction (hull.rs
is_valid_hull_impl + create_hull asserts), immutable behind Arc; debug
builds always assert, so every test run exercises the contract. Measured
(paired, retrained PGO): junkyard -3.6%, washer -2%, nothing elsewhere —
documented honestly that the checks were NOT most of the hull residue.
Tests 179 green with and without the feature; hash 0x61E35C31 both.
README: evaluation of the newly-stabilized algebraic float ops idea —
incompatible with the determinism contract as a default (compiler-
version/ISA-dependent results break cross-arch equality and cross-build
replay), modest expected upside since hot paths are already hand-
contracted; possible future opt-in, not planned.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
- contact solver wide ops + V32 now have real SSE2 and NEON paths selected
by target arch; scalar fallback behind the disable-simd feature. All three
paths are bit-identical (cross-arch determinism verified: same ragdoll
hash on NEON, SSE2 under Rosetta, and scalar).
- double-precision feature (C BOX3D_DOUBLE_PRECISION): f64 world positions
with the exact C boundary-function semantics; enables the far-from-origin
test halves (157 tests in DP mode, 151 default).
- world snapshots: recording substrate subset (buffer/writers/geometry
registry/readers) + world_snapshot.c port; bit-identical continuation
after restore, corrupt-image rejection.
- examples/benchmark.rs: all 10 C benchmark scenarios; serial Rust runs
1.05-1.55x slower than C -O2 at one worker (geomean ~1.3x with fat LTO).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Full engine port in libs/box3d: math, geometry, GJK/TOI, hull builder,
dynamic tree, manifolds, constraint graph, solver (serial, scalar SIMD
path), all 8 joint types, sensors, mover, world API. 147 ported C unit
tests green in debug and release. See libs/box3d/README.md for the
upstream revision and sync notes, PORTING.md for conventions.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
