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Hanzo AI
2e22541859
Add corona/gpu package — the single, decomplecting point where corona opts into the lattice library's per-SubRing GPU NTT dispatcher. Architecture (decomplected). The lattice library already owns ALL build-tag plumbing for GPU NTT: ring.SetGPUDispatchers (subring_ops.go) is the canonical hook; the lattice/gpu package installs it under `cgo && gpu` build tags and provides a real CPU fallback under !cgo or !gpu. Output is byte-equal to ring.SubRing.NTT by lattice's own contract. corona/gpu adds the corona-side bridge: UseAccelerator() flips a global flag, NewParams() across corona consults the flag via MaybeRegister and binds each created Ring's SubRings into the lattice GPU registry. Single source of truth for the opt-in; no build tags inside corona. Threshold gating (honest). Single-poly Metal NTT at corona's production N=256 is roughly 4-6x SLOWER than pure-Go ring.SubRing.NTT (measured: BenchmarkPulsarSign_ 5of7 force-GPU 7.1s vs CPU 1.1s; 14of21 force-GPU 23.5s vs CPU 5.9s). The GPU win exists only in BATCHED dispatch (many polynomials per kernel launch), which requires future engine-layer plumbing of lattice/gpu.MontgomeryNTTContext.Forward(data, batch>=4) bypassing the per-poly r.NTT() pinch point. Therefore UseAccelerator() picks defaultThreshold=1024 — above corona's N=256 — so the SubRing dispatch is armed but does not fire on single-poly NTT. The registry remains primed for any future batch caller (e.g. FHE bootstraps in thresholdvm sharing this library). UseAcceleratorForce() (threshold=1) is provided strictly for the correctness gate: every NTT call routes through the GPU so the byte-equality test in threshold/threshold_gpu_test.go exercises the GPU path end-to-end. Production callers use UseAccelerator() instead. Byte-equality. TestThresholdSign_CPU_vs_GPU_ByteIdentical runs the full 2-round Pulsar signing protocol with GPU dispatch off and forced-on (same deterministic dealer randomness, same message) and asserts byte-equal sig.C / sig.Z / sig.Delta. Passes under CGO_ENABLED=0, CGO_ENABLED=1, and CGO_ENABLED=1 -tags gpu. Existing TestDKG2_GPU_ByteEqual coverage extends across n=3,5,7,11,21 (production shape). Wiring. NewParams() in sign-bound packages — threshold, dkg2, dkg, reshare — calls corona/gpu.MaybeRegister(r) for the main Q ring. RXi and RNu are power-of-two moduli; the NTT path is not taken on them. Tests. Full corona test suite passes under both build modes: - CGO_ENABLED=0 go test ./... => all green - CGO_ENABLED=1 -tags gpu test => all green