March 17, 2026

BOOM RISC-V Out-of-Order Core

SmallBoomV3 from Chipyard

187,356
Lines of SystemVerilog
1,732 / 1,784
Properties proven (97.1%)
46 min
Zero manual assertions
Control signals 4,280 / 4,280 — 100%
Data signals 4,804 / 4,804 — 100%
Memory index bounds 789 / 803 — 98.3%
Assume-guarantee closure 9,084 / 9,084 — 100%

268 modules received automated formal analysis. Every proof ran on an open-source formal solver. The generated properties are standard SVA, portable to any commercial formal tool.

Bug Detection Demo

We injected a 3-line microarchitectural bug into BOOM's reorder buffer. When an exception and a branch mispredict arrive on the exact same cycle, a latch permanently blocks the commit pointer. The processor hangs. Simulation never triggers it.

Clean Design
Rob
F1_EVENTUAL_DRAIN
PASS_KINDUCTION
3 Lines Changed
Rob
F1_EVENTUAL_DRAIN
COUNTEREXAMPLE

Caught in 17 seconds with a concrete counterexample trace. The formal solver explores every reachable state — no random stimulus, no directed tests needed. This class of bug sits at the intersection of two independent recovery paths in the microarchitecture and is vanishingly rare in simulation across billions of cycles.

Cross-Module Assume-Guarantee Closure

9,084 contract edges automatically discharged across 266 modules. Guarantees extracted from proven probes, matched to downstream assumptions via geometry-based port matching over RTL wiring topology. Transitive propagation through combinational paths. Zero manual pairs.