Runs authoritative TCI first, snapshots its result, rewinds guest state,
runs the compiled TB as a disposable shadow, compares GPRs/DRAM, then
restores TCI. Opt-in via wasm_diff_enable(); normal execution unchanged.
Valid comparison required restoring all state a single TB can touch:
- full CPUNegativeOffsetState (the env-8 interrupt check sits before env)
- deep CPUTLB.f[].table / d[].fulltlb per MMU mode
- and skipping async cpu_exit() force-exit races.
Only side-effect-safe candidates compared (store TB, no general helper).
Result: 160k+ store-TB comparisons during reader-open, zero divergence.
Per-TB store codegen is exonerated; corruption is emergent across TBs.
evan
1473b7ab10