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https://github.com/RetroPortingToolKit/psxrecomp
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Matthew Stanley
f8aefefec1
End the "somewhere upstream" blindness with a reusable first-divergence
instrument (PRINCIPLES.md "find the first divergence; is the value WRONG or the
behavior MISSING"). A TCB-scoped, freeze-on-trigger control-flow ring with an
identical struct + JSON wire format on both processes, so a generic sequence-diff
(tools/parity_diff.py) locates the first logical divergence between recomp and
oracle — not a frame diff.
- parity_trace.{h,c}: armed-from-boot ring, gated on current_tcb==watched_tcb,
latches on a configured trigger target so the pre-divergence window survives
the wedge loop. Up to 6 watch-word snapshots/row. Self-contained TU shared by
both binaries; frame source decoupled via parity_host_frame().
- fntrace.c: per-dispatch producer hook (cheap armed gate on the hot path).
- traps.c: YIELD control-event hook in the scheduler switch.
- main.cpp: env-armed from boot (PSX_PARITY_TRACE=1; TCB/trigger/watch tunable),
defaults target the MMX6 cutscene wedge.
- debug_server.c: parity_dump + parity_ctl commands.
- tools/parity_diff.py: pulls both rings, sequence-diffs by (kind,pc,target).
First use (MMX6 freeze) confirmed MISSING behavior, not a wrong value: native
thread1 is permanently parked at func_8002000C resume (TCB EPC 0x800200F4),
handshake flag 0x8006D9AC never set (0 across 16384 rows), setter func_8001344C
never runs; thread1 re-resumes a dead func_8002000C frame whose saved-ra slot was
reused -> jr 0x800CD3F8 wedge. Upstream context-staleness/scheduling root.
Beetle mirror producer + the cross-process diff are the next step.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>