Two distinct bugs were causing OPTIONS-black hard freezes after 12K-65K
frames:
1. interrupts.c + traps.c: exception_jmpbuf is a single global. setjmp
captures the running fiber, but longjmp may be requested from a
different fiber via psx_exception_longjmp / psx_restore_state_escape
during chain-handler dispatch. Cross-fiber longjmp restores RSP to
the wrong stack while Win32 still tracks the calling fiber, corrupting
fiber state until SwitchToFiber eventually hangs.
Fix: track g_exception_owner_fiber at setjmp time. New
deferred_exception_longjmp checks the current fiber; if it's not the
owner, sets a pending flag and SwitchToFiber's back to the owner.
psx_change_thread_fiber's post-SwitchToFiber path observes the flag
and executes the longjmp on the correct stack.
2. gpu.c: gpu_read_gpustat fired gpu_vblank_tick() after 1000 polls,
which invoked sdl_vblank_present (SDL_Delay -> Sleep) from inside
an MMIO read code path. That meant recompiled MIPS spent wall time
in Sleep deep inside the fiber call tree -- confusing to reason
about and a contributor to fiber/longjmp interactions.
Fix: synthetic VBLANK from a poll-storm only updates emulation state
(LCF + I_STAT). The host-side render+sleep happens only at the proper
cycle-paced VBLANK trigger in psx_check_interrupts.
Also adds: dirty_block ring slice to the freeze auto-dump, Win32 main-
thread stack capture for wedge_kind=1 hard freezes (SuspendThread +
StackWalk64 + SymFromAddr), and dbghelp link.
Validated: TombaRecomp psx-runtime ran 30+ minutes / 105K+ frames at
OPTIONS with no hard freeze. Previous freezes consistently hit at
11900, 20493, and 64596 frames.
Diagnostic tooling under tools/_options_session/ that produced this
diagnosis is included.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Matthew Stanley