Detect a side-effect-free poll loop by its repeated same-PC interrupt
checks and, when the window touched no MMIO and issued no stores,
fast-forward guest time to the next internal device event
(vblank/timer/cdrom/dma/sio) in whole loop quanta — bit-exact versus
executing the spins one by one. Off switch: PSX_IDLE_SKIP=0 env or the
idle_skip TCP command; gated off in exception context, precise mode, and
lockstep.
memory.c adds the two always-on gates the skip requires: g_guest_store_count
(bumped at every raw store chokepoint) and g_mmio_access_count (bumped on
every device-page read/write). Any store or MMIO touch in the window
disqualifies it as a pure poll loop.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Matthew Stanley
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