sched_sim_driver_start() now registers the core's tlog format function and
marks its core active for logging right after the virtual clock is seeded
(xce_core_register_tlog_format()/xce_core_set_active_for_logging()) --
every log line for the rest of the run shows frozen/scaled replay time
instead of real wall-clock time, matching what an operator debugging
against a replay's own timeline needs. sched_sim_driver_run() deactivates
on all 7 of its return paths, since there's no sim-driver teardown
function and g_active_core_for_logging would otherwise dangle past the
caller's stack frame.
Also fixes a genuine pre-existing ASAN stack-use-after-return (bug-1598)
the new deactivation test exposed: sim_picker_thread_fn is spawned but, by
design, never joined/cancelled, so a stack-local `xce_sched_sim_driver_t
sim` in test_sim_event_loop.c was always a latent UAF once its owning test
function returned -- just not previously triggered by any prior test
ordering. Switched the three affected fixtures in that file to `static`
storage (safe: sched_sim_driver_start() memsets the whole struct on entry,
and none of the three call sites are re-entrant).
Add sim_loop.c implementing sched_sim_driver_run(): decode .replay
messages in file order, jump the virtual clock to each ReplayEvent's
exact timestamp as it's queued, and run a real push-events/go/drain/
end-session cycle on each ReplaySession boundary (AC 14, AC 18).
Task 11.1 left no picker registered against the isolated core and no
thread backing its cbufs, which deadlocks the decision drain the moment
a real event loop exists. Add plugin_register_core() (registers a
picker against a bare xce_sched_core_t*, no xce_scheduler_t* required)
and extract builtin_fcfs_new_plugin() from register_builtin_fcfs() as a
behavior-preserving factory, plus a picker-driving thread for the sim
driver. Since real resource allocation is unreachable without a live
xce_scheduler_t* (scheduler-allocation spec's job), the sim picker
thread conservatively PENDs every candidate rather than dispatching.
28/28 scheduler suite, 32/32 whole-project tests green.
Add sim.h/sim.c implementing AC 13 steps 1-4: open+validate ReplayHeader,
locate the most recent SnapshotEntry at/before --sim-start-ts, load it via
xce_sched_core_load_snapshot(), and set the virtual clock anchors. Wire
all seven simulation CLI flags into main.c's task-5.2 mode-selection
branch. Event loop itself (step 5) deferred to task 11.2. Fixes two real
bugs found during TDD: a SnapshotEntry_get_ts() use-after-free and a
pend_updates NULL-deref in xce_sched_core_fini() for bare-core callers.
27/27 scheduler suite green, full project build clean.
