The previous section withdrew this localisation for resting on a stale
PPCContext. It is now re-established by a sound method.
Xenia has a CPU cvar, emit_source_annotations, that makes MarkSourceOffset emit
"nop; nop; mov eax,<guest_address>; nop; nop" at EVERY guest instruction
boundary -- 90 90 B8 xx xx xx xx 90 90 in the code bytes. So the guest PC reads
straight out of memory around rip, with no context and no offset guessing.
Dumping backwards from rip gives a clean run of them -- 0x82457874, 78, 7C, 80,
84 -- and the annotation immediately before rip is 0x824578A0. That is
`sth r6, 0(r9)` inside sub_82457780: the exact instruction predicted from the
disassembly last time, now reached independently.
The loop advances r11 by 8 and terminates on `bne cr6` -- exact inequality. If
r31 - r7 is not a positive multiple of 8, the comparison never becomes equal and
the loop never exits.
And the thread is genuinely running: over 4 s, Main XThread consumed 890 ms of
CPU, the top of any thread, with the process at ~238%. A spin, not a block.
One bad metric recorded: I tried to show the loop marching through memory by
watching the last non-zero byte above 0x70200000. It never moved -- but that
statistic saturates in an already-written region, so it could not have moved.
Not evidence either way, though it briefly looked like a refutation.
Open and now narrow: what makes r31 - r7 non-congruent to 0 mod 8. r7 comes
from 0(r30), r31 is the container end, and r3 holds a fresh buffer from
0x824F7240 -- read those three from HOST registers at the freeze.
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