- AUDITED .run/giants/s18_func_8017D960_b2.c (pins $25 $17 $19 $20 $21) WITHOUT recompiling:
the SESSION-18 match_one object survives and cmp proves its t.c is this draft.
- VERDICT SAFE. The corrupting form of the §72 hazard is a CALLER-SAVED pin ($25=$t9) whose
live range spans a jal — gcc-2.7.2 does not save/restore an explicit-register variable
across a call. Byte-checked: exactly 3 jal, all at 0x2c-0x50; first pin write at 0x58 =>
NO call after the pins are established. Corroborated by a token census of the C (every
call-shaped token after line 270 is a file-local macro: gte_*, BOXTEST, ATTEN, CLAMP80).
- The observed excess writes (2/3/3/5/5 vs 2 assignments each + 1 epilogue lw) are the BENIGN
§72 mode: gcc using the pinned reg as scratch before the pinned value lands (lui/lw/addiu on
$20, with addu t9,s4,zero routing r1's value out through it). Nothing live was clobbered.
- cookbook §74: the reusable audit (objdump the surviving object; compare jal addresses against
the first pin write; expect writes == assignments + 1 epilogue restore) + the standing rule —
prefer a callee-saved register for any pin outliving a call; a caller-saved pin across a jal
is a real wall verdict, not a drafting slip.
Drew T
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