Worker C found the strongest structural signal of the phase and asked me to act
on it rather than merely record it. I re-derived the census independently before
acting: 50 of the 1,937 exact extents contain trapping add/sub (funct 0x20/0x22,
410 instructions) and 0 of the 144 then-registered regions does. All four
unmatched duplicate groups are inside the class. Ten cc1 builds plus the real
CC1PSX 4.0-4.6 over ~30 C shapes and 15 flags never emit the trapping forms, and
-ftrapv is rejected by all of them.
tools/sf3_triage now detects the class and excludes it by default
(excluded_trapping_arith=50, --allow-trapping to list it), with three synthetic
tests, so no worker can spend budget on it by accident. Recorded as cookbook
finding 26 with the neg-macro clue that points at a macro-print-style difference
rather than a source difference. The class is now the best candidate for part of
the unresolved library-versus-game-code boundary - a hypothesis, not a claim.
Also recorded: worker A's maspsx load-delay defect (its predicate tests whether
the next instruction loads FROM the register, not whether it reads it at all, so
a load followed by a store of that register gets no delay nop), four mechanical
layout tells, and the struct-assignment lever for the base-in-register class.
Finding 22 is refined with worker C's third spelling: the written order of the +
operands decides the emitted addu order.
Cycle 5 merge: 65 claims, 8 accepted, 57 skipped, 0 rejected. Candidate gate
c_regions=152, 0 differing bytes; promoted; make check green at 203 tests.
Distinct matched bodies: 143.
Christopher Williams
591923a32f