Matching conventions require a duplicate check before registering, because a
shared body is matched once and registered once per address. Phase 6 did that
check by hand and found one 12-byte pair. tools/sf3_dupes now hashes every
derived extent body and groups exact duplicates.
Results: 2284 extents, 65 multi-address groups, 2104 singletons. Only 10 groups
contain code (24 addresses, all exact-graded); 55 are all-zero bodies. The
hand-found pair 0x800262E0/0x800262EC is reproduced as g0002, which is the check
that the census measures what it claims. The largest real groups are 712 bytes
(0x8001084C/0x800189E8) and 436 bytes.
The zero groups are a real finding: 252 extents have all-zero bodies, 245 inside
the zero band 0x80147000..0x80170000. The cause is the inventory's jal grade,
which decodes every word as an instruction -- in a data region a word with
opcode 3 is graded as a call whose target lands in the zero band. The census
flags those groups rather than hiding them, and the worklist must exclude
degenerate bodies.
The census is tracked rather than ignored as the plan said, because it holds
addresses, sizes and grades only (the same class as the tracked inventory and
extents tables) and the worklist must be reproducible from tracked inputs. The
content hash is computed and never written.
Phase 6 graded function starts and left every end to be derived by hand. This
adds tools/sf3_extents, which explores all reachable control flow from each hard
start (jal/entry) and reports an extent plus how far it can be trusted.
Measured decisions, not stylistic ones:
- Soft starts are not walk boundaries. A body's second instruction can satisfy
the prologue grade exactly (0x800152AC is lw v1,8(gp) / addiu sp,sp,-176, so
0x800152B0 looks like a start). Enforcing soft boundaries stopped 155 of 416
walks inside a real body.
- The walk is a full reachability computation, not a first-terminal search: a
function whose paths return at different addresses must report the whole body.
Grades: exact 1940 (1666 packed, gap=0), fallthrough 256, indirect 73,
escape 15, contained 153, standalone 438; 63.8% of the payload covered.
Verification: all 12 registered regions reproduce exactly (make extents-verify,
now part of make check), 29 new synthetic tests (115 total), byte-identical
across two runs, and Ghidra's independent body for FUN_80017ad4 agrees. Two
defects were caught by writing the tests first and are recorded: reach had to be
an exclusive end, and a terminal j's delay slot must not continue linearly.
The table holds addresses, sizes, grades and site addresses only -- no bytes.
P5-T6. Adds docs/MATCHING_COOKBOOK.md (nine byte-proven compiler/assembler
findings, each with basis and limit), docs/MATCHING_CONVENTIONS.md (what counts
as a match, registry format, source naming, duplicate sharing, symbols, the
verification procedure, the firewall) and docs/PHASE5_VERIFICATION.md (outcome,
clean gates, bounded negatives, milestone request).
Tooling: make test and make check targets; region objects are now
symbol-localized so the documented duplicate-sharing mechanism (N registry rows
-> 1 source) links, covered by a synthetic test (53 tests).
Clean gates: 53/53 tests; make clean/all/cmp/SHA-1 green; make gate with one C
region -> c_regions=1, 0 differing bytes, SHA-1 e173426c...; 57 tracked files, 0
under any prohibited root. Phase 5 is not closed until the milestone is
confirmed.
make gate on the empty registry prints result=MATCH, which is the data baseline
being copied through the ordered layout, not a C match. The harness now prints
c_regions=<n> and, when zero, an explicit note that the build contains no C.
Adds two synthetic tests (52 total).
P5-T4: tools/sf3_match provides range/plan/build/gate. It compiles a C candidate
with the identified toolchain (egcs-2.91.66 psx, -O2 -G0 -mno-split-addresses),
compares the exact instruction range byte-for-byte against the original, and
builds the address-ordered executable from the tracked registry config/regions.tsv
(header 0x800 + data gaps + C regions, LMA 0x800, metadata discarded).
Promotes the Phase 4 ordered workflow from an ignored experiment to tracked
tooling. Verified: make gate with an empty registry and with one real C region
both reproduce SHA-1 e173426c...; the Phase 3 baseline is unchanged and green;
the synthetic suite is now 50 tests including deliberate-corruption failures and
safe refusal of an existing destination. No ROM-derived material is tracked.
Christopher Williams