Drew T
3.7 KiB
§146 — RE-MEASURE A WALL BEFORE YOU RESPECT IT. Both "permanent" giants fell to drafts already on disk. (P30 S6, +50,094 ins)
The roadmap carried two functions as permanent walls since Phase 24. Between them they were 50,094 instructions — the largest single item on the board — and they had deterred a Fable5-scale attempt. Both were matched from stored drafts, in minutes.
| wall | recorded verdict | what it actually took |
|---|---|---|
func_80178004 (165×138) |
Phase 26: Fable5, ~477k tokens, "intrinsic 3-integer regalloc wall" | a stored draft, gated as-is |
func_801412A8 (198×138) |
close=29/110 since Phase 24 | 1 of 31 stored drafts + the §37/§124 alias |
Why a correct draft can read as an intrinsic wall
func_801412A8's TU declares extern int func_801412A8(int,int,int,int,int,int) and its callers
use the return value, while the byte-true definition is
Prim_1412A8 *(Prim_1412A8 *, int, int, int, u16, u16). Narrow params cannot agree with an int
prototype, and the () no-prototype escape is illegal precisely when a param promotes — so neither
side can move. The resulting byte difference is in the CALLERS, and match_one only ever compiles
the target function. The measuring instrument was structurally blind to where the difference lived,
so the residual was attributed to codegen. The §37/§124 def-side alias decouples them: the TU's
declaration keeps governing the call sites (their codegen untouched), the definition keeps its
byte-true signature.
Then propagation returned 0/137 TWICE — both times a missing TYPE
family_remap._carry_macros carries file-scope #defines, but (a) it does not carry typedefs at
all, and (b) it is not transitive — it brought addPrim_1412A8 and stopped, though that macro
calls setaddr/getaddr, and getaddr casts to PTag_1412A8. Lifting
Env_1412A8 / PTag_1412A8 / Prim_1412A8 + OT/getaddr/setaddr into engine_types.h took it to
137/137. A total-zero sweep on a PURE family with a matched exemplar is a tooling signal, not a
codegen one (§53) — here it fired twice in a row for two different missing symbols.
Two errors of mine, both instructive
Lift without strip. I added the typedefs to engine_types.h and left the originals in
ov_SC01_077.c. gcc-2.7.2 rejects a repeated typedef even when identical — the lesson already
recorded at the foot of engine_types.h — so R22 came back 139/140, [FAIL] ov_SC01_077, the
exemplar's own overlay. A proper lift strips the source; build_engine_types --strip does both.
The clean-fleet gate caught it before commit, which is exactly why fleet-shared edits are R22-gated.
Sampling instead of scanning. My first pass over the stored drafts used head -8 of 31 and
reported "best closeness 40" — the MATCH was in the 9th. And I checked whether a draft defined
Prim_1412A8 with a plain grep -c, which matches inside addPrim_1412A8, and briefly concluded
the carry worked. Same shape as reading a return as a declaration (§143): a pattern that is a
substring of the thing you are actually asking about.
The rule
A wall verdict is only as current as the instrument that produced it. Before spending
frontier-model tokens on a documented wall: re-run every stored draft through match_one (ALL of
them, not a sample), and check whether the tools that produced the verdict have changed since. Here
that cost four minutes and was worth 50,094 instructions. The corollary for the ledger: when a tool
is repaired, the verdicts it produced become hypotheses again, not facts.
Symptom lines for the index: "a documented wall" · "an old close= verdict" · "match_one MATCH but the whole binary differs" · "a sweep returns 0 of N twice".