A code object contributes exactly ONE contiguous .rodata run, so a subseg owning raw
jump tables in >=2 non-adjacent island spans makes every switch function outside the one
carveable span unbankable at any effort. main sat in that state from Phase 7 to Phase 31
and eleven functions were written off as 'PROVEN gate-rejects' because of it. The
evidence is derivable from the raw image on day one; nothing was comparing it.
FIRST FLEET RUN: 209/213 OK, 4 overlays flagged — ov_SC01_084, ov_SC02_005, ov_SC02_011,
ov_SC03_105 — holding 16 open functions / 3,613 instructions (18% of the non-main
frontier). All 16 were already in the S71 exclude list, i.e. recorded as if unmatchable
rather than as 'needs a subseg split'. 3.7s fleet-wide.
Self-test covers all three directions: fires on main's pre-S72 island (fed
synthetically, because the real tree no longer holds that state), stays silent on main
today, and does not over-fire on a one-span subseg. Linked-library subsegs are excluded
on principle — their code comes from a .a so cc1 emits no table for them; without that
filter main reports NEEDS SPLIT on libgs6, which the self-test caught.
Wired into make tools-health. accelerators #20 gains the when-to-split rule: split where
the BUILD forces a boundary (decidable at 0% matched), at the span-owner boundaries and
nowhere else, never on TU archaeology.
Drew T