Hojun-Cho
140755d221
Trace at the c2 tip (rebuilt binaries, #80-c4 form): ret_widen's mk()
emitted `MOVQ -16(BP),AX / MOVQ AX,DX / MOVQ $0,CX` — the scalar
shuffle arm, payload word 1 ZEROED (s.b/e.aux dropped, cs silent
exit 1). Deciding predicate: the vu single peel left an alias struct
source TY_NAMED → isstruct false → scalar arm. The rt single peel was
the succ half: a 2-LEVEL alias return type stayed NAMED → the whole
tagged-return block was skipped → no tag synthesis at any return
(kb5_succ's three paired return-position insertions). Fix = the three
granted peels (bare-return rt, value-return rt, vu) →
type_chase_named; the route predicates (istagged/isstruct/istuple/
passthrough) key on the chased vu. Raw `->under` in cgen.c 62→59.
#89 CLOSES.
TRAIN INVARIANT holds: cs-only; _ww binaries bit-identical to the
bcd948d baseline md5s. cs movers vs the c2 tip bounded to EXACTLY the
return-route family: ret_widen, kb4_xret, kna_ret_errunion, kb5_succ.
Zero ww movers; detectors pinned (kb4_xampdef stays 139/139 #94;
def93/x93/l2_local stay cs-SEGV — c4's targets; fill/tuparg/v2
families unchanged).
Graduations (cs1/ww0 BYTE-DIVERGE → 0/0 BYTE-ID): g89_ret_widen (the
banked spelling), g89_ret_errunion (the live e.aux truncation seed),
and succ_2lvl flips K_RUN_NOID → K_RUN exactly as C1-CORR-1 predicted
(pins-follow-the-layer). g89_ret_named_ctl (bare NAMED control) held
0/0 byte-id throughout.
944_alias_cgen_b5_run 25→28 rows (75 checks); 944 family green;
sizelint 0.