Hojun-Cho b2e4388792 w6c_ww: cgtypetest resolves non-ident scrutinees, no-spill tag compare (fix #45) ...

Pre-#45 wwstage `is` resolved only N_IDENT scrutinees; xs[i] / p.field
/ call() fell through with scrutoff=0 + scrutt=nil and emitted
MOVQ (BP),AX; CMPQ $0,AX — tag read off the saved-BP word, variant
clamped to 0 (SILENT cs≠ww; cstage cgexprs the scrutinee and compares
the real tag in AX). The non-ident arm now cgexprs the scrutinee (tag
lands in AX) and compares directly. NOT the `as` twin's @asrt_spill
(#200): cmp against cstage shows N_TYPETEST never spills — `as`
re-reads payload words after the check, `is` consumes only the tag,
and a spill would break rule-10 byte-id. Variant index resolves from
the STAMPED scrutinee type via flatvariantidx/flatslicevariantidx
(matchscrutt's node walk can't carry N_DOT through cgtypetest's
N_TTAGGED gate). Ident path untouched (control row + hand-cmp vs
pre-#45 w6c_ww). wwstage-only source change; cs==ww byte-id pinned
per row in 927_is_nonident_run.

2026-06-04 04:40:54 +09:00

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