Hojun-Cho
404705b6fd
C cgen has carried defer for a while (defers[] global + reverse walk on every return). Selfhost cgen now mirrors: - cgen struct: deferbuf (**node, LIFO stack) + defertop counter. - cgstmt N_DEFER: push n.lhs. - cgreturn: rundefers() at entry — same as the C cgen pattern. - cgfn fall-through return: rundefers() before zero-AX+RET. DEFER_MAX = 16 matches C cgen. Two new e2e rows: defer with an explicit `return acc;` (321 mod 256 = 65), and defer firing on an implicit void-fn fall-through (87). Both rows verified via the wwstage cgen too. Defer's semantics: queued exprs fire LIFO before the return expr is evaluated, so a return that reads memory mutated by a deferred call sees the post-defer state. Matches C cgen and Hare.