w6c+wwstage: array return-by-value via the struct-return ABI (#267 fold-2)
Wire TY_ARRAY into the existing struct-return gates so arrays ride the
same reg-class (<=24B in AX:DX:CX) / sret-class (>24B) path the struct
return ABI already emits byte-identically. No new ABI machinery.
Both stages, uniform gate-widen:
- cg_sret_retsize / sretretsize: +TY_ARRAY (natural size sub.size*len,
the type table) -> auto-enables sret send/recv + the >24B sret N_IDENT
word-copy + return-forward, all keyed on the shared sret SSoT.
- cgreturn <=24B reg-send: +TY_ARRAY (N_IDENT scratch word-copy ->
AX/DX/CX). reg-class return-forward rides the default cgexpr passthrough.
- let-init / assign <=24B recv: +TY_ARRAY (AX/DX/CX sized stores).
struct_float_class stays struct-only: pure-int element arrays only; no
pure-float-array-return consumer exists today.
949 +11 rows: reg-class 8/16/24B + sret-class 32B, [N]u32 and [N]u8,
at let-init/assign/return-forward, full-member readback, + a struct-
return regression control. All cstage-run + cs==ww byte-id.
Hojun-Cho
ebbc3f98c2