From the S76 func_80039308 agent (518 ins, 402 -> 154, length exact).
Writing a varying-address load as a struct member (((VMask*)q)->w rather than
*(u32*)q) sets MEM_IN_STRUCT_P, which lets true_dependence prove the load
cannot alias a scalar-global store. Both loads hoist above both stores and
three load-delay nops vanish — semantically identical C, different alias
info.
It also needed a 16-byte s16 sav[8] memory local because reload rounds every
spill slot to BIGGEST_ALIGNMENT=8 — the same law §463 derived from alter_reg
on a different function via a different agent that had not seen it. Two
independent derivations, and a second use for the law: it tells you when a
stack layout can only come from a declared local, never from spilling.
Drew T
978a086ebb