Function word_uses_spilled_reg 

pub fn word_uses_spilled_reg(w: u32) -> bool

Spilled-register predicate on a raw 4-byte word, for the recompiler.

True iff the word names x3 or x4 (the two host-spilled GPRs) in a real register field. The recompiler tests this after word_uses_reserved_reg to route an x3/x4 instruction to its cold spill path; the interpreter needs no equivalent (it executes x3/x4 as ordinary slot-13/14 GPRs). For every conformant word the toolchain emits this is false, so the recompiler’s fast path is untouched.