The inverse of A1: A1 sinks an INIT to shorten a live range; this sinks the CONSUMER to delete the
allocno outright. A value defined in both if/else arms and consumed only by a call at the join becomes
a cross-block global allocno whose copy-prefs include the ARG register — and find_reg's copy-pref
override scans ascending regno (NOT reg_alloc_order), so $5 deterministically beats $16. The only
escape is allocno_calls_crossed>0 (global.c:906 strips caller-saved prefs), which a pseudo defined
after one call and dead before the next does not get. Duplicating the consumer call into the arms
demotes it to a call-crossing BLOCK-LOCAL -> local-alloc gives it a callee-saved reg, preserving the
§48-A2 $s0 occupant; the identical post-reload tails are re-merged by cross_jump, so the duplication
costs ZERO bytes. 10 of the 12 wave cores now MATCH.
Drew T
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