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Drew T
f1bbcd241f
The 'unsteerable' regalloc-order class is NOT unsteerable. Drew's directive (hand-match
everything) exposed the lever I'd skipped: explicit register pinning.
- func_8012B8E4 (the flagship circular reach-134 'unsteerable' fn): 21 -> MATCH via
* register pins: register s32 d __asm__("$16"); register s32 s1ang __asm__("$17")
-> FORCES the $s0/$s1 global allocation gcc otherwise density-orders the other way
* branch-polarity invert (§3-T4): 24->21
* explicit clamp temps (t=u6+0x1000; iVar4=u5-t): fixes the reassociation, 7->3
* scheduling barrier __asm__ __volatile__("" : : "r"(u5)): anchors the last sll, 3->MATCH
- byte-gated (harvest_verify, G3/P9) + propagated x134 (per-overlay gate); 134 byte-identical
- recipe = §10-family hand technique (pins + barriers); labor-intensive (per-fn register map
from the asm) but it WORKS -> the circular tail IS hand-matchable, not asm-only
- supersedes the T1-T5 'unsteerable' verdict; cookbook §17 + PhaseEnd to be revised accordingly