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Drew T
dfa366c7c6
func_8017F510 (1,511 ins): EXACT length, frame 0x258 exact, byte-exact prologue AND epilogue,
identical sp-slot set, 99.5% register-masked structural / 93.3% byte-aligned, SYMS-OK, 97 divergent.
Not a match (G3). §71's callee-set lever delivered ~90% of the C and a first compile at 1528/1511.
- CORRECTNESS FINDING (qualifies §17): a local `register s32 x __asm__("$30")` pin produced a
seductive 1511 ins / 98.9% and was a MISCOMPILE -- gcc-2.7.2 ALSO allocated $s8 to an unrelated
live value. A pin is a HINT to the allocator, not a reservation. Never ship one without inspecting
the pinned register's defs. Banked work is safe by construction (the byte-gate rejects a
miscompile); the exposure is UN-GATED drafts. ACTION: behemoth-2's draft carries FIVE pins
($25 $17 $19 $20 $21) and must be re-checked before anyone builds on it.
- THE HONEST FIX was source-level: the +17 drift was live-range stretching from REUSING w/wz for the
vertex-word reads (spilling amb, 7 lw+nop pairs). Dedicated temps -> 1528->1511, 88%->99.6%, no pin.
- GIV RECORD ORDER (§70 family): part->prim must be read BEFORE part->nprim -- loop.c:combine_givs
walks bl->giv in REVERSE record order, so the last-recorded giv becomes the combined base.
- RESIDUAL 97 traced to ONE seed: c3 is $a2 in the target, $a3 in the draft; tp takes the other of
the pair and renames the whole 4-tail block. Fix c3 -> $a2 and ~93 should fall together.
- SPENT, byte-recorded: decl-order permutations, block-scoping, splitting/inlining tp, reusing f0,
vertex axis orders, and decomp-permuter (4,724 candidates, base 97, ZERO improvement -- a §3 hard
tail outside the C-randomisation space).
- b3_align.py / b3_pos.py supersede the b2_* aligners.