Tested candidate.c across GCC-15 and clang-19 optimization levels:
gcc -Os → 116 B (+12)
clang -O2/Os/Oz → 108 B (+4) ← best
vendor → 104 B (0)
Vendor output is SMALLER than GCC -Os, which rules out 'spa-appointment
dumb compiler' (hypothesis b). Clang being only 4 bytes off suggests
the vendor uses armclang or a similarly-tuned LLVM fork (hypothesis a).
Immediate consequence: default compiler for matching-decomp on this
blob is clang, not GCC. Our train_phy_block starting score jumps
from 89.7% (GCC -Os) to 96% (clang -Oz) before any C tweaking.
Pushing past 96% likely needs armclang or per-site inline asm.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
marfrit
cf6ddf8e91