Remove fe_normalize/reduceSelf from the end of field multiply and
square. After reduceWide, the output is in [0, 2^256) which may
include values in [P, P+C) where C = 2^32+977. This is the same
"unreduced" range that lazy fe_add produces, and is safe because:
- mul/sqr: mulWide handles any 256-bit input via reduceWide ✓
- add: carry fold handles overflow past 2^256 ✓
- sub: P-add-back on underflow produces correct field element ✓
- neg/half: already normalize input via reduceSelf ✓
- isZero/cmp/toBytes: caller normalizes before use ✓
Native C-to-C results (x86_64, vs ACINQ):
verifyFast: 0.95x → 0.99x (essentially tied with ACINQ!)
sign (cached): 1.18x → 1.24x faster
ECDH: 1.05x → 1.06x faster
batch(200)/event: 7.2µs → 6.4µs
Kotlin JVM results (vs previous lazy-add-only):
Kotlin numbers stable — reduceSelf in reduceWide was already
cheap on JVM since the branch is almost never taken.
https://claude.ai/code/session_011KVZhDcV2G7idNWEBz12GY
Claude
4dea4b5db5