ChainHash at a0116ea: same-binary refresh on Xeon and M2

The chart's ChainHash and ChainHash-128 cells on the Xeon and M2 tabs are measured at thomasahle/chainhash a0116ea. The AMD EPYC 9R14 (Zen 4) tab measures the same revision (records/zen4), so all three tabs show one revision of each function.

Since the previously published cells, the headers gained only exact-output speed changes:

• shorter paths for inputs up to 128 bytes, and faster key expansion;
• prefetch-parameterized bulk kernels and a stream fast path;
• fused PMULL+EOR kernels on Apple cores;
• vector tails on every x86 backend;
• a spill-free ChainHash-128 ZMM accumulation and a register-bounded XMM kernel;
• the ChainHash-128 product method chosen by the PCLMULQDQ issue rate.

The calibration header is opt-in and is not used here. Both functions are unchanged: the verification values are the repository's, 0x66672BD6 (ChainHash) and 0x1FCA728C (ChainHash-128), on every registration and host.

Each binary links two revisions of the headers side by side: a0116ea and 0a03c63 as a control. PolyXOR128 and XXH3-128 run in the same binary.

These replace the previously published cells:

Method

• Unmodified SMHasher3 --test=Speed, one process at a time. Every start waits until no other SMHasher3 process runs. A whole-machine scan every 15 s discards and repeats any run that overlaps another SMHasher3 process; none was discarded.
• Xeon 8375C: the post's build-release-20260917 objects and the PolyXOR128 lane's objects, as in records/polyxor. Runs use nice -n 10 taskset -c 16-23. The cell takes the higher bulk of two passes and, independently, the lower small-key average. Units are bytes per TSC tick (TSC 2.900 GHz).
• M2 Pro: the public reproduction's arm64 build. This is the base of the records/polyxor M2 binary; the post's original M2 base binary is no longer available. Runs use nice -n 10, gated on load1 < 4.5. The cell takes medians of three passes. Units are SMHasher3's calibrated cycles. The largest M2 spreads are about 4% (bulk passes: ChainHash 30.15 / 31.32 / 30.11, ChainHash-128 16.85 / 17.38 / 16.73), with no run more than 15% from its median.
• Every registration passes SMHasher3 Sanity and its verification value on both hosts (evidence/*/NAME.sanity.txt). The two revisions' verification values are identical, as SMHasher3's duplicate-code warning in the logs notes.

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