Builds without a native DT3 kernel rename the generic symbol to
ggml_vec_dot_dt3_q8_0 (arch-fallback.h), so test-dt3 failed to link on
them. With a weak declaration the test links everywhere and skips,
loudly, when there is no separate generic to compare against. MSVC has
no weak symbols, so there the test is compiled out.
Calls the actual ggml_vec_dot_dt3_q8_0_generic symbol against the
dispatched vec_dot and requires memcmp-equal floats. Blocks exercise
the three regions, the 79/80 and 119/120 boundaries, non-trivial qh
bytes (would expose a vectorization reading their padding 5th digit),
and scales of both and mixed signs; y reaches the full q8_0 range.
Mutation-checked: flipping one bit of a digit blend mask in the
AVX-512 kernel makes 94 of the 96 reps fail.
The previous byte-position test packed with the test's own packer on
both sides of the comparison, so it exercised none of the library code.
It now pins hand-computed byte values (43/100/127/42/124...) at the
region boundaries (79/80, 119/120) as ground truth and drives both
directions through the library: to_float must place each literal byte's
trit at the exact element, and from_float must produce the exact literal
byte, for both planes.
Also probes ggml_validate_row_data over all 256 byte values in qs and
qh positions (must accept exactly the 243/81 reachable codes), the
all-0xaa block, and a well-formed packed block.
test-dt3 checks the layout against an independent packer written from
the format spec: single-trit position mapping for all 256 (plane, pos)
pairs, structural byte-position checks at the region boundaries
(79/80, 119/120), exact round-trips with negative scales, byte parity
of the in-tree quantizer on already-ternary inputs, and the vec_dot
against a hand-made sum over the known trits (catches any path that
reads the padding 5th trit of the qh bytes).
test-dt3-rust-parity.py packs known trits with ternaria's pack_dt3 and
verifies that dequantize_row_dt3 (via test-dt3 --dequant) reproduces
d1*t1 + d2*t2 bit-exactly.
Also wires DT3 into the test-quantize-fns thresholds (ternary class).
Millaguie