* Makefile: support Linux PowerPC (ppc64le) builds
PowerPC GCC uses -mcpu instead of -march, so the Linux branch failed
with unrecognized option -march=native on ppc64le. Detect ppc64le and
ppc64 via uname -m and use -mcpu=$(ARCH) there. The x86-64 path is
unchanged.
Validated on an IBM POWER8 S824 (Ubuntu 20.04, gcc 9.4): make test-c
passes, teacher forcing 32/32 positions and greedy 20/20 tokens against
the transformers oracle, engine reports the scalar idot fallback.
Signed-off-by: Scott <scottbphone12@gmail.com>
* VSX integer-dot kernels for POWER8 (12.8x int8, 7.6x int4 over scalar)
Adds a VSX path to dot_i8i8 and dot_i4i8 using vec_msum, which sums
byte products directly into s32 lanes, so the 16-bit saturation bound
of the AVX2 maddubs trick does not apply. abs(w) is built with a
modulo-subtract select instead of vec_abs so w=-128 wraps to 128
unsigned instead of saturating to 127. Nibble unpack uses
vec_mergeh/vec_mergel, which interleave like x86 unpacklo/unpackhi on
ppc64le (verified on hardware). g_i4s=1 on VSX since the f32 fallback
is plain scalar there: measured 5.5x for int4 IDOT at S=1.
Measured on an IBM POWER8 S824 (gcc 9.4, Ubuntu 20.04 ppc64le),
single thread, 1536x6144:
dot_i8i8 1.48 -> 18.99 Gops/s (12.8x)
dot_i4i8 2.33 -> 17.72 Gops/s (7.6x)
S=1 int4 matmul path: 3.925 -> 0.505 ms/call (7.8x vs scalar build)
Adds tests/test_idot.c: exactness test of the compiled idot kernels
(any arch) against a plain-C reference, covering odd tails and the
w=-128 edge. Passes on avx512-vnni (x86) and vsx (POWER8). The tiny
oracle stays token-exact on the VSX build: TF 32/32, greedy 20/20.
Signed-off-by: Scott <scottbphone12@gmail.com>
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Signed-off-by: Scott <scottbphone12@gmail.com>
Co-authored-by: Scott <scottbphone12@gmail.com>
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