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ggml : vectorize Q6_K unpack on WASM SIMD128 (strict, deterministic) #22134

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ggml : vectorize Q6_K unpack on WASM SIMD128 (strict, deterministic) #22134

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43 changes: 37 additions & 6 deletions ggml/src/ggml-cpu/arch/wasm/quants.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1137,17 +1137,48 @@ void ggml_vec_dot_q6_K_q8_K(int n, float * GGML_RESTRICT s, size_t bs, const voi
int32_t aux32[8] __attribute__((aligned(16))) = {0};
float sums[8] __attribute__((aligned(16))) = {0};

// Vectorized unpack constants (strict SIMD only, deterministic)
const v128_t mask_0F = wasm_i8x16_splat(0x0F);
const v128_t mask_03 = wasm_i8x16_splat(0x03);
const v128_t bias_32 = wasm_i8x16_splat(32);

for (int i = 0; i < nb; ++i) {
// Unpack 6-bit quantized data into aux8 (unchanged)
// Unpack 6-bit quantized data into aux8 (vectorized)
const uint8_t * GGML_RESTRICT q4 = x[i].ql;
const uint8_t * GGML_RESTRICT qh = x[i].qh;
int8_t * a = aux8;
for (int j = 0; j < QK_K; j += 128) {
for (int l = 0; l < 32; ++l) {
a[l + 0] = (int8_t)((q4[l + 0] & 0xF) | (((qh[l] >> 0) & 3) << 4)) - 32;
a[l + 32] = (int8_t)((q4[l + 32] & 0xF) | (((qh[l] >> 2) & 3) << 4)) - 32;
a[l + 64] = (int8_t)((q4[l + 0] >> 4) | (((qh[l] >> 4) & 3) << 4)) - 32;
a[l + 96] = (int8_t)((q4[l + 32] >> 4) | (((qh[l] >> 6) & 3) << 4)) - 32;
// Two 16-lane chunks per j-iteration (covers l = 0..31 of the
// scalar version). Each chunk decodes 64 output weights.
for (int chunk = 0; chunk < 32; chunk += 16) {
const v128_t q4_lo_src = wasm_v128_load(q4 + chunk);
const v128_t q4_hi_src = wasm_v128_load(q4 + chunk + 32);
const v128_t qh_src = wasm_v128_load(qh + chunk);

const v128_t q4_lo_nib = wasm_v128_and(q4_lo_src, mask_0F);
const v128_t q4_hi_nib = wasm_v128_and(q4_hi_src, mask_0F);
const v128_t q4_lo_hnib = wasm_u8x16_shr(q4_lo_src, 4);
const v128_t q4_hi_hnib = wasm_u8x16_shr(q4_hi_src, 4);

const v128_t qh_b01 = wasm_v128_and(qh_src, mask_03);
const v128_t qh_b23 = wasm_v128_and(wasm_u8x16_shr(qh_src, 2), mask_03);
const v128_t qh_b45 = wasm_v128_and(wasm_u8x16_shr(qh_src, 4), mask_03);
const v128_t qh_b67 = wasm_u8x16_shr(qh_src, 6); // only 2 bits left

const v128_t qh_b01_sh = wasm_i8x16_shl(qh_b01, 4);
const v128_t qh_b23_sh = wasm_i8x16_shl(qh_b23, 4);
const v128_t qh_b45_sh = wasm_i8x16_shl(qh_b45, 4);
const v128_t qh_b67_sh = wasm_i8x16_shl(qh_b67, 4);

const v128_t out_0 = wasm_i8x16_sub(wasm_v128_or(q4_lo_nib, qh_b01_sh), bias_32);
const v128_t out_32 = wasm_i8x16_sub(wasm_v128_or(q4_hi_nib, qh_b23_sh), bias_32);
const v128_t out_64 = wasm_i8x16_sub(wasm_v128_or(q4_lo_hnib, qh_b45_sh), bias_32);
const v128_t out_96 = wasm_i8x16_sub(wasm_v128_or(q4_hi_hnib, qh_b67_sh), bias_32);

wasm_v128_store(a + chunk + 0, out_0);
wasm_v128_store(a + chunk + 32, out_32);
wasm_v128_store(a + chunk + 64, out_64);
wasm_v128_store(a + chunk + 96, out_96);
}
a += 128;
q4 += 64;
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