Fix missed block_q8_x2 bf16 -> i16 change (#540)

Closes #538

Co-authored-by: Iwan Kawrakow <[email protected]>

Author: ikawrakow

ggml/src/iqk/iqk_gemm_legacy_quants.cpp

@@ -188,20 +188,14 @@ struct ScaleHelperQ8_2 {
     inline __m256 prepare4(__m256 other_scales, const Q * y) {
         return _mm256_mul_ps(other_scales, prepare4<Q>(y));
     }
-    template <typename Q> inline std::pair<float, float> prepare1(const Q * y) const {
-        float   d = GGML_BF16_TO_FP32(y->d);
+    template <typename Q> static inline std::pair<float, float> prepare1(const Q * y) {
+        float   d = GGML_BF16_TO_FP32(ggml_bf16_t{y->d});
         int16_t m = *(const int16_t *)&y->s;
         return std::make_pair(d, d*m);
     }
-    template <typename Q> inline std::pair<float, float> prepare1(const std::pair<float, float>& dm, const Q * y) const {
-        float   d = GGML_BF16_TO_FP32(y->d);
-        int16_t m = *(const int16_t *)&y->s;
-        return std::make_pair(dm.first*d, dm.second*d*m);
-    }
-    std::pair<float, float> inline prepare1(const std::pair<float, float>& dm, const block_q8_2 * y) const {
-        ggml_bf16_t dy; dy.bits = y->d; int16_t s = *(const int16_t *)&y->s;
-        float d = GGML_BF16_TO_FP32(dy);
-        return std::make_pair(dm.first*d, dm.second*d*s);
+    static inline std::pair<float, float> prepare1(const std::pair<float, float>& dm, const block_q8_2 * y) {
+        auto d = prepare1(y);
+        return std::make_pair(dm.first*d.first, dm.second*d.second);
     }
 };
 
@@ -1484,14 +1478,14 @@ static void mul_mat_q8_0_r8_q8_2(int n, const void * vx, size_t bx, const DataIn
                 }
             }
             if (4*(nb/4) < nb) {
-                auto qy = (const block_q8_1 *)q8.y[0];
+                auto qy = (const block_q8_2 *)q8.y[0];
                 for (int ib = 4*(nb/4); ib < nb; ++ib) {
                     auto scales = _mm256_cvtph_ps(_mm_loadu_si128((const __m128i *)iq8[ib].d));
                     auto sumi = q8_0_r8_dot_product((const uint8_t *)iq8[ib].qs, qy[ib].qs, qx);
-                    ggml_bf16_t d, s; d.bits = qy[ib].d; s.bits = qy[ib].s;
-                    auto d4d8 = _mm256_mul_ps(scales, _mm256_set1_ps(GGML_BF16_TO_FP32(d)));
+                    auto [d8, m8] = ScaleHelperQ8_2::prepare1(qy + ib);
+                    auto d4d8 = _mm256_mul_ps(scales, _mm256_set1_ps(d8));
                     acc[0] = _mm256_fmadd_ps(d4d8, _mm256_cvtepi32_ps(sumi), acc[0]);
-                    acc[1] = _mm256_fmadd_ps(scales, _mm256_set1_ps(GGML_BF16_TO_FP32(s)), acc[1]);
+                    acc[1] = _mm256_fmadd_ps(scales, _mm256_set1_ps(m8), acc[1]);
                 }
             }
             info.store(ix, 0, _mm256_fmadd_ps(_mm256_set1_ps(-127.f), acc[1], acc[0]));
@@ -1535,12 +1529,12 @@ static void mul_mat_q8_0_r8_q8_2(int n, const void * vx, size_t bx, const DataIn
                     qx[j] = _mm512_add_epi8(qx[j], _mm512_set1_epi8(127));
                 }
                 for (int iy = 0; iy < nrc_y; ++iy) {
-                    auto qy = (const block_q8_1 *)q8.y[iy];
+                    auto qy = (const block_q8_2 *)q8.y[iy];
                     auto sumi = qx_r8_q8_dot_product(qx, qy[ib].qs);
-                    ggml_bf16_t d, s; d.bits = qy[ib].d; s.bits = qy[ib].s;
-                    auto dy = _mm512_set1_ps(GGML_BF16_TO_FP32(d));
+                    auto [d8, m8] = ScaleHelperQ8_2::prepare1(qy + ib);
+                    auto dy = _mm512_set1_ps(d8);
                     acc[2*iy+0] = _mm512_fmadd_ps(_mm512_mul_ps(scales, dy), _mm512_cvtepi32_ps(sumi), acc[2*iy+0]);
-                    acc[2*iy+1] = _mm512_fmadd_ps(scales, _mm512_set1_ps(GGML_BF16_TO_FP32(s)), acc[2*iy+1]);
+                    acc[2*iy+1] = _mm512_fmadd_ps(scales, _mm512_set1_ps(m8), acc[2*iy+1]);
                 }
             }
             for (int iy = 0; iy < nrc_y; ++iy) {