iq3_s: much faster GEMM via repacking to q8_0_r8 (#518)

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

Author: ikawrakow

ggml/src/ggml.c

@@ -1153,7 +1153,11 @@ static const ggml_type_traits_t type_traits[GGML_TYPE_COUNT] = {
         .from_float               = quantize_row_iq3_s,
         .from_float_ref           = (ggml_from_float_t)quantize_row_iq3_s_ref,
         .vec_dot                  = ggml_vec_dot_iq3_s_q8_K,
+#ifdef __AVX2__
+        .vec_dot_type             = GGML_TYPE_Q8_2_X4,
+#else
         .vec_dot_type             = GGML_TYPE_Q8_K,
+#endif
         .nrows                    = 1,
         .row_meta_size            = 0,
     },

ggml/src/iqk/iqk_gemm_iquants.cpp

@@ -115,8 +115,10 @@ struct SignHelper {
         return _mm256_sign_epi8(value, make_signs(sign_bits[0] | (sign_bits[1] << 16)));
 #endif
     }
-    inline void sign_4_values(const uint16_t * sign_bits, __m256i * values) const {
-#ifdef HAVE_FANCY_SIMD
+    IQK_ALWAYS_INLINE void sign_4_values(const uint16_t * sign_bits, __m256i * values) const {
+        // Somehow the FANCY_SIMD version has become 50% slower for TG???
+#ifdef z_HAVE_FANCY_SIMD
+        //__mmask32 mask[4]; std::memcpy(mask, sign_bits, 4*sizeof(__mmask32));
         const __mmask32 * mask = (const __mmask32 *)sign_bits;
         values[0] = _mm256_mask_sub_epi8(values[0], mask[0], _mm256_setzero_si256(), values[0]);
         values[1] = _mm256_mask_sub_epi8(values[1], mask[1], _mm256_setzero_si256(), values[1]);
@@ -534,7 +536,7 @@ struct DequantizerIQ3XXS final : public BaseDequantizer<block_iq3_xxs> {
 
 };
 
-#ifdef HAVE_FANCY_SIMD
+#ifdef z_HAVE_FANCY_SIMD
 // Strangely enough, the following implementation makes PP ~6% slower and TG ~6% faster
 // compared to the vanilla AVX2 version below.
 struct IndexHelperIQ3S {
@@ -597,6 +599,15 @@ struct DequantizerIQ3S final : public BaseDequantizer<block_iq3_s> {
         auto scales16 = make_scales(i, d);
         scales[0] = MM256_SET_M128I(scales16, scales16);
     }
+    inline void new_block_f(int i, __m256 * scales) {
+        auto sc16 = make_scales(i, d);
+        auto scf  = _mm256_mul_ps(_mm256_set1_ps(d), _mm256_cvtepi32_ps(_mm256_cvtepi16_epi32(sc16)));
+        auto scf_l = _mm256_castps256_ps128(scf);
+        auto scf_h = _mm256_extractf128_ps(scf, 1);
+        scales[0] = _mm256_set_m128(scf_l, scf_l);
+        scales[1] = _mm256_set_m128(scf_h, scf_h);
+        scales[2] = _mm256_mul_ps(scf, _mm256_set1_ps(-minv));
+    }
     inline float new_block(int i, __m256i * scales, __m256i& mins) {
         auto scales16 = make_scales(i, d);
         mins = scb.shuffle(scales16);
@@ -1832,6 +1843,60 @@ void iqk_convert_iq3_xxs_q8_0_r8(int n, const void * vx, size_t bx, void * vy, i
     }
 }
 
+void iqk_convert_iq3_s_q8_0_r8(int n, const void * vx, size_t bx, void * vy, int nrc_x) {
+    GGML_ASSERT(n%QK_K == 0);
+    GGML_ASSERT(nrc_x%8 == 0);
+
+    int nb = n/QK_K;
+
+    const block_iq3_s * x8[8];
+
+    block_q8_0_r8 * y = (block_q8_0_r8 *)vy;
+
+    ggml_half dh[8];
+    uint16_t all_ls[64];
+    SignHelper sh;
+    IndexHelperIQ3S helper;
+
+    uint32_t block[8];
+    __m256i values[8];
+
+    for (int ix = 0; ix < nrc_x; ix += 8) {
+        for (int k = 0; k < 8; ++k) x8[k] = (const block_iq3_s *)((const char *)vx + (ix + k)*bx);
+        for (int i = 0; i < nb; ++i) {
+            for (int k = 0; k < 8; ++k) {
+                dh[k] = x8[k][i].d;
+                auto qs = x8[k][i].qs;
+                auto qh = x8[k][i].qh;
+                auto signs = (const uint16_t *)x8[k][i].signs;
+                helper.make2(qs+ 0, qh+0, values+0);
+                helper.make2(qs+16, qh+2, values+2);
+                sh.sign_4_values(signs+0, values+0);
+                helper.make2(qs+32, qh+4, values+4);
+                helper.make2(qs+48, qh+6, values+6);
+                sh.sign_4_values(signs+8, values+4);
+                for (int ib32 = 0; ib32 < 8; ++ib32) {
+                    all_ls[8*ib32 + k] = (2*((x8[k][i].scales[ib32/2] >> 4*(ib32%2)) & 0xf) + 1);
+                    _mm256_storeu_si256((__m256i *)block, values[ib32]);
+                    auto q8 = (uint32_t *)y[ib32].qs;
+                    for (int l = 0; l < 4; ++l) {
+                        q8[8*l + k +  0] = block[l + 0];
+                        q8[8*l + k + 32] = block[l + 4];
+                    }
+                }
+            }
+            auto vd = _mm256_cvtph_ps(_mm_loadu_si128((const __m128i *)dh));
+            for (int ib32 = 0; ib32 < QK_K/32; ++ib32) {
+                auto iscales16 = _mm_loadu_si128((const __m128i *)all_ls + ib32);
+                auto iscales32 = _mm256_cvtepi16_epi32(iscales16);
+                auto scales = _mm256_mul_ps(vd, _mm256_cvtepi32_ps(iscales32));
+                _mm_storeu_si128((__m128i *)y[ib32].d, _mm256_cvtps_ph(scales, _MM_FROUND_TO_NEAREST_INT));
+            }
+            y += QK_K/32;
+        }
+    }
+}
+
 template <typename Dequantizer> void set_functions(std::array<mul_mat_t, IQK_MAX_NY>& funcs) {
     funcs[0] = mul_mat_qX_K_q8_K_IQ<Dequantizer, 1>;
     funcs[1] = mul_mat_qX_K_q8_K_IQ<Dequantizer, 2>;
@@ -1867,6 +1932,15 @@ bool iqk_set_kernels_iquants(int ne00, int typeA, int typeB, std::array<mul_mat_
         return false;
     }
 
+    if (ggml_type(typeA) == GGML_TYPE_IQ3_S) {
+        if (ggml_type(typeB) == GGML_TYPE_Q8_2_X4) {
+            IQK_SET_MUL_MAT_FUNCTIONS_T(mul_mat_qX_K_q8_2_IQ_N, DequantizerIQ3S, kernels);
+            func16 = nullptr;
+            return true;
+        }
+        return false;
+    }
+
     if (ggml_type(typeB) != GGML_TYPE_Q8_K) {
         return false;
     }
@@ -1926,6 +2000,7 @@ bool iqk_convert_iquants_q80_r8(int type, int n, const void * vx, size_t bx, voi
     switch (ggml_type(type)) {
         case GGML_TYPE_IQ2_XXS: iqk_convert_iq2_xxs_q8_0_r8(n, vx, bx, vy, nrc_x); break;
         case GGML_TYPE_IQ3_XXS: iqk_convert_iq3_xxs_q8_0_r8(n, vx, bx, vy, nrc_x); break;
+        case GGML_TYPE_IQ3_S  : iqk_convert_iq3_s_q8_0_r8  (n, vx, bx, vy, nrc_x); break;
         default: return false;
     }
     return true;

ggml/src/iqk/iqk_mul_mat.cpp

@@ -241,6 +241,7 @@ struct MulMat {
             case GGML_TYPE_IQ4_KT : return nrc_y >= 32 ? GGML_TYPE_F32 : type;
             case GGML_TYPE_IQ2_XXS: return nrc_y >= 32 ? GGML_TYPE_Q8_0_R8 : type;
             case GGML_TYPE_IQ3_XXS: return nrc_y >= 32 ? GGML_TYPE_Q8_0_R8 : type;
+            case GGML_TYPE_IQ3_S  : return nrc_y >= 32 ? GGML_TYPE_Q8_0_R8 : type;
             case GGML_TYPE_IQ1_S  : return nrc_y >= 32 ? GGML_TYPE_Q8_0_R8 : type;
             default: break;
         }