Try to support float16 for flat.cc

Author: jjyaoao

src/index/flat/flat.cc

@@ -41,6 +41,13 @@ class FlatIndexNode : public IndexNode {
         return err;
     }
 
+    std::vector<float>
+    convertFloat16ToFloat32(const std::vector<float16>& input) {
+        std::vector<float> output(input.size());
+        std::transform(input.begin(), input.end(), output.begin(), [](float16 f) { return static_cast<float>(f); });
+        return output;
+    }
+
     Status
     Train(const DataSet& dataset, const Config& cfg) override {
         const FlatConfig& f_cfg = static_cast<const FlatConfig&>(cfg);
@@ -55,6 +62,14 @@ class FlatIndexNode : public IndexNode {
             LOG_KNOWHERE_WARNING_ << "please check metric type: " << f_cfg.metric_type;
             return metric.error();
         }
+
+        auto dim_data = dataset.GetDim();
+
+        // If dim_data is float16, convert it to float32
+        if (typeid(dim_data[0]) == typeid(float16)) {
+            dim_data = convertFloat16ToFloat32(dim_data);
+        }
+
         index_ = std::make_unique<T>(dataset.GetDim(), metric.value());
         return Status::success;
     }
@@ -63,6 +78,12 @@ class FlatIndexNode : public IndexNode {
     Add(const DataSet& dataset, const Config& cfg) override {
         auto x = dataset.GetTensor();
         auto n = dataset.GetRows();
+
+        if (typeid(x[0]) == typeid(float16)) {
+            std::vector<float> x_float32(x.begin(), x.end());
+            x = x_float32;
+        }
+
         if constexpr (std::is_same<T, faiss::IndexFlat>::value) {
             index_->add(n, (const float*)x);
         }
@@ -92,6 +113,11 @@ class FlatIndexNode : public IndexNode {
         auto x = dataset.GetTensor();
         auto dim = dataset.GetDim();
 
+        // If x is float16, convert it to float32
+        if (typeid(x[0]) == typeid(float16)) {
+            x = convertFloat16ToFloat32(x);
+        }
+
         auto len = k * nq;
         int64_t* ids = nullptr;
         float* distances = nullptr;
@@ -150,6 +176,11 @@ class FlatIndexNode : public IndexNode {
         auto xq = dataset.GetTensor();
         auto dim = dataset.GetDim();
 
+        // If xq is float16, convert it to float32
+        if (typeid(xq[0]) == typeid(float16)) {
+            xq = convertFloat16ToFloat32(xq);
+        }
+
         int64_t* ids = nullptr;
         float* distances = nullptr;
         size_t* lims = nullptr;
@@ -212,7 +243,14 @@ class FlatIndexNode : public IndexNode {
                 for (int64_t i = 0; i < rows; i++) {
                     index_->reconstruct(ids[i], data + i * dim);
                 }
-                return GenResultDataSet(rows, dim, data);
+                // If original data was float16, convert it back before returning
+                if (typeid(dataset.GetTensor()[0]) == typeid(float16)) {
+                    auto data16 = convertFloat32ToFloat16(data, rows * dim);
+                    delete[] data;
+                    return GenResultDataSet(rows, dim, data16);
+                } else {
+                    return GenResultDataSet(rows, dim, data);
+                }
             } catch (const std::exception& e) {
                 std::unique_ptr<float[]> auto_del(data);
                 LOG_KNOWHERE_WARNING_ << "faiss inner error: " << e.what();