Update interpreter and subgraph to provide external buffer id and tensor mapping

tflite/core/interpreter_builder.cc

@@ -725,7 +725,8 @@ TfLiteStatus InterpreterBuilder::ParseTensors(
       if (subgraph->SetTensorParametersReadOnly(
               i, type, get_name(tensor), dims, quantization, buffer_ptr,
               buffer_size, allocation_, sparsity,
-              /*buffer_identifier=*/tensor->buffer()) != kTfLiteOk) {
+              /*buffer_identifier=*/tensor->buffer(),
+              /*external_buffer_id=*/tensor->external_buffer()) != kTfLiteOk) {
         TF_LITE_REPORT_ERROR(error_reporter_,
                              "Tensor %d is invalidly specified in schema.\n",
                              i);

tflite/core/subgraph.cc

@@ -1917,7 +1917,7 @@ TfLiteStatus Subgraph::SetTensorParametersReadOnly(
     int tensor_index, TfLiteType type, const char* name, const size_t ndims,
     const int* dims, TfLiteQuantization quantization, const char* buffer,
     size_t bytes, const Allocation* allocation, TfLiteSparsity* sparsity,
-    const size_t buffer_identifier) {
+    const size_t buffer_identifier, const size_t external_buffer_id) {
   // Ensure quantization cleanup on failure.
   ScopedTfLiteQuantization scoped_quantization(&quantization);
   ScopedTfLiteSparsity scoped_sparsity(sparsity);
@@ -1968,6 +1968,10 @@ TfLiteStatus Subgraph::SetTensorParametersReadOnly(
   if (buffer_identifier != kTfLiteNoBufferIdentifier) {
     tensor_buffer_identifiers_[tensor_index] = buffer_identifier;
   }
+  if (external_buffer_id != kTfLiteNoBufferIdentifier &&
+      external_buffer_id != 0) {
+    tensor_external_buffer_ids_[tensor_index] = external_buffer_id;
+  }
   return kTfLiteOk;
 }
 

tflite/core/subgraph.h

@@ -130,22 +130,32 @@ class Subgraph {
   // This variant assumes an external buffer has been allocated of size
   // bytes. The lifetime of buffer must be ensured to be greater or equal
   // to Interpreter. `quantization` ownership is passed to the subgraph.
+  // `buffer_identifier`: An optional value to identify the buffer. If set to
+  // a value other than kTfLiteNoBufferIdentifier, this tensor is considered a
+  // constant tensor shared across multiple subgraphs / interpreters.
+  // `external_buffer_id`: An optional value to identify the external buffer. If
+  // set to a value other than kTfLiteNoBufferIdentifier, this tensor is
+  // considered a tensor using an external buffer shared across multiple
+  // subgraphs / interpreters.
   inline TfLiteStatus SetTensorParametersReadOnly(
       int tensor_index, TfLiteType type, const char* name,
       const std::vector<int>& dims, TfLiteQuantization quantization,
       const char* buffer, size_t bytes, const Allocation* allocation = nullptr,
       TfLiteSparsity* sparsity = nullptr,
-      size_t buffer_identifier = kTfLiteNoBufferIdentifier) {
+      size_t buffer_identifier = kTfLiteNoBufferIdentifier,
+      size_t external_buffer_id = kTfLiteNoBufferIdentifier) {
     return SetTensorParametersReadOnly(tensor_index, type, name, dims.size(),
                                        dims.data(), quantization, buffer, bytes,
-                                       allocation, sparsity, buffer_identifier);
+                                       allocation, sparsity, buffer_identifier,
+                                       external_buffer_id);
   }
   TfLiteStatus SetTensorParametersReadOnly(
       int tensor_index, TfLiteType type, const char* name, size_t ndims,
       const int* dims, TfLiteQuantization quantization, const char* buffer,
       size_t bytes, const Allocation* allocation = nullptr,
       TfLiteSparsity* sparsity = nullptr,
-      size_t buffer_identifier = kTfLiteNoBufferIdentifier);
+      size_t buffer_identifier = kTfLiteNoBufferIdentifier,
+      size_t external_buffer_id = kTfLiteNoBufferIdentifier);
 
   // Set description of inputs/outputs/data/fptrs for node `node_index`.
   // This variant assumes an external buffer has been allocated of size
@@ -611,6 +621,11 @@ class Subgraph {
     return tensor_buffer_identifiers_;
   }
 
+  const std::unordered_map<size_t, size_t>& GetExternalTensorBufferIdentifiers()
+      const {
+    return tensor_external_buffer_ids_;
+  }
+
   // Replaces the node for the given execution index with the subgraph.
   //
   // - The node and subgraph tensor counts must match.
@@ -1220,6 +1235,10 @@ class Subgraph {
   // Maps tensor constant buffers used in the subgraph to a model-wide
   // identifiers.
   std::unordered_map<size_t, size_t> tensor_buffer_identifiers_;
+
+  // Maps tensor external buffer ids used in the subgraph to a model-wide
+  // identifiers.
+  std::unordered_map<size_t, size_t> tensor_external_buffer_ids_;
 };
 
 }  // namespace tflite