Sync from tflite-micro. (#146)

Author: TFLM-bot

src/tensorflow/lite/micro/kernels/conv.h

@@ -45,6 +45,10 @@ struct OpDataConv {
   // uint8_t these would be 0 and 255.
   int32_t output_activation_min;
   int32_t output_activation_max;
+
+  // A buffer used to store unpacked filter values. This is used if the source
+  // tensor is of n-bit precision that cannot be easily processed by kernels.
+  int filter_buffer_index;
 };
 
 extern const int kConvInputTensor;

src/tensorflow/lite/micro/kernels/conv_common.cpp

@@ -14,12 +14,8 @@ limitations under the License.
 ==============================================================================*/
 
 #include "tensorflow/lite/c/builtin_op_data.h"
+#include "tensorflow/lite/c/c_api_types.h"
 #include "tensorflow/lite/c/common.h"
-#include "tensorflow/lite/kernels/internal/common.h"
-#include "tensorflow/lite/kernels/internal/quantization_util.h"
-#include "tensorflow/lite/kernels/internal/reference/conv.h"
-#include "tensorflow/lite/kernels/internal/reference/integer_ops/conv.h"
-#include "tensorflow/lite/kernels/internal/tensor_ctypes.h"
 #include "tensorflow/lite/kernels/kernel_util.h"
 #include "tensorflow/lite/kernels/padding.h"
 #include "tensorflow/lite/micro/kernels/conv.h"
@@ -188,6 +184,15 @@ TfLiteStatus ConvPrepare(TfLiteContext* context, TfLiteNode* node) {
       context, node, params, input_width, input_height, filter_width,
       filter_height, output_width, output_height, input->type, data));
 
+  if (filter->type == kTfLiteInt4) {
+    int filter_size =
+        RuntimeShape(filter->dims->size,
+                     reinterpret_cast<const int32_t*>(filter->dims->data))
+            .FlatSize();
+    context->RequestScratchBufferInArena(context, filter_size,
+                                         &data->filter_buffer_index);
+  }
+
   micro_context->DeallocateTempTfLiteTensor(filter);
   micro_context->DeallocateTempTfLiteTensor(input);
   micro_context->DeallocateTempTfLiteTensor(output);

src/tensorflow/lite/micro/memory_helpers.cpp

@@ -90,6 +90,9 @@ TfLiteStatus TfLiteTypeSizeOf(TfLiteType type, size_t* size) {
     case kTfLiteComplex128:
       *size = sizeof(double) * 2;
       break;
+    case kTfLiteInt4:
+      *size = sizeof(int8_t);
+      break;
     default:
       return kTfLiteError;
   }