!717 Feature: repair dynamic_stitch_kernel folding bug

From: @lixiwen1
Reviewed-by: @xchu42,@wqtshg,@ji_chen
Signed-off-by: @ji_chen

ge/host_kernels/dynamic_stitch_kernel.cc

@@ -33,6 +33,8 @@ namespace {
 const int kDoubleAttrN = 2;
 const int kFirstOutputDescIdx = 0;
 const int kMergedShapeSecondDim = 1;
+const size_t kNullTensorDimNum = 1;
+const int64_t kNullTensorDimValue = 0;
 const std::set<DataType> kSupportedTypeSet = {DT_INT8,  DT_UINT8, DT_INT16,   DT_UINT16, DT_INT32,
                                               DT_INT64, DT_BOOL,  DT_FLOAT16, DT_FLOAT,  DT_DOUBLE};
 }  // namespace
@@ -177,7 +179,14 @@ Status DynamicStitchKernel::StitchDataFollowIndices(int64_t data_unit, const vec
   int64_t src_offset = 0;
   std::set<int32_t> indices_set;
   for (int i = 0; i < n_; i++) {
-    auto indices_shape_size = input[i]->GetTensorDesc().GetShape().GetShapeSize();
+    GeShape indices_shape = input[i]->GetTensorDesc().GetShape();
+    size_t indices_dim_num = indices_shape.GetDimNum();
+    // skip null indices tensor
+    if (indices_dim_num == kNullTensorDimNum && indices_shape.GetDim(0) == kNullTensorDimValue) {
+      GELOGD("Input indices[%d] has null tensor, skip it.", i);
+      continue;
+    }
+    auto indices_shape_size = indices_shape.GetShapeSize();
     // to normalize logic, assume scalar as vector with shape of [1].
     indices_shape_size = (indices_shape_size == 0) ? 1 : indices_shape_size;
     // all index for input is less than size of input