Merge pull request #1708 from NervanaSystems/aprocter/cherry-pick-1663

Cherry-pick "zero dim elem fix (#1663)"

Author: Adam Procter

src/ngraph/pass/zero_dim_tensor_elimination.cpp

@@ -37,7 +37,9 @@ static bool has_zero_dim(std::shared_ptr<Node> node)
     {
         throw ngraph_error("has_zero_dim is called on multi-output op");
     }
-    return shape_size(node->get_shape()) == 0;
+
+    const auto& shape = node->get_shape();
+    return std::find(shape.begin(), shape.end(), 0) != shape.end();
 }
 
 static bool verify_no_internal_zero_length_ops(std::shared_ptr<ngraph::Function> f)
@@ -75,6 +77,7 @@ static bool verify_no_internal_zero_length_ops(std::shared_ptr<ngraph::Function>
 bool ngraph::pass::ZeroDimTensorElimination::run_on_function(std::shared_ptr<ngraph::Function> f)
 {
     bool replaced = false;
+    auto cvals = std::vector<std::string>(0);
     // we need to go over all nodes since we could have sum or any other 0-length-tensor-to scalar op
     // as an internal node (i.e. a node that isn't an argument to `op::Result`)
     for (auto n : f->get_ordered_ops())
@@ -93,7 +96,6 @@ bool ngraph::pass::ZeroDimTensorElimination::run_on_function(std::shared_ptr<ngr
         {
             // we don't have to create constants every time but this is the easiest
             // and it's CSE's job to eliminate the same ones
-            auto cvals = std::vector<std::string>(0);
             auto constant =
                 std::make_shared<op::Constant>(n->get_element_type(), n->get_shape(), cvals);
             replace_node(n, constant);
@@ -102,8 +104,21 @@ bool ngraph::pass::ZeroDimTensorElimination::run_on_function(std::shared_ptr<ngr
             continue;
         }
 
+        if (n->get_inputs().size() == 0)
+        {
+            continue;
+        }
+
+        auto arg = n->get_inputs().at(0).get_output().get_node();
+
+        if (arg->get_outputs().size() != 1 || !has_zero_dim(arg))
+        {
+            continue;
+        }
+
         auto new_node = n->get_default_value();
-        if (!new_node || !has_zero_dim(n->get_argument(0)))
+
+        if (!new_node)
         {
             continue;
         }