toco thinks Stack is the same as Pack.

Stack is not Pack.  tf.stack() yields Pack ops. Pack ops stack tensors.  Stack ops manipulate the TF runtime stack.

This cl unaliases "Stack" and "Pack" ops in toco, and renames most things that refer to "Stack" ops to "Pack" to be consistent across the codebase.

In summary:

Stack is whack.  'Stack' should be 'Pack'.  Hack 'Stack's into 'Pack's like a maniac.  This keeps 'Stack's from wracking runtime graphs.

(We apologize for the fault in the change description.  Those responsible have been...er...sacked).

PiperOrigin-RevId: 204951155

1 files changed, 10 insertions, 7 deletions

diff --git a/tensorflow/contrib/lite/toco/import_tensorflow.cc b/tensorflow/contrib/lite/toco/import_tensorflow.cc
index 2ffab49e7a..576eb71534 100644
--- a/tensorflow/contrib/lite/toco/import_tensorflow.cc
+++ b/tensorflow/contrib/lite/toco/import_tensorflow.cc
@@ -1518,11 +1518,15 @@ tensorflow::Status ConvertRangeOperator(
   return tensorflow::Status::OK();
 }
 
-tensorflow::Status ConvertStackOperator(
+// Note that it's easy to confuse/conflate "Stack" and "Pack" operators, but
+// they aren't the same thing.  tf.stack results in a "Pack" operator.  "Stack"
+// operators also exist, but involve manipulating the TF runtime stack, and are
+// not directly related to tf.stack() usage.
+tensorflow::Status ConvertPackOperator(
     const NodeDef& node, const TensorFlowImportFlags& tf_import_flags,
     Model* model) {
-  CHECK((node.op() == "Stack") || (node.op() == "Pack"));
-  auto* op = new StackOperator;
+  CHECK_EQ(node.op(), "Pack");
+  auto op = absl::make_unique<PackOperator>();
   const int num_inputs = GetInputsCount(node, tf_import_flags);
   QCHECK_GE(num_inputs, 1)
       << node.op()
@@ -1532,10 +1536,10 @@ tensorflow::Status ConvertStackOperator(
   for (int i = 0; i < num_inputs; ++i) {
     op->inputs.push_back(node.input(i));
   }
-  // Both "Stack" and "Pack" have the "axis" attribute.
   op->axis = HasAttr(node, "axis") ? GetIntAttr(node, "axis") : 0;
+  op->dtype = ConvertDataType(toco::GetDataTypeAttr(node, "T"));
   op->outputs.push_back(node.name());
-  model->operators.emplace_back(op);
+  model->operators.emplace_back(std::move(op));
   return tensorflow::Status::OK();
 }
 
@@ -1873,7 +1877,7 @@ ConverterMapType GetTensorFlowNodeConverterMap() {
       {"NextIteration", ConvertOperatorSpecialCasedAsRNNBackEdge},
       {"NoOp", ConvertNoOpOperator},
       {"NotEqual", ConvertSimpleOperator<TensorFlowNotEqualOperator, 2>},
-      {"Pack", ConvertStackOperator},
+      {"Pack", ConvertPackOperator},
       {"Pad", ConvertSimpleOperator<PadOperator, 2>},
       {"PadV2", ConvertSimpleOperator<PadV2Operator, 3>},
       {"ParallelDynamicStitch", ConvertDynamicStitchOperator},
@@ -1903,7 +1907,6 @@ ConverterMapType GetTensorFlowNodeConverterMap() {
       {"Sqrt", ConvertSimpleOperator<TensorFlowSqrtOperator, 1>},
       {"Square", ConvertSimpleOperator<TensorFlowSquareOperator, 1>},
       {"Squeeze", ConvertSqueezeOperator},
-      {"Stack", ConvertStackOperator},
       {"StopGradient", ConvertIdentityOperator},
       {"StridedSlice", ConvertStridedSliceOperator},
       {"Sub", ConvertSimpleOperator<SubOperator, 2>},