From f9a6477826c567a799cbc54111b7cbe5c49c38a0 Mon Sep 17 00:00:00 2001
From: Benoit Steiner <bsteiner@google.com>
Date: Mon, 19 Jun 2017 16:39:29 -0700
Subject: [PATCH] Dont fold constant string.

PiperOrigin-RevId: 159497483
---
 tensorflow/core/grappler/optimizers/constant_folding.cc | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tensorflow/core/grappler/optimizers/constant_folding.cc b/tensorflow/core/grappler/optimizers/constant_folding.cc
index 4fccd4e19b0346..325ce8f5fe1f11 100644
--- a/tensorflow/core/grappler/optimizers/constant_folding.cc
+++ b/tensorflow/core/grappler/optimizers/constant_folding.cc
@@ -293,10 +293,16 @@ bool ConstantFolding::IsFoldable(const NodeDef& node) const {
     if (IsControlInput(input)) {
       continue;
     }
-    bool is_const = IsConstant(*node_map_->GetNode(input));
+    const NodeDef* input_node = node_map_->GetNode(input);
+    bool is_const = IsConstant(*input_node);
     if (!is_const && !is_merge) {
       return false;
     }
+    // Don't fold strings constants for now since this causes problems with
+    // checkpointing.
+    if (is_const && input_node->attr().at("dtype").type() == DT_STRING) {
+      return false;
+    }
     has_constant_input |= is_const;
   }
   if (is_merge) {