From 6716edf2322b341f6619d3771a9322c9bad379aa Mon Sep 17 00:00:00 2001
From: LaiyuanGong <30686426+HisiFish@users.noreply.github.com>
Date: Wed, 11 Dec 2019 19:47:50 -0600
Subject: [PATCH] [NODE][Serialization]fix serialization precision loss in
 float (#4503)
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* fix serialization precision loss in float

When we want to serialize a tvm.tensor object(like pickle)， we will get a precision loss cause by std::to_string()。
For example, a2.value will be 0.0 while a.value=0.00000001 in the following:
    import tvm
    import pickle
    a = tvm.const(0.00000001, 'float32')
    a2 = pickle.loads(pickle.dumps(a))

* remove line end spaces
---
 src/node/serialization.cc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/node/serialization.cc b/src/node/serialization.cc
index d270e72d3958..cb310eb2cda9 100644
--- a/src/node/serialization.cc
+++ b/src/node/serialization.cc
@@ -167,7 +167,11 @@ class JSONAttrGetter : public AttrVisitor {
   ReflectionVTable* reflection_ = ReflectionVTable::Global();
 
   void Visit(const char* key, double* value) final {
-    node_->attrs[key] = std::to_string(*value);
+    std::ostringstream s;
+    // Type <double> have approximately 16 decimal digits
+    s.precision(16);
+    s << (*value);
+    node_->attrs[key] = s.str();
   }
   void Visit(const char* key, int64_t* value) final {
     node_->attrs[key] = std::to_string(*value);