From 309dfef4890ca823cf6e32dea2d8066566e0a689 Mon Sep 17 00:00:00 2001
From: Ruihang Lai <lairuihangdongdong@qq.com>
Date: Thu, 15 Apr 2021 00:55:14 +0800
Subject: [PATCH] [BugFix] Print doubles with precision 17 in SaveJSON and TVM
 script printer (#7846)

* [BugFix] SaveJSON type double with precision 17

* [BugFix] Fix for TVM script printer
---
 src/node/serialization.cc                     |  4 ++--
 src/printer/tvmscript_printer.cc              |  3 +++
 tests/python/unittest/test_node_reflection.py | 11 +++++++++++
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/node/serialization.cc b/src/node/serialization.cc
index ad42799b55e5d..75f03fbc79546 100644
--- a/src/node/serialization.cc
+++ b/src/node/serialization.cc
@@ -214,8 +214,8 @@ class JSONAttrGetter : public AttrVisitor {
 
   void Visit(const char* key, double* value) final {
     std::ostringstream s;
-    // Type <double> have approximately 16 decimal digits
-    s.precision(16);
+    // Save 17 decimal digits for type <double> to avoid precision loss during loading JSON
+    s.precision(17);
     s << (*value);
     node_->attrs[key] = s.str();
   }
diff --git a/src/printer/tvmscript_printer.cc b/src/printer/tvmscript_printer.cc
index 7afdcab371daa..f6586ce7000a5 100644
--- a/src/printer/tvmscript_printer.cc
+++ b/src/printer/tvmscript_printer.cc
@@ -232,6 +232,9 @@ class TVMScriptPrinter : public StmtFunctor<Doc(const Stmt&)>,
   static Doc PrintConstScalar(DataType dtype, const T* data) {
     Doc doc;
     std::ostringstream os;
+    if (dtype.is_float() || dtype.is_float16() || dtype.is_bfloat16()) {
+      os.precision(17);
+    }
     os << data[0];
     if (dtype == DataType::Int(32)) {
       doc << Doc::Text(os.str());
diff --git a/tests/python/unittest/test_node_reflection.py b/tests/python/unittest/test_node_reflection.py
index 67c8283b641bd..c1298b56f7fbd 100644
--- a/tests/python/unittest/test_node_reflection.py
+++ b/tests/python/unittest/test_node_reflection.py
@@ -43,6 +43,16 @@ def test_infinity_value():
     _test_infinity_value(float("-inf"), "float32")
 
 
+def _test_minmax_value(value):
+    json_str = tvm.ir.save_json(value)
+    tvm.ir.assert_structural_equal(value, tvm.ir.load_json(json_str))
+
+
+def test_minmax_value():
+    _test_minmax_value(tvm.tir.min_value("float32"))
+    _test_minmax_value(tvm.tir.max_value("float32"))
+
+
 def test_make_smap():
     # save load json
     x = tvm.tir.const(1, "int32")
@@ -160,3 +170,4 @@ def test_dict():
     test_pass_config()
     test_dict()
     test_infinity_value()
+    test_minmax_value()