Fix from_unixtime for NaN input (#2936)

Summary:
from_unixtime(NaN, '<timezone>') should return zero. Before the fix it was crashing under UBSAN:

```
velox/functions/prestosql/FromUnixTime.cpp:24:10: runtime error: nan is outside the range of representable values of type 'long'

 UndefinedBehaviorSanitizer: float-cast-overflow velox/functions/prestosql/FromUnixTime.cpp:24:10 in
```

Fixes #2791

Pull Request resolved: #2936

Reviewed By: xiaoxmeng

Differential Revision: D40648988

Pulled By: mbasmanova

fbshipit-source-id: 752068a1e17da540f031c98367bd9a4baaa6a604

velox/functions/prestosql/FromUnixTime.cpp

@@ -21,6 +21,9 @@ namespace facebook::velox::functions {
 namespace {
 
 inline int64_t toMillis(double unixtime) {
+  if (UNLIKELY(std::isnan(unixtime))) {
+    return 0;
+  }
   return std::floor(unixtime * 1'000);
 }
 

velox/functions/prestosql/tests/DateTimeFunctionsTest.cpp

@@ -275,6 +275,8 @@ TEST_F(DateTimeFunctionsTest, fromUnixtimeRountTrip) {
 }
 
 TEST_F(DateTimeFunctionsTest, fromUnixtimeWithTimeZone) {
+  static const double kNan = std::numeric_limits<double>::quiet_NaN();
+
   vector_size_t size = 37;
 
   auto unixtimeAt = [](vector_size_t row) -> double {
@@ -295,6 +297,17 @@ TEST_F(DateTimeFunctionsTest, fromUnixtimeWithTimeZone) {
         makeConstant((int16_t)900, size),
     });
     assertEqualVectors(expected, result);
+
+    // NaN timestamp.
+    result = evaluate<RowVector>(
+        "from_unixtime(c0, '+01:00')",
+        makeRowVector({makeFlatVector<double>({kNan, kNan})}));
+    ASSERT_TRUE(isTimestampWithTimeZoneType(result->type()));
+    expected = makeRowVector({
+        makeFlatVector<int64_t>({0, 0}),
+        makeFlatVector<int16_t>({900, 900}),
+    });
+    assertEqualVectors(expected, result);
   }
 
   // Variable timezone parameter.
@@ -317,6 +330,20 @@ TEST_F(DateTimeFunctionsTest, fromUnixtimeWithTimeZone) {
             size, [&](auto row) { return timezoneIds[row % 5]; }),
     });
     assertEqualVectors(expected, result);
+
+    // NaN timestamp.
+    result = evaluate<RowVector>(
+        "from_unixtime(c0, c1)",
+        makeRowVector({
+            makeFlatVector<double>({kNan, kNan}),
+            makeNullableFlatVector<StringView>({"+01:00", "+02:00"}),
+        }));
+    ASSERT_TRUE(isTimestampWithTimeZoneType(result->type()));
+    expected = makeRowVector({
+        makeFlatVector<int64_t>({0, 0}),
+        makeFlatVector<int16_t>({900, 960}),
+    });
+    assertEqualVectors(expected, result);
   }
 }