Fix comment

velox/exec/Window.cpp

@@ -312,9 +312,9 @@ void Window::updateKRowsFrameBounds(
 
     if (isKPreceding) {
       if (startValue < INT32_MIN) {
-        // Overflow happens for certain number of preceding rows. Moreover,
-        // considering partition size cannot be larger than INT32_MAX to produce
-        // positive value as upper bound, we directly use 0 for all rows.
+        // For overflow in kPreceding frames, k < INT32_MIN. Since the max
+        // number of rows in a partition is INT32_MAX, the frameBound will
+        // always be bound to the first row of the partition
         std::fill_n(rawFrameBounds, numRows, 0);
         return;
       }

velox/functions/prestosql/window/tests/AggregateWindowTest.cpp

@@ -216,14 +216,14 @@ TEST_F(AggregateWindowTest, integerOverflowRowsFrame) {
        2147483645});
   auto c3 = makeFlatVector<int64_t>(
       {2147483651,
+       1,
        2147483650,
-       2147483649,
+       10,
        2147483648,
        2147483647,
-       21474836,
-       2147483650,
+       2,
+       2147483646,
        2147483650,
-       2147483649,
        2147483648});
   auto input = makeRowVector({c0, c1, c2, c3});
   std::string overClause = "partition by c0 order by c1 desc";
@@ -268,7 +268,7 @@ TEST_F(AggregateWindowTest, integerOverflowRowsFrame) {
        c1,
        c2,
        c3,
-       makeFlatVector<int64_t>({6, 5, 4, 3, 2, 1, 4, 3, 2, 1})});
+       makeFlatVector<int64_t>({6, 2, 4, 3, 2, 1, 3, 3, 2, 1})});
   WindowTestBase::testWindowFunction(
       {input}, "count(c1)", overClause, frameClause, expected);