[VL] Fix high precision rounding (#6707)

apache · Aug 12, 2024 · a1f3198 · a1f3198
1 parent 0d1adea
commit a1f3198
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Showing 4 changed files with 17 additions and 4 deletions.
diff --git a/cpp/velox/operators/functions/Arithmetic.h b/cpp/velox/operators/functions/Arithmetic.h
@@ -17,6 +17,7 @@
 #include <folly/CPortability.h>
 #include <stdint.h>
 #include <cmath>
+#include <limits>
 #include <type_traits>
 
 namespace gluten {
@@ -38,14 +39,16 @@ struct RoundFunction {
       return number;
     }
 
-    double factor = std::pow(10, decimals);
+    // Using long double for high precision during intermediate calculations.
+    // TODO: Make this more efficient with Boost to support high arbitrary precision at runtime.
+    long double factor = std::pow(10.0L, static_cast<long double>(decimals));
     static const TNum kInf = std::numeric_limits<TNum>::infinity();
+
     if (number < 0) {
-      return (std::round(std::nextafter(number, -kInf) * factor * -1) / factor) * -1;
+      return static_cast<TNum>((std::round(std::nextafter(number, -kInf) * factor * -1) / factor) * -1);
     }
-    return std::round(std::nextafter(number, kInf) * factor) / factor;
+    return static_cast<TNum>(std::round(std::nextafter(number, kInf) * factor) / factor);
   }
-
   template <typename TInput>
   FOLLY_ALWAYS_INLINE void call(TInput& result, const TInput& a, const int32_t b = 0) {
     result = round(a, b);

diff --git a/...src/test/scala/org/apache/spark/sql/catalyst/expressions/GlutenMathExpressionsSuite.scala b/...src/test/scala/org/apache/spark/sql/catalyst/expressions/GlutenMathExpressionsSuite.scala
@@ -121,6 +121,9 @@ class GlutenMathExpressionsSuite extends MathExpressionsSuite with GlutenTestsTr
     checkEvaluation(Round(-3.5, 0), -4.0)
     checkEvaluation(Round(-0.35, 1), -0.4)
     checkEvaluation(Round(-35, -1), -40)
+    checkEvaluation(Round(1.12345678901234567, 8), 1.12345679)
+    checkEvaluation(Round(-0.98765432109876543, 5), -0.98765)
+    checkEvaluation(Round(12345.67890123456789, 6), 12345.678901)
     checkEvaluation(BRound(2.5, 0), 2.0)
     checkEvaluation(BRound(3.5, 0), 4.0)
     checkEvaluation(BRound(-2.5, 0), -2.0)

diff --git a/...src/test/scala/org/apache/spark/sql/catalyst/expressions/GlutenMathExpressionsSuite.scala b/...src/test/scala/org/apache/spark/sql/catalyst/expressions/GlutenMathExpressionsSuite.scala
@@ -249,6 +249,10 @@ class GlutenMathExpressionsSuite extends MathExpressionsSuite with GlutenTestsTr
     checkEvaluation(Round(-3.5, 0), -4.0)
     checkEvaluation(Round(-0.35, 1), -0.4)
     checkEvaluation(Round(-35, -1), -40)
+    checkEvaluation(Round(1.12345678901234567, 8), 1.12345679)
+    checkEvaluation(Round(-0.98765432109876543, 5), -0.98765)
+    checkEvaluation(Round(12345.67890123456789, 6), 12345.678901)
+    checkEvaluation(Round(-35, -1), -40)
     checkEvaluation(Round(BigDecimal("45.00"), -1), BigDecimal(50))
     checkEvaluation(BRound(2.5, 0), 2.0)
     checkEvaluation(BRound(3.5, 0), 4.0)

diff --git a/...src/test/scala/org/apache/spark/sql/catalyst/expressions/GlutenMathExpressionsSuite.scala b/...src/test/scala/org/apache/spark/sql/catalyst/expressions/GlutenMathExpressionsSuite.scala
@@ -248,6 +248,9 @@ class GlutenMathExpressionsSuite extends MathExpressionsSuite with GlutenTestsTr
     checkEvaluation(BRound(-3.5, 0), -4.0)
     checkEvaluation(BRound(-0.35, 1), -0.4)
     checkEvaluation(BRound(-35, -1), -40)
+    checkEvaluation(Round(1.12345678901234567, 8), 1.12345679)
+    checkEvaluation(Round(-0.98765432109876543, 5), -0.98765)
+    checkEvaluation(Round(12345.67890123456789, 6), 12345.678901)
     checkEvaluation(BRound(BigDecimal("45.00"), -1), BigDecimal(40))
     checkEvaluation(checkDataTypeAndCast(RoundFloor(Literal(2.5), Literal(0))), Decimal(2))
     checkEvaluation(checkDataTypeAndCast(RoundFloor(Literal(3.5), Literal(0))), Decimal(3))