From 516154e39ec08be7cabbe3b7f5ec23b09d684b2f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=AB=98=E9=98=B3=E9=98=B3?= <gyycoder@gmail.com>
Date: Fri, 12 Jul 2024 09:00:12 +0800
Subject: [PATCH] [VL] Offload Spark Pi function as a literal (#6408)

---
 .../apache/gluten/backendsapi/velox/VeloxBackend.scala |  5 +++--
 .../execution/ScalarFunctionsValidateSuite.scala       | 10 ++++++++++
 .../apache/gluten/expression/ExpressionConverter.scala |  2 ++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/backends-velox/src/main/scala/org/apache/gluten/backendsapi/velox/VeloxBackend.scala b/backends-velox/src/main/scala/org/apache/gluten/backendsapi/velox/VeloxBackend.scala
index 31f0324e32eb..e4efa22055fc 100644
--- a/backends-velox/src/main/scala/org/apache/gluten/backendsapi/velox/VeloxBackend.scala
+++ b/backends-velox/src/main/scala/org/apache/gluten/backendsapi/velox/VeloxBackend.scala
@@ -27,7 +27,7 @@ import org.apache.gluten.substrait.rel.LocalFilesNode.ReadFileFormat
 import org.apache.gluten.substrait.rel.LocalFilesNode.ReadFileFormat.{DwrfReadFormat, OrcReadFormat, ParquetReadFormat}
 
 import org.apache.spark.sql.catalyst.catalog.BucketSpec
-import org.apache.spark.sql.catalyst.expressions.{Alias, CumeDist, DenseRank, Descending, EulerNumber, Expression, Lag, Lead, Literal, MakeYMInterval, NamedExpression, NthValue, NTile, PercentRank, Rand, RangeFrame, Rank, RowNumber, SortOrder, SparkPartitionID, SpecialFrameBoundary, SpecifiedWindowFrame, Uuid}
+import org.apache.spark.sql.catalyst.expressions.{Alias, CumeDist, DenseRank, Descending, EulerNumber, Expression, Lag, Lead, Literal, MakeYMInterval, NamedExpression, NthValue, NTile, PercentRank, Pi, Rand, RangeFrame, Rank, RowNumber, SortOrder, SparkPartitionID, SpecialFrameBoundary, SpecifiedWindowFrame, Uuid}
 import org.apache.spark.sql.catalyst.expressions.aggregate.{AggregateExpression, ApproximatePercentile, Count, Sum}
 import org.apache.spark.sql.catalyst.plans.{JoinType, LeftOuter, RightOuter}
 import org.apache.spark.sql.catalyst.util.CharVarcharUtils
@@ -430,7 +430,8 @@ object VeloxBackendSettings extends BackendSettingsApi {
       expr match {
         // Block directly falling back the below functions by FallbackEmptySchemaRelation.
         case alias: Alias => checkExpr(alias.child)
-        case _: Rand | _: Uuid | _: MakeYMInterval | _: SparkPartitionID | _: EulerNumber => true
+        case _: Rand | _: Uuid | _: MakeYMInterval | _: SparkPartitionID | _: EulerNumber | _: Pi =>
+          true
         case _ => false
       }
     }
diff --git a/backends-velox/src/test/scala/org/apache/gluten/execution/ScalarFunctionsValidateSuite.scala b/backends-velox/src/test/scala/org/apache/gluten/execution/ScalarFunctionsValidateSuite.scala
index fc3bf320ec66..cb1d63c90a5a 100644
--- a/backends-velox/src/test/scala/org/apache/gluten/execution/ScalarFunctionsValidateSuite.scala
+++ b/backends-velox/src/test/scala/org/apache/gluten/execution/ScalarFunctionsValidateSuite.scala
@@ -687,6 +687,16 @@ class ScalarFunctionsValidateSuite extends FunctionsValidateTest {
     }
   }
 
+  test("Test Pi function") {
+    runQueryAndCompare("""SELECT Pi() from lineitem limit 100""".stripMargin) {
+      checkGlutenOperatorMatch[ProjectExecTransformer]
+    }
+    runQueryAndCompare("""SELECT Pi(), l_orderkey
+                         | from lineitem limit 100""".stripMargin) {
+      checkGlutenOperatorMatch[ProjectExecTransformer]
+    }
+  }
+
   test("Test spark_partition_id function") {
     runQueryAndCompare("""SELECT spark_partition_id(), l_orderkey
                          | from lineitem limit 100""".stripMargin) {
diff --git a/gluten-core/src/main/scala/org/apache/gluten/expression/ExpressionConverter.scala b/gluten-core/src/main/scala/org/apache/gluten/expression/ExpressionConverter.scala
index 6911d5ee8061..c285c11945c7 100644
--- a/gluten-core/src/main/scala/org/apache/gluten/expression/ExpressionConverter.scala
+++ b/gluten-core/src/main/scala/org/apache/gluten/expression/ExpressionConverter.scala
@@ -684,6 +684,8 @@ object ExpressionConverter extends SQLConfHelper with Logging {
         )
       case e: EulerNumber =>
         LiteralTransformer(Literal(Math.E))
+      case p: Pi =>
+        LiteralTransformer(Literal(Math.PI))
       case expr =>
         GenericExpressionTransformer(
           substraitExprName,