## What changes were proposed in this pull request?
The PR takes over #14036 and it introduces a new expression `IntegralDivide` in order to avoid the several unneded cast added previously.
In order to prove the performance gain, the following benchmark has been run:
```
test("Benchmark IntegralDivide") {
val r = new scala.util.Random(91)
val nData = 1000000
val testDataInt = (1 to nData).map(_ => (r.nextInt(), r.nextInt()))
val testDataLong = (1 to nData).map(_ => (r.nextLong(), r.nextLong()))
val testDataShort = (1 to nData).map(_ => (r.nextInt().toShort, r.nextInt().toShort))
// old code
val oldExprsInt = testDataInt.map(x =>
Cast(Divide(Cast(Literal(x._1), DoubleType), Cast(Literal(x._2), DoubleType)), LongType))
val oldExprsLong = testDataLong.map(x =>
Cast(Divide(Cast(Literal(x._1), DoubleType), Cast(Literal(x._2), DoubleType)), LongType))
val oldExprsShort = testDataShort.map(x =>
Cast(Divide(Cast(Literal(x._1), DoubleType), Cast(Literal(x._2), DoubleType)), LongType))
// new code
val newExprsInt = testDataInt.map(x => IntegralDivide(x._1, x._2))
val newExprsLong = testDataLong.map(x => IntegralDivide(x._1, x._2))
val newExprsShort = testDataShort.map(x => IntegralDivide(x._1, x._2))
Seq(("Long", "old", oldExprsLong),
("Long", "new", newExprsLong),
("Int", "old", oldExprsInt),
("Int", "new", newExprsShort),
("Short", "old", oldExprsShort),
("Short", "new", oldExprsShort)).foreach { case (dt, t, ds) =>
val start = System.nanoTime()
ds.foreach(e => e.eval(EmptyRow))
val endNoCodegen = System.nanoTime()
println(s"Running $nData op with $t code on $dt (no-codegen): ${(endNoCodegen - start) / 1000000} ms")
}
}
```
The results on my laptop are:
```
Running 1000000 op with old code on Long (no-codegen): 600 ms
Running 1000000 op with new code on Long (no-codegen): 112 ms
Running 1000000 op with old code on Int (no-codegen): 560 ms
Running 1000000 op with new code on Int (no-codegen): 135 ms
Running 1000000 op with old code on Short (no-codegen): 317 ms
Running 1000000 op with new code on Short (no-codegen): 153 ms
```
Showing a 2-5X improvement. The benchmark doesn't include code generation as it is pretty hard to test the performance there as for such simple operations the most of the time is spent in the code generation/compilation process.
## How was this patch tested?
added UTs
Closes#22395 from mgaido91/SPARK-16323.
Authored-by: Marco Gaido <marcogaido91@gmail.com>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
553af22f2c