Github user davies commented on a diff in the pull request:
https://github.com/apache/spark/pull/10333#discussion_r47838978
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
---
@@ -424,19 +431,30 @@ abstract class BinaryExpression extends Expression {
val eval1 = left.gen(ctx)
val eval2 = right.gen(ctx)
val resultCode = f(eval1.value, eval2.value)
- s"""
- ${eval1.code}
- boolean ${ev.isNull} = ${eval1.isNull};
- ${ctx.javaType(dataType)} ${ev.value} =
${ctx.defaultValue(dataType)};
- if (!${ev.isNull}) {
- ${eval2.code}
- if (!${eval2.isNull}) {
- $resultCode
- } else {
- ${ev.isNull} = true;
+ if (nullable) {
+ s"""
+ ${eval1.code}
+ boolean ${ev.isNull} = ${eval1.isNull};
+ ${ctx.javaType(dataType)} ${ev.value} =
${ctx.defaultValue(dataType)};
+ if (!${ev.isNull}) {
+ ${eval2.code}
+ if (!${eval2.isNull}) {
+ $resultCode
+ } else {
+ ${ev.isNull} = true;
+ }
}
- }
- """
+ """
+
+ } else {
+ ev.isNull = "false"
--- End diff --
I think it's not necessary (in terms of performance). Compiler can do all
these, but not sure how far Janino had achieved on constant folding.
We don't need to do this for every expression, but since
UnaryExpression/BinaryExpression/TernaryExpression are used by many, this
changes may worse it.
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