MaxGekk commented on code in PR #59984:
URL: https://github.com/apache/spark/pull/59984#discussion_r4466784140
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sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/codegen/CodegenSubexpressionEliminationSuite.scala:
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@@ -56,18 +56,81 @@ class CodegenSubexpressionEliminationSuite extends
SparkFunSuite {
}
}
+ test("SPARK-60332: GeneratePredicate evaluates a common subexpression of
later conjuncts " +
+ "after the conjuncts before it") {
+ // `Not(leaf)` is common to the last two conjuncts, and evaluated just
before the first of
+ // them, so the first conjunct decides whether `leaf` is evaluated at all:
a FALSE one stops
+ // the evaluation, while a TRUE or a NULL one does not, as `And.eval` does.
+ Seq(true, false).foreach { useSubexprElimination =>
+ Seq((false, false, false), (true, true, true), (null, true,
false)).foreach {
+ case (first, leafEvaluated, result) =>
+ // Distinct `id`s, so that the first conjunct and the leaf are not
the same expression.
+ val leaf = ExprWithEvaluatedState(id = 1)
+ val cond = And(And(ExprWithEvaluatedState(first, isNullable = first
== null),
+ Not(leaf)), Not(leaf))
+ val instance = GeneratePredicate.generate(cond,
useSubexprElimination)
+ instance.initialize(0)
+ withClue(s"useSubexprElimination = $useSubexprElimination, first =
$first: ") {
+ assert(instance.eval(null) === result)
+ assert(leaf.evaluated === leafEvaluated)
Review Comment:
Done in 358d156dde6: `ExprWithEvaluatedState` counts its evaluations, and
the tests assert exact counts, so a recomputation shows (once with the
elimination, twice without). The stale read in a branch is covered by the `(a +
c) + b` test over rows with different values.
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