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List(...) optimization to avoid intermediate array (#17166)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,88 @@ | ||
| object Test: | ||
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| var counter = 0 | ||
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| def next = | ||
| counter += 1 | ||
| counter.toString | ||
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| def main(args: Array[String]): Unit = | ||
| //List.apply is subject to an optimisation in cleanup | ||
| //ensure that the arguments are evaluated in the currect order | ||
| // Rewritten to: | ||
| // val myList: List = new collection.immutable.::(Test.this.next(), new collection.immutable.::(Test.this.next(), new collection.immutable.::(Test.this.next(), scala.collection.immutable.Nil))); | ||
| val myList = List(next, next, next) | ||
| assert(myList == List("1", "2", "3"), myList) | ||
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| val mySeq = Seq(next, next, next) | ||
| assert(mySeq == Seq("4", "5", "6"), mySeq) | ||
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| val emptyList = List[Int]() | ||
| assert(emptyList == Nil) | ||
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| // just assert it doesn't throw CCE to List | ||
| val queue = scala.collection.mutable.Queue[String]() | ||
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| // test for the cast instruction described in checkApplyAvoidsIntermediateArray | ||
| def lub(b: Boolean): List[(String, String)] = | ||
| if b then List(("foo", "bar")) else Nil | ||
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| // from minimising CI failure in oslib | ||
| // again, the lub of :: and Nil is Product, which breaks ++ (which requires IterableOnce) | ||
| def lub2(b: Boolean): Unit = | ||
| Seq(1) ++ (if (b) Seq(2) else Nil) | ||
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| // Examples of arity and nesting arity | ||
| // to find the thresholds and reproduce the behaviour of nsc | ||
| def examples(): Unit = | ||
| val max1 = List[Object]("1", "2", "3", "4", "5", "6", "7") // 7 cons w/ 7 string heads + nil | ||
| val max2 = List[Object]("1", "2", "3", "4", "5", "6", List[Object]()) // 7 cons w/ 6 string heads + 1 nil head + nil | ||
| val max3 = List[Object]("1", "2", "3", "4", "5", List[Object]("6")) | ||
| val max4 = List[Object]("1", "2", "3", "4", List[Object]("5", "6")) | ||
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| val over1 = List[Object]("1", "2", "3", "4", "5", "6", "7", "8") // wrap 8-sized array | ||
| val over2 = List[Object]("1", "2", "3", "4", "5", "6", "7", List[Object]()) // wrap 8-sized array | ||
| val over3 = List[Object]("1", "2", "3", "4", "5", "6", List[Object]("7")) // wrap 1-sized array with 7 | ||
| val over4 = List[Object]("1", "2", "3", "4", "5", List[Object]("6", "7")) // wrap 2 | ||
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| val max5 = | ||
| List[Object]( | ||
| List[Object]( | ||
| List[Object]( | ||
| List[Object]( | ||
| List[Object]( | ||
| List[Object]( | ||
| List[Object]( | ||
| List[Object]( | ||
| )))))))) // 7 cons + 1 nil | ||
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| val over5 = | ||
| List[Object]( | ||
| List[Object]( | ||
| List[Object]( | ||
| List[Object]( | ||
| List[Object]( | ||
| List[Object]( | ||
| List[Object]( | ||
| List[Object]( List[Object]() | ||
| )))))))) // 7 cons + 1-sized array wrapping nil | ||
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| val max6 = | ||
| List[Object]( // ::( | ||
| "1", "2", List[Object]( // 1, ::(2, ::(::( | ||
| "3", "4", List[Object]( // 3, ::(4, ::(::( | ||
| List[Object]() // Nil, Nil | ||
| ) // ), Nil)) | ||
| ) // ), Nil)) | ||
| ) // ) | ||
| // 7 cons + 4 string heads + 4 nils for nested lists | ||
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| val max7 = | ||
| List[Object]( // ::( | ||
| "1", "2", List[Object]( // 1, ::(2, ::(::( | ||
| "3", "4", List[Object]( // 3, ::(4, ::(::( | ||
| "5" // 5, Nil | ||
| ) // ), Nil)) | ||
| ) // ), Nil)) | ||
| ) // ) | ||
| // 7 cons + 5 string heads + 3 nils for nested lists |