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Fix #3857: partial fix to generate more shallow tree in LabelDef #3994

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Feb 20, 2018
Merged

Fix #3857: partial fix to generate more shallow tree in LabelDef #3994

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3489972
fix #3857: partial fix to generate more shallow tree in LabelDef
liufengyun Feb 13, 2018
060b239
address review: add comment
liufengyun Feb 13, 2018
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24 changes: 21 additions & 3 deletions compiler/src/dotty/tools/backend/jvm/LabelDefs.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,7 @@ import scala.collection.mutable
* <label> def foo(i: Int) = dough(i)
* <label> def dough(i: Int) = if (i == 0) bar else foo(i-1)
* <label> def bar = 2
* foo(100)
* foo(100)
* ```
*
* Proposed way to generate this pattern in backend is:
Expand All @@ -49,7 +49,7 @@ import scala.collection.mutable
* Unreachable jumps will be eliminated by local dead code analysis.
* After JVM is smart enough to remove next-line jumps
*
* Note that his phase Ychecking this phase required softening scoping rules
* Note that Ychecking this phase requires softening scoping rules
* as it intentionally allowed to break scoping rules inside methods for labels.
* This is modified by setting `labelsReordered` flag in Phases.
*
Expand All @@ -76,7 +76,25 @@ class LabelDefs extends MiniPhase {
case t: DefDef =>
assert(t.symbol is Label)
EmptyTree
case _ => if (!labelDefs.isEmpty) super.transform(tree) else tree
case t: If =>
// Trees generated by pattern matcher usually looks like the
// following:
//
// ...
// }
// else case58(x704)
// }
// else case58(x704)
// }
// else case58(x704)
//
// First transform on the else branch will make labeldef
// inserted on a shallow node.
val elsep2 = transform(t.elsep)
val thenp2 = transform(t.thenp)
cpy.If(tree)(transform(t.cond), thenp2, elsep2)
case _ =>
if (!labelDefs.isEmpty) super.transform(tree) else tree
}
}
}
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59 changes: 59 additions & 0 deletions tests/pos/i3857.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,59 @@
object foo {
abstract sealed class num
final case class One() extends num
final case class Bit0(a: num) extends num
final case class Bit1(a: num) extends num

abstract sealed class abschar
final case class zero_char() extends abschar
final case class Char(a: num) extends abschar

def integer_of_char(x0: abschar): BigInt = {
def f(x: Int): Int = x
x0 match {
case Char(Bit0(Bit1(Bit0(Bit1(Bit0(One())))))) => BigInt(42)
case Char(Bit1(Bit0(Bit0(Bit1(Bit0(One())))))) => BigInt(41)
case Char(Bit0(Bit0(Bit0(Bit1(Bit0(One())))))) => BigInt(40)
case Char(Bit1(Bit1(Bit1(Bit0(Bit0(One())))))) => BigInt(39)
case Char(Bit0(Bit1(Bit1(Bit0(Bit0(One())))))) => BigInt(38)
case Char(Bit1(Bit0(Bit1(Bit0(Bit0(One())))))) => BigInt(37)
case Char(Bit0(Bit0(Bit1(Bit0(Bit0(One())))))) => BigInt(36)
case Char(Bit1(Bit1(Bit0(Bit0(Bit0(One())))))) => BigInt(35)
case Char(Bit0(Bit1(Bit0(Bit0(Bit0(One())))))) => BigInt(34)
case Char(Bit1(Bit0(Bit0(Bit0(Bit0(One())))))) => BigInt(33)
case Char(Bit0(Bit0(Bit0(Bit0(Bit0(One())))))) => BigInt(32)
case Char(Bit1(Bit1(Bit1(Bit1(One()))))) => BigInt(31)
case Char(Bit0(Bit1(Bit1(Bit1(One()))))) => BigInt(30)
case Char(Bit1(Bit0(Bit1(Bit1(One()))))) => BigInt(29)
case Char(Bit0(Bit0(Bit1(Bit1(One()))))) => BigInt(28)
case Char(Bit1(Bit1(Bit0(Bit1(One()))))) => BigInt(27)
case Char(Bit0(Bit1(Bit0(Bit1(One()))))) => BigInt(26)
case Char(Bit1(Bit0(Bit0(Bit1(One()))))) => BigInt(25)
case Char(Bit0(Bit0(Bit0(Bit1(One()))))) => BigInt(24)
case Char(Bit1(Bit1(Bit1(Bit0(One()))))) => BigInt(23)
case Char(Bit0(Bit1(Bit1(Bit0(One()))))) => BigInt(22)
case Char(Bit1(Bit0(Bit1(Bit0(One()))))) => BigInt(21)
case Char(Bit0(Bit0(Bit1(Bit0(One()))))) => BigInt(20)
case Char(Bit1(Bit1(Bit0(Bit0(One()))))) => BigInt(19)
case Char(Bit0(Bit1(Bit0(Bit0(One()))))) => BigInt(18)
case Char(Bit1(Bit0(Bit0(Bit0(One()))))) => BigInt(17)
case Char(Bit0(Bit0(Bit0(Bit0(One()))))) => BigInt(16)
case Char(Bit1(Bit1(Bit1(One())))) => BigInt(15)
case Char(Bit0(Bit1(Bit1(One())))) => BigInt(14)
case Char(Bit1(Bit0(Bit1(One())))) => BigInt(13)
case Char(Bit0(Bit0(Bit1(One())))) => BigInt(12)
case Char(Bit1(Bit1(Bit0(One())))) => BigInt(11)
case Char(Bit0(Bit1(Bit0(One())))) => BigInt(10)
case Char(Bit1(Bit0(Bit0(One())))) => BigInt(9)
case Char(Bit0(Bit0(Bit0(One())))) => BigInt(8)
case Char(Bit1(Bit1(One()))) => BigInt(7)
case Char(Bit0(Bit1(One()))) => BigInt(6)
case Char(Bit1(Bit0(One()))) => BigInt(5)
case Char(Bit0(Bit0(One()))) => BigInt(4)
case Char(Bit1(One())) => BigInt(3)
case Char(Bit0(One())) => BigInt(2)
case Char(One()) => BigInt(1)
case zero_char() => BigInt(0)
}
}
}