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Extend caching in the space engine beyond local context #23483

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Extend caching in the space engine beyond local context #23483

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14 changes: 9 additions & 5 deletions compiler/src/dotty/tools/dotc/transform/patmat/Space.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -48,19 +48,21 @@ import SpaceEngine.*
*
*/

/** A key to be used in a context property that caches the unpickled trees */
private val IsSubspaceCacheKey = new Property.Key[mutable.HashMap[(Space, Space), Boolean]]

/** space definition */
sealed trait Space extends Showable:

@sharable private val isSubspaceCache = mutable.HashMap.empty[Space, Boolean]

def isSubspace(b: Space)(using Context): Boolean =
val a = this
val a2 = a.simplify
val b2 = b.simplify
if (a ne a2) || (b ne b2) then a2.isSubspace(b2)
else if a == Empty then true
else if b == Empty then false
else isSubspaceCache.getOrElseUpdate(b, computeIsSubspace(a, b))
else
ctx.property(IsSubspaceCacheKey).get.getOrElseUpdate((a, b), computeIsSubspace(a, b))

@sharable private var mySimplified: Space | Null = null

Expand Down Expand Up @@ -968,6 +970,8 @@ object SpaceEngine {
end checkReachability

def checkMatch(m: Match)(using Context): Unit =
if exhaustivityCheckable(m.selector) then checkExhaustivity(m)
if reachabilityCheckable(m.selector) then checkReachability(m)
inContext(ctx.withProperty(IsSubspaceCacheKey, Some(mutable.HashMap.empty))) {
if exhaustivityCheckable(m.selector) then checkExhaustivity(m)
if reachabilityCheckable(m.selector) then checkReachability(m)
}
}
26 changes: 26 additions & 0 deletions tests/pos/i23317.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
import scala.quoted.*

def goImpl(using Quotes): Expr[Int] =
List.empty[Type[?]] match
case Nil =>
Expr(0)
case '[t1] :: Nil =>
Expr(1)
case '[t1] :: '[t2] :: Nil =>
Expr(2)
case '[t1] :: '[t2] :: '[t3] :: Nil =>
Expr(3)
case '[t1] :: '[t2] :: '[t3] :: '[t4] :: Nil =>
Expr(4)
case '[t1] :: '[t2] :: '[t3] :: '[t4] :: '[t5] :: Nil =>
Expr(5)
case '[t1] :: '[t2] :: '[t3] :: '[t4] :: '[t5] :: '[t6] :: Nil =>
Expr(6)
case '[t1] :: '[t2] :: '[t3] :: '[t4] :: '[t5] :: '[t6] :: '[t7] :: Nil =>
Expr(7)
case '[t1] :: '[t2] :: '[t3] :: '[t4] :: '[t5] :: '[t6] :: '[t7] :: '[t8] :: Nil =>
Expr(8)
case '[t1] :: '[t2] :: '[t3] :: '[t4] :: '[t5] :: '[t6] :: '[t7] :: '[t8] :: '[t9] :: Nil =>
Expr(9)
case _ =>
Expr(999)
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