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Fix #4846: Allow transparent parameters at any stage #4856

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merged 2 commits into from
Jul 31, 2018
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Fix #4846: Allow transparent parameters at any stage #4856

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f497ad9
Fix #4846: Allow transparent parameters at any stage
nicolasstucki Jul 27, 2018
817cc9b
Update ReifyQuotes.scala
nicolasstucki Jul 31, 2018
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61 changes: 13 additions & 48 deletions compiler/src/dotty/tools/dotc/transform/ReifyQuotes.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -225,7 +225,7 @@ class ReifyQuotes extends MacroTransformWithImplicits {
def levelOK(sym: Symbol)(implicit ctx: Context): Boolean = levelOf.get(sym) match {
case Some(l) =>
l == level ||
l == 0 && level == -1 && isStageNegOneValue(sym)
level == -1 && sym == defn.TastyTopLevelSplice_tastyContext
case None =>
!sym.is(Param) || levelOK(sym.owner)
}
Expand Down Expand Up @@ -359,18 +359,12 @@ class ReifyQuotes extends MacroTransformWithImplicits {
}
else body match {
case body: RefTree if isCaptured(body.symbol, level + 1) =>
if (isStageNegOneValue(body.symbol)) {
// Optimization: avoid the full conversion when capturing inlined `x`
// in '{ x } to '{ x$1.toExpr.unary_~ } and go directly to `x$1.toExpr`
liftInlineParamValue(capturers(body.symbol)(body))
} else {
// Optimization: avoid the full conversion when capturing `x`
// in '{ x } to '{ x$1.unary_~ } and go directly to `x$1`
capturers(body.symbol)(body)
}
// Optimization: avoid the full conversion when capturing `x`
// in '{ x } to '{ x$1.unary_~ } and go directly to `x$1`
capturers(body.symbol)(body)
case _=>
val (body1, splices) = nested(isQuote = true).split(body)
if (level >= 0) pickledQuote(body1, splices, body.tpe, isType).withPos(quote.pos)
if (level == 0 && !ctx.inTransparentMethod) pickledQuote(body1, splices, body.tpe, isType).withPos(quote.pos)
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Small question. We don't split if we are in a transparent method but the level is above or equal zero?
If yes, we can move splitting inside the if now.

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@nicolasstucki nicolasstucki Jul 31, 2018 •
edited
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We do not split, but we still need to perform the checks that split does. We should be able to improve the performance by calling transform directly in another branch. I will try that later, nice catch :)

else {
// In top-level splice in an transparent def. Keep the tree as it is, it will be transformed at inline site.
body
Expand Down Expand Up @@ -464,7 +458,6 @@ class ReifyQuotes extends MacroTransformWithImplicits {
val tpw = tree.tpe.widen
val argTpe =
if (tree.isType) defn.QuotedTypeType.appliedTo(tpw)
else if (isStageNegOneValue(tree.symbol)) tpw
else defn.QuotedExprType.appliedTo(tpw)
val selectArg = arg.select(nme.apply).appliedTo(Literal(Constant(i))).asInstance(argTpe)
val capturedArg = SyntheticValDef(UniqueName.fresh(tree.symbol.name.toTermName).toTermName, selectArg)
Expand All @@ -489,21 +482,17 @@ class ReifyQuotes extends MacroTransformWithImplicits {
val captured = mutable.LinkedHashMap.empty[Symbol, Tree]
val captured2 = capturer(captured)

outer.enteredSyms.foreach(sym => capturers.put(sym, captured2))
outer.enteredSyms.foreach(sym => if (!sym.is(Transparent)) capturers.put(sym, captured2))

val tree2 = transform(tree)
capturers --= outer.enteredSyms

seq(captured.result().valuesIterator.toList, tree2)
}

/** Returns true if this tree will be captured by `makeLambda` */
private def isCaptured(sym: Symbol, level: Int)(implicit ctx: Context): Boolean = {
// Check phase consistency and presence of capturer
( (level == 1 && levelOf.get(sym).contains(1)) ||
(level == 0 && isStageNegOneValue(sym))
) && capturers.contains(sym)
}
/** Returns true if this tree will be captured by `makeLambda`. Checks phase consistency and presence of capturer. */
private def isCaptured(sym: Symbol, level: Int)(implicit ctx: Context): Boolean =
level == 1 && levelOf.get(sym).contains(1) && capturers.contains(sym)

/** Transform `tree` and return the resulting tree and all `embedded` quotes
* or splices as a pair, after performing the `addTags` transform.
Expand Down Expand Up @@ -539,13 +528,11 @@ class ReifyQuotes extends MacroTransformWithImplicits {
splice(ref(splicedType).select(tpnme.UNARY_~).withPos(tree.pos))
case tree: Select if tree.symbol.isSplice =>
splice(tree)
case tree: RefTree if tree.symbol.is(Transparent) && tree.symbol.is(Param) =>
tree
case tree: RefTree if isCaptured(tree.symbol, level) =>
val capturer = capturers(tree.symbol)
def captureAndSplice(t: Tree) =
splice(t.select(if (tree.isTerm) nme.UNARY_~ else tpnme.UNARY_~))
if (!isStageNegOneValue(tree.symbol)) captureAndSplice(capturer(tree))
else if (level == 0) capturer(tree)
else captureAndSplice(liftInlineParamValue(capturer(tree)))
val t = capturers(tree.symbol).apply(tree)
splice(t.select(if (tree.isTerm) nme.UNARY_~ else tpnme.UNARY_~))
case Block(stats, _) =>
val last = enteredSyms
stats.foreach(markDef)
Expand Down Expand Up @@ -589,28 +576,6 @@ class ReifyQuotes extends MacroTransformWithImplicits {
}
}

/** Takes a reference to an transparent parameter `tree` and lifts it to an Expr */
private def liftInlineParamValue(tree: Tree)(implicit ctx: Context): Tree = {
val tpSym = tree.tpe.widenDealias.classSymbol

val lifter =
if (tpSym eq defn.BooleanClass) defn.QuotedLiftable_BooleanIsLiftable
else if (tpSym eq defn.ByteClass) defn.QuotedLiftable_ByteIsLiftable
else if (tpSym eq defn.CharClass) defn.QuotedLiftable_CharIsLiftable
else if (tpSym eq defn.ShortClass) defn.QuotedLiftable_ShortIsLiftable
else if (tpSym eq defn.IntClass) defn.QuotedLiftable_IntIsLiftable
else if (tpSym eq defn.LongClass) defn.QuotedLiftable_LongIsLiftable
else if (tpSym eq defn.FloatClass) defn.QuotedLiftable_FloatIsLiftable
else if (tpSym eq defn.DoubleClass) defn.QuotedLiftable_DoubleIsLiftable
else defn.QuotedLiftable_StringIsLiftable

ref(lifter).select("toExpr".toTermName).appliedTo(tree)
}

private def isStageNegOneValue(sym: Symbol)(implicit ctx: Context): Boolean =
(sym.is(Transparent) && sym.owner.is(Transparent) && !defn.isFunctionType(sym.info)) ||
sym == defn.TastyTopLevelSplice_tastyContext // intrinsic value at stage 0

private def liftList(list: List[Tree], tpe: Type)(implicit ctx: Context): Tree = {
list.foldRight[Tree](ref(defn.NilModule)) { (x, acc) =>
acc.select("::".toTermName).appliedToType(tpe).appliedTo(x)
Expand Down
6 changes: 6 additions & 0 deletions tests/pos/i4846.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
import scala.quoted._

object Test {
transparent def foo(transparent x: Int): Int = ~fooImpl(x, '(x), '( '(x) ), '( '( '(x) ) ))
def fooImpl(a: Int, b: Expr[Int], c: Expr[Expr[Int]], d: Expr[Expr[Expr[Int]]]): Expr[Int] = ???
}