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Merged
merged 2 commits into from
Sep 26, 2018
Merged

Move TailRec after Erasure. #5112

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b1008d8
Move TailRec after Erasure.
sjrd Sep 15, 2018
f102203
Feature Removal: Do not check call-site @tailrec anymore.
sjrd Sep 18, 2018
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2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/dotc/Compiler.scala
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Expand Up @@ -67,7 +67,6 @@ class Compiler {
new ProtectedAccessors, // Add accessors for protected members
new ExtensionMethods, // Expand methods of value classes with extension methods
new ShortcutImplicits, // Allow implicit functions without creating closures
new TailRec, // Rewrite tail recursion to loops
new ByNameClosures, // Expand arguments to by-name parameters to closures
new LiftTry, // Put try expressions that might execute on non-empty stacks into their own methods
new HoistSuperArgs, // Hoist complex arguments of supercalls to enclosing scope
Expand Down Expand Up @@ -96,6 +95,7 @@ class Compiler {
List(new Erasure) :: // Rewrite types to JVM model, erasing all type parameters, abstract types and refinements.
List(new ElimErasedValueType, // Expand erased value types to their underlying implmementation types
new VCElideAllocations, // Peep-hole optimization to eliminate unnecessary value class allocations
new TailRec, // Rewrite tail recursion to loops
new Mixin, // Expand trait fields and trait initializers
new LazyVals, // Expand lazy vals
new Memoize, // Add private fields to getters and setters
Expand Down
5 changes: 5 additions & 0 deletions compiler/src/dotty/tools/dotc/ast/TreeTypeMap.scala
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Expand Up @@ -116,6 +116,11 @@ class TreeTypeMap(
val guard1 = tmap.transform(guard)
val rhs1 = tmap.transform(rhs)
cpy.CaseDef(cdef)(pat1, guard1, rhs1)
case labeled @ Labeled(bind, expr) =>
val tmap = withMappedSyms(bind.symbol :: Nil)
val bind1 = tmap.transformSub(bind)
val expr1 = tmap.transform(expr)
cpy.Labeled(labeled)(bind1, expr1)
case Hole(n, args) =>
Hole(n, args.mapConserve(transform)).withPos(tree.pos).withType(mapType(tree.tpe))
case tree1 =>
Expand Down
30 changes: 15 additions & 15 deletions compiler/src/dotty/tools/dotc/core/Types.scala
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Expand Up @@ -208,17 +208,17 @@ object Types {
def loop(tp: Type): Boolean = tp match {
case tp: TypeRef =>
val sym = tp.symbol
if (sym.isClass) sym.derivesFrom(cls) else loop(tp.superType): @tailrec
if (sym.isClass) sym.derivesFrom(cls) else loop(tp.superType)
case tp: AppliedType =>
tp.superType.derivesFrom(cls)
case tp: MatchType =>
tp.bound.derivesFrom(cls) || tp.reduced.derivesFrom(cls)
case tp: TypeProxy =>
loop(tp.underlying): @tailrec
loop(tp.underlying)
case tp: AndType =>
loop(tp.tp1) || loop(tp.tp2): @tailrec
loop(tp.tp1) || loop(tp.tp2)
case tp: OrType =>
loop(tp.tp1) && loop(tp.tp2): @tailrec
loop(tp.tp1) && loop(tp.tp2)
case tp: JavaArrayType =>
cls == defn.ObjectClass
case _ =>
Expand Down Expand Up @@ -403,16 +403,16 @@ object Types {
*/
final def classSymbol(implicit ctx: Context): Symbol = this match {
case ConstantType(constant) =>
constant.tpe.classSymbol: @tailrec
constant.tpe.classSymbol
case tp: TypeRef =>
val sym = tp.symbol
if (sym.isClass) sym else tp.superType.classSymbol: @tailrec
if (sym.isClass) sym else tp.superType.classSymbol
case tp: ClassInfo =>
tp.cls
case tp: SingletonType =>
NoSymbol
case tp: TypeProxy =>
tp.underlying.classSymbol: @tailrec
tp.underlying.classSymbol
case AndType(l, r) =>
val lsym = l.classSymbol
val rsym = r.classSymbol
Expand All @@ -436,9 +436,9 @@ object Types {
tp.cls :: Nil
case tp: TypeRef =>
val sym = tp.symbol
if (sym.isClass) sym.asClass :: Nil else tp.superType.classSymbols: @tailrec
if (sym.isClass) sym.asClass :: Nil else tp.superType.classSymbols
case tp: TypeProxy =>
tp.underlying.classSymbols: @tailrec
tp.underlying.classSymbols
case AndType(l, r) =>
l.classSymbols union r.classSymbols
case OrType(l, r) =>
Expand Down Expand Up @@ -479,7 +479,7 @@ object Types {
case tp: ClassInfo =>
tp.decls
case tp: TypeProxy =>
tp.underlying.decls: @tailrec
tp.underlying.decls
case _ =>
EmptyScope
}
Expand Down Expand Up @@ -725,7 +725,7 @@ object Types {
val ns = tp.parent.memberNames(keepOnly, pre)
if (keepOnly(pre, tp.refinedName)) ns + tp.refinedName else ns
case tp: TypeProxy =>
tp.underlying.memberNames(keepOnly, pre): @tailrec
tp.underlying.memberNames(keepOnly, pre)
case tp: AndType =>
tp.tp1.memberNames(keepOnly, pre) | tp.tp2.memberNames(keepOnly, pre)
case tp: OrType =>
Expand Down Expand Up @@ -1042,21 +1042,21 @@ object Types {
case tp: TypeRef =>
if (tp.symbol.isClass) tp
else tp.info match {
case TypeAlias(alias) => alias.dealias1(keep): @tailrec
case TypeAlias(alias) => alias.dealias1(keep)
case _ => tp
}
case app @ AppliedType(tycon, args) =>
val tycon1 = tycon.dealias1(keep)
if (tycon1 ne tycon) app.superType.dealias1(keep): @tailrec
if (tycon1 ne tycon) app.superType.dealias1(keep)
else this
case tp: TypeVar =>
val tp1 = tp.instanceOpt
if (tp1.exists) tp1.dealias1(keep): @tailrec else tp
if (tp1.exists) tp1.dealias1(keep) else tp
case tp: AnnotatedType =>
val tp1 = tp.parent.dealias1(keep)
if (keep(tp)(ctx)) tp.derivedAnnotatedType(tp1, tp.annot) else tp1
case tp: LazyRef =>
tp.ref.dealias1(keep): @tailrec
tp.ref.dealias1(keep)
case _ => this
}

Expand Down
2 changes: 1 addition & 1 deletion compiler/src/dotty/tools/dotc/transform/MixinOps.scala
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Expand Up @@ -24,7 +24,7 @@ class MixinOps(cls: ClassSymbol, thisPhase: DenotTransformer)(implicit ctx: Cont
name = member.name.stripScala2LocalSuffix,
flags = member.flags &~ Deferred,
info = cls.thisType.memberInfo(member)).enteredAfter(thisPhase).asTerm
res.addAnnotations(member.annotations)
res.addAnnotations(member.annotations.filter(_.symbol != defn.TailrecAnnot))
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Sorry, I missed this. Is this needed if you move TailRec after Mixin within the same group?

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Even more so. But right now it's necessary above all for extension methods (for AnyVals, which also use this forwarder() method). In general, when creating a forwarder of any sort, we must remove the @tailrec annotation.

Previously, no forwarder was ever created before TailRec ran. But now that TailRec runs after the creation of extension methods, we must ensure that forwarder drops @tailrec).

res
}

Expand Down
1 change: 0 additions & 1 deletion compiler/src/dotty/tools/dotc/transform/PatternMatcher.scala
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Expand Up @@ -27,7 +27,6 @@ class PatternMatcher extends MiniPhase {

override def phaseName = PatternMatcher.name
override def runsAfter = Set(ElimRepeated.name)
override def runsAfterGroupsOf = Set(TailRec.name) // tailrec is not capable of reversing the patmat tranformation made for tree

override def transformMatch(tree: Match)(implicit ctx: Context): Tree = {
val translated = new Translator(tree.tpe, this).translateMatch(tree)
Expand Down
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