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Merge the IR node This into VarRef, with a magic LocalName. #5090

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Merged
merged 1 commit into from
Dec 27, 2024
Merged

Merge the IR node This into VarRef, with a magic LocalName. #5090

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8 changes: 4 additions & 4 deletions compiler/src/main/scala/org/scalajs/nscplugin/GenJSCode.scala
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Expand Up @@ -1107,7 +1107,7 @@ abstract class GenJSCode[G <: Global with Singleton](val global: G)
selfVarDef :: memberDefinitions
}

// After the super call, substitute `selfRef` for `This()`
// After the super call, substitute `selfRef` for `this`
val afterSuper = new ir.Transformers.Transformer {
override def transform(tree: js.Tree): js.Tree = tree match {
case js.This() =>
Expand Down Expand Up @@ -2430,7 +2430,7 @@ abstract class GenJSCode[G <: Global with Singleton](val global: G)
tree match {
case js.Block(stats :+ expr) =>
js.Block(stats :+ exprToStat(expr))
case _:js.Literal | _:js.This | _:js.VarRef =>
case _:js.Literal | _:js.VarRef =>
js.Skip()
case _ =>
tree
Expand Down Expand Up @@ -4907,8 +4907,8 @@ abstract class GenJSCode[G <: Global with Singleton](val global: G)
val newReceiver = genExpr(receiver)
val newArg = genStatOrExpr(arg, isStat)
newReceiver match {
case js.This() =>
// common case for which there is no side-effect nor NPE
case newReceiver: js.VarRef if !newReceiver.tpe.isNullable =>
// common case (notably for `this`) for which there is no side-effect nor NPE
newArg
case _ =>
js.Block(
Expand Down
13 changes: 7 additions & 6 deletions ir/shared/src/main/scala/org/scalajs/ir/Hashers.scala
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Expand Up @@ -497,12 +497,13 @@ object Hashers {
mixTypeRef(typeRef)

case VarRef(name) =>
mixTag(TagVarRef)
mixName(name)
mixType(tree.tpe)

case This() =>
mixTag(TagThis)
if (name.isThis) {
// "Optimized" representation, like in Serializers
mixTag(TagThis)
} else {
mixTag(TagVarRef)
mixName(name)
}
mixType(tree.tpe)

case Closure(arrow, captureParams, params, restParam, body, captureValues) =>
Expand Down
30 changes: 26 additions & 4 deletions ir/shared/src/main/scala/org/scalajs/ir/Names.scala
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Expand Up @@ -64,6 +64,10 @@ object Names {
*
* Local names must be non-empty, and can contain any Unicode code point
* except `/ . ; [`.
*
* As an exception, the local name `".this"` represents the `this` binding.
* It cannot be used to declare variables (in `VarDef`s or `ParamDef`s) but
* can be referred to with a `VarRef`.
*/
final class LocalName private (encoded: UTF8String)
extends Name(encoded) with Comparable[LocalName] {
Expand All @@ -79,22 +83,40 @@ object Names {

protected def stringPrefix: String = "LocalName"

final def withPrefix(prefix: LocalName): LocalName =
final def isThis: Boolean =
this eq LocalName.This

final def withPrefix(prefix: LocalName): LocalName = {
require(!isThis && !prefix.isThis, "cannot concatenate LocalName.This")
new LocalName(prefix.encoded ++ this.encoded)
}

final def withPrefix(prefix: String): LocalName =
LocalName(UTF8String(prefix) ++ this.encoded)

final def withSuffix(suffix: LocalName): LocalName =
final def withSuffix(suffix: LocalName): LocalName = {
require(!isThis && !suffix.isThis, "cannot concatenate LocalName.This")
new LocalName(this.encoded ++ suffix.encoded)
}

final def withSuffix(suffix: String): LocalName =
LocalName(this.encoded ++ UTF8String(suffix))
}

object LocalName {
def apply(name: UTF8String): LocalName =
new LocalName(validateSimpleEncodedName(name))
private final val ThisEncodedName: UTF8String =
UTF8String(".this")

/** The unique `LocalName` with encoded name `.this`. */
val This: LocalName =
new LocalName(ThisEncodedName)

def apply(name: UTF8String): LocalName = {
if (UTF8String.equals(name, ThisEncodedName))
This
else
new LocalName(validateSimpleEncodedName(name))
}

def apply(name: String): LocalName =
LocalName(UTF8String(name))
Expand Down
9 changes: 4 additions & 5 deletions ir/shared/src/main/scala/org/scalajs/ir/Printers.scala
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Expand Up @@ -570,7 +570,6 @@ object Printers {
case JSPrivateSelect(qual, _) => containsOnlySelectsFromAtom(qual)
case JSSelect(qual, _) => containsOnlySelectsFromAtom(qual)
case VarRef(_) => true
case This() => true
case _ => false // in particular, Apply
}
if (containsOnlySelectsFromAtom(ctor)) {
Expand Down Expand Up @@ -844,10 +843,10 @@ object Printers {
// Atomic expressions

case VarRef(name) =>
print(name)

case This() =>
print("this")
if (name.isThis)
print("this")
else
print(name)

case Closure(arrow, captureParams, params, restParam, body, captureValues) =>
if (arrow)
Expand Down
24 changes: 14 additions & 10 deletions ir/shared/src/main/scala/org/scalajs/ir/Serializers.scala
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Expand Up @@ -524,12 +524,13 @@ object Serializers {
writeTypeRef(typeRef)

case VarRef(name) =>
writeTagAndPos(TagVarRef)
writeName(name)
writeType(tree.tpe)

case This() =>
writeTagAndPos(TagThis)
if (name.isThis) {
// "Optimized" representation that is compatible with IR < 1.18
writeTagAndPos(TagThis)
} else {
writeTagAndPos(TagVarRef)
writeName(name)
}
writeType(tree.tpe)

case Closure(arrow, captureParams, params, restParam, body, captureValues) =>
Expand Down Expand Up @@ -1155,10 +1156,13 @@ object Serializers {
if (hacks.use13) {
val cls = readClassName()
val rhs = readTree()
if (cls != enclosingClassName || !rhs.isInstanceOf[This]) {
throw new IOException(
s"Illegal legacy StoreModule(${cls.nameString}, $rhs) " +
s"found in class ${enclosingClassName.nameString}")
rhs match {
case This() if cls == enclosingClassName =>
// ok
case _ =>
throw new IOException(
s"Illegal legacy StoreModule(${cls.nameString}, $rhs) " +
s"found in class ${enclosingClassName.nameString}")
}
}
StoreModule()
Expand Down
2 changes: 1 addition & 1 deletion ir/shared/src/main/scala/org/scalajs/ir/Transformers.scala
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Expand Up @@ -195,7 +195,7 @@ object Transformers {
case _:Skip | _:Debugger | _:LoadModule | _:StoreModule |
_:SelectStatic | _:SelectJSNativeMember | _:LoadJSConstructor |
_:LoadJSModule | _:JSNewTarget | _:JSImportMeta |
_:Literal | _:VarRef | _:This | _:JSGlobalRef | _:LinkTimeProperty =>
_:Literal | _:VarRef | _:JSGlobalRef | _:LinkTimeProperty =>
tree
}
}
Expand Down
2 changes: 1 addition & 1 deletion ir/shared/src/main/scala/org/scalajs/ir/Traversers.scala
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Expand Up @@ -201,7 +201,7 @@ object Traversers {
case _:Skip | _:Debugger | _:LoadModule | _:StoreModule |
_:SelectStatic | _:SelectJSNativeMember | _:LoadJSConstructor |
_:LoadJSModule | _:JSNewTarget | _:JSImportMeta |
_:Literal | _:VarRef | _:This | _:JSGlobalRef | _:LinkTimeProperty =>
_:Literal | _:VarRef | _:JSGlobalRef | _:LinkTimeProperty =>
}

def traverseClassDef(tree: ClassDef): Unit = {
Expand Down
10 changes: 8 additions & 2 deletions ir/shared/src/main/scala/org/scalajs/ir/Trees.scala
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Expand Up @@ -1081,8 +1081,14 @@ object Trees {
sealed case class VarRef(name: LocalName)(val tpe: Type)(
implicit val pos: Position) extends AssignLhs

sealed case class This()(val tpe: Type)(implicit val pos: Position)
extends Tree
/** Convenience constructor and extractor for `VarRef`s representing `this` bindings. */
object This {
def apply()(tpe: Type)(implicit pos: Position): VarRef =
VarRef(LocalName.This)(tpe)

def unapply(tree: VarRef): Boolean =
tree.name.isThis
}

/** Closure with explicit captures.
*
Expand Down
3 changes: 0 additions & 3 deletions ir/shared/src/test/scala/org/scalajs/ir/PrintersTest.scala
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Expand Up @@ -863,9 +863,6 @@ class PrintersTest {

@Test def printVarRef(): Unit = {
assertPrintEquals("x", VarRef("x")(IntType))
}

@Test def printThis(): Unit = {
assertPrintEquals("this", This()(AnyType))
}

Expand Down
45 changes: 18 additions & 27 deletions linker/shared/src/main/scala/org/scalajs/linker/backend/emitter/FunctionEmitter.scala
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Expand Up @@ -1261,7 +1261,6 @@ private[emitter] class FunctionEmitter(sjsGen: SJSGen) {
def test(tree: Tree): Boolean = tree match {
// Atomic expressions
case _: Literal => true
case _: This => true
case _: JSNewTarget => true
case _: LinkTimeProperty => true

Expand Down Expand Up @@ -2468,18 +2467,18 @@ private[emitter] class FunctionEmitter(sjsGen: SJSGen) {
genCallHelper(VarField.systemIdentityHashCode, newLhs)

case WrapAsThrowable =>
val newLhsVar = newLhs.asInstanceOf[js.VarRef]
assert(newLhs.isInstanceOf[js.VarRef] || newLhs.isInstanceOf[js.This], newLhs)
js.If(
genIsInstanceOfClass(newLhsVar, ThrowableClass),
newLhsVar,
genScalaClassNew(JavaScriptExceptionClass, AnyArgConstructorName, newLhsVar))
genIsInstanceOfClass(newLhs, ThrowableClass),
newLhs,
genScalaClassNew(JavaScriptExceptionClass, AnyArgConstructorName, newLhs))

case UnwrapFromThrowable =>
val newLhsVar = newLhs.asInstanceOf[js.VarRef]
assert(newLhs.isInstanceOf[js.VarRef] || newLhs.isInstanceOf[js.This], newLhs)
js.If(
genIsInstanceOfClass(newLhsVar, JavaScriptExceptionClass),
genSelect(newLhsVar, FieldIdent(exceptionFieldName)),
newLhsVar)
genIsInstanceOfClass(newLhs, JavaScriptExceptionClass),
genSelect(newLhs, FieldIdent(exceptionFieldName)),
newLhs)
}

case BinaryOp(op, lhs, rhs) =>
Expand Down Expand Up @@ -2519,7 +2518,10 @@ private[emitter] class FunctionEmitter(sjsGen: SJSGen) {
* that the body of `Object.equals__O__Z` can be compiled as
* `this === that` instead of `Object.is(this, that)`.
*/
!tree.isInstanceOf[This]
tree match {
case This() => false
case _ => true
}
case ClassType(BoxedByteClass | BoxedShortClass |
BoxedIntegerClass | BoxedFloatClass | BoxedDoubleClass, _) =>
true
Expand Down Expand Up @@ -3021,12 +3023,6 @@ private[emitter] class FunctionEmitter(sjsGen: SJSGen) {
case Transient(JSVarRef(name, _)) =>
js.VarRef(name)

case This() =>
if (env.hasExplicitThis)
fileLevelVar(VarField.thiz)
else
js.This()

case tree: Closure =>
transformClosure(tree)

Expand Down Expand Up @@ -3180,12 +3176,6 @@ private[emitter] class FunctionEmitter(sjsGen: SJSGen) {
VarKind.Immutable
}

case This() if env.hasExplicitThis =>
VarKind.ExplicitThisAlias

case This() if permitImplicitJSThisCapture =>
VarKind.ThisAlias

case _ =>
explicitCapture()
VarKind.Immutable
Expand Down Expand Up @@ -3415,7 +3405,6 @@ private object FunctionEmitter {
// Environment

final class Env private (
val hasExplicitThis: Boolean,
val expectedReturnType: Type,
val enclosingClassName: Option[ClassName],
vars: Map[LocalName, VarKind],
Expand Down Expand Up @@ -3448,7 +3437,7 @@ private object FunctionEmitter {
copy(enclosingClassName = enclosingClassName)

def withExplicitThis(): Env =
copy(hasExplicitThis = true)
copy(vars = vars + (LocalName.This -> VarKind.ExplicitThisAlias))

def withVars(newVars: Map[LocalName, VarKind]): Env =
copy(vars = vars ++ newVars)
Expand Down Expand Up @@ -3483,7 +3472,6 @@ private object FunctionEmitter {
copy(inLoopForVarCapture = inLoopForVarCapture)

private def copy(
hasExplicitThis: Boolean = this.hasExplicitThis,
expectedReturnType: Type = this.expectedReturnType,
enclosingClassName: Option[ClassName] = this.enclosingClassName,
vars: Map[LocalName, VarKind] = this.vars,
Expand All @@ -3492,15 +3480,18 @@ private object FunctionEmitter {
defaultBreakTargets: Set[LabelName] = this.defaultBreakTargets,
defaultContinueTargets: Set[LabelName] = this.defaultContinueTargets,
inLoopForVarCapture: Boolean = this.inLoopForVarCapture): Env = {
new Env(hasExplicitThis, expectedReturnType, enclosingClassName, vars,
new Env(expectedReturnType, enclosingClassName, vars,
labeledExprLHSes, labelsTurnedIntoContinue, defaultBreakTargets,
defaultContinueTargets, inLoopForVarCapture)
}
}

object Env {
private val InitVars: Map[LocalName, VarKind] =
Map(LocalName.This -> VarKind.ThisAlias)

def empty(expectedReturnType: Type): Env = {
new Env(false, expectedReturnType, None, Map.empty, Map.empty, Set.empty,
new Env(expectedReturnType, None, InitVars, Map.empty, Set.empty,
Set.empty, Set.empty, false)
}
}
Expand Down
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