Performance tweaks for completion flags checking

Author: anatoliykmetyuk

compiler/src/dotty/tools/dotc/core/Flags.scala

@@ -406,9 +406,7 @@ object Flags {
   /** A denotation that is valid in all run-ids */
   val (Permanent @ _, _, _) = newFlags(61, "<permanent>")
 
-  /** Denotation is being loaded. If `Completing` is not set,
-   *  this means this denotation was loaded from an external file.
-   */
+  /** Denotation is being loaded */
   val (Loading @ _, _, _) = newFlags(62, "<loading>")
 
 // --------- Combined Flag Sets and Conjunctions ----------------------
@@ -456,19 +454,6 @@ object Flags {
   val AfterLoadFlags: FlagSet = commonFlags(
     FromStartFlags, Opaque, AccessFlags, Final, AccessorOrSealed, LazyOrTrait, SelfName, JavaDefined)
 
-  /** Flags that are not mutated during completion when a certain
-   *  condition is satisfied
-   */
-  object ConditionallyImmutableFlags {
-    val flagsAndConditions: List[(Flag, (given Contexts.Context) => SymDenotations.SymDenotation => Boolean)] = List(
-      Deferred -> { denot => denot.is(Opaque) && denot.isType }
-    )
-
-    val flags: FlagSet = flagsAndConditions.map(_._1)
-      .foldLeft(EmptyFlags) { (accum, next) => accum | next }
-  }
-
-
   /** A value that's unstable unless complemented with a Stable flag */
   val UnstableValueFlags: FlagSet = Mutable | Method
 

compiler/src/dotty/tools/dotc/core/SymDenotations.scala

@@ -161,10 +161,11 @@ object SymDenotations {
     private[dotc] final def flagsUNSAFE: FlagSet = myFlags
 
     private def setMyFlags(flags: FlagSet) =
-      lazy val immutableFlags = if myInfo.isInstanceOf[SymbolLoader] then AfterLoadFlags else FromStartFlags
-      lazy val changedImmutableFlags = (myFlags ^ flags) & immutableFlags
-      if myFlags.is(Touched, butNot = Loading) then assert(changedImmutableFlags.isEmpty,
-        s"Illegal mutation of flags ${changedImmutableFlags.flagsString} on completion of $this")
+      if myFlags.is(Touched, butNot = Loading) then
+        val immutableFlags = if myInfo.isInstanceOf[SymbolLoader] then AfterLoadFlags else FromStartFlags
+        val changedImmutableFlags = (myFlags ^ flags) & immutableFlags
+        assert(changedImmutableFlags.isEmpty,
+          s"Illegal mutation of flags ${changedImmutableFlags.flagsString} on completion of $this")
       myFlags = flags
 
     final def startedLoading() =
@@ -204,11 +205,8 @@ object SymDenotations {
         else AfterLoadFlags
       val mutableFlagsBeingQueried = fs &~ immutableFlags
 
-      mutableFlagsBeingQueried.isEmpty || ( // All flags are immutable wrt completion
-        mutableFlagsBeingQueried <= ConditionallyImmutableFlags.flags && // All the mutable flags being queried are not mutated during completion under certain conditions
-        ConditionallyImmutableFlags.flagsAndConditions.forall { case (flag, condition) =>
-          (flag & mutableFlagsBeingQueried).isEmpty || !condition(this)
-        }
+      mutableFlagsBeingQueried.isEmpty || (
+        mutableFlagsBeingQueried <= Deferred && !(is(Opaque) && isType)
       )