[FIR] Extract mayHaveTopLevelClassifier from composite symbol provider

- The implementation is not trivial and should be usable in other symbol
  providers.

compiler/fir/providers/src/org/jetbrains/kotlin/fir/resolve/providers/FirSymbolProvider.kt

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.fir.types.coneTypeSafe
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.fir.types.functionTypeService
 
 @RequiresOptIn
 annotation class FirSymbolProviderInternals
@@ -78,6 +79,31 @@ abstract class FirSymbolProvider(val session: FirSession) : FirSessionComponent
      * @returns top-level callable names that belong to `packageFqName` or null if it's complicated to compute the set
      */
     abstract fun computeCallableNamesInPackage(packageFqName: FqName): Set<Name>?
+
+    /**
+     * Whether [classId] may be contained in the [knownClassifierNames].
+     *
+     * If it's certain that [classId] cannot be a function class (for example when [classId] is known to come from a package without
+     * function classes), [mayBeFunctionClass] can be set to `false`. This avoids a hash map access in
+     * [org.jetbrains.kotlin.builtins.functions.FunctionTypeKindExtractor.getFunctionalClassKindWithArity].
+     */
+    protected fun mayHaveTopLevelClassifier(
+        classId: ClassId,
+        knownClassifierNames: Set<String>,
+        mayBeFunctionClass: Boolean = true,
+    ): Boolean {
+        if (mayBeFunctionClass && isNameForFunctionClass(classId)) return true
+
+        val outerClassId = classId.outerClassId
+        if (outerClassId == null && classId.shortClassName.asString() !in knownClassifierNames) return false
+        if (outerClassId != null && classId.outermostClassId.shortClassName.asString() !in knownClassifierNames) return false
+
+        return true
+    }
+
+    private fun isNameForFunctionClass(classId: ClassId): Boolean {
+        return session.functionTypeService.getKindByClassNamePrefix(classId.packageFqName, classId.shortClassName.asString()) != null
+    }
 }
 
 /**

compiler/fir/providers/src/org/jetbrains/kotlin/fir/resolve/providers/impl/FirCachingCompositeSymbolProvider.kt

@@ -106,11 +106,7 @@ class FirCachingCompositeSymbolProvider(
 
     override fun getClassLikeSymbolByClassId(classId: ClassId): FirClassLikeSymbol<*>? {
         val knownClassifierNames = knownTopLevelClassifierNamesInPackage.getValue(classId.packageFqName)
-        if (knownClassifierNames != null && !isNameForFunctionClass(classId)) {
+        if (knownClassifierNames != null && !mayHaveTopLevelClassifier(classId, knownClassifierNames)) return null
-            val outerClassId = classId.outerClassId
-            if (outerClassId == null && classId.shortClassName.asString() !in knownClassifierNames) return null
-            if (outerClassId != null && classId.outermostClassId.shortClassName.asString() !in knownClassifierNames) return null
-        }
 
         return classLikeCache.getValue(classId)
     }