Do not call findKotlinClass when loading class annotations

The main change is in AbstractBinaryClassAnnotationAndConstantLoader, where we
no longer perform unnecessary IO operations for classes which are already
loaded to memory

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/kotlin/AbstractBinaryClassAnnotationAndConstantLoader.kt

@@ -38,8 +38,7 @@ import java.util.*
 
 abstract class AbstractBinaryClassAnnotationAndConstantLoader<A : Any, C : Any, T : Any>(
         storageManager: StorageManager,
-        private val kotlinClassFinder: KotlinClassFinder,
-        private val errorReporter: ErrorReporter
+        private val kotlinClassFinder: KotlinClassFinder
 ) : AnnotationAndConstantLoader<A, C, T> {
     private val storage = storageManager.createMemoizedFunction<KotlinJvmBinaryClass, Storage<A, C>> {
         kotlinClass ->
@@ -66,14 +65,11 @@ abstract class AbstractBinaryClassAnnotationAndConstantLoader<A : Any, C : Any,
         return loadAnnotation(annotationClassId, source, result)
     }
 
+    private fun ProtoContainer.Class.toBinaryClass(): KotlinJvmBinaryClass? =
+            (source as? KotlinJvmBinarySourceElement)?.binaryClass
+
     override fun loadClassAnnotations(container: ProtoContainer.Class): List<A> {
-        val kotlinClass = kotlinClassFinder.findKotlinClass(container.classId)
-        if (kotlinClass == null) {
-            // This means that the resource we're constructing the descriptor from is no longer present: KotlinClassFinder had found the
-            // class earlier, but it can't now
-            errorReporter.reportLoadingError("Kotlin class for loading class annotations is not found: ${container.debugFqName()}", null)
-            return listOf()
-        }
+        val kotlinClass = container.toBinaryClass() ?: error("Class for loading annotations is not found: ${container.debugFqName()}")
 
         val result = ArrayList<A>(1)
 
@@ -208,18 +204,28 @@ abstract class AbstractBinaryClassAnnotationAndConstantLoader<A : Any, C : Any,
     private fun findClassWithAnnotationsAndInitializers(
             container: ProtoContainer, implClassName: ClassId?, field: Boolean
     ): KotlinJvmBinaryClass? {
-        if (implClassName != null) {
-            return kotlinClassFinder.findKotlinClass(implClassName)
-        }
-
         if (container is ProtoContainer.Class) {
+            val containerBinaryClass = container.toBinaryClass()
+
+            if (implClassName == container.classId) {
+                return containerBinaryClass
+            }
+
+            if (implClassName != null) {
+                return kotlinClassFinder.findKotlinClass(implClassName)
+            }
+
             if (field && container.kind == ProtoBuf.Class.Kind.COMPANION_OBJECT &&
                 (container.outerClassKind == ClassKind.CLASS || container.outerClassKind == ClassKind.ENUM_CLASS)) {
                 // Backing fields of properties of a companion object in a class are generated in the outer class
                 return kotlinClassFinder.findKotlinClass(container.classId.outerClassId)
             }
 
-            return kotlinClassFinder.findKotlinClass(container.classId)
+            return containerBinaryClass
+        }
+
+        if (implClassName != null) {
+            return kotlinClassFinder.findKotlinClass(implClassName)
         }
 
         return null

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/kotlin/BinaryClassAnnotationAndConstantLoaderImpl.kt

@@ -30,7 +30,10 @@ import org.jetbrains.kotlin.resolve.constants.AnnotationValue
 import org.jetbrains.kotlin.resolve.constants.ConstantValue
 import org.jetbrains.kotlin.resolve.constants.ConstantValueFactory
 import org.jetbrains.kotlin.serialization.ProtoBuf
-import org.jetbrains.kotlin.serialization.deserialization.*
+import org.jetbrains.kotlin.serialization.deserialization.AnnotationDeserializer
+import org.jetbrains.kotlin.serialization.deserialization.NameResolver
+import org.jetbrains.kotlin.serialization.deserialization.NotFoundClasses
+import org.jetbrains.kotlin.serialization.deserialization.findNonGenericClassAcrossDependencies
 import org.jetbrains.kotlin.storage.StorageManager
 import java.util.*
 
@@ -38,10 +41,9 @@ class BinaryClassAnnotationAndConstantLoaderImpl(
         private val module: ModuleDescriptor,
         private val notFoundClasses: NotFoundClasses,
         storageManager: StorageManager,
-        kotlinClassFinder: KotlinClassFinder,
-        errorReporter: ErrorReporter
+        kotlinClassFinder: KotlinClassFinder
 ) : AbstractBinaryClassAnnotationAndConstantLoader<AnnotationDescriptor, ConstantValue<*>, AnnotationWithTarget>(
-        storageManager, kotlinClassFinder, errorReporter
+        storageManager, kotlinClassFinder
 ) {
     private val annotationDeserializer = AnnotationDeserializer(module, notFoundClasses)
     private val factory = ConstantValueFactory(module.builtIns)

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/kotlin/KotlinJvmBinarySourceElement.kt

@@ -18,8 +18,9 @@ package org.jetbrains.kotlin.load.kotlin
 
 import org.jetbrains.kotlin.descriptors.SourceElement
 import org.jetbrains.kotlin.descriptors.SourceFile
+import org.jetbrains.kotlin.serialization.deserialization.descriptors.BinarySource
 
-class KotlinJvmBinarySourceElement(val binaryClass: KotlinJvmBinaryClass) : SourceElement {
+class KotlinJvmBinarySourceElement(val binaryClass: KotlinJvmBinaryClass) : SourceElement, BinarySource {
     override fun toString() = javaClass.name + ": " + binaryClass.toString()
     override fun getContainingFile(): SourceFile = SourceFile.NO_SOURCE_FILE
 }