[JS IR] Add annotation for eager property initialization

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsIntrinsics.kt

@@ -282,6 +282,8 @@ class JsIntrinsics(private val irBuiltIns: IrBuiltIns, val context: JsIrBackendC
     val doNotIntrinsifyAnnotationSymbol = context.symbolTable.referenceClass(context.getJsInternalClass("DoNotIntrinsify"))
     val jsFunAnnotationSymbol = context.symbolTable.referenceClass(context.getJsInternalClass("JsFun"))
 
+    val jsEagerInitializationAnnotationSymbol = context.symbolTable.referenceClass(context.getJsInternalClass("JsEagerInitialization"))
+
     // TODO move CharSequence-related stiff to IntrinsifyCallsLowering
     val charSequenceClassSymbol = context.symbolTable.referenceClass(context.getClass(FqName("kotlin.CharSequence")))
     val charSequenceLengthPropertyGetterSymbol by context.lazy2 {

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/PropertyLazyInitLowering.kt

@@ -21,6 +21,7 @@ import org.jetbrains.kotlin.ir.builders.declarations.buildField
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.declarations.persistent.PersistentIrElementBase
 import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.util.hasAnnotation
 import org.jetbrains.kotlin.name.Name
 import kotlin.collections.component1
 import kotlin.collections.component2
@@ -51,7 +52,7 @@ class PropertyLazyInitLowering(
         if (container !is IrField && container !is IrSimpleFunction && container !is IrProperty)
             return
 
-        if (!container.isCompatibleDeclaration()) return
+        if (!container.isCompatibleDeclaration(context)) return
 
         val file = container.parent as? IrFile
             ?: return
@@ -98,7 +99,8 @@ class PropertyLazyInitLowering(
         val declarations = file.declarations.toList()
 
         val fieldToInitializer = calculateFieldToExpression(
-            declarations
+            declarations,
+            context
         )
 
         if (fieldToInitializer.isEmpty()) return null
@@ -206,7 +208,7 @@ class RemoveInitializersForLazyProperties(
 
         if (declaration !is IrField) return null
 
-        if (!declaration.isCompatibleDeclaration()) return null
+        if (!declaration.isCompatibleDeclaration(context)) return null
 
         val file = declaration.parent as? IrFile ?: return null
 
@@ -232,7 +234,7 @@ class RemoveInitializersForLazyProperties(
 
     private fun calculateFileFieldsPureness(file: IrFile): Boolean {
         val declarations = file.declarations.toList()
-        val expressions = calculateFieldToExpression(declarations)
+        val expressions = calculateFieldToExpression(declarations, context)
             .values
 
         val allFieldsInFilePure = allFieldsInFilePure(expressions)
@@ -241,10 +243,10 @@ class RemoveInitializersForLazyProperties(
     }
 }
 
-private fun calculateFieldToExpression(declarations: Collection<IrDeclaration>): Map<IrField, IrExpression> =
+private fun calculateFieldToExpression(declarations: Collection<IrDeclaration>, context: JsIrBackendContext): Map<IrField, IrExpression> =
     declarations
         .asSequence()
-        .filter { it.isCompatibleDeclaration() }
+        .filter { it.isCompatibleDeclaration(context) }
         .map { it.correspondingProperty }
         .filterNotNull()
         .filter { it.isForLazyInit() }
@@ -274,12 +276,19 @@ private val IrDeclaration.correspondingProperty: IrProperty?
     }
 
 private fun IrDeclaration.propertyWithPersistentSafe(transform: IrDeclaration.() -> IrProperty?): IrProperty? =
+    withPersistentSafe(transform)
+
+private fun <T> IrDeclaration.withPersistentSafe(transform: IrDeclaration.() -> T?): T? =
     if (this !is PersistentIrElementBase<*> || this.createdOn <= this.factory.stageController.currentStage) {
         transform()
     } else null
 
-private fun IrDeclaration.isCompatibleDeclaration() =
-    origin in compatibleOrigins
+private fun IrDeclaration.isCompatibleDeclaration(context: JsIrBackendContext) =
+    (this as? IrField)
+        ?.correspondingProperty
+        ?.hasAnnotation(context.intrinsics.jsEagerInitializationAnnotationSymbol) != true &&
+            withPersistentSafe { origin in compatibleOrigins } == true
+
 
 private fun IrDeclaration.assertCompatibleDeclaration() {
     assert(this !is PersistentIrElementBase<*> || createdOn == 0)

compiler/testData/codegen/box/properties/eagerInitializationGlobal1.kt

@@ -0,0 +1,27 @@
+// TARGET_BACKEND: JS_IR
+// DONT_TARGET_EXACT_BACKEND: WASM
+// PROPERTY_LAZY_INITIALIZATION
+
+// FILE: lib.kt
+var z1 = false
+var z2 = false
+
+// FILE: lib2.kt
+
+@OptIn(kotlin.ExperimentalStdlibApi::class)
+@JsEagerInitialization
+val x = foo()
+
+private fun foo(): Int {
+    z1 = true
+    return 42
+}
+
+// Will be initialized since [x]'s initializer calls a function from the file.
+val y = run { z2 = true; 117 }
+
+// FILE: main.kt
+
+fun box(): String {
+    return return if (z1 && z2) "OK" else "fail"
+}

compiler/testData/codegen/box/properties/eagerInitializationGlobal2.kt

@@ -0,0 +1,22 @@
+// TARGET_BACKEND: JS_IR
+// DONT_TARGET_EXACT_BACKEND: WASM
+// PROPERTY_LAZY_INITIALIZATION
+
+// FILE: lib.kt
+var z1 = false
+var z2 = false
+
+// FILE: lib2.kt
+
+@OptIn(kotlin.ExperimentalStdlibApi::class)
+@JsEagerInitialization
+val x = run { z1 = true; 42 }
+
+// Won't be initialized (cause no function from the file will be called during [x] initialization).
+val y = run { z2 = true; 117 }
+
+// FILE: main.kt
+
+fun box(): String {
+    return if (z1 && !z2) "OK" else "fail"
+}

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java

@@ -19842,6 +19842,16 @@ public class IrJsCodegenBoxES6TestGenerated extends AbstractIrJsCodegenBoxES6Tes
             runTest("compiler/testData/codegen/box/properties/complexPropertyInitializer.kt");
         }
 
+        @TestMetadata("eagerInitializationGlobal1.kt")
+        public void testEagerInitializationGlobal1() throws Exception {
+            runTest("compiler/testData/codegen/box/properties/eagerInitializationGlobal1.kt");
+        }
+
+        @TestMetadata("eagerInitializationGlobal2.kt")
+        public void testEagerInitializationGlobal2() throws Exception {
+            runTest("compiler/testData/codegen/box/properties/eagerInitializationGlobal2.kt");
+        }
+
         @TestMetadata("field.kt")
         public void testField() throws Exception {
             runTest("compiler/testData/codegen/box/properties/field.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java

@@ -19248,6 +19248,16 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/properties/complexPropertyInitializer.kt");
         }
 
+        @TestMetadata("eagerInitializationGlobal1.kt")
+        public void testEagerInitializationGlobal1() throws Exception {
+            runTest("compiler/testData/codegen/box/properties/eagerInitializationGlobal1.kt");
+        }
+
+        @TestMetadata("eagerInitializationGlobal2.kt")
+        public void testEagerInitializationGlobal2() throws Exception {
+            runTest("compiler/testData/codegen/box/properties/eagerInitializationGlobal2.kt");
+        }
+
         @TestMetadata("field.kt")
         public void testField() throws Exception {
             runTest("compiler/testData/codegen/box/properties/field.kt");

libraries/stdlib/js/src/kotlin/annotations.kt

@@ -191,3 +191,11 @@ public annotation class JsQualifier(val value: String)
 @Target(CLASS, PROPERTY, FUNCTION, FILE)
 @SinceKotlin("1.3")
 public actual annotation class JsExport
+
+/**
+ * Forces a top-level property to be initialized eagerly, opposed to lazily on the first access to file and/or property.
+ */
+@Target(AnnotationTarget.PROPERTY)
+@Retention(AnnotationRetention.BINARY)
+@ExperimentalStdlibApi
+public annotation class JsEagerInitialization