[K/Wasm] Refactor the fix for the non-capturing lambda singletons

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt

@@ -475,12 +475,6 @@ private val wasmVarargExpressionLoweringPhase = makeIrModulePhase(
     description = "Lower varargs"
 )
 
-private val fieldInitializersLoweringPhase = makeIrModulePhase(
-    ::FieldInitializersLowering,
-    name = "FieldInitializersLowering",
-    description = "Move field initializers to start function"
-)
-
 private val builtInsLoweringPhase0 = makeIrModulePhase(
     ::BuiltInsLowering,
     name = "BuiltInsLowering0",
@@ -505,7 +499,7 @@ private val objectDeclarationLoweringPhase = makeIrModulePhase(
     ::ObjectDeclarationLowering,
     name = "ObjectDeclarationLowering",
     description = "Create lazy object instance generator functions",
-    prerequisite = setOf(enumClassCreateInitializerLoweringPhase)
+    prerequisite = setOf(enumClassCreateInitializerLoweringPhase, staticCallableReferenceLoweringPhase)
 )
 
 private val objectUsageLoweringPhase = makeIrModulePhase(
@@ -606,6 +600,13 @@ private val inlineObjectsWithPureInitializationLoweringPhase = makeIrModulePhase
     prerequisite = setOf(purifyObjectInstanceGettersLoweringPhase)
 )
 
+private val fieldInitializersLoweringPhase = makeIrModulePhase(
+    ::FieldInitializersLowering,
+    name = "FieldInitializersLowering",
+    description = "Move field initializers to start function",
+    prerequisite = setOf(purifyObjectInstanceGettersLoweringPhase)
+)
+
 val constEvaluationPhase = makeIrModulePhase(
     { context ->
         val configuration = IrInterpreterConfiguration(

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/dce/WasmUsefulDeclarationProcessor.kt

@@ -7,7 +7,6 @@ package org.jetbrains.kotlin.backend.wasm.dce
 
 import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
 import org.jetbrains.kotlin.backend.wasm.ir2wasm.*
-import org.jetbrains.kotlin.backend.wasm.lower.isFunctionReferenceInstanceField
 import org.jetbrains.kotlin.backend.wasm.utils.*
 import org.jetbrains.kotlin.ir.backend.js.dce.UsefulDeclarationProcessor
 import org.jetbrains.kotlin.ir.backend.js.utils.*
@@ -49,7 +48,7 @@ internal class WasmUsefulDeclarationProcessor(
         }
 
         override fun visitSetField(expression: IrSetField, data: IrDeclaration) {
-            if (!expression.symbol.owner.run { isObjectInstanceField() || isFunctionReferenceInstanceField() }) {
+            if (!expression.symbol.owner.isObjectInstanceField()) {
                 super.visitSetField(expression, data)
             }
         }
@@ -57,7 +56,7 @@ internal class WasmUsefulDeclarationProcessor(
         override fun visitGetField(expression: IrGetField, data: IrDeclaration) {
             val field = expression.symbol.owner
 
-            if (field.isObjectInstanceField() || field.isFunctionReferenceInstanceField()) {
+            if (field.isObjectInstanceField()) {
                 field.type.classOrFail.owner.primaryConstructor?.enqueue(field, "object lazy initialization")
             }
 

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/dce/WasmUselessDeclarationsRemover.kt

@@ -6,14 +6,11 @@
 package org.jetbrains.kotlin.backend.wasm.dce
 
 import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
-import org.jetbrains.kotlin.backend.wasm.lower.isFunctionReferenceInstanceField
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.backend.js.utils.isObjectInstanceField
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrBlockBody
 import org.jetbrains.kotlin.ir.expressions.IrSetField
-import org.jetbrains.kotlin.ir.types.classOrFail
-import org.jetbrains.kotlin.ir.util.primaryConstructor
 import org.jetbrains.kotlin.ir.util.transformFlat
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
@@ -57,7 +54,7 @@ class WasmUselessDeclarationsRemover(
 
     private fun IrSimpleFunction.removeUnusedObjectsInitializers() {
         (body as? IrBlockBody)?.statements?.removeIf {
-            it is IrSetField && it.symbol.owner.run { isObjectInstanceField() || isFunctionReferenceInstanceField() } && it.symbol.owner !in usefulDeclarations
+            it is IrSetField && it.symbol.owner.isObjectInstanceField() && it.symbol.owner !in usefulDeclarations
         }
     }
 }

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/FieldInitializersLowering.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.backend.common.lower.at
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
 import org.jetbrains.kotlin.ir.IrElement
+import org.jetbrains.kotlin.ir.backend.js.utils.isObjectInstanceField
 import org.jetbrains.kotlin.ir.builders.irSetField
 import org.jetbrains.kotlin.ir.declarations.IrField
 import org.jetbrains.kotlin.ir.declarations.IrFile
@@ -55,9 +56,11 @@ class FieldInitializersLowering(val context: WasmBackendContext) : FileLoweringP
                 }
 
                 val initializerStatement = builder.at(initValue).irSetField(null, declaration, initValue)
+                val statements = startFunctionBody.statements
 
-                when (declaration.fqNameWhenAvailable) {
-                    stringPoolFqName -> startFunctionBody.statements.add(0, initializerStatement)
+                when {
+                    declaration.fqNameWhenAvailable == stringPoolFqName -> statements.add(0, initializerStatement)
+                    declaration.isObjectInstanceField() -> statements.add(if (statements.size >= 1) 1 else 0, initializerStatement)
                     else -> startFunctionBody.statements.add(initializerStatement)
                 }
 

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/WasmStaticCallableReferenceLowering.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.backend.common.getOrPut
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
 import org.jetbrains.kotlin.backend.wasm.lower.WasmPropertyReferenceLowering.Companion.DECLARATION_ORIGIN_KPROPERTIES_FOR_DELEGATION
+import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
 import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.backend.js.lower.CallableReferenceLowering.Companion.FUNCTION_REFERENCE_IMPL
@@ -21,6 +22,7 @@ import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.impl.IrGetFieldImpl
+import org.jetbrains.kotlin.ir.expressions.impl.IrGetObjectValueImpl
 import org.jetbrains.kotlin.ir.types.makeNullable
 import org.jetbrains.kotlin.ir.util.constructedClass
 import org.jetbrains.kotlin.ir.util.defaultType
@@ -31,20 +33,11 @@ import org.jetbrains.kotlin.name.Name
 
 class WasmStaticCallableReferenceLowering(val context: WasmBackendContext) : FileLoweringPass {
     override fun lower(irFile: IrFile) {
-        val irFields = mutableSetOf<IrField>()
-        val firstKProperty = irFile.declarations.indexOfFirst { it.origin == DECLARATION_ORIGIN_KPROPERTIES_FOR_DELEGATION }
-
         irFile.transformChildrenVoid(object : IrElementTransformerVoid() {
             override fun visitClass(declaration: IrClass): IrStatement {
                 declaration.transformChildrenVoid()
                 if (declaration.isSyntheticSingleton) {
-                    val functionReferenceField = declaration.getOrCreateInstanceField().apply {
-                        parent = irFile
-                        initializer = context.createIrBuilder(symbol).run {
-                            irExprBody(irCall(declaration.primaryConstructor!!))
-                        }
-                    }
-                    irFields.add(functionReferenceField)
+                    declaration.kind = ClassKind.OBJECT
                 }
                 return declaration
             }
@@ -54,39 +47,10 @@ class WasmStaticCallableReferenceLowering(val context: WasmBackendContext) : Fil
                 if (!constructedClass.isSyntheticSingleton)
                     return super.visitConstructorCall(expression)
 
-                val instanceField = constructedClass.getOrCreateInstanceField()
-                return IrGetFieldImpl(expression.startOffset, expression.endOffset, instanceField.symbol, expression.type)
+                return IrGetObjectValueImpl(expression.startOffset, expression.endOffset, expression.type, constructedClass.symbol)
             }
         })
-
-        // Should be placed before KProperty initializations
-        if (firstKProperty != -1) {
-            irFile.declarations.addAll(firstKProperty, irFields)
-        } else {
-            irFile.declarations.addAll(irFields)
-        }
     }
-
-
-    private fun IrClass.getOrCreateInstanceField(): IrField = context.mapping.functionToInstanceField.getOrPut(this) {
-        val klass = this
-        context.irFactory.buildField {
-            name = Name.identifier(klass.name.asString() + "_instance")
-            type = klass.defaultType.makeNullable()
-            isStatic = true
-            isFinal = true
-            origin = FUNCTION_REFERENCE_SINGLETON_FIELD
-            visibility = DescriptorVisibilities.PRIVATE
-        }.apply {
-            initializer = null
-        }
-    }
-}
-
-val FUNCTION_REFERENCE_SINGLETON_FIELD by IrDeclarationOriginImpl
-
-fun IrField.isFunctionReferenceInstanceField(): Boolean {
-    return origin == FUNCTION_REFERENCE_SINGLETON_FIELD
 }
 
 val IrClass.isSyntheticSingleton: Boolean