From 98122913647c58911a942b3fe33a84a536936561 Mon Sep 17 00:00:00 2001
From: Anton Bannykh <anton.bannykh@jetbrains.com>
Date: Tue, 24 Dec 2019 23:03:13 +0300
Subject: [PATCH] BlockDecomposerLowering

---
 .../kotlin/ir/backend/js/JsLoweringPhases.kt  |  7 +-
 .../js/lower/BlockDecomposerLowering.kt       | 97 ++++++++-----------
 2 files changed, 45 insertions(+), 59 deletions(-)

diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt
index 10afbca21ac..5a05c0f54c8 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt
@@ -383,11 +383,8 @@ private val autoboxingTransformerPhase = makeJsModulePhase(
     description = "Insert box/unbox intrinsics"
 )
 
-private val blockDecomposerLoweringPhase = makeCustomJsModulePhase(
-    { context, module ->
-        JsBlockDecomposerLowering(context).lower(module)
-        module.patchDeclarationParents()
-    },
+private val blockDecomposerLoweringPhase = makeJsModulePhase(
+    ::JsBlockDecomposerLowering,
     name = "BlockDecomposerLowering",
     description = "Transform statement-like-expression nodes into pure-statement to make it easily transform into JS",
     prerequisite = setOf(typeOperatorLoweringPhase, suspendFunctionsLoweringPhase)
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/BlockDecomposerLowering.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/BlockDecomposerLowering.kt
index d60ddc98086..7a6960f72d3 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/BlockDecomposerLowering.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/BlockDecomposerLowering.kt
@@ -5,8 +5,10 @@
 
 package org.jetbrains.kotlin.ir.backend.js.lower
 
+import org.jetbrains.kotlin.backend.common.BodyLoweringPass
 import org.jetbrains.kotlin.backend.common.CommonBackendContext
 import org.jetbrains.kotlin.backend.common.DeclarationContainerLoweringPass
+import org.jetbrains.kotlin.backend.common.DeclarationTransformer
 import org.jetbrains.kotlin.backend.common.ir.isElseBranch
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.ir.IrElement
@@ -30,31 +32,54 @@ class JsBlockDecomposerLowering(val context: JsIrBackendContext) : AbstractBlock
         JsIrBuilder.buildCall(context.intrinsics.unreachable.symbol, context.irBuiltIns.nothingType)
 }
 
-abstract class AbstractBlockDecomposerLowering(context: CommonBackendContext) : DeclarationContainerLoweringPass {
+abstract class AbstractBlockDecomposerLowering(
+    context: CommonBackendContext
+) : BodyLoweringPass {
+
+    private val nothingType = context.irBuiltIns.nothingType
 
     // Expression with Nothing type to be inserted in places of unreachable expression
     abstract fun unreachableExpression(): IrExpression
 
     private val decomposerTransformer = BlockDecomposerTransformer(context, ::unreachableExpression)
-    private val nothingType = context.irBuiltIns.nothingType
 
-    override fun lower(irDeclarationContainer: IrDeclarationContainer) {
-        irDeclarationContainer.transformDeclarationsFlat { declaration ->
-            when (declaration) {
-                is IrScript -> {
-                    lower(declaration)
-                    listOf(declaration)
+    override fun lower(irBody: IrBody, container: IrDeclaration) {
+        when (container) {
+            is IrFunction -> {
+                container.accept(decomposerTransformer, null)
+                irBody.patchDeclarationParents(container)
+            }
+            is IrField -> {
+                container.initializer?.apply {
+
+                    val initFunction = JsIrBuilder.buildFunction(
+                        container.name.asString() + "\$init\$",
+                        container.type,
+                        container.parent,
+                        Visibilities.PRIVATE
+                    )
+
+                    val newBody = toBlockBody(initFunction)
+                    newBody.patchDeclarationParents(initFunction)
+                    initFunction.body = newBody
+
+                    initFunction.accept(decomposerTransformer, null)
+
+                    val lastStatement = newBody.statements.last()
+                    val actualParent = if (newBody.statements.size > 1 || lastStatement !is IrReturn || lastStatement.value != expression) {
+                        expression = JsIrBuilder.buildCall(initFunction.symbol, expression.type)
+                        (container.parent as IrDeclarationContainer).declarations += initFunction
+                        initFunction
+                    } else {
+                        container
+                    }
+
+                    patchDeclarationParents(actualParent)
                 }
-                is IrFunction -> {
-                    lower(declaration)
-                    listOf(declaration)
-                }
-                is IrField -> lower(declaration, irDeclarationContainer)
-                else -> listOf(declaration)
             }
         }
 
-        irDeclarationContainer.transformChildrenVoid(CodeCleaner())
+//        irDeclarationContainer.transformChildrenVoid(CodeCleaner()) TODO
     }
 
     private inner class CodeCleaner : IrElementTransformerVoid() {
@@ -98,49 +123,13 @@ abstract class AbstractBlockDecomposerLowering(context: CommonBackendContext) :
         }
     }
 
-    fun lower(irScript: IrScript) {
-        irScript.transform(decomposerTransformer, null)
-    }
-
-    fun lower(irFunction: IrFunction) {
-        (irFunction.body as? IrExpressionBody)?.apply {
-            irFunction.body = toBlockBody(irFunction)
-        }
-        irFunction.accept(decomposerTransformer, null)
-    }
-
     private fun IrExpressionBody.toBlockBody(containingFunction: IrFunction): IrBlockBody {
-        expression.patchDeclarationParents(containingFunction)
-        val returnStatement = JsIrBuilder.buildReturn(containingFunction.symbol, expression, nothingType)
-        return IrBlockBodyImpl(expression.startOffset, expression.endOffset).apply {
+        return IrBlockBodyImpl(startOffset, endOffset) {
+            expression.patchDeclarationParents(containingFunction)
+            val returnStatement = JsIrBuilder.buildReturn(containingFunction.symbol, expression, nothingType)
             statements += returnStatement
         }
     }
-
-    fun lower(irField: IrField, container: IrDeclarationContainer): List<IrDeclaration> {
-        irField.initializer?.apply {
-            val initFunction = JsIrBuilder.buildFunction(
-                irField.name.asString() + "\$init\$",
-                expression.type,
-                container,
-                Visibilities.PRIVATE
-            )
-
-            val newBody = toBlockBody(initFunction)
-            newBody.patchDeclarationParents(initFunction)
-            initFunction.body = newBody
-
-            lower(initFunction)
-
-            val lastStatement = newBody.statements.last()
-            if (newBody.statements.size > 1 || lastStatement !is IrReturn || lastStatement.value != expression) {
-                expression = JsIrBuilder.buildCall(initFunction.symbol, expression.type)
-                return listOf(initFunction, irField)
-            }
-        }
-
-        return listOf(irField)
-    }
 }
 
 class BlockDecomposerTransformer(