From b5af28b28d51eed8ff9a62e2cb24bec6245e72ba Mon Sep 17 00:00:00 2001
From: Roman Artemev <roman.artemev@jetbrains.com>
Date: Thu, 5 Dec 2019 21:36:54 +0300
Subject: [PATCH] [JS IR] Fix state machine builder to fit into switch
 optimizer requirements

---
 .../coroutines/JsSuspendFunctionsLowering.kt  | 26 ++++++++++---------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/coroutines/JsSuspendFunctionsLowering.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/coroutines/JsSuspendFunctionsLowering.kt
index 97ca941dec7..4776560bb23 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/coroutines/JsSuspendFunctionsLowering.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/coroutines/JsSuspendFunctionsLowering.kt
@@ -16,10 +16,7 @@ import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.*
-import org.jetbrains.kotlin.ir.symbols.IrFieldSymbol
-import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
-import org.jetbrains.kotlin.ir.symbols.IrValueParameterSymbol
-import org.jetbrains.kotlin.ir.symbols.IrValueSymbol
+import org.jetbrains.kotlin.ir.symbols.*
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.util.explicitParameters
 import org.jetbrains.kotlin.ir.util.patchDeclarationParents
@@ -83,7 +80,12 @@ class JsSuspendFunctionsLowering(ctx: JsIrBackendContext) : AbstractSuspendFunct
         val unit = context.irBuiltIns.unitType
 
         val switch = IrWhenImpl(body.startOffset, body.endOffset, unit, COROUTINE_SWITCH)
-        val rootTry = IrTryImpl(body.startOffset, body.endOffset, unit).apply { tryResult = switch }
+        val stateVar = JsIrBuilder.buildVar(context.irBuiltIns.intType, stateMachineFunction)
+        val switchBlock = IrBlockImpl(switch.startOffset, switch.endOffset, switch.type).apply {
+            statements += stateVar
+            statements += switch
+        }
+        val rootTry = IrTryImpl(body.startOffset, body.endOffset, unit).apply { tryResult = switchBlock }
         val rootLoop = IrDoWhileLoopImpl(
             body.startOffset,
             body.endOffset,
@@ -97,6 +99,9 @@ class JsSuspendFunctionsLowering(ctx: JsIrBackendContext) : AbstractSuspendFunct
 
         val suspendableNodes = collectSuspendableNodes(body)
         val thisReceiver = (stateMachineFunction.dispatchReceiverParameter as IrValueParameter).symbol
+        stateVar.initializer = JsIrBuilder.buildCall(coroutineImplLabelPropertyGetter.symbol).apply {
+            dispatchReceiver = JsIrBuilder.buildGetValue(thisReceiver)
+        }
 
         val stateMachineBuilder = StateMachineBuilder(
             suspendableNodes,
@@ -118,7 +123,7 @@ class JsSuspendFunctionsLowering(ctx: JsIrBackendContext) : AbstractSuspendFunct
 
         rootTry.catches += stateMachineBuilder.globalCatch
 
-        assignStateIds(stateMachineBuilder.entryState, thisReceiver, switch, rootLoop)
+        assignStateIds(stateMachineBuilder.entryState, stateVar.symbol, switch, rootLoop)
 
         exceptionTrapId = stateMachineBuilder.rootExceptionTrap.id
 
@@ -147,7 +152,7 @@ class JsSuspendFunctionsLowering(ctx: JsIrBackendContext) : AbstractSuspendFunct
         var localCounter = 0
         // TODO: optimize by using the same property for different locals.
         liveLocals.forEach {
-            if (it != suspendState && it != suspendResult) {
+            if (it !== suspendState && it !== suspendResult && it !== stateVar) {
                 localToPropertyMap.getOrPut(it.symbol) {
                     coroutineClass.addField(Name.identifier("${it.name}${localCounter++}"), it.type, (it as? IrVariable)?.isVar ?: false)
                         .symbol
@@ -163,7 +168,7 @@ class JsSuspendFunctionsLowering(ctx: JsIrBackendContext) : AbstractSuspendFunct
         stateMachineFunction.transform(LiveLocalsTransformer(localToPropertyMap, { JsIrBuilder.buildGetValue(thisReceiver) }, unit), null)
     }
 
-    private fun assignStateIds(entryState: SuspendState, thisReceiver: IrValueParameterSymbol, switch: IrWhen, rootLoop: IrLoop) {
+    private fun assignStateIds(entryState: SuspendState, subject: IrVariableSymbol, switch: IrWhen, rootLoop: IrLoop) {
         val visited = mutableSetOf<SuspendState>()
 
         val sortedStates = DFS.topologicalOrder(listOf(entryState), { it.successors }, { visited.add(it) })
@@ -173,9 +178,7 @@ class JsSuspendFunctionsLowering(ctx: JsIrBackendContext) : AbstractSuspendFunct
 
         for (state in sortedStates) {
             val condition = JsIrBuilder.buildCall(eqeqeqInt).apply {
-                putValueArgument(0, JsIrBuilder.buildCall(coroutineImplLabelPropertyGetter.symbol).also {
-                    it.dispatchReceiver = JsIrBuilder.buildGetValue(thisReceiver)
-                })
+                putValueArgument(0, JsIrBuilder.buildGetValue(subject))
                 putValueArgument(1, JsIrBuilder.buildInt(context.irBuiltIns.intType, state.id))
             }
 
@@ -208,7 +211,6 @@ class JsSuspendFunctionsLowering(ctx: JsIrBackendContext) : AbstractSuspendFunct
         return result
     }
 
-
     override fun initializeStateMachine(coroutineConstructors: List<IrConstructor>, coroutineClassThis: IrValueDeclaration) {
         for (it in coroutineConstructors) {
             (it.body as? IrBlockBody)?.run {