Replace CHECKCAST kotlin/Unit with ARETURN for tail call optimization

Sometimes instead of {POP, GETSTATIC Unit.INSTANCE, ARETURN} sequence
the codegen emits {CHECKCAST Unit, ARETURN} sequence, which breaks tail
call optimization. By replacing CHECKCAST with ARETURN we eliminate
this issue.

 #KT-19790: Fixed

compiler/testData/codegen/bytecodeListing/tailcall/tailCallIntrinsics.kt

@@ -0,0 +1,18 @@
+// WITH_RUNTIME
+import kotlin.coroutines.experimental.*
+import kotlin.coroutines.experimental.intrinsics.*
+
+var p: Int = 5846814
+private suspend fun withoutInline() {
+    val c = { c: Continuation<Unit> ->
+        if (p > 52158) Unit else COROUTINE_SUSPENDED
+    }
+
+    return suspendCoroutineOrReturn(c)
+}
+
+private suspend fun withInline() {
+    return suspendCoroutineOrReturn { c ->
+        if (p > 52158) Unit else COROUTINE_SUSPENDED
+    }
+}

compiler/testData/codegen/bytecodeListing/tailcall/tailCallIntrinsics.txt

@@ -0,0 +1,20 @@
+@kotlin.Metadata
+final class TailCallIntrinsicsKt$withoutInline$c$1 {
+    public final static field INSTANCE: TailCallIntrinsicsKt$withoutInline$c$1
+    inner class TailCallIntrinsicsKt$withoutInline$c$1
+    static method <clinit>(): void
+    method <init>(): void
+    public final @org.jetbrains.annotations.NotNull method invoke(@org.jetbrains.annotations.NotNull p0: kotlin.coroutines.experimental.Continuation): java.lang.Object
+    public synthetic method invoke(p0: java.lang.Object): java.lang.Object
+}
+
+@kotlin.Metadata
+public final class TailCallIntrinsicsKt {
+    private static field p: int
+    inner class TailCallIntrinsicsKt$withoutInline$c$1
+    static method <clinit>(): void
+    public final static method getP(): int
+    public final static method setP(p0: int): void
+    final static @org.jetbrains.annotations.Nullable method withInline(@org.jetbrains.annotations.NotNull p0: kotlin.coroutines.experimental.Continuation): java.lang.Object
+    final static @org.jetbrains.annotations.Nullable method withoutInline(@org.jetbrains.annotations.NotNull p0: kotlin.coroutines.experimental.Continuation): java.lang.Object
+}

compiler/testData/codegen/bytecodeListing/tailcall/tailSuspendUnitFun.kt

@@ -0,0 +1,61 @@
+suspend fun empty() {}
+suspend fun withoutReturn() { empty() }
+suspend fun withReturn() { return empty() }
+suspend fun notTailCall() { empty(); empty() }
+suspend fun lambdaAsParameter(c: suspend ()->Unit) { c() }
+suspend fun lambdaAsParameterNotTailCall(c: suspend ()->Unit) { c(); c() }
+suspend fun lambdaAsParameterReturn(c: suspend ()->Unit) { return c() }
+suspend fun returnsInt() = 42
+// This should not be tail-call, since the caller should push Unit.INSTANCE on stack
+suspend fun callsIntNotTailCall() { returnsInt() }
+suspend fun multipleExitPoints(b: Boolean) { if (b) empty() else withoutReturn() }
+suspend fun multipleExitPointsNotTailCall(b: Boolean) { if (b) empty() else returnsInt() }
+
+fun ordinary() = 1
+inline fun ordinaryInline() { ordinary() }
+suspend fun multipleExitPointsWithOrdinaryInline(b: Boolean) { if (b) empty() else ordinaryInline() }
+
+suspend fun multipleExitPointsWhen(i: Int) {
+    when(i) {
+        1 -> empty()
+        2 -> withReturn()
+        3 -> withoutReturn()
+        else -> lambdaAsParameter {}
+    }
+}
+
+suspend fun <T> generic(): T = TODO()
+suspend fun useGenericReturningUnit() {
+    generic<Unit>()
+}
+
+class Generic<T> {
+    suspend fun foo(): T = TODO()
+}
+suspend fun useGenericClass(g: Generic<Unit>) {
+    g.foo()
+}
+
+suspend fun <T> genericInferType(c: () -> T): T = TODO()
+suspend fun useGenericIngerType() {
+    genericInferType {}
+}
+
+suspend fun nullableUnit(): Unit? = null
+suspend fun useNullableUnit() {
+    nullableUnit()
+}
+
+suspend fun useRunRunRunRunRun() {
+    run {
+        run {
+            run {
+                run {
+                    run {
+                        empty()
+                    }
+                }
+            }
+        }
+    }
+}

compiler/testData/codegen/bytecodeListing/tailcall/tailSuspendUnitFun.txt

@@ -0,0 +1,115 @@
+@kotlin.Metadata
+public final class Generic {
+    public method <init>(): void
+    public final @org.jetbrains.annotations.Nullable method foo(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+}
+
+@kotlin.Metadata
+final class TailSuspendUnitFunKt$callsIntNotTailCall$1 {
+    synthetic field data: java.lang.Object
+    synthetic field exception: java.lang.Throwable
+    inner class TailSuspendUnitFunKt$callsIntNotTailCall$1
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    synthetic final method getLabel(): int
+    synthetic final method setLabel(p0: int): void
+}
+
+@kotlin.Metadata
+final class TailSuspendUnitFunKt$lambdaAsParameterNotTailCall$1 {
+    field L$0: java.lang.Object
+    synthetic field data: java.lang.Object
+    synthetic field exception: java.lang.Throwable
+    inner class TailSuspendUnitFunKt$lambdaAsParameterNotTailCall$1
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    synthetic final method getLabel(): int
+    synthetic final method setLabel(p0: int): void
+}
+
+@kotlin.Metadata
+final class TailSuspendUnitFunKt$multipleExitPointsNotTailCall$1 {
+    field Z$0: boolean
+    synthetic field data: java.lang.Object
+    synthetic field exception: java.lang.Throwable
+    inner class TailSuspendUnitFunKt$multipleExitPointsNotTailCall$1
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    synthetic final method getLabel(): int
+    synthetic final method setLabel(p0: int): void
+}
+
+@kotlin.Metadata
+final class TailSuspendUnitFunKt$multipleExitPointsWhen$2 {
+    inner class TailSuspendUnitFunKt$multipleExitPointsWhen$2
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method create(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    public final @org.jetbrains.annotations.Nullable method invoke(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+}
+
+@kotlin.Metadata
+final class TailSuspendUnitFunKt$notTailCall$1 {
+    synthetic field data: java.lang.Object
+    synthetic field exception: java.lang.Throwable
+    inner class TailSuspendUnitFunKt$notTailCall$1
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    synthetic final method getLabel(): int
+    synthetic final method setLabel(p0: int): void
+}
+
+@kotlin.Metadata
+final class TailSuspendUnitFunKt$useGenericIngerType$2 {
+    public final static field INSTANCE: TailSuspendUnitFunKt$useGenericIngerType$2
+    inner class TailSuspendUnitFunKt$useGenericIngerType$2
+    static method <clinit>(): void
+    method <init>(): void
+    public synthetic method invoke(): java.lang.Object
+    public final method invoke(): void
+}
+
+@kotlin.Metadata
+final class TailSuspendUnitFunKt$useNullableUnit$1 {
+    synthetic field data: java.lang.Object
+    synthetic field exception: java.lang.Throwable
+    inner class TailSuspendUnitFunKt$useNullableUnit$1
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    synthetic final method getLabel(): int
+    synthetic final method setLabel(p0: int): void
+}
+
+@kotlin.Metadata
+public final class TailSuspendUnitFunKt {
+    inner class TailSuspendUnitFunKt$callsIntNotTailCall$1
+    inner class TailSuspendUnitFunKt$lambdaAsParameterNotTailCall$1
+    inner class TailSuspendUnitFunKt$multipleExitPointsNotTailCall$1
+    inner class TailSuspendUnitFunKt$multipleExitPointsWhen$2
+    inner class TailSuspendUnitFunKt$notTailCall$1
+    inner class TailSuspendUnitFunKt$useGenericIngerType$2
+    inner class TailSuspendUnitFunKt$useNullableUnit$1
+    public final static @org.jetbrains.annotations.Nullable method callsIntNotTailCall(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method empty(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method generic(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method genericInferType(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function0, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method lambdaAsParameter(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method lambdaAsParameterNotTailCall(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method lambdaAsParameterReturn(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method multipleExitPoints(p0: boolean, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method multipleExitPointsNotTailCall(p0: boolean, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method multipleExitPointsWhen(p0: int, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method multipleExitPointsWithOrdinaryInline(p0: boolean, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method notTailCall(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method nullableUnit(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static method ordinary(): int
+    public final static method ordinaryInline(): void
+    public final static @org.jetbrains.annotations.Nullable method returnsInt(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method useGenericClass(@org.jetbrains.annotations.NotNull p0: Generic, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method useGenericIngerType(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method useGenericReturningUnit(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method useNullableUnit(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method useRunRunRunRunRun(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method withReturn(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method withoutReturn(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+}

compiler/testData/codegen/bytecodeListing/tailcall/tryCatchTailCall.kt

@@ -0,0 +1,10 @@
+suspend fun catchException(): String {
+    try {
+        return suspendWithException()
+    }
+    catch(e: Exception) {
+        return e.message!!
+    }
+}
+
+suspend fun suspendWithException(): String = TODO()

compiler/testData/codegen/bytecodeListing/tailcall/tryCatchTailCall.txt

@@ -0,0 +1,17 @@
+@kotlin.Metadata
+final class TryCatchTailCallKt$catchException$1 {
+    synthetic field data: java.lang.Object
+    synthetic field exception: java.lang.Throwable
+    inner class TryCatchTailCallKt$catchException$1
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    synthetic final method getLabel(): int
+    synthetic final method setLabel(p0: int): void
+}
+
+@kotlin.Metadata
+public final class TryCatchTailCallKt {
+    inner class TryCatchTailCallKt$catchException$1
+    public final static @org.jetbrains.annotations.Nullable method catchException(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method suspendWithException(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+}

compiler/testData/codegen/bytecodeListing/tailcall/unreachable.kt

@@ -0,0 +1,118 @@
+suspend fun empty() {}
+suspend fun withoutReturn() {
+    empty()
+}
+
+suspend fun twoReturns() {
+    return empty()
+    return empty()
+}
+
+suspend fun notTailCall() {
+    empty()
+    return empty()
+    empty()
+}
+
+suspend fun lambdaAsParameter(c: suspend () -> Unit) {
+    c()
+}
+
+suspend fun lambdaAsParameterNotTailCall(c: suspend () -> Unit) {
+    c()
+    return c()
+    c()
+}
+
+suspend fun lambdaAsParameterReturn(c: suspend () -> Unit) {
+    return c()
+    c()
+}
+
+suspend fun returnsInt() = 42
+suspend fun callsIntNotTailCall() {
+    returnsInt()
+    return
+    empty()
+}
+
+suspend fun multipleExitPoints(b: Boolean) {
+    if (b) empty() else withoutReturn()
+    return
+    empty()
+}
+
+suspend fun multipleExitPointsNotTailCall(b: Boolean) {
+    if (b) empty() else returnsInt()
+    return
+    empty()
+}
+
+fun ordinary() = 1
+inline fun ordinaryInline() {
+    ordinary()
+}
+
+suspend fun multipleExitPointsWithOrdinaryInline(b: Boolean) {
+    if (b) empty() else ordinaryInline()
+    return
+    empty()
+}
+
+suspend fun multipleExitPointsWhen(i: Int) {
+    when (i) {
+        1 -> empty()
+        2 -> twoReturns()
+        3 -> withoutReturn()
+        else -> lambdaAsParameter {}
+    }
+    return
+    empty()
+}
+
+suspend fun <T> generic(): T = TODO()
+suspend fun useGenericReturningUnit() {
+    generic<Unit>()
+    return
+    empty()
+}
+
+class Generic<T> {
+    suspend fun foo(): T = TODO()
+}
+
+suspend fun useGenericClass(g: Generic<Unit>) {
+    g.foo()
+    return
+    empty()
+}
+
+suspend fun <T> genericInferType(c: () -> T): T = TODO()
+suspend fun useGenericInferType() {
+    genericInferType {}
+    return
+    empty()
+}
+
+suspend fun nullableUnit(): Unit? = null
+suspend fun useNullableUnit() {
+    nullableUnit()
+    return
+    empty()
+}
+
+suspend fun useRunRunRunRunRun() {
+    run {
+        run {
+            run {
+                run {
+                    run {
+                        empty()
+                    }
+                }
+            }
+        }
+    }
+    return
+    empty()
+}

compiler/testData/codegen/bytecodeListing/tailcall/unreachable.txt

@@ -0,0 +1,115 @@
+@kotlin.Metadata
+public final class Generic {
+    public method <init>(): void
+    public final @org.jetbrains.annotations.Nullable method foo(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+}
+
+@kotlin.Metadata
+final class UnreachableKt$callsIntNotTailCall$1 {
+    synthetic field data: java.lang.Object
+    synthetic field exception: java.lang.Throwable
+    inner class UnreachableKt$callsIntNotTailCall$1
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    synthetic final method getLabel(): int
+    synthetic final method setLabel(p0: int): void
+}
+
+@kotlin.Metadata
+final class UnreachableKt$lambdaAsParameterNotTailCall$1 {
+    field L$0: java.lang.Object
+    synthetic field data: java.lang.Object
+    synthetic field exception: java.lang.Throwable
+    inner class UnreachableKt$lambdaAsParameterNotTailCall$1
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    synthetic final method getLabel(): int
+    synthetic final method setLabel(p0: int): void
+}
+
+@kotlin.Metadata
+final class UnreachableKt$multipleExitPointsNotTailCall$1 {
+    field Z$0: boolean
+    synthetic field data: java.lang.Object
+    synthetic field exception: java.lang.Throwable
+    inner class UnreachableKt$multipleExitPointsNotTailCall$1
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    synthetic final method getLabel(): int
+    synthetic final method setLabel(p0: int): void
+}
+
+@kotlin.Metadata
+final class UnreachableKt$multipleExitPointsWhen$2 {
+    inner class UnreachableKt$multipleExitPointsWhen$2
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method create(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    public final @org.jetbrains.annotations.Nullable method invoke(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+}
+
+@kotlin.Metadata
+final class UnreachableKt$notTailCall$1 {
+    synthetic field data: java.lang.Object
+    synthetic field exception: java.lang.Throwable
+    inner class UnreachableKt$notTailCall$1
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    synthetic final method getLabel(): int
+    synthetic final method setLabel(p0: int): void
+}
+
+@kotlin.Metadata
+final class UnreachableKt$useGenericInferType$2 {
+    public final static field INSTANCE: UnreachableKt$useGenericInferType$2
+    inner class UnreachableKt$useGenericInferType$2
+    static method <clinit>(): void
+    method <init>(): void
+    public synthetic method invoke(): java.lang.Object
+    public final method invoke(): void
+}
+
+@kotlin.Metadata
+final class UnreachableKt$useNullableUnit$1 {
+    synthetic field data: java.lang.Object
+    synthetic field exception: java.lang.Throwable
+    inner class UnreachableKt$useNullableUnit$1
+    method <init>(p0: kotlin.coroutines.experimental.Continuation): void
+    public final @org.jetbrains.annotations.Nullable method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): java.lang.Object
+    synthetic final method getLabel(): int
+    synthetic final method setLabel(p0: int): void
+}
+
+@kotlin.Metadata
+public final class UnreachableKt {
+    inner class UnreachableKt$callsIntNotTailCall$1
+    inner class UnreachableKt$lambdaAsParameterNotTailCall$1
+    inner class UnreachableKt$multipleExitPointsNotTailCall$1
+    inner class UnreachableKt$multipleExitPointsWhen$2
+    inner class UnreachableKt$notTailCall$1
+    inner class UnreachableKt$useGenericInferType$2
+    inner class UnreachableKt$useNullableUnit$1
+    public final static @org.jetbrains.annotations.Nullable method callsIntNotTailCall(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method empty(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method generic(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method genericInferType(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function0, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method lambdaAsParameter(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method lambdaAsParameterNotTailCall(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method lambdaAsParameterReturn(@org.jetbrains.annotations.NotNull p0: kotlin.jvm.functions.Function1, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method multipleExitPoints(p0: boolean, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method multipleExitPointsNotTailCall(p0: boolean, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method multipleExitPointsWhen(p0: int, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method multipleExitPointsWithOrdinaryInline(p0: boolean, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method notTailCall(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method nullableUnit(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static method ordinary(): int
+    public final static method ordinaryInline(): void
+    public final static @org.jetbrains.annotations.Nullable method returnsInt(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method twoReturns(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method useGenericClass(@org.jetbrains.annotations.NotNull p0: Generic, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method useGenericInferType(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method useGenericReturningUnit(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method useNullableUnit(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method useRunRunRunRunRun(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method withoutReturn(@org.jetbrains.annotations.Nullable p0: java.lang.Object): java.lang.Object
+}

compiler/testData/codegen/bytecodeListing/tailcall/whenUnit.kt

@@ -0,0 +1,12 @@
+sealed class X {
+    class A : X()
+    class B : X()
+}
+
+suspend fun process(a: X.A) {}
+suspend fun process(b: X.B) {}
+
+suspend fun process(x: X) = when (x) {
+    is X.A -> process(x)
+    is X.B -> process(x)
+}

compiler/testData/codegen/bytecodeListing/tailcall/whenUnit.txt

@@ -0,0 +1,26 @@
+@kotlin.Metadata
+public final class WhenUnitKt {
+    public final static @org.jetbrains.annotations.Nullable method process(@org.jetbrains.annotations.NotNull p0: X$A, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method process(@org.jetbrains.annotations.NotNull p0: X$B, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+    public final static @org.jetbrains.annotations.Nullable method process(@org.jetbrains.annotations.NotNull p0: X, @org.jetbrains.annotations.Nullable p1: java.lang.Object): java.lang.Object
+}
+
+@kotlin.Metadata
+public final class X$A {
+    inner class X$A
+    public method <init>(): void
+}
+
+@kotlin.Metadata
+public final class X$B {
+    inner class X$B
+    public method <init>(): void
+}
+
+@kotlin.Metadata
+public abstract class X {
+    inner class X$A
+    inner class X$B
+    private method <init>(): void
+    public synthetic method <init>(p0: kotlin.jvm.internal.DefaultConstructorMarker): void
+}