Fixup end label of local variable if it is before start label

In that case, put end label to next label after start label.

Author: ilmirus

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/InplaceArgumentsMethodTransformer.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.codegen.inline
 
 import org.jetbrains.kotlin.codegen.optimization.boxing.isMethodInsnWith
 import org.jetbrains.kotlin.codegen.optimization.common.InsnSequence
+import org.jetbrains.kotlin.codegen.optimization.common.findNextOrNull
 import org.jetbrains.kotlin.codegen.optimization.common.removeUnusedLocalVariables
 import org.jetbrains.kotlin.codegen.optimization.common.updateMaxStack
 import org.jetbrains.kotlin.codegen.optimization.transformer.MethodTransformer
@@ -25,6 +26,8 @@ class InplaceArgumentsMethodTransformer : MethodTransformer() {
 
             transformMethod(methodContext)
 
+            methodNode.fixupLVT()
+
             methodNode.removeUnusedLocalVariables()
             methodNode.updateMaxStack()
         }
@@ -356,4 +359,16 @@ class InplaceArgumentsMethodTransformer : MethodTransformer() {
             insn = insn.next
         }
     }
+}
+
+// HACK: if new end label is before start label, change to the next one
+private fun MethodNode.fixupLVT() {
+    for (localVariable in localVariables) {
+        val startIndex = instructions.indexOf(localVariable.start)
+        val endIndex = instructions.indexOf(localVariable.end)
+        if (endIndex < startIndex) {
+            val newEnd = localVariable.start.findNextOrNull { it is LabelNode } as? LabelNode
+            localVariable.end = newEnd ?: localVariable.start
+        }
+    }
 }

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java

@@ -0,0 +1,60 @@
+// WITH_RUNTIME
+// FULL_JDK
+
+import kotlin.coroutines.*
+
+fun ticker(
+    delayMillis: Long,
+    initialDelayMillis: Long = delayMillis
+): ReceiveChannel<Unit> = object : ReceiveChannel<Unit> {
+    override fun cancel() {}
+    override fun receive() {}
+}
+
+suspend fun <T> withTimeoutOrNull(timeMillis: Long, block: suspend CoroutineScope.() -> T): T? = null
+
+interface ReceiveChannel<out E> {
+    fun receive(): E
+    fun cancel()
+}
+
+interface CoroutineScope
+
+suspend fun delay(i: Int) {}
+
+suspend fun test() {
+    val tickerChannel = ticker(delayMillis = 100, initialDelayMillis = 0) // create ticker channel
+    var nextElement = withTimeoutOrNull(1) { tickerChannel.receive() }
+    println("Initial element is available immediately: $nextElement") // no initial delay
+
+    nextElement = withTimeoutOrNull(50) { tickerChannel.receive() } // all subsequent elements have 100ms delay
+    println("Next element is not ready in 50 ms: $nextElement")
+
+    nextElement = withTimeoutOrNull(60) { tickerChannel.receive() }
+    println("Next element is ready in 100 ms: $nextElement")
+
+    // Emulate large consumption delays
+    println("Consumer pauses for 150ms")
+    delay(150)
+    // Next element is available immediately
+    nextElement = withTimeoutOrNull(1) { tickerChannel.receive() }
+    println("Next element is available immediately after large consumer delay: $nextElement")
+    // Note that the pause between `receive` calls is taken into account and next element arrives faster
+    nextElement = withTimeoutOrNull(60) { tickerChannel.receive() }
+    println("Next element is ready in 50ms after consumer pause in 150ms: $nextElement")
+
+    tickerChannel.cancel() // indicate that no more elements are needed
+}
+
+fun builder(c: suspend () -> Unit) {
+    c.startCoroutine(Continuation(EmptyCoroutineContext) {
+        it.getOrThrow()
+    })
+}
+
+fun box(): String {
+    builder {
+        test()
+    }
+    return "OK"
+}