Ignore unreachable code on tail call optimization

#KT-21759: Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/CoroutineTransformerMethodVisitor.kt

@@ -41,6 +41,7 @@ import org.jetbrains.org.objectweb.asm.Opcodes
 import org.jetbrains.org.objectweb.asm.Type
 import org.jetbrains.org.objectweb.asm.commons.InstructionAdapter
 import org.jetbrains.org.objectweb.asm.tree.*
+import org.jetbrains.org.objectweb.asm.tree.analysis.Frame
 import org.jetbrains.org.objectweb.asm.tree.analysis.SourceInterpreter
 import org.jetbrains.org.objectweb.asm.tree.analysis.SourceValue
 
@@ -689,14 +690,16 @@ private fun allSuspensionPointsAreTailCalls(
     methodNode: MethodNode,
     suspensionPoints: List<SuspensionPoint>
 ): Boolean {
-    val safelyReachableReturns = findSafelyReachableReturns(methodNode)
     val sourceFrames = MethodTransformer.analyze(thisName, methodNode, IgnoringCopyOperationSourceInterpreter())
+    val safelyReachableReturns = findSafelyReachableReturns(methodNode, sourceFrames)
 
     val instructions = methodNode.instructions
     return suspensionPoints.all { suspensionPoint ->
         val beginIndex = instructions.indexOf(suspensionPoint.suspensionCallBegin)
         val endIndex = instructions.indexOf(suspensionPoint.suspensionCallEnd)
 
+        if (isUnreachable(beginIndex, sourceFrames)) return@all true
+
         val insideTryBlock = methodNode.tryCatchBlocks.any { block ->
             val tryBlockStartIndex = instructions.indexOf(block.start)
             val tryBlockEndIndex = instructions.indexOf(block.end)
@@ -728,7 +731,7 @@ internal class IgnoringCopyOperationSourceInterpreter : SourceInterpreter() {
  *
  * @return indices of safely reachable returns for each instruction in the method node
  */
-private fun findSafelyReachableReturns(methodNode: MethodNode): Array<Set<Int>?> {
+private fun findSafelyReachableReturns(methodNode: MethodNode, sourceFrames: Array<Frame<SourceValue?>?>): Array<Set<Int>?> {
     val controlFlowGraph = ControlFlowGraph.build(methodNode)
 
     val insns = methodNode.instructions
@@ -736,6 +739,7 @@ private fun findSafelyReachableReturns(methodNode: MethodNode): Array<Set<Int>?>
         val insn = insns[index]
 
         if (insn.opcode == Opcodes.ARETURN) {
+            if (isUnreachable(index, sourceFrames)) return@init null
             return@init setOf(index)
         }
 
@@ -770,6 +774,9 @@ private fun findSafelyReachableReturns(methodNode: MethodNode): Array<Set<Int>?>
     return reachableReturnsIndices
 }
 
+// Check whether this instruction is unreachable, i.e. there is no path leading to this instruction
+internal fun isUnreachable(index: Int, sourceFrames: Array<Frame<SourceValue?>?>) = sourceFrames[index] == null
+
 private fun AbstractInsnNode?.isInvisibleInDebugVarInsn(methodNode: MethodNode): Boolean {
     val insns = methodNode.instructions
     val index = insns.indexOf(this)

compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/ReturnUnitMethodTransformer.kt

@@ -112,7 +112,9 @@ object ReturnUnitMethodTransformer : MethodTransformer() {
     ): Map<AbstractInsnNode, Collection<AbstractInsnNode>> {
         val frames = analyze(internalClassName, methodNode, IgnoringCopyOperationSourceInterpreter())
         return pops.keysToMap {
-            frames[methodNode.instructions.indexOf(it)].getStack(0).insns
+            val index = methodNode.instructions.indexOf(it)
+            if (isUnreachable(index, frames)) return@keysToMap emptySet<AbstractInsnNode>()
+            frames[index].getStack(0).insns
         }
     }
 

compiler/testData/codegen/box/coroutines/tailCallOptimizations/unreachable.kt

@@ -0,0 +1,24 @@
+// WITH_RUNTIME
+// WITH_COROUTINES
+import helpers.*
+import kotlin.coroutines.experimental.*
+import kotlin.coroutines.experimental.intrinsics.*
+
+suspend fun twoReturns(c: suspend () -> Unit) {
+    return c()
+    throw RuntimeException("FAIL 1")
+}
+
+fun builder(c: suspend () -> Unit) {
+    c.startCoroutine(EmptyContinuation)
+}
+
+fun box(): String {
+    var res = "FAIL"
+    builder {
+        twoReturns {
+            res = "OK"
+        }
+    }
+    return res
+}

compiler/testData/codegen/bytecodeListing/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/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/tests-ir-jvm/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -6394,6 +6394,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/tailCallOptimizations/tryCatch.kt");
                 doTest(fileName);
             }
+
+            @TestMetadata("unreachable.kt")
+            public void testUnreachable() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/tailCallOptimizations/unreachable.kt");
+                doTest(fileName);
+            }
         }
 
         @TestMetadata("compiler/testData/codegen/box/coroutines/tailOperations")

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -6394,6 +6394,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/tailCallOptimizations/tryCatch.kt");
                 doTest(fileName);
             }
+
+            @TestMetadata("unreachable.kt")
+            public void testUnreachable() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/tailCallOptimizations/unreachable.kt");
+                doTest(fileName);
+            }
         }
 
         @TestMetadata("compiler/testData/codegen/box/coroutines/tailOperations")

compiler/tests/org/jetbrains/kotlin/codegen/BytecodeListingTestGenerated.java

@@ -169,6 +169,12 @@ public class BytecodeListingTestGenerated extends AbstractBytecodeListingTest {
         doTest(fileName);
     }
 
+    @TestMetadata("unreachable.kt")
+    public void testUnreachable() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeListing/unreachable.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("compiler/testData/codegen/bytecodeListing/annotations")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)

compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -6394,6 +6394,12 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/tailCallOptimizations/tryCatch.kt");
                 doTest(fileName);
             }
+
+            @TestMetadata("unreachable.kt")
+            public void testUnreachable() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/tailCallOptimizations/unreachable.kt");
+                doTest(fileName);
+            }
         }
 
         @TestMetadata("compiler/testData/codegen/box/coroutines/tailOperations")

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -6952,6 +6952,12 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/tailCallOptimizations/tryCatch.kt");
                 doTest(fileName);
             }
+
+            @TestMetadata("unreachable.kt")
+            public void testUnreachable() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/tailCallOptimizations/unreachable.kt");
+                doTest(fileName);
+            }
         }
 
         @TestMetadata("compiler/testData/codegen/box/coroutines/tailOperations")