Use tail call optimization if ARETURN has multiple sources

#KT-21977: Fixed

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

@@ -701,12 +701,11 @@ private fun allSuspensionPointsAreTailCalls(
         if (insideTryBlock) return@all false
 
         safelyReachableReturns[endIndex + 1]?.all { returnIndex ->
-            val sourceInsn =
+            sourceFrames[returnIndex].top().sure {
-                    sourceFrames[returnIndex].top().sure {
+                "There must be some value on stack to return"
-                        "There must be some value on stack to return"
+            }.insns.all { sourceInsn ->
-                    }.insns.singleOrNull()
+                sourceInsn?.let(instructions::indexOf) in beginIndex..endIndex
-
+            }
-            sourceInsn?.let(instructions::indexOf) in beginIndex..endIndex
         } ?: false
     }
 }

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

@@ -151,6 +151,12 @@ public class BytecodeListingTestGenerated extends AbstractBytecodeListingTest {
         doTest(fileName);
     }
 
+    @TestMetadata("tailCallIntrinsics.kt")
+    public void testTailCallIntrinsics() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeListing/tailCallIntrinsics.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("tailSuspendUnitFun.kt")
     public void testTailSuspendUnitFun() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/bytecodeListing/tailSuspendUnitFun.kt");