From 325ad14ac9b3bffd8d2825df370435357045e470 Mon Sep 17 00:00:00 2001
From: Ilmir Usmanov <ilmir.usmanov@jetbrains.com>
Date: Thu, 20 Feb 2020 18:49:06 +0100
Subject: [PATCH] JVM_IR: Treat suspend main wrapper as always tail-call
 function

In other words, never generate suspend call markers inside it.
---
 .../kotlin/backend/jvm/codegen/CoroutineCodegen.kt          | 6 +++++-
 .../testData/codegen/bytecodeText/coroutines/suspendMain.kt | 6 ++++++
 .../jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java | 5 +++++
 .../kotlin/codegen/ir/IrBytecodeTextTestGenerated.java      | 5 +++++
 4 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 compiler/testData/codegen/bytecodeText/coroutines/suspendMain.kt

diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/CoroutineCodegen.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/CoroutineCodegen.kt
index a3254b35347..6755c7e7f1c 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/CoroutineCodegen.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/CoroutineCodegen.kt
@@ -113,6 +113,10 @@ internal fun IrFunction.isInvokeSuspendOfContinuation(): Boolean =
 internal fun IrFunction.isInvokeOfSuspendCallableReference(): Boolean = isSuspend && name.asString() == "invoke" &&
         parentAsClass.origin == JvmLoweredDeclarationOrigin.FUNCTION_REFERENCE_IMPL
 
+// Wrapper of suspend main is always tail-call and it is not generated as suspend function.
+private fun IrFunction.isInvokeOfSuspendMainWrapper(): Boolean = !isSuspend && name.asString() == "invoke" &&
+        parentAsClass.origin == JvmLoweredDeclarationOrigin.LAMBDA_IMPL
+
 internal fun IrFunction.isKnownToBeTailCall(): Boolean =
     when (origin) {
         IrDeclarationOrigin.FUNCTION_FOR_DEFAULT_PARAMETER,
@@ -125,7 +129,7 @@ internal fun IrFunction.isKnownToBeTailCall(): Boolean =
         IrDeclarationOrigin.BRIDGE,
         IrDeclarationOrigin.BRIDGE_SPECIAL,
         IrDeclarationOrigin.DELEGATED_MEMBER -> true
-        else -> isInvokeOfSuspendCallableReference()
+        else -> isInvokeOfSuspendMainWrapper() || isInvokeOfSuspendCallableReference()
     }
 
 internal fun IrFunction.shouldNotContainSuspendMarkers(): Boolean =
diff --git a/compiler/testData/codegen/bytecodeText/coroutines/suspendMain.kt b/compiler/testData/codegen/bytecodeText/coroutines/suspendMain.kt
new file mode 100644
index 00000000000..5ac3fb83012
--- /dev/null
+++ b/compiler/testData/codegen/bytecodeText/coroutines/suspendMain.kt
@@ -0,0 +1,6 @@
+// WITH_COROUTINES
+// TREAT_AS_ONE_FILE
+
+suspend fun main() {}
+
+// 0 INVOKESTATIC kotlin/jvm/internal/InlineMarker.mark
\ No newline at end of file
diff --git a/compiler/tests/org/jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java
index c78b24f070d..f2b03872fee 100644
--- a/compiler/tests/org/jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java
@@ -1371,6 +1371,11 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
             runTestWithPackageReplacement("compiler/testData/codegen/bytecodeText/coroutines/returnUnitInLambda.kt", "kotlin.coroutines");
         }
 
+        @TestMetadata("suspendMain.kt")
+        public void testSuspendMain() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/coroutines/suspendMain.kt");
+        }
+
         @TestMetadata("throwOnFailure.kt")
         public void testThrowOnFailure() throws Exception {
             runTest("compiler/testData/codegen/bytecodeText/coroutines/throwOnFailure.kt");
diff --git a/compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBytecodeTextTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBytecodeTextTestGenerated.java
index d8b8339682d..f08b76cdee8 100644
--- a/compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBytecodeTextTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBytecodeTextTestGenerated.java
@@ -1376,6 +1376,11 @@ public class IrBytecodeTextTestGenerated extends AbstractIrBytecodeTextTest {
             runTestWithPackageReplacement("compiler/testData/codegen/bytecodeText/coroutines/returnUnitInLambda.kt", "kotlin.coroutines");
         }
 
+        @TestMetadata("suspendMain.kt")
+        public void testSuspendMain() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/coroutines/suspendMain.kt");
+        }
+
         @TestMetadata("throwOnFailure.kt")
         public void testThrowOnFailure() throws Exception {
             runTest("compiler/testData/codegen/bytecodeText/coroutines/throwOnFailure.kt");