Minor. Add tests.

compiler/testData/codegen/bytecodeText/coroutines/cleanup/backEdge.kt

@@ -0,0 +1,16 @@
+fun blackhole(vararg a: Any?) {}
+
+suspend fun dummy() {}
+
+suspend fun test() {
+    for (i in 0..10) {
+        // Should be cleanup, since there is a back edge from the rest of the loop
+        dummy()
+        val a = ""
+        dummy()
+        blackhole(a)
+    }
+}
+
+// 1 ACONST_NULL
+// 2 PUTFIELD .*L\$0 : Ljava/lang/Object;

compiler/testData/codegen/bytecodeText/coroutines/cleanup/if.kt

@@ -0,0 +1,24 @@
+fun blackhole(vararg a: Any?) {}
+
+suspend fun dummy() {}
+
+fun check(): Boolean = true
+
+suspend fun test() {
+    if (check()) {
+        val a = ""
+        dummy()
+        blackhole(a)
+    } else {
+        val a = ""
+        val b = ""
+        dummy()
+        blackhole(a, b)
+    }
+    // Cleanup both a and b, since the compiler does not know, which branch is going to executed
+    dummy()
+}
+
+// 2 ACONST_NULL
+// 3 PUTFIELD .*L\$0 : Ljava/lang/Object;
+// 2 PUTFIELD .*L\$1 : Ljava/lang/Object;

compiler/testData/codegen/bytecodeText/coroutines/cleanup/nullCleanup.kt

@@ -0,0 +1,17 @@
+fun blackhole(vararg a: Any?) {}
+
+suspend fun dummy() {}
+
+suspend fun test() {
+    var a: String? = ""
+    dummy()
+    blackhole(a)
+    a = null
+    // a is null, known at compile time, do not spill, but cleanup
+    dummy()
+    blackhole(a)
+}
+
+// jsut before suspension point
+// 1 ACONST_NULL
+// 2 PUTFIELD .*L\$0 : Ljava/lang/Object;

compiler/testData/codegen/bytecodeText/coroutines/cleanup/nullNotSpill.kt

@@ -0,0 +1,15 @@
+fun blackhole(vararg a: Any?) {}
+
+suspend fun dummy() {}
+
+suspend fun test() {
+    val a = null
+    // a is null, known at compile time, do not spill
+    dummy()
+    blackhole(a)
+    dummy()
+}
+
+// before and after suspension point
+// 2 ACONST_NULL
+// 0 PUTFIELD .*L\$0 : Ljava/lang/Object;

compiler/testData/codegen/bytecodeText/coroutines/cleanup/simple.kt

@@ -0,0 +1,14 @@
+fun blackhole(vararg a: Any?) {}
+
+suspend fun dummy() {}
+
+suspend fun test() {
+    val a = ""
+    dummy()
+    blackhole(a)
+    // a is dead, cleanup
+    dummy()
+}
+
+// 1 ACONST_NULL
+// 2 PUTFIELD .*L\$0 : Ljava/lang/Object;

compiler/testData/codegen/bytecodeText/coroutines/cleanup/when.kt

@@ -0,0 +1,34 @@
+fun blackhole(vararg a: Any?) {}
+
+suspend fun dummy() {}
+
+fun check(): Int = 1
+
+suspend fun test() {
+    when (check()) {
+        0 -> {
+            val a = ""
+            dummy()
+            blackhole(a)
+        }
+        1 -> {
+            val a = ""
+            val b = ""
+            dummy()
+            blackhole(a, b)
+        }
+        else -> {
+            val a = ""
+            val b = ""
+            val c = 1
+            dummy()
+            blackhole(a, b, c)
+        }
+    }
+    // Cleanup both a and b, but c is primitive, so no need to clean it up
+    dummy()
+}
+
+// 2 ACONST_NULL
+// 4 PUTFIELD .*L\$0 : Ljava/lang/Object;
+// 3 PUTFIELD .*L\$1 : Ljava/lang/Object;