IR KT-50258 rewrite enum-based 'when' more carefully

compiler/testData/codegen/box/when/enumOptimization/kt50258.kt

@@ -0,0 +1,23 @@
+enum class MyEnum {
+    First,
+    Second
+}
+
+fun getValue() = MyEnum.First
+
+var result = "Failed"
+
+fun getLambda(): (Int) -> Unit =
+    when (val value = getValue()) {
+        MyEnum.Second -> { _ -> }
+        MyEnum.First -> { _ ->
+            if (value == MyEnum.First) {
+                result = "OK"
+            }
+        }
+    }
+
+fun box(): String {
+    getLambda().invoke(2)
+    return result
+}

compiler/testData/codegen/box/when/enumOptimization/nestedWhenInCondition.kt

@@ -0,0 +1,19 @@
+enum class ABCD {
+    A, B, C, D
+}
+
+fun test(x: ABCD, y: ABCD, ok: String): String =
+    when (x) {
+        when (y) {
+            ABCD.A -> ABCD.B
+            ABCD.B -> ABCD.C
+            ABCD.C -> ABCD.D
+            ABCD.D -> ABCD.A
+        } ->
+            ok
+        ABCD.A, ABCD.B, ABCD.C, ABCD.D ->
+            x.toString()
+    }
+
+fun box(): String =
+    test(ABCD.B, ABCD.A, "O") + test(ABCD.A, ABCD.D, "K")

compiler/testData/codegen/box/when/enumOptimization/nestedWhenInResult.kt

@@ -0,0 +1,21 @@
+enum class ABCD {
+    A, B, C, D
+}
+
+fun test(x: ABCD, y: ABCD, ok: String): String =
+    when (x) {
+        ABCD.A, ABCD.B ->
+            when (y) {
+                ABCD.A, ABCD.B -> ok
+                ABCD.C, ABCD.D -> y.toString()
+            }
+        ABCD.C, ABCD.D ->
+            x.toString()
+    }
+
+fun box(): String =
+    test(ABCD.B, ABCD.A, "O") + test(ABCD.A, ABCD.B, "K")
+
+// CHECK_BYTECODE_TEXT
+// JVM_IR_TEMPLATES
+// 2 (TABLE|LOOKUP)SWITCH