[JVM IR] Use reference equality when comparing enums.

compiler/testData/codegen/bytecodeText/enum/kt18731.kt

@@ -1,6 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
-// TODO KT-36772 Equality compaison between enums should use reference equality in JVM_IR
-
 enum class Bar {
     ONE,
     TWO
@@ -9,11 +6,12 @@ enum class Bar {
 fun isOne(i: Bar) = i == Bar.ONE
 
 fun box(): String {
-    return when (isOne(Bar.ONE) && !isOne(Bar.TWO)) {
+    return when (isOne(Bar.ONE) && !isOne(Bar.TWO) && Bar.ONE != Bar.TWO) {
         true -> "OK"
         else -> "Failure"
     }
 }
 
 // 1 IF_ACMPNE
+// 1 IF_ACMPEQ
 // 0 INVOKESTATIC kotlin/jvm/internal/Intrinsics.areEqual \(Ljava/lang/Object;Ljava/lang/Object;\)Z

compiler/testData/codegen/bytecodeText/enum/kt18731_2.kt

@@ -0,0 +1,16 @@
+enum class Bar {
+    ONE {
+        override fun toString(): String {
+            if (this != TWO && this == ONE) return "OK" else return "FAIL"
+        }
+    },
+    TWO;
+}
+
+fun box(): String {
+    return Bar.ONE.toString()
+}
+
+// 1 IF_ACMPNE
+// 1 IF_ACMPEQ
+// 0 INVOKESTATIC kotlin/jvm/internal/Intrinsics.areEqual \(Ljava/lang/Object;Ljava/lang/Object;\)Z