[Wasm] Introducing private identityHashCode shared between Any's hashCode and toString

It splits the dependency of toString from hashCode that prevents keeping hashCode when toString is used.

compiler/testData/codegen/box/size/add.kt

@@ -1,7 +1,7 @@
 // TARGET_BACKEND: WASM
 
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 146_294 
-// WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs   8_247 
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 139_730 
+// WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs  6_629 
 
 // FILE: test.kt
 

compiler/testData/codegen/box/size/helloWorld.kt

@@ -1,7 +1,7 @@
 // TARGET_BACKEND: WASM
 
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 146_626 
-// WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs   8_188 
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 140_062 
+// WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs  6_570 
 
 fun box(): String {
     println("Hello, World!")

compiler/testData/codegen/box/size/helloWorldDOM.kt

@@ -1,7 +1,7 @@
 // TARGET_BACKEND: WASM
 
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 149_186 
-// WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs   8_686 
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 142_622 
+// WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs  7_068 
 
 // FILE: test.kt
 

compiler/testData/codegen/box/size/ok.kt

@@ -1,6 +1,6 @@
 // TARGET_BACKEND: WASM
 
-// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 146_345 
-// WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs   8_119 
+// WASM_DCE_EXPECTED_OUTPUT_SIZE: wasm 139_781 
+// WASM_DCE_EXPECTED_OUTPUT_SIZE:  mjs  6_501 
 
 fun box() = "OK"

libraries/stdlib/wasm/builtins/kotlin/Any.kt

@@ -41,6 +41,13 @@ public open class Any @WasmPrimitiveConstructor constructor() {
      */
     internal var _hashCode: Int = 0
     public open fun hashCode(): Int {
+        return identityHashCode()
+    }
+
+    // Don't use outside, otherwise it could break classes reusing `_hashCode` field, like String.
+    // Don't inline it into usages, specifically to `hashCode`. 
+    // It was extracted to remove `toString`'s dependency on `hashCode`, which improves output size when DCE is involved.
+    private fun identityHashCode(): Int {
         if (_hashCode == 0)
             _hashCode = Random.nextInt(1, Int.MAX_VALUE)
         return _hashCode
@@ -52,6 +59,6 @@ public open class Any @WasmPrimitiveConstructor constructor() {
     public open fun toString(): String {
         val typeData = getTypeInfoTypeDataByPtr(typeInfo)
         val qualifiedName = if (typeData.packageName.isEmpty()) typeData.typeName else "${typeData.packageName}.${typeData.typeName}"
-        return "$qualifiedName@${hashCode()}"
+        return "$qualifiedName@${identityHashCode()}"
     }
 }