Mark additional methods and classes as final where possible

Signed-off-by: Graham <gpe@openrs2.dev>

deob/src/main/java/dev/openrs2/deob/transform/FinalTransformer.kt

@@ -1,18 +1,63 @@
 package dev.openrs2.deob.transform
 
 import com.github.michaelbull.logging.InlineLogger
+import dev.openrs2.asm.MemberRef
 import dev.openrs2.asm.classpath.ClassPath
 import dev.openrs2.asm.classpath.Library
 import dev.openrs2.asm.transform.Transformer
+import dev.openrs2.util.collect.DisjointSet
 import org.objectweb.asm.Opcodes
 import org.objectweb.asm.tree.ClassNode
 import org.objectweb.asm.tree.MethodNode
 
 class FinalTransformer : Transformer() {
-    private var redundantFinals = 0
+    private val superClasses = mutableListOf<String>()
+    private lateinit var inheritedMethodSets: DisjointSet<MemberRef>
+    private var methodsChanged = 0
 
     override fun preTransform(classPath: ClassPath) {
-        redundantFinals = 0
+        superClasses.clear()
+        inheritedMethodSets = classPath.createInheritedMethodSets()
+        methodsChanged = 0
+    }
+
+    override fun transformClass(classPath: ClassPath, library: Library, clazz: ClassNode): Boolean {
+        val superClass = clazz.superName
+        if (superClass != null) {
+            superClasses += superClass
+        }
+
+        superClasses.addAll(clazz.interfaces)
+
+        return false
+    }
+
+    private fun isMethodFinal(classPath: ClassPath, clazz: ClassNode, method: MethodNode): Boolean {
+        if (method.name == "<init>") {
+            return false
+        } else if ((method.access and (Opcodes.ACC_ABSTRACT or Opcodes.ACC_PRIVATE or Opcodes.ACC_STATIC)) != 0) {
+            return false
+        }
+
+        val thisClass = classPath[clazz.name]!!
+
+        val partition = inheritedMethodSets[MemberRef(clazz, method)]!!
+        for (methodRef in partition) {
+            if (methodRef.owner == clazz.name) {
+                continue
+            }
+
+            val otherClass = classPath[methodRef.owner]!!
+            if (otherClass.methods.none { it.name == methodRef.name && it.desc == methodRef.desc }) {
+                continue
+            }
+
+            if (thisClass.isAssignableFrom(otherClass)) {
+                return false
+            }
+        }
+
+        return true
     }
 
     override fun preTransformMethod(
@@ -21,19 +66,49 @@ class FinalTransformer : Transformer() {
         clazz: ClassNode,
         method: MethodNode
     ): Boolean {
-        if (method.access and Opcodes.ACC_FINAL == 0) {
-            return false
+        val access = method.access
+
+        if (isMethodFinal(classPath, clazz, method)) {
+            method.access = access or Opcodes.ACC_FINAL
+        } else {
+            method.access = access and Opcodes.ACC_FINAL.inv()
         }
 
-        if (method.access and (Opcodes.ACC_PRIVATE or Opcodes.ACC_STATIC) != 0) {
-            method.access = method.access and Opcodes.ACC_FINAL.inv()
-            redundantFinals++
+        if (method.access != access) {
+            methodsChanged++
         }
+
         return false
     }
 
+    private fun isClassFinal(clazz: ClassNode): Boolean {
+        if ((clazz.access and (Opcodes.ACC_ABSTRACT or Opcodes.ACC_INTERFACE)) != 0) {
+            return false
+        }
+
+        return !superClasses.contains(clazz.name)
+    }
+
     override fun postTransform(classPath: ClassPath) {
-        logger.info { "Removed $redundantFinals redundant final modifiers" }
+        var classesChanged = 0
+
+        for (library in classPath.libraries) {
+            for (clazz in library) {
+                val access = clazz.access
+
+                if (isClassFinal(clazz)) {
+                    clazz.access = access or Opcodes.ACC_FINAL
+                } else {
+                    clazz.access = access and Opcodes.ACC_FINAL.inv()
+                }
+
+                if (clazz.access != access) {
+                    classesChanged++
+                }
+            }
+        }
+
+        logger.info { "Updated final modifier on $classesChanged classes and $methodsChanged methods" }
     }
 
     companion object {