From f0eabb06190a8924a2d632cff90974a66289daf9 Mon Sep 17 00:00:00 2001
From: Graham <gpe@openrs2.dev>
Date: Mon, 27 Jan 2020 21:24:44 +0000
Subject: [PATCH] Add generic data flow analysis framework

---
 .../openrs2/deob/analysis/DataFlowAnalyzer.kt | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 deob/src/main/java/dev/openrs2/deob/analysis/DataFlowAnalyzer.kt

diff --git a/deob/src/main/java/dev/openrs2/deob/analysis/DataFlowAnalyzer.kt b/deob/src/main/java/dev/openrs2/deob/analysis/DataFlowAnalyzer.kt
new file mode 100644
index 0000000000..4885b044cf
--- /dev/null
+++ b/deob/src/main/java/dev/openrs2/deob/analysis/DataFlowAnalyzer.kt
@@ -0,0 +1,71 @@
+package dev.openrs2.deob.analysis
+
+import com.google.common.graph.Graph
+import com.google.common.graph.Graphs
+import org.objectweb.asm.tree.AbstractInsnNode
+import org.objectweb.asm.tree.MethodNode
+
+abstract class DataFlowAnalyzer<T>(owner: String, private val method: MethodNode, backwards: Boolean = false) {
+    private val graph: Graph<Int>
+    private val inSets = mutableMapOf<Int, T>()
+    private val outSets = mutableMapOf<Int, T>()
+
+    init {
+        val forwardsGraph = ControlFlowAnalyzer().createGraph(owner, method)
+        graph = if (backwards) {
+            Graphs.transpose(forwardsGraph)
+        } else {
+            forwardsGraph
+        }
+    }
+
+    protected abstract fun createInitialSet(): T
+    protected abstract fun join(set1: T, set2: T): T
+    protected abstract fun transfer(set: T, insn: AbstractInsnNode): T
+
+    fun getInSet(insn: AbstractInsnNode): T? {
+        return getInSet(method.instructions.indexOf(insn))
+    }
+
+    fun getInSet(index: Int): T? {
+        return inSets[index]
+    }
+
+    fun getOutSet(insn: AbstractInsnNode): T? {
+        return getOutSet(method.instructions.indexOf(insn))
+    }
+
+    fun getOutSet(index: Int): T? {
+        return outSets[index]
+    }
+
+    fun analyze() {
+        for (node in graph.nodes()) {
+            outSets[node] = createInitialSet()
+        }
+
+        var changed: Boolean
+        do {
+            changed = false
+
+            for (node in graph.nodes()) {
+                val predecessors = graph.predecessors(node).map { pred -> outSets[pred]!! }
+
+                val inSet = if (predecessors.isEmpty()) {
+                    createInitialSet()
+                } else {
+                    predecessors.reduce(this::join)
+                }
+
+                inSets[node] = inSet
+
+                val outSet = transfer(inSet, method.instructions[node])
+
+                if (outSets[node] != outSet) {
+                    outSets[node] = outSet
+                    changed = true
+                }
+            }
+        } while (changed)
+    }
+}