From 2f9d42d4ad91a0f836c84bfdcb84d301803347a0 Mon Sep 17 00:00:00 2001
From: Laborratte5 <laborratte5@gmail.com>
Date: Mon, 19 May 2025 21:55:57 +0200
Subject: [PATCH] Implement liveness analysis

---
 .../backend/x86asm/X68RegisterAllocator.java  | 141 ++++++++++++++++++
 1 file changed, 141 insertions(+)
 create mode 100644 src/main/java/edu/kit/kastel/vads/compiler/backend/x86asm/X68RegisterAllocator.java

diff --git a/src/main/java/edu/kit/kastel/vads/compiler/backend/x86asm/X68RegisterAllocator.java b/src/main/java/edu/kit/kastel/vads/compiler/backend/x86asm/X68RegisterAllocator.java
new file mode 100644
index 0000000..72d1acb
--- /dev/null
+++ b/src/main/java/edu/kit/kastel/vads/compiler/backend/x86asm/X68RegisterAllocator.java
@@ -0,0 +1,141 @@
+package edu.kit.kastel.vads.compiler.backend.x86asm;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Queue;
+import java.util.Set;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.stream.Collectors;
+
+import edu.kit.kastel.vads.compiler.backend.regalloc.Register;
+import edu.kit.kastel.vads.compiler.backend.regalloc.RegisterAllocator;
+import edu.kit.kastel.vads.compiler.ir.IrGraph;
+import edu.kit.kastel.vads.compiler.ir.node.BinaryOperationNode;
+import edu.kit.kastel.vads.compiler.ir.node.Block;
+import edu.kit.kastel.vads.compiler.ir.node.ConstIntNode;
+import edu.kit.kastel.vads.compiler.ir.node.Node;
+import edu.kit.kastel.vads.compiler.ir.node.ProjNode;
+import edu.kit.kastel.vads.compiler.ir.node.ReturnNode;
+import edu.kit.kastel.vads.compiler.ir.node.StartNode;
+
+public class X68RegisterAllocator implements RegisterAllocator {
+
+    private class InterferenceGraph {
+
+    }
+
+    private final Map<Node, Set<Node>> temps;
+    private int nextTemp;
+
+    public X68RegisterAllocator() {
+        temps = new HashMap<>();
+        nextTemp = 0;
+    }
+
+    @Override
+    public Map<Node, Register> allocateRegisters(IrGraph graph) {
+        analyseLive(graph);
+
+        System.out.println("=====");
+        printTemps();
+        throw new UnsupportedOperationException();
+        //InterferenceGraph interference = buildInterferenceGraph(temps);
+        //return allocateRegisters(interference);
+    }
+
+    private void analyseLive(IrGraph graph) {
+        boolean change = false;
+        do {
+            change = analyseLiveSinglePass(graph.endBlock(), new HashSet<>());
+        } while (change);
+    }
+
+    private boolean analyseLiveSinglePass(Node node, Set<Node> visited) {
+        boolean changed = false;
+
+        if (needsRegister(node)) {
+            // Get Live Out of node
+            Set<Node> liveOut = temps.getOrDefault(node, Set.of());
+
+            Set<Node> kill = getKillOf(node);
+            Set<Node> gen = getGenOf(node);
+
+            Set<Node> liveIn = new HashSet<>(liveOut);
+            liveIn.removeAll(kill);
+            liveIn.addAll(gen);
+
+            Set<Node> old = temps.put(node, liveIn);
+            changed |= old == null || !old.equals(liveIn);
+
+            //if (changed) {
+                System.out.println("Node " + node);
+                System.out.println("Out: " + Arrays.toString(liveOut.toArray()));
+                System.out.println("Kill: " + Arrays.toString(kill.toArray()));
+                System.out.println("Gen: " + Arrays.toString(gen.toArray()));
+                System.out.println("In: " + Arrays.toString(liveIn.toArray()));
+                System.out.println();
+                //printTemps();
+                //System.out.println();
+            //}
+
+        }
+
+        for (Node predecessor : node.predecessors()) {
+            if (visited.add(predecessor)) {
+                changed |= analyseLiveSinglePass(predecessor, visited);
+            }
+        }
+
+        return changed;
+    }
+
+    private Set<Node> getSuccessors(Node node) {
+        return node.graph().successors(node);
+    }
+
+    private InterferenceGraph buildInterferenceGraph(Map<Node, Set<Node>> temps) {
+        // TODO Auto-generated method stub
+        throw new UnsupportedOperationException("Unimplemented method 'buildInterferenceGraph'");
+    }
+
+    private Map<Node, Register> allocateRegisters(InterferenceGraph graph) {
+        // TODO Auto-generated method stub
+        throw new UnsupportedOperationException("Unimplemented method 'allocateRegisters'");
+    }
+
+    private static boolean needsRegister(Node node) {
+        return !(node instanceof ProjNode || node instanceof StartNode || node instanceof Block);
+    }
+
+    private Set<Node> getKillOf(Node node) {
+        return switch (node) {
+            case BinaryOperationNode bin -> Set.of(bin);
+            case ConstIntNode c -> Set.of(c);
+            case ReturnNode _ -> Set.of();
+            default -> throw new UnsupportedOperationException("No 'kill' set for " + node + "implemented.");
+        };
+    }
+
+    private Set<Node> getGenOf(Node node) {
+        return switch (node) {
+            // TODO special case div/mod
+            case BinaryOperationNode bin -> Set.of(bin.predecessor(BinaryOperationNode.LEFT), bin.predecessor(BinaryOperationNode.RIGHT));
+            case ConstIntNode _ -> Set.of();
+            case ReturnNode ret -> Set.of(ret.predecessor(ReturnNode.RESULT));
+            default -> throw new UnsupportedOperationException("No 'kill' set for " + node + "implemented.");
+        };
+    }
+
+    private void printTemps() {
+
+        for (Entry<Node, Set<Node>> e : temps.entrySet()) {
+            //System.out.println(e.getValue().size());
+            System.out.println(e.getKey() + ": " + e.getValue().stream().map(r -> String.valueOf(r.hashCode())).collect(Collectors.joining(", ")));
+        }
+
+    }
+
+}