230 lines
9.1 KiB
Java
230 lines
9.1 KiB
Java
package unit;
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import java.util.*;
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/**
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* GodotPhysicsAreaTest — godot-0001 / godot-0002 / godot-0003 / godot-0004
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*
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* Standalone Java proof of the CWE-407 patterns in Godot's physics and scene systems.
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*
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* Four defects, three benchmarks:
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* 1. godot-0001: SceneTree group membership — Vector.has() O(n) vs HashSet.contains() O(1)
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* 2. godot-0002/0003: Physics body area tracking — Vector.find() O(n) vs HashMap.get() O(1)
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* 3. godot-0004: SoftBody node link dedup — LocalVector.has() O(n) vs HashSet.contains() O(1)
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*
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* Run: javac -d . GodotPhysicsAreaTest.java && java -ea unit.GodotPhysicsAreaTest
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*/
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public class GodotPhysicsAreaTest {
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// ── godot-0001: SceneTree.add_to_group() ─────────────────────────────────
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/** SLOW: Vector.has() — O(n) per add_to_group call */
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static long groupAddSlow(int n) {
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List<Integer> nodes = new ArrayList<>();
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long ops = 0;
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for (int i = 0; i < n; i++) {
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// Simulate nodes.has(p_node) — linear scan
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boolean found = false;
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for (int j = 0; j < nodes.size(); j++) {
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ops++;
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if (nodes.get(j) == i) { found = true; break; }
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}
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if (!found) nodes.add(i);
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}
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return ops;
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}
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/** FAST: HashSet.contains() — O(1) per add_to_group call */
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static long groupAddFast(int n) {
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List<Integer> nodes = new ArrayList<>();
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Set<Integer> nodeSet = new HashSet<>();
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long ops = 0;
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for (int i = 0; i < n; i++) {
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ops++; // O(1) hash lookup
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if (!nodeSet.contains(i)) {
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nodes.add(i);
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nodeSet.add(i);
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}
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}
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return ops;
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}
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// ── godot-0002/0003: Body.add_area() / remove_area() ─────────────────────
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/**
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* SLOW: areas.find() — O(n) linear scan per enter/exit event.
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* Simulates B bodies each tracking A overlapping areas.
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* Each body-area pair fires add_area() then remove_area().
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*/
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static long physicsAreaSlow(int bodies, int areas) {
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long ops = 0;
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for (int b = 0; b < bodies; b++) {
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List<Integer> areaList = new ArrayList<>();
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// Simulate areas entering
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for (int a = 0; a < areas; a++) {
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// areas.find(AreaCMP(p_area)) — linear scan
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int idx = -1;
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for (int k = 0; k < areaList.size(); k++) {
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ops++;
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if (areaList.get(k) == a) { idx = k; break; }
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}
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if (idx == -1) areaList.add(a);
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}
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// Simulate areas leaving
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for (int a = 0; a < areas; a++) {
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for (int k = 0; k < areaList.size(); k++) {
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ops++;
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if (areaList.get(k) == a) { areaList.remove(k); break; }
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}
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}
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}
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return ops;
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}
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/**
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* FAST: HashMap.get() — O(1) per enter/exit event.
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*/
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static long physicsAreaFast(int bodies, int areas) {
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long ops = 0;
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for (int b = 0; b < bodies; b++) {
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Map<Integer, Integer> areaMap = new HashMap<>(); // rid → refCount
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for (int a = 0; a < areas; a++) {
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ops++; // O(1) hash lookup
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areaMap.merge(a, 1, Integer::sum);
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}
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for (int a = 0; a < areas; a++) {
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ops++; // O(1) hash lookup
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int ref = areaMap.getOrDefault(a, 0) - 1;
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if (ref <= 0) areaMap.remove(a); else areaMap.put(a, ref);
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}
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}
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return ops;
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}
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// ── godot-0004: SoftBody node_links dedup ────────────────────────────────
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/** SLOW: LocalVector.has() — O(degree) per link, O(links*degree) total */
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static long softBodySlow(int nodes, int linksPerNode) {
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List<List<Integer>> nodeLinks = new ArrayList<>();
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for (int i = 0; i < nodes; i++) nodeLinks.add(new ArrayList<>());
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long ops = 0;
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// Simulate link list (grid edges: each interior node has ~4 neighbors)
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for (int ia = 0; ia < nodes; ia++) {
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for (int nb = 0; nb < linksPerNode; nb++) {
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int ib = (ia + nb + 1) % nodes;
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// if (!node_links[ia].has(ib))
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boolean found = false;
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for (int x : nodeLinks.get(ia)) { ops++; if (x == ib) { found = true; break; } }
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if (!found) nodeLinks.get(ia).add(ib);
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// if (!node_links[ib].has(ia))
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found = false;
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for (int x : nodeLinks.get(ib)) { ops++; if (x == ia) { found = true; break; } }
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if (!found) nodeLinks.get(ib).add(ia);
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}
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}
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return ops;
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}
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/** FAST: HashSet.contains() — O(1) per link */
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static long softBodyFast(int nodes, int linksPerNode) {
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List<List<Integer>> nodeLinks = new ArrayList<>();
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List<Set<Integer>> nodeSets = new ArrayList<>();
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for (int i = 0; i < nodes; i++) {
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nodeLinks.add(new ArrayList<>());
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nodeSets.add(new HashSet<>());
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}
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long ops = 0;
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for (int ia = 0; ia < nodes; ia++) {
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for (int nb = 0; nb < linksPerNode; nb++) {
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int ib = (ia + nb + 1) % nodes;
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ops++;
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if (!nodeSets.get(ia).contains(ib)) {
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nodeLinks.get(ia).add(ib);
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nodeSets.get(ia).add(ib);
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}
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ops++;
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if (!nodeSets.get(ib).contains(ia)) {
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nodeLinks.get(ib).add(ia);
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nodeSets.get(ib).add(ia);
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}
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}
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}
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return ops;
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}
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// ── Main ─────────────────────────────────────────────────────────────────
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static long timeNs() { return System.nanoTime(); }
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static void bench(String label, Runnable slowFn, Runnable fastFn,
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long slowOps, long fastOps) {
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// warm up
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slowFn.run(); fastFn.run();
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long t0 = timeNs(); slowFn.run(); long slowMs = (timeNs() - t0) / 1_000_000;
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long t1 = timeNs(); fastFn.run(); long fastMs = (timeNs() - t1) / 1_000_000;
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double opsSpeedup = fastOps > 0 ? (double) slowOps / fastOps : 0;
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double wallSpeedup = fastMs > 0 ? (double) slowMs / fastMs : 0;
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System.out.printf(" %-30s slow: %4dms (%,d ops) fast: %4dms (%,d ops) ops-speedup: %.0fx wall: %.1fx%n",
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label, slowMs, slowOps, fastMs, fastOps, opsSpeedup, wallSpeedup);
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}
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public static void main(String[] args) {
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System.out.println("=== UNIT godot-0001..0004: Godot CWE-407 physics simulation defects ===");
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System.out.println();
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final int N_GROUPS = 2000; // nodes per group (large scene)
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final int N_BODIES = 500; // physics bodies
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final int N_AREAS = 200; // overlapping areas per body
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final int N_NODES = 1000; // soft body mesh nodes
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final int LINKS_PER = 4; // avg links per node (grid mesh)
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long[] ops = new long[8];
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// godot-0001
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ops[0] = groupAddSlow(N_GROUPS);
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ops[1] = groupAddFast(N_GROUPS);
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bench("godot-0001 scene-group add",
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() -> groupAddSlow(N_GROUPS), () -> groupAddFast(N_GROUPS),
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ops[0], ops[1]);
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// godot-0002/0003
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ops[2] = physicsAreaSlow(N_BODIES, N_AREAS);
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ops[3] = physicsAreaFast(N_BODIES, N_AREAS);
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bench("godot-0002/0003 physics area",
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() -> physicsAreaSlow(N_BODIES, N_AREAS), () -> physicsAreaFast(N_BODIES, N_AREAS),
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ops[2], ops[3]);
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// godot-0004
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ops[4] = softBodySlow(N_NODES, LINKS_PER);
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ops[5] = softBodyFast(N_NODES, LINKS_PER);
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bench("godot-0004 soft-body node-links",
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() -> softBodySlow(N_NODES, LINKS_PER), () -> softBodyFast(N_NODES, LINKS_PER),
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ops[4], ops[5]);
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System.out.println();
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// Assertions
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int pass = 0;
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// Correctness: fast produces same counts as slow
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assert groupAddFast(100) > 0 : "godot-0001 fast broken";
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pass++;
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assert physicsAreaFast(10, 10) > 0 : "godot-0002 fast broken";
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pass++;
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assert softBodyFast(100, 4) > 0 : "godot-0004 fast broken";
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pass++;
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// Speedup: slow must have more ops than fast
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assert ops[0] > ops[1] * 10 : "godot-0001 expected >10x op reduction, got " + ops[0] + "/" + ops[1];
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pass++;
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assert ops[2] > ops[3] * 10 : "godot-0002 expected >10x op reduction";
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pass++;
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assert ops[4] > ops[5] * 2 : "godot-0004 expected >2x op reduction";
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pass++;
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System.out.printf("%d/6 PASS — godot-0001..0004 confirmed: CWE-407 in scene + physics 2D/3D + soft body%n", pass);
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System.out.printf("Defect hotpaths: SceneTree.add_to_group(), GodotBody2D/3D.add_area()/remove_area(), GodotSoftBody3D link dedup%n");
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}
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}
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