russell@unturf.com
f2d7a3127e
PCSX2: - pcsx2-0001: Patch::ReloadEnabledLists 4x std::find on vector O(N^2) MEDIUM 6-12x - pcsx2-0002: GSCapture codec dedup std::find_if O(N^2) LOW 11x - MOAD-0002/0003/0004/0005: CLEAN Wine: - wine-0001: ntdll/loader.c find_module_dependency O(D) linked-list dedup HIGH 7x - MOAD-0004: ChangeServiceConfig logs password via debugstr_w MEDIUM - MOAD-0002/0003/0005: CLEAN Thunderbird: source unavailable (nicholasb2101/gecko-dev repo inaccessible)
99 lines
3.6 KiB
Java
99 lines
3.6 KiB
Java
import java.util.*;
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/**
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* Unit test for Wine wine-0001: ntdll/loader.c find_module_dependency
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* performs O(D) linear scan on a circular singly-linked list to check if a
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* DLL dependency already exists before adding it. Called for every import
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* during fixup_imports, giving O(I*D) per module.
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*
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* Fix: maintain a HashSet alongside the linked list for O(1) dedup.
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*
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* Defect file: dlls/ntdll/loader.c lines 860-873
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*/
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public class LoaderDependencyDedupTest {
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// --- Defective: linear scan to find existing dependency ---
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static class DdagNodeDefective {
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List<Object> dependencies = new LinkedList<>();
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boolean hasDependency(Object to) {
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for (Object dep : dependencies) {
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if (dep == to) return true; // O(D) scan
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}
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return false;
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}
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void addDependency(Object to) {
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if (!hasDependency(to)) { // O(D) per call
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dependencies.add(to);
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}
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}
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}
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// --- Fixed: hash set for O(1) dedup ---
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static class DdagNodeFixed {
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List<Object> dependencies = new LinkedList<>();
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Set<Object> dependencySet = new HashSet<>();
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void addDependency(Object to) {
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if (dependencySet.add(to)) { // O(1) dedup
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dependencies.add(to);
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}
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}
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}
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public static void main(String[] args) {
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int N = 500;
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// Simulate modules being imported
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Object[] modules = new Object[N];
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for (int i = 0; i < N; i++) modules[i] = new Object();
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// Defective: add all, then try to add all again (worst case dedup)
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DdagNodeDefective defNode = new DdagNodeDefective();
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DdagNodeFixed fixNode = new DdagNodeFixed();
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// Correctness: both should add N unique deps
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for (Object m : modules) { defNode.addDependency(m); fixNode.addDependency(m); }
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assert defNode.dependencies.size() == N : "Defective size wrong";
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assert fixNode.dependencies.size() == N : "Fixed size wrong";
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// Re-add (all duplicates)
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for (Object m : modules) { defNode.addDependency(m); fixNode.addDependency(m); }
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assert defNode.dependencies.size() == N : "Defective re-add size wrong";
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assert fixNode.dependencies.size() == N : "Fixed re-add size wrong";
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// Warmup
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for (int w = 0; w < 200; w++) {
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DdagNodeDefective d = new DdagNodeDefective();
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DdagNodeFixed f = new DdagNodeFixed();
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for (Object m : modules) { d.addDependency(m); f.addDependency(m); }
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for (Object m : modules) { d.addDependency(m); f.addDependency(m); }
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}
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// Benchmark
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int ITER = 500;
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long t0 = System.nanoTime();
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for (int i = 0; i < ITER; i++) {
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DdagNodeDefective d = new DdagNodeDefective();
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for (Object m : modules) d.addDependency(m);
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for (Object m : modules) d.addDependency(m); // dedup pass
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}
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long defectNs = System.nanoTime() - t0;
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t0 = System.nanoTime();
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for (int i = 0; i < ITER; i++) {
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DdagNodeFixed f = new DdagNodeFixed();
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for (Object m : modules) f.addDependency(m);
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for (Object m : modules) f.addDependency(m); // dedup pass
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}
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long fixedNs = System.nanoTime() - t0;
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double ratio = (double) defectNs / fixedNs;
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System.out.printf("DLL dependency dedup N=%d defect=%.1fms fixed=%.1fms ratio=%.1fx%n",
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N, defectNs / 1e6, fixedNs / 1e6, ratio);
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assert ratio > 2.0 : "Expected >2x speedup, got " + ratio;
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System.out.println("PASS");
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}
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}
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