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openmw: 4 CWE-407 defects, MOAD 0002-0005 CLEAN

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openmw-0001: pathgrid.cpp Tarjan SCC std::find(mSCCStack) O(V^2), 2.3x (HIGH)
openmw-0002: pathgrid.cpp A* openset std::find O(V*E), 4.4x op-count (HIGH)
openmw-0003: cellstore.cpp mMovedRefs std::find O(R*M), 15.6x (MEDIUM)
openmw-0004: objectpaging.cpp mMovedRefs std::find O(R*M), 4.9x (MEDIUM)

MOAD-0002 (Intertangle): CLEAN, typical game engine global state
MOAD-0003 (Leaked Context): CLEAN, no thread_local identity carriers
MOAD-0004 (Logged Secret): CLEAN, game engine has no credentials
MOAD-0005 (Thundering Herd): CLEAN, no unsynchronized cache patterns

8/8 unit tests PASS.
This commit is contained in:
russell@unturf.com 2026-03-31 12:11:13 -04:00
parent 1b98cac200
commit 4e3dcc8d2a
8 changed files with 826 additions and 0 deletions
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43
defects/openmw-0001/patch/openmw-0001.patch Normal file
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# UNDF: UNDF-2026-000000963
--- a/apps/openmw/mwmechanics/pathgrid.cpp
+++ b/apps/openmw/mwmechanics/pathgrid.cpp
@@ -1,6 +1,7 @@
#include "pathgrid.hpp"
#include <algorithm>
+#include <unordered_set>
#include <list>
#include <set>
@@ -57,6 +58,7 @@
int mSCCId = 0;
size_t mSCCIndex = 0;
std::vector<size_t> mSCCStack;
+ std::unordered_set<size_t> mSCCOnStack;
std::vector<std::pair<size_t, size_t>> mSCCPoint; // first is index, second is lowlink
// v is the pathgrid point index (some call them vertices)
@@ -66,6 +68,7 @@
mSCCPoint[v].second = mSCCIndex; // lowlink
mSCCIndex++;
mSCCStack.push_back(v);
+ mSCCOnStack.insert(v);
size_t w;
for (const auto& edge : mGraph[v].edges)
@@ -77,7 +80,7 @@
mSCCPoint[v].second = std::min(mSCCPoint[v].second, mSCCPoint[w].second);
}
- else if (std::find(mSCCStack.begin(), mSCCStack.end(), w) != mSCCStack.end())
+ else if (mSCCOnStack.count(w))
mSCCPoint[v].second = std::min(mSCCPoint[v].second, mSCCPoint[w].first);
}
@@ -88,6 +91,7 @@
{
w = mSCCStack.back();
mSCCStack.pop_back();
+ mSCCOnStack.erase(w);
mGraph[w].componentId = mSCCId;
} while (w != v);
mSCCId++;

196
defects/openmw-0001/test/openmw-0001-test.cpp Normal file
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// openmw-0001-test.cpp
// CWE-407: Tarjan SCC std::find(mSCCStack) O(V^2) in pathgrid.cpp
//
// The Tarjan SCC algorithm in PathgridGraph::Builder::recursiveStrongConnect
// uses std::find(mSCCStack.begin(), mSCCStack.end(), w) to check if a vertex
// is on the stack. This is O(S) per edge where S is the stack size, making the
// overall algorithm O(V*E) instead of the correct O(V+E).
//
// Fix: add an unordered_set<size_t> mSCCOnStack for O(1) membership checks.
#include <algorithm>
#include <cassert>
#include <chrono>
#include <cstdio>
#include <unordered_set>
#include <vector>
struct Edge {
size_t index;
};
struct Node {
int componentId = -1;
std::vector<Edge> edges;
};
static constexpr size_t NoIndex = static_cast<size_t>(-1);
// ---------- DEFECTIVE (original): std::find on vector ----------
namespace Defective {
struct Builder {
std::vector<Node>& mGraph;
int mSCCId = 0;
size_t mSCCIndex = 0;
std::vector<size_t> mSCCStack;
std::vector<std::pair<size_t, size_t>> mSCCPoint;
Builder(std::vector<Node>& g) : mGraph(g) {}
void recursiveStrongConnect(const size_t v) {
mSCCPoint[v].first = mSCCIndex;
mSCCPoint[v].second = mSCCIndex;
mSCCIndex++;
mSCCStack.push_back(v);
size_t w;
for (const auto& edge : mGraph[v].edges) {
w = edge.index;
if (mSCCPoint[w].first == NoIndex) {
recursiveStrongConnect(w);
mSCCPoint[v].second = std::min(mSCCPoint[v].second, mSCCPoint[w].second);
}
// DEFECT: O(S) linear scan on the stack vector
else if (std::find(mSCCStack.begin(), mSCCStack.end(), w) != mSCCStack.end())
mSCCPoint[v].second = std::min(mSCCPoint[v].second, mSCCPoint[w].first);
}
if (mSCCPoint[v].second == mSCCPoint[v].first) {
do {
w = mSCCStack.back();
mSCCStack.pop_back();
mGraph[w].componentId = mSCCId;
} while (w != v);
mSCCId++;
}
}
void build() {
size_t n = mGraph.size();
mSCCPoint.assign(n, {NoIndex, NoIndex});
for (size_t i = 0; i < n; i++)
if (mSCCPoint[i].first == NoIndex)
recursiveStrongConnect(i);
}
};
}
// ---------- PATCHED: unordered_set for O(1) on-stack check ----------
namespace Patched {
struct Builder {
std::vector<Node>& mGraph;
int mSCCId = 0;
size_t mSCCIndex = 0;
std::vector<size_t> mSCCStack;
std::unordered_set<size_t> mSCCOnStack;
std::vector<std::pair<size_t, size_t>> mSCCPoint;
Builder(std::vector<Node>& g) : mGraph(g) {}
void recursiveStrongConnect(const size_t v) {
mSCCPoint[v].first = mSCCIndex;
mSCCPoint[v].second = mSCCIndex;
mSCCIndex++;
mSCCStack.push_back(v);
mSCCOnStack.insert(v);
size_t w;
for (const auto& edge : mGraph[v].edges) {
w = edge.index;
if (mSCCPoint[w].first == NoIndex) {
recursiveStrongConnect(w);
mSCCPoint[v].second = std::min(mSCCPoint[v].second, mSCCPoint[w].second);
}
// PATCHED: O(1) hash set lookup
else if (mSCCOnStack.count(w))
mSCCPoint[v].second = std::min(mSCCPoint[v].second, mSCCPoint[w].first);
}
if (mSCCPoint[v].second == mSCCPoint[v].first) {
do {
w = mSCCStack.back();
mSCCStack.pop_back();
mSCCOnStack.erase(w);
mGraph[w].componentId = mSCCId;
} while (w != v);
mSCCId++;
}
}
void build() {
size_t n = mGraph.size();
mSCCPoint.assign(n, {NoIndex, NoIndex});
for (size_t i = 0; i < n; i++)
if (mSCCPoint[i].first == NoIndex)
recursiveStrongConnect(i);
}
};
}
// Build a chain graph: 0->1->2->...->N-1->0 (one big cycle = one SCC)
std::vector<Node> buildChainGraph(size_t N) {
std::vector<Node> graph(N);
for (size_t i = 0; i < N; i++) {
graph[i].edges.push_back(Edge{(i + 1) % N});
// Add a back-edge every 10 nodes to increase stack probes
if (i >= 10)
graph[i].edges.push_back(Edge{i - 10});
}
return graph;
}
int main() {
const size_t N = 2000;
// Correctness: both must produce the same component IDs
{
auto g1 = buildChainGraph(N);
auto g2 = buildChainGraph(N);
Defective::Builder(g1).build();
Patched::Builder(g2).build();
for (size_t i = 0; i < N; i++)
assert(g1[i].componentId == g2[i].componentId);
printf("PASS correctness: component IDs match for N=%zu\n", N);
}
// Performance: measure defective vs patched
auto benchDefective = [&]() {
auto g = buildChainGraph(N);
auto t0 = std::chrono::high_resolution_clock::now();
Defective::Builder(g).build();
auto t1 = std::chrono::high_resolution_clock::now();
return std::chrono::duration<double, std::milli>(t1 - t0).count();
};
auto benchPatched = [&]() {
auto g = buildChainGraph(N);
auto t0 = std::chrono::high_resolution_clock::now();
Patched::Builder(g).build();
auto t1 = std::chrono::high_resolution_clock::now();
return std::chrono::duration<double, std::milli>(t1 - t0).count();
};
// Warmup
benchDefective();
benchPatched();
double defMs = 0, patMs = 0;
const int runs = 5;
for (int i = 0; i < runs; i++) {
defMs += benchDefective();
patMs += benchPatched();
}
defMs /= runs;
patMs /= runs;
double ratio = defMs / patMs;
printf("Defective: %.2f ms Patched: %.2f ms Ratio: %.1fx (N=%zu)\n",
defMs, patMs, ratio, N);
assert(ratio > 2.0 && "Patched should be at least 2x faster");
printf("PASS performance: %.1fx speedup\n", ratio);
return 0;
}

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# UNDF: UNDF-2026-000000964
--- a/apps/openmw/mwmechanics/pathgrid.cpp
+++ b/apps/openmw/mwmechanics/pathgrid.cpp
@@ -1,6 +1,7 @@
#include "pathgrid.hpp"
#include <algorithm>
+#include <unordered_set>
#include <list>
#include <set>
@@ -250,6 +251,7 @@
std::list<size_t> openset;
std::set<size_t> closedset;
+ std::unordered_set<size_t> opensetMembership;
openset.push_back(start);
+ opensetMembership.insert(start);
size_t current = start;
@@ -260,6 +262,7 @@
current = openset.front(); // front has the lowest cost
openset.pop_front();
+ opensetMembership.erase(current);
if (current == goal)
break;
@@ -274,7 +277,7 @@
size_t dest = edge.index;
float tentativeG = gScore[current] + edge.cost;
- bool isInOpenSet = std::find(openset.begin(), openset.end(), dest) != openset.end();
+ bool isInOpenSet = opensetMembership.count(dest) > 0;
if (!isInOpenSet || tentativeG < gScore[dest])
{
graphParent[dest] = current;
@@ -282,6 +285,7 @@
fScore[dest] = tentativeG + costAStar(mPathgrid->mPoints[dest], mPathgrid->mPoints[goal]);
if (!isInOpenSet)
{
+ opensetMembership.insert(dest);
// add this edge to openset, lowest cost goes to the front
// TODO: if this causes performance problems a hash table may help
auto it = openset.begin();

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defects/openmw-0002/test/openmw-0002-test.cpp Normal file
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@ -0,0 +1,221 @@
// openmw-0002-test.cpp
// CWE-407: A* pathfinding std::find(openset) O(V*E) in pathgrid.cpp
//
// The A* implementation in PathgridGraph::aStarSearch uses
// std::find(openset.begin(), openset.end(), dest) to check if a point is in
// the open set. The openset is a std::list<size_t>, so this is O(N) per edge
// check. The code even has a TODO: "if this causes performance problems a
// hash table may help".
//
// Fix: add an unordered_set<size_t> opensetMembership for O(1) membership.
// This test validates correctness and measures operation counts.
#include <algorithm>
#include <cassert>
#include <chrono>
#include <cmath>
#include <cstdio>
#include <deque>
#include <list>
#include <set>
#include <unordered_set>
#include <vector>
struct Edge {
size_t index;
float cost;
};
struct Point {
int mX, mY, mZ;
};
static constexpr size_t NoIndex = static_cast<size_t>(-1);
float costAStar(const Point& a, const Point& b) {
return 300.0f * (std::abs(a.mX - b.mX) + std::abs(a.mY - b.mY) + std::abs(a.mZ - b.mZ));
}
struct Node {
std::vector<Edge> edges;
};
static size_t gProbeCount = 0;
// ---------- DEFECTIVE: std::find on list, counting probes ----------
namespace Defective {
std::deque<size_t> aStarSearch(const std::vector<Node>& graph,
const std::vector<Point>& points,
size_t start, size_t goal) {
std::deque<size_t> path;
size_t graphSize = graph.size();
std::vector<float> gScore(graphSize, -1);
std::vector<float> fScore(graphSize, -1);
std::vector<size_t> graphParent(graphSize, NoIndex);
gScore[start] = 0;
fScore[start] = costAStar(points[start], points[goal]);
std::list<size_t> openset;
std::set<size_t> closedset;
openset.push_back(start);
size_t current = start;
while (!openset.empty()) {
current = openset.front();
openset.pop_front();
if (current == goal) break;
closedset.insert(current);
for (const auto& edge : graph[current].edges) {
if (!closedset.contains(edge.index)) {
size_t dest = edge.index;
float tentativeG = gScore[current] + edge.cost;
// DEFECT: O(N) linear scan. Count each element comparison.
bool isInOpenSet = false;
for (auto it = openset.begin(); it != openset.end(); ++it) {
gProbeCount++;
if (*it == dest) { isInOpenSet = true; break; }
}
if (!isInOpenSet || tentativeG < gScore[dest]) {
graphParent[dest] = current;
gScore[dest] = tentativeG;
fScore[dest] = tentativeG + costAStar(points[dest], points[goal]);
if (!isInOpenSet) {
auto it = openset.begin();
for (; it != openset.end(); ++it)
if (fScore[*it] > fScore[dest]) break;
openset.insert(it, dest);
}
}
}
}
}
if (current != goal) return path;
while (graphParent[current] != NoIndex) {
path.push_front(current);
current = graphParent[current];
}
path.push_front(start);
return path;
}
}
// ---------- PATCHED: unordered_set for membership ----------
namespace Patched {
std::deque<size_t> aStarSearch(const std::vector<Node>& graph,
const std::vector<Point>& points,
size_t start, size_t goal) {
std::deque<size_t> path;
size_t graphSize = graph.size();
std::vector<float> gScore(graphSize, -1);
std::vector<float> fScore(graphSize, -1);
std::vector<size_t> graphParent(graphSize, NoIndex);
gScore[start] = 0;
fScore[start] = costAStar(points[start], points[goal]);
std::list<size_t> openset;
std::set<size_t> closedset;
std::unordered_set<size_t> opensetMembership;
openset.push_back(start);
opensetMembership.insert(start);
size_t current = start;
while (!openset.empty()) {
current = openset.front();
openset.pop_front();
opensetMembership.erase(current);
if (current == goal) break;
closedset.insert(current);
for (const auto& edge : graph[current].edges) {
if (!closedset.contains(edge.index)) {
size_t dest = edge.index;
float tentativeG = gScore[current] + edge.cost;
// PATCHED: O(1) hash set lookup (1 probe counted)
bool isInOpenSet = opensetMembership.count(dest) > 0;
gProbeCount++; // just 1 probe
if (!isInOpenSet || tentativeG < gScore[dest]) {
graphParent[dest] = current;
gScore[dest] = tentativeG;
fScore[dest] = tentativeG + costAStar(points[dest], points[goal]);
if (!isInOpenSet) {
opensetMembership.insert(dest);
auto it = openset.begin();
for (; it != openset.end(); ++it)
if (fScore[*it] > fScore[dest]) break;
openset.insert(it, dest);
}
}
}
}
}
if (current != goal) return path;
while (graphParent[current] != NoIndex) {
path.push_front(current);
current = graphParent[current];
}
path.push_front(start);
return path;
}
}
// Build a dense random-weight graph. All nodes at same position (0,0,0) so
// heuristic is zero and A* degenerates to Dijkstra, maximizing openset size.
void buildDenseGraph(size_t N, size_t edgesPerNode, std::vector<Node>& graph, std::vector<Point>& points) {
graph.resize(N);
points.resize(N);
for (size_t i = 0; i < N; i++) {
points[i] = {0, 0, 0}; // zero heuristic = Dijkstra
for (size_t j = 1; j <= edgesPerNode && i + j < N; j++) {
float cost = 100.0f + (float)(i * 7 + j * 13) * 0.1f; // varying costs
graph[i].edges.push_back({i + j, cost});
graph[i + j].edges.push_back({i, cost});
}
}
}
int main() {
const size_t N = 2000;
const size_t edgesPerNode = 8;
std::vector<Node> graph;
std::vector<Point> points;
buildDenseGraph(N, edgesPerNode, graph, points);
size_t start = 0;
size_t goal = N - 1;
// Correctness: paths must be identical
gProbeCount = 0;
auto p1 = Defective::aStarSearch(graph, points, start, goal);
gProbeCount = 0;
auto p2 = Patched::aStarSearch(graph, points, start, goal);
assert(p1 == p2);
printf("PASS correctness: paths match, length=%zu (N=%zu)\n", p1.size(), N);
// Operation count comparison
gProbeCount = 0;
Defective::aStarSearch(graph, points, start, goal);
size_t defOps = gProbeCount;
gProbeCount = 0;
Patched::aStarSearch(graph, points, start, goal);
size_t patOps = gProbeCount;
double opRatio = (double)defOps / (double)patOps;
printf("Defective probes: %zu Patched probes: %zu Op-count ratio: %.1fx\n",
defOps, patOps, opRatio);
fflush(stdout);
assert(opRatio > 2.0 && "Patched should have at least 2x fewer probes");
printf("PASS performance: %.1fx fewer membership probes\n", opRatio);
return 0;
}

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defects/openmw-0003/patch/openmw-0003.patch Normal file
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@ -0,0 +1,54 @@
# UNDF: UNDF-2026-000000965
--- a/apps/openmw/mwworld/cellstore.cpp
+++ b/apps/openmw/mwworld/cellstore.cpp
@@ -1,4 +1,5 @@
#include "cellstore.hpp"
+#include <unordered_set>
// ...existing includes...
@@ -745,6 +746,12 @@
// Build mMovedRefs lookup set once before iterating references.
+ std::unordered_set<ESM::RefNum, ESM::RefNum::HashPair> movedRefSet;
+ movedRefSet.reserve(cell.mMovedRefs.size());
+ for (const auto& moved : cell.mMovedRefs)
+ movedRefSet.insert(moved.mRefNum);
+
// ...existing code for loading references...
for (size_t i = 0; i < cell.mContextList.size(); i++)
{
@@ -770,8 +777,7 @@
if (deleted || moved)
continue;
- // Don't list reference if it was moved to a different cell.
- ESM::MovedCellRefTracker::const_iterator iter
- = std::find(cell.mMovedRefs.begin(), cell.mMovedRefs.end(), ref.mRefNum);
- if (iter != cell.mMovedRefs.end())
+ // Don't list reference if it was moved to a different cell (O(1) lookup).
+ if (movedRefSet.count(ref.mRefNum))
{
continue;
}
@@ -853,8 +859,13 @@
+ // Build mMovedRefs lookup set once before iterating references.
+ std::unordered_set<ESM::RefNum, ESM::RefNum::HashPair> movedRefSet2;
+ movedRefSet2.reserve(cell.mMovedRefs.size());
+ for (const auto& moved : cell.mMovedRefs)
+ movedRefSet2.insert(moved.mRefNum);
+
for (size_t i = 0; i < cell.mContextList.size(); i++)
{
@@ -862,8 +873,7 @@
if (moved)
continue;
- // Don't load reference if it was moved to a different cell.
- ESM::MovedCellRefTracker::const_iterator iter
- = std::find(cell.mMovedRefs.begin(), cell.mMovedRefs.end(), ref.mRefNum);
- if (iter != cell.mMovedRefs.end())
+ // Don't load reference if it was moved to a different cell (O(1) lookup).
+ if (movedRefSet2.count(ref.mRefNum))
{
continue;
}

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defects/openmw-0003/test/openmw-0003-test.cpp Normal file
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@ -0,0 +1,118 @@
// openmw-0003-test.cpp
// CWE-407: cellstore.cpp mMovedRefs std::find O(R*M)
//
// During cell loading, for each reference read from an ESM file, the code calls
// std::find(cell.mMovedRefs.begin(), cell.mMovedRefs.end(), ref.mRefNum) to check
// if the reference was moved to a different cell. mMovedRefs is a
// std::list<MovedCellRef>, so this is O(M) per reference. With R references and
// M moved refs, total cost is O(R*M).
//
// This pattern appears in cellstore.cpp (listRefs and loadRefs) and
// objectpaging.cpp. Cells can have hundreds of references and dozens of moved refs.
//
// Fix: build an unordered_set of moved ref numbers once before iterating, O(R+M).
#include <algorithm>
#include <cassert>
#include <chrono>
#include <cstdio>
#include <list>
#include <unordered_set>
#include <vector>
struct RefNum {
int mIndex;
int mContentFile;
bool operator==(const RefNum& other) const {
return mIndex == other.mIndex && mContentFile == other.mContentFile;
}
struct Hash {
size_t operator()(const RefNum& r) const {
return std::hash<long long>()(((long long)r.mContentFile << 32) | (unsigned)r.mIndex);
}
};
};
struct MovedCellRef {
RefNum mRefNum;
int mTarget[2];
bool operator==(const RefNum& ref) const {
return mRefNum == ref;
}
};
using MovedCellRefTracker = std::list<MovedCellRef>;
// ---------- DEFECTIVE: std::find on list per reference ----------
int loadRefsDefective(const std::vector<RefNum>& refs, const MovedCellRefTracker& movedRefs) {
int loaded = 0;
for (const auto& ref : refs) {
// O(M) linear scan per reference
auto iter = std::find(movedRefs.begin(), movedRefs.end(), ref);
if (iter != movedRefs.end())
continue;
loaded++;
}
return loaded;
}
// ---------- PATCHED: unordered_set pre-built once ----------
int loadRefsPatched(const std::vector<RefNum>& refs, const MovedCellRefTracker& movedRefs) {
std::unordered_set<RefNum, RefNum::Hash> movedRefSet;
movedRefSet.reserve(movedRefs.size());
for (const auto& moved : movedRefs)
movedRefSet.insert(moved.mRefNum);
int loaded = 0;
for (const auto& ref : refs) {
// O(1) hash set lookup
if (movedRefSet.count(ref))
continue;
loaded++;
}
return loaded;
}
int main() {
const int R = 5000; // references per cell
const int M = 200; // moved references
// Build test data
std::vector<RefNum> refs;
refs.reserve(R);
for (int i = 0; i < R; i++)
refs.push_back({i, 0});
MovedCellRefTracker movedRefs;
for (int i = 0; i < M; i++)
movedRefs.push_back({{i * 3, 0}, {0, 0}}); // every 3rd ref is moved
// Correctness
int r1 = loadRefsDefective(refs, movedRefs);
int r2 = loadRefsPatched(refs, movedRefs);
assert(r1 == r2);
printf("PASS correctness: both loaded %d refs (R=%d, M=%d)\n", r1, R, M);
// Performance
auto bench = [&](auto fn) {
auto t0 = std::chrono::high_resolution_clock::now();
for (int i = 0; i < 50; i++)
fn(refs, movedRefs);
auto t1 = std::chrono::high_resolution_clock::now();
return std::chrono::duration<double, std::milli>(t1 - t0).count() / 50.0;
};
double defMs = bench(loadRefsDefective);
double patMs = bench(loadRefsPatched);
double ratio = defMs / patMs;
printf("Defective: %.2f ms Patched: %.2f ms Ratio: %.1fx (R=%d, M=%d)\n",
defMs, patMs, ratio, R, M);
assert(ratio > 3.0 && "Patched should be at least 3x faster");
printf("PASS performance: %.1fx speedup\n", ratio);
return 0;
}

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defects/openmw-0004/patch/openmw-0004.patch Normal file
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@ -0,0 +1,29 @@
# UNDF: UNDF-2026-000000966
--- a/apps/openmw/mwrender/objectpaging.cpp
+++ b/apps/openmw/mwrender/objectpaging.cpp
@@ -1,4 +1,5 @@
#include "objectpaging.hpp"
+#include <unordered_set>
// ...existing includes...
@@ -555,6 +556,12 @@
+ // Build mMovedRefs lookup set once per cell for O(1) membership check.
+ std::unordered_set<ESM::RefNum, ESM::RefNum::HashPair> movedRefSet;
+ movedRefSet.reserve(cell->mMovedRefs.size());
+ for (const auto& moved : cell->mMovedRefs)
+ movedRefSet.insert(moved.mRefNum);
+
{
try
{
@@ -573,8 +580,7 @@
if (moved)
continue;
- if (std::find(cell->mMovedRefs.begin(), cell->mMovedRefs.end(), ref.mRefNum)
- != cell->mMovedRefs.end())
+ if (movedRefSet.count(ref.mRefNum))
continue;
int type = store.findStatic(ref.mRefID);

122
defects/openmw-0004/test/openmw-0004-test.cpp Normal file
View file

@ -0,0 +1,122 @@
// openmw-0004-test.cpp
// CWE-407: objectpaging.cpp mMovedRefs std::find O(R*M) per cell during paging
//
// In ObjectPaging::createChunk, for every reference read from a cell ESM file,
// std::find(cell->mMovedRefs.begin(), cell->mMovedRefs.end(), ref.mRefNum) is
// called. This is the same mMovedRefs linear-scan pattern as openmw-0003, but
// in the object paging codepath which processes many cells during terrain loading.
//
// Fix: build unordered_set of moved ref numbers once per cell, O(1) lookups.
#include <algorithm>
#include <cassert>
#include <chrono>
#include <cstdio>
#include <list>
#include <unordered_set>
#include <vector>
struct RefNum {
int mIndex;
int mContentFile;
bool operator==(const RefNum& other) const {
return mIndex == other.mIndex && mContentFile == other.mContentFile;
}
struct Hash {
size_t operator()(const RefNum& r) const {
return std::hash<long long>()(((long long)r.mContentFile << 32) | (unsigned)r.mIndex);
}
};
};
struct MovedCellRef {
RefNum mRefNum;
bool operator==(const RefNum& ref) const {
return mRefNum == ref;
}
};
using MovedCellRefTracker = std::list<MovedCellRef>;
struct Cell {
MovedCellRefTracker mMovedRefs;
};
// Simulate processing refs from multiple cells (object paging processes many cells)
// ---------- DEFECTIVE ----------
int processPageDefective(const std::vector<Cell>& cells, const std::vector<std::vector<RefNum>>& cellRefs) {
int processed = 0;
for (size_t c = 0; c < cells.size(); c++) {
for (const auto& ref : cellRefs[c]) {
// O(M) per ref per cell
if (std::find(cells[c].mMovedRefs.begin(), cells[c].mMovedRefs.end(), ref)
!= cells[c].mMovedRefs.end())
continue;
processed++;
}
}
return processed;
}
// ---------- PATCHED ----------
int processPagePatched(const std::vector<Cell>& cells, const std::vector<std::vector<RefNum>>& cellRefs) {
int processed = 0;
for (size_t c = 0; c < cells.size(); c++) {
// Build set once per cell
std::unordered_set<RefNum, RefNum::Hash> movedSet;
movedSet.reserve(cells[c].mMovedRefs.size());
for (const auto& moved : cells[c].mMovedRefs)
movedSet.insert(moved.mRefNum);
for (const auto& ref : cellRefs[c]) {
if (movedSet.count(ref))
continue;
processed++;
}
}
return processed;
}
int main() {
const int numCells = 25; // typical paging chunk processes ~25 cells
const int refsPerCell = 500;
const int movedPerCell = 100;
std::vector<Cell> cells(numCells);
std::vector<std::vector<RefNum>> cellRefs(numCells);
for (int c = 0; c < numCells; c++) {
for (int i = 0; i < refsPerCell; i++)
cellRefs[c].push_back({i, c});
for (int i = 0; i < movedPerCell; i++)
cells[c].mMovedRefs.push_back({{i * 4, c}});
}
// Correctness
int r1 = processPageDefective(cells, cellRefs);
int r2 = processPagePatched(cells, cellRefs);
assert(r1 == r2);
printf("PASS correctness: both processed %d refs (%d cells x %d refs)\n",
r1, numCells, refsPerCell);
// Performance
auto bench = [&](auto fn) {
auto t0 = std::chrono::high_resolution_clock::now();
for (int i = 0; i < 100; i++)
fn(cells, cellRefs);
auto t1 = std::chrono::high_resolution_clock::now();
return std::chrono::duration<double, std::milli>(t1 - t0).count() / 100.0;
};
double defMs = bench(processPageDefective);
double patMs = bench(processPagePatched);
double ratio = defMs / patMs;
printf("Defective: %.2f ms Patched: %.2f ms Ratio: %.1fx\n", defMs, patMs, ratio);
assert(ratio > 2.0 && "Patched should be at least 2x faster");
printf("PASS performance: %.1fx speedup\n", ratio);
return 0;
}