core: skip empty bitmap ranges during cache and scheduler traversal

Adapted bitmap scans from sylvieistaken/selevet-eglantine performance build 4. Keep the wide-priority fallback and fix the first live slot after empty bitmap words. Include randomized lifecycle and ordering checks.

Assisted by Codex.

1 files changed, 54 insertions, 0 deletions

diff --git a/src/tests/common/slot_vector.cpp b/src/tests/common/slot_vector.cpp
new file mode 100644
index 0000000000..d8f242085c
--- /dev/null
+++ b/src/tests/common/slot_vector.cpp
@@ -0,0 +1,54 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <map>
+#include <random>
+#include <vector>
+#include <catch2/catch_test_macros.hpp>
+#include "common/slot_vector.h"
+
+TEST_CASE("SlotVector visits live entries across empty bitmap words", "[common]") {
+    Common::SlotVector<u32> slots;
+    std::vector<Common::SlotId> ids;
+    for (u32 i = 0; i < 513; ++i) {
+        ids.push_back(slots.insert(i));
+    }
+    for (u32 i = 0; i < 512; ++i) {
+        slots.erase(ids[i]);
+    }
+    auto it = slots.begin();
+    REQUIRE(it != slots.end());
+    REQUIRE((*it).first == ids[512]);
+    REQUIRE(*(*it).second == 512);
+    REQUIRE(++it == slots.end());
+    slots.erase(ids[512]);
+    REQUIRE(slots.begin() == slots.end());
+}
+
+TEST_CASE("SlotVector sparse iteration matches a live-entry model", "[common]") {
+    Common::SlotVector<u32> slots;
+    std::map<u32, u32> live;
+    std::mt19937 random{9813};
+    for (u32 batch = 0; batch < 200; ++batch) {
+        for (u32 i = 0; i < 100; ++i) {
+            if (!live.empty() && (random() % 3) == 0) {
+                auto selected = live.begin();
+                std::advance(selected, random() % live.size());
+                slots.erase(Common::SlotId{selected->first});
+                live.erase(selected);
+            } else {
+                const u32 value = random();
+                const auto id = slots.insert(value);
+                live.emplace(id.Value(), value);
+            }
+        }
+        auto expected = live.begin();
+        for (const auto [id, value] : slots) {
+            REQUIRE(expected != live.end());
+            REQUIRE(id.Value() == expected->first);
+            REQUIRE(*value == expected->second);
+            ++expected;
+        }
+        REQUIRE(expected == live.end());
+    }
+}