i#4842 drcachesim unit tests: Add cache_lru unit test (#5405)

Adds a unit test for clients/drcachesim/simulators/cache_lru.cpp.
This unit test catches a bug reported in i#4881 which was tested by
reverting the fix for that issue (PR #4883).

Issue: #4842, #4881

clients/drcachesim/CMakeLists.txt

@@ -499,7 +499,8 @@ endif ()
 # Be sure to give the targets qualified test names ("tool.drcache*...").
 
 if (BUILD_TESTS)
-  add_executable(tool.drcachesim.unit_tests tests/drcachesim_unit_tests.cpp)
+  add_executable(tool.drcachesim.unit_tests tests/drcachesim_unit_tests.cpp
+    tests/cache_replacement_policy_unit_test.cpp)
   if (ZLIB_FOUND)
     target_link_libraries(tool.drcachesim.unit_tests drmemtrace_simulator
       drmemtrace_static drmemtrace_analyzer ${ZLIB_LIBRARIES})

clients/drcachesim/tests/cache_replacement_policy_unit_test.cpp

@@ -0,0 +1,113 @@
+/* **********************************************************
+ * Copyright (c) 2016-2022 Google, Inc.  All rights reserved.
+ * **********************************************************/
+
+/*
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Google, Inc. nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without
+ *   specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL GOOGLE, INC. OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ */
+
+// Unit tests for cache replacement policies
+#include <iostream>
+#undef NDEBUG
+#include <assert.h>
+#include "cache_replacement_policy_unit_test.h"
+#include "simulator/cache_lru.h"
+
+class cache_lru_test_t : public cache_lru_t {
+public:
+    void
+    initialize_cache(int associativity, int line_size, int total_size)
+    {
+        caching_device_stats_t *stats = new cache_stats_t(line_size, "", true);
+        if (!init(associativity, line_size, total_size, nullptr, stats, nullptr)) {
+            std::cerr << "LRU cache failed to initialize\n";
+            exit(1);
+        }
+    }
+
+    int
+    get_block_index(const addr_t addr)
+    {
+        addr_t tag = compute_tag(addr);
+        int block_idx = compute_block_idx(tag);
+        return block_idx;
+    }
+
+    void
+    access_and_check_lru(const addr_t addr,
+                         const int expected_replacement_way_after_access)
+    {
+        memref_t ref;
+        ref.data.type = TRACE_TYPE_READ;
+        ref.data.size = 1;
+        ref.data.addr = addr;
+        request(ref);
+        assert(replace_which_way(get_block_index(addr)) ==
+               expected_replacement_way_after_access);
+    }
+};
+
+void
+unit_test_cache_lru_four_way()
+{
+    cache_lru_test_t cache_lru_test;
+    cache_lru_test.initialize_cache(/*associativity=*/4, /*line_size=*/32,
+                                    /*total_size=*/256);
+    const addr_t ADDRESS_A = 0;
+    const addr_t ADDRESS_B = 64;
+    const addr_t ADDRESS_C = 128;
+    const addr_t ADDRESS_D = 192;
+    const addr_t ADDRESS_E = 72;
+
+    assert(cache_lru_test.get_block_index(ADDRESS_A) ==
+           cache_lru_test.get_block_index(ADDRESS_B));
+    assert(cache_lru_test.get_block_index(ADDRESS_B) ==
+           cache_lru_test.get_block_index(ADDRESS_C));
+    assert(cache_lru_test.get_block_index(ADDRESS_C) ==
+           cache_lru_test.get_block_index(ADDRESS_D));
+    assert(cache_lru_test.get_block_index(ADDRESS_D) ==
+           cache_lru_test.get_block_index(ADDRESS_E));
+
+    // Access the cache line in the following fashion. This sequence follows the
+    // sequence shown in i#4881.
+    // Lower-case letter shows the least recently used way.
+    cache_lru_test.access_and_check_lru(ADDRESS_A, 1); // A x X X
+    cache_lru_test.access_and_check_lru(ADDRESS_B, 2); // A B x X
+    cache_lru_test.access_and_check_lru(ADDRESS_C, 3); // A B C x
+    cache_lru_test.access_and_check_lru(ADDRESS_D, 0); // a B C D
+    cache_lru_test.access_and_check_lru(ADDRESS_A, 1); // A b C D
+    cache_lru_test.access_and_check_lru(ADDRESS_A, 1); // A b C D
+    cache_lru_test.access_and_check_lru(ADDRESS_A, 1); // A b C D
+    cache_lru_test.access_and_check_lru(ADDRESS_E, 2); // A E c D
+}
+
+void
+unit_test_cache_replacement_policy()
+{
+    unit_test_cache_lru_four_way();
+    // XXX i#4842: Add more test sequences.
+}

clients/drcachesim/tests/cache_replacement_policy_unit_test.h

@@ -0,0 +1,39 @@
+/* **********************************************************
+ * Copyright (c) 2016-2022 Google, Inc.  All rights reserved.
+ * **********************************************************/
+
+/*
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Google, Inc. nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without
+ *   specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL GOOGLE, INC. OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ */
+
+#ifndef _CACHE_REPLACEMENT_POLICY_UNIT_TESTS_
+#define _CACHE_REPLACEMENT_POLICY_UNIT_TESTS_ 1
+
+void
+unit_test_cache_replacement_policy();
+
+#endif /* _CACHE_REPLACEMENT_POLICY_UNIT_TESTS_ */

clients/drcachesim/tests/drcachesim_unit_tests.cpp

@@ -33,7 +33,9 @@
 // Unit tests for drcachesim
 #include <iostream>
 #include <cstdlib>
+#undef NDEBUG
 #include <assert.h>
+#include "cache_replacement_policy_unit_test.h"
 #include "simulator/cache_simulator.h"
 #include "../common/memref.h"
 
@@ -313,5 +315,6 @@ main(int argc, const char *argv[])
     unit_test_warmup_refs();
     unit_test_sim_refs();
     unit_test_child_hits();
+    unit_test_cache_replacement_policy();
     return 0;
 }