[libc-commits] [libc] [llvm] [libc] Improve qsort (PR #120450)

[Michael Jones via libc-commits]

================
@@ -315,15 +278,76 @@ class SortingTest : public LIBC_NAMESPACE::testing::Test {
   void test_single_element(SortingRoutine sort_func) {
     int array[] = {12345};
 
-    constexpr size_t ARRAY_SIZE = sizeof(array) / sizeof(int);
-
-    auto arr = Array(reinterpret_cast<uint8_t *>(array), ARRAY_SIZE,
-                     sizeof(int), Comparator(int_compare));
+    constexpr size_t ARRAY_LEN = sizeof(array) / sizeof(int);
 
-    sort_func(arr);
+    int_sort(sort_func, array, ARRAY_LEN);
 
     ASSERT_EQ(array[0], 12345);
   }
+
+  void test_different_elem_size(SortingRoutine sort_func) {
+    // Random order of values [0,50) to avoid only testing pre-sorted handling.
+    // Long enough to reach interesting code.
+    constexpr uint8_t ARRAY_INITIAL_VALS[] = {
+        42, 13, 8,  4,  17, 28, 20, 32, 22, 29, 7,  2,  46, 37, 26, 49, 24,
+        38, 10, 18, 40, 36, 47, 15, 11, 48, 44, 33, 1,  5,  16, 35, 39, 41,
+        14, 23, 3,  9,  6,  27, 21, 25, 31, 45, 12, 43, 34, 30, 19, 0};
+
+    constexpr size_t ARRAY_LEN = sizeof(ARRAY_INITIAL_VALS);
+    constexpr size_t MAX_ELEM_SIZE = 150;
+    constexpr size_t BUF_SIZE = ARRAY_LEN * MAX_ELEM_SIZE;
+
+    static_assert(ARRAY_LEN < 256); // so we can encode the values.
+
+    // Minimum alignment to test implementation for bugs related to assuming
+    // incorrect association between alignment and element size.
+    alignas(1) uint8_t buf[BUF_SIZE];
+
+    const auto fill_buf = [&buf](size_t elem_size) {
+      for (size_t i = 0; i < BUF_SIZE; ++i) {
+        buf[i] = 0;
+      }
+
+      for (size_t elem_i = 0, buf_i = 0; elem_i < ARRAY_LEN; ++elem_i) {
+        const uint8_t elem_val = ARRAY_INITIAL_VALS[elem_i];
+        for (size_t elem_byte_i = 0; elem_byte_i < elem_size; ++elem_byte_i) {
+          buf[buf_i] = elem_val;
+          buf_i += 1;
+        }
+      }
+    };
----------------
michaelrj-google wrote:

this might be better as a standalone function instead of a lambda.

https://github.com/llvm/llvm-project/pull/120450