Function test_large_memory_utilities

scripts/test_stringzilla.cpp:1344–1415

* @brief Tests memory utilities on large buffers (>1MB) that trigger special code paths * in AVX2/AVX512 implementations. This specifically tests the bidirectional * traversal optimization used for huge buffers. */

 *          traversal optimization used for huge buffers.
 */
void test_large_memory_utilities() {
    // Test sizes that trigger the "huge buffer" path (> 1MB)
    std::vector<std::size_t> test_sizes = {
        1024ull * 1024ull + 1,       // Just over 1MB
        1024ull * 10ull * 103ull,    // From GitHub issue #228: 1,055,360 bytes
        2ull * 1024ull * 1024ull,    // 2MB
        3ull * 1024ull * 1024ull + 7 // 3MB + 7 (unaligned size)
    };

    for (std::size_t size : test_sizes) {
        // Test memcpy with aligned buffers
        {
            std::vector<char> src(size);
            std::vector<char> dst_std(size);
            std::vector<char> dst_sz(size);

            // Fill source with pattern to detect copying errors
            for (std::size_t i = 0; i < size; i++) { src[i] = static_cast<char>('A' + (i % 26)); }

            std::memcpy(dst_std.data(), src.data(), size);
            sz::memcpy(dst_sz.data(), src.data(), size);

            expect_equality(dst_std.data(), dst_sz.data(), size);
        }

        // Test memcpy with unaligned buffers
        {
            std::vector<char> src_buf(size + 64);
            std::vector<char> dst_std_buf(size + 64);
            std::vector<char> dst_sz_buf(size + 64);

            // Use unaligned pointers
            char *src = src_buf.data() + 7;
            char *dst_std = dst_std_buf.data() + 11;
            char *dst_sz = dst_sz_buf.data() + 11;

            for (std::size_t i = 0; i < size; i++) { src[i] = static_cast<char>('a' + (i % 26)); }

            std::memcpy(dst_std, src, size);
            sz::memcpy(dst_sz, src, size);

            expect_equality(dst_std, dst_sz, size);
        }

        // Test memset
        {
            std::vector<char> buf_std(size);
            std::vector<char> buf_sz(size);

            std::memset(buf_std.data(), 'Z', size);
            sz::memset(buf_sz.data(), 'Z', size);

            expect_equality(buf_std.data(), buf_sz.data(), size);
        }

        // Test memmove with overlapping regions
        {
            std::vector<char> buf_std(size);