static void crc_init()

in common/checksum/crc.cpp [127:155]

• 29 lines of code
• 10 McCabe index (conditional complexity)

static void crc_init() {
#if defined(__x86_64__)
    __builtin_cpu_init();
    crc32c_auto = __builtin_cpu_supports("sse4.2") ? crc32c_hw : crc32c_sw;
    auto avx512 = __builtin_cpu_supports("avx512f")  &&
                  __builtin_cpu_supports("avx512dq") &&
                  __builtin_cpu_supports("avx512vl") &&
                  __builtin_cpu_supports("vpclmulqdq");
    crc64ecma_auto = avx512 ? crc64ecma_hw_avx512 :
                 (__builtin_cpu_supports("sse") &&
                  __builtin_cpu_supports("pclmul")) ?
                        crc64ecma_hw_sse128 : crc64ecma_sw;
#elif defined(__aarch64__)
#ifdef __APPLE__  // apple silicon has hw for both crc
    crc32c_auto = crc32c_hw;
    crc64ecma_auto = crc64ecma_hw_sse128;
#elif defined(__linux__)  // linux on arm: runtime detection
    long hwcaps= getauxval(AT_HWCAP);
    crc32c_auto = (hwcaps & HWCAP_CRC32) ? crc32c_hw : crc32c_sw;
    crc64ecma_auto = (hwcaps & HWCAP_PMULL) ? crc64ecma_hw_sse128 : crc64ecma_sw;
#else
    crc32c_auto = crc32c_sw;
    crc64ecma_auto = crc64ecma_sw;
#endif
#else // not __aarch64__, not __x86_64__
    crc32c_auto = crc32c_sw;
    crc64ecma_auto = crc64ecma_sw;
#endif
}