On Thu, 1 Aug 2019 at 08:47, Valdis Klētnieks <valdis.kletnieks@xxxxxx> wrote: > > On Thu, 01 Aug 2019 08:01:54 +0300, Ard Biesheuvel said: > > > > ERROR: "crypto_aegis128_decrypt_chunk_simd" [crypto/aegis128.ko] undefined! > > > ERROR: "crypto_aegis128_update_simd" [crypto/aegis128.ko] undefined! > > > ERROR: "crypto_aegis128_encrypt_chunk_simd" [crypto/aegis128.ko] undefined! > > > make[1]: *** [scripts/Makefile.modpost:105: modules-modpost] Error 1 > > > make: *** [Makefile:1299: modules] Error 2 > > > Which compiler version are you using? All references to the > > crypt_aegis128_xx_simd() routines should disappear if > > CONFIG_CRYPTO_AEGIS128_SIMD is not set (in which case have_simd will > > always be false and so the compiler should optimize away those calls). > > gcc 9.1.1 obviously doesn't think it can be optimized away. Apparently, it's > not smart enough to realize that nothing sets have_simd in any of the functions > and therefor it's guaranteed to be zero, and it can do dead code optimization > based on that. > > Now, if we had something like: > > #ifdef CONFIG_CRYPTO_AEGIS_128_SIMD > static bool have_simd; > #else > #define have_simd (0) > #endif > > then that should be enough to tell the compiler it can optimize it away, except > that then runs into problems here: > > if (IS_ENABLED(CONFIG_CRYPTO_AEGIS128_SIMD)) > have_simd = crypto_aegis128_have_simd(); > > because it will whine about the lack of an lvalue before it optimizes the assignment away... The fact that crypto_aegis128_have_simd() does get optimized away, but crypto_aegis128_update_simd() doesn't (which is only called directly and not via a function pointer like the other two routines) makes me suspicious that this is some pathology in the compiler. Is this a distro build of gcc? Also, which architecture are you compiling for?
