https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57202
--- Comment #7 from Jeffrey Walton <noloader at gmail dot com> --- Please forgive my ignorance... What was fixed? The problem statement is/was "Please make all headers for intrinsics be includable without special compiler flags." But it appears the intrinsics are not available. I'm working with Ubuntu 16/GCC 5.4 on an old VIA C7 (SSE and SSE2, and some other extensions): flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge cmov pat clflush acpi mmx fxsr sse sse2 tm nx pni est tm2 xtpr rng rng_en ace ace_en ace2 ace2_en phe phe_en pmm pmm_en The SSSE3 intrinsics are causing a compile error: g++ -g2 -O2 -march=native -pipe -c test.cpp In file included from /usr/lib/gcc/i686-linux-gnu/5/include/x86intrin.h:37:0, from cpu.h:40, from aria.cpp:8: /usr/lib/gcc/i686-linux-gnu/5/include/tmmintrin.h: In member function void ‘test_ssse3()’: /usr/lib/gcc/i686-linux-gnu/5/include/tmmintrin.h:136:1: error: inlining failed in call to always_inline ‘__m128i _mm_shuffle_epi8(__m128i, __m128i)’: target specific option mismatch _mm_shuffle_epi8 (__m128i __X, __m128i __Y) It appears the intrinsics are not available.