The answer is obviously "no" because there's no such thing as "the set of all x86 instructions." Every vendor has many vendor-specific x86 extensions inside the

The answer is obviously "no" because there's no such thing as "the set of all x86 instructions." Every vendor has many vendor-specific x86 extensions inside their microcode, some of which end up being adopted by all other vendors (essentially becoming "canonized" as x86 proper). In some cases, these extensions are widely accepted (like x86-64, which was initially developed by AMD, hence its amd64 moniker). In other cases, these extensions die a quiet death, like 3DNow! (also one of AMD's extensions, introduced in their K6-2 line). And in other cases, extensions are only implemented for specific lines of processors (Xeons famously include AVX-512[1]). To look at a more concrete exemplification of this, gcc has both AVX-512 and 3DNow! flags[2] (because it was around back in 1998), while go only has AVX-512 flags (and doesn't care about deprecated extensions like 3DNow!). [1] https://colfaxresearch.com/skl-avx512/ https://colfaxresearch.com/skl-avx512/ [2] https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html