If somebody writes a + x(b + x(c + ...)) one should expect this code to be future-proof and work with any compiler. But if code is mixed with inline assembly,

If somebody writes a + x(b + x(c + ...)) one should expect this code to be future-proof and work with any compiler. But if code is mixed with inline assembly, the result will be doubtful, at least. No need to be a prophet. First CPU with AVX appeared 3 years ago. Haswell was announced 6 months ago. There are no AVX-512 solutions for home users yet, but one can write AVX512-opimized code without any special knowledge.