&gt; The way the x87 FP stack works is a bit weird, and these days it’s better to do floating-point arithmetic using xmm registers<p>x87 allows to do calculations in extended precision, i.e. word width is 80 bits. SSE is limited to double precision (64-bit words). Also FPU has some advanced math instructions, like sin, cos, tan, exp, etc., and these operations will be available in AVX512F.