assembly - Is x87 FP stack still relevant? -

assembly - Is x87 FP stack still relevant? -

i notice compilers generate code targets simd registers every time double arithmetic used. applies non-optimized optimized code. mean x87 fp unit can considered obsolete , nowadays backward compatibility?

i notice other "popular" platforms rely on respective simd implementations rather fp designed stack.

also simd implementations tend @ to the lowest degree 128bit wide, wonder mean (internal) precision of operations higher x87 fp unit?

i wonder performance, throughput , latency, considering simd has been conceived vector execution in mind, wonder how scalars.

also simd implementations tend @ to the lowest degree 128bit wide, wonder mean (internal) precision of operations higher x87 fp unit?

the width of simd register not width of 1 individual component of vector represents. available simd instruction sets offer @ ieee 754 binary64 format (64-bit wide). not historical 80-bit extended format precision or range.

many c compilers create 80-bit format available long double type. utilize often. utilize intermediate computations: using contributes create end result more accurate if end result destined returned binary64 double. 1 illustration function in this question, mathematically intuitive property holds of final result if intermediate computations done long double, not if intermediate computations done same double type inputs , output.

similarly, among many constraints had balanced in selection of parameters extended 80-bit format, 1 consideration is perfect compute binary64 function pow() composing 80-bit expl() , logl(). precision necessary in order obtain accuracy end-result.

i should note, however, when “intermediate” computations single basic operation, improve not go through extended precision. in other words, when x , y of type double, accuracy of (double)(x * (long double)y) worse accuracy of x * y. 2 expressions produce same results, , in rare cases differ, x * y more accurate. phenomenon called double-rounding.

assembly floating-point stack obsolete x87