Comment by astrange

ffmpeg only writes inner loops in assembly, and doesn't suffer too much. There would be speed gain in a few situations, but it's just not worth it when it would be so much harder to change the code.

But inside inner loops, you don't need to change code, and assembly can be easier to read and write than C. Have you seen Intel's C SIMD intrinsics? They're so ugly!

> C compiler are getting comparatively worse at optimizing for current hardware than an expert in assembly.

It seems to be Intel's opinion that optimizing compilers for specific desktop CPUs is not worth it. GCC and LLVM have machine-specific models for Atom CPUs, but almost nothing for desktops, even though Intel engineers work on those compilers.

They're probably right, since most people are running generic binaries.