Yep - and there are absolutely some cases where you do want to manually use it which is why the x86_64 ABI on SysV (used by Linux and OS X, still specifies the long double type as 80-bits, and why GCC and Clang will still emit these instructions when long doubles are used!

(Sorry, this is more for the folks who aren't familiar with this, since it seems like you are familiar, but I didn't want it to seem like this isn't widely supported when they read "legacy" or "some platforms")

Here is a good toy examples that runs into the same numbers shown in the parent, showing the two different instruction types, and that long double can give you the correct answer, while still being run in hardware, vs. going all the way to float128s which are currently emulated in software!

Code w/ Assembly: https://godbolt.org/z/W3ZmqJ Output: https://onlinegdb.com/Sy_I3Q1ME