[Bug inline-asm/66631] inability to clobber segment regs makes tls problematic

[stsp at users dot sourceforge.net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66631

--- Comment #12 from Stas Sergeev <stsp at users dot sourceforge.net> ---
Note that on x86_64 you can't set FS without a syscall.
I would really hate doing that in asm it seems.