[Bug rtl-optimization/126290] x86-64 -fPIC drops `register asm` operands of an `asm` when a `__thread` address is another operand

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126290

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Note, in GCC 16+ you can use hard register constraints:
https://gcc.gnu.org/onlinedocs/gcc-16.1.0/gcc/Hard-Register-Constraints.html