https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100758
--- Comment #17 from Erich Eckner <gcc at eckner dot net> --- With that, I get a segfault in cpuid(): (gdb) run Starting program: /tmp/a.out [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/libthread_db.so.1". Program received signal SIGSEGV, Segmentation fault. 0x0000555555555191 in cpuid () (gdb) bt #0 0x0000555555555191 in cpuid () #1 0x00005555555551ef in main () (gdb) ... same on x86_64 - maybe, there's a typo, somewhere?