-mcet was removed by
commit
231baae28ef7ff784683fa5a80df119da2b9a99b
Author: H.J. Lu <hongjiu.lu@intel.com>
Date: Tue Apr 24 16:56:04 2018 +0000
x86/CET: Remove the -mcet command-lint option
PR target/98162
* doc/extend.texi: Remove -mcet.
unsigned int __builtin_ia32_rdpkru ()
@end smallexample
-The following built-in functions are available when @option{-mcet} or
+The following built-in functions are available when
@option{-mshstk} option is used. They support shadow stack
machine instructions from Intel Control-flow Enforcement Technology (CET).
Each built-in function generates the machine instruction that is part