The builtin function `__builtin_ia32_rdtscp()` is undocumented

Marc Glisse marc.glisse@inria.fr
Mon Apr 24 06:29:00 GMT 2017


On Mon, 24 Apr 2017, Liu Hao wrote:

> Today I accidentally found the built-in function `__builtin_ia32_rdtscp()` on 
> GCC6, but there is no documentation about it on 
> <http://gcc.gnu.org/onlinedocs/gcc/x86-Built-in-Functions.html>. Is this an 
> oversight?

I don't know if it is an oversight, but I think documenting the builtins 
is a bad idea, you are supposed to use the intrinsics instead, in this 
case __rdtscp, which is documented by Intel (and Microsoft).

-- 
Marc Glisse



More information about the Gcc-help mailing list