[Bug target/59874] Missing builtin (__builtin_clzs) when compiling with g++

[Bug target/59874] Missing builtin (__builtin_clzs) when compiling with g++

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59874

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |x86_64-*-*
          Component|c++                         |target

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
It seems

#pragma GCC push_options
#pragma GCC target("lzcnt")

from lzcntintrin.h doesn't work with C++?

[Bug target/59874] Missing builtin (__builtin_clzs) when compiling with g++

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59874

Sam James <sjames at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sjames at gcc dot gnu.org
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=112789

--- Comment #18 from Sam James <sjames at gcc dot gnu.org> ---
(In reply to Allan Jensen from comment #8)
> Thanks that looks good. I will test it when I have a chance. I am changing
> the Qt sources to not assume the presence of __builtin_clzs when __BMI__ is
> defined. It can use __builtin_clz() and __builtin_ctz()-16U instead, but for
> general compatibility it is nice that GCC also keeps it around. 
> 
> Note, it would be even better though if GCC could support the short forms as
> generic builtins. That changes the semantics slightly, but they are named so
> similarly to the clz, clzl and clzll it would be easy to assume they also
> are generics, with similar semantics, and can work across all targets.
> 

GCC 14 will have __builtin_clzg, if you want to start using that:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112789#c4.