[PATCH] x86: Merge i386/x86_64 atomic-machine.h

[H.J. Lu]

On Mon, Dec 17, 2018 at 11:44 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 12/12/2018 19:36, H.J. Lu wrote:
> > Merge i386 and x86_64 atomic-machine.h to x86 atomic-machine.h.
> >
> > Tested on i686 and x86_64 as well as with build-many-glibcs.py.  There
> > are no code changes in libc.so, ld.so and libpthread.so on i686 and
> > x86_64.
> >
> >       * sysdeps/i386/atomic-machine.h: Merged with ...
> >       * sysdeps/x86_64/atomic-machine.h: To ...
> >       * sysdeps/x86/atomic-machine.h: This.  New file.
>
> LGTM with the only expection where I am not sure how to handle invalid
> sizes for x86_32 (comments below).
>

> > -#define __HAVE_64B_ATOMICS 1
> > -#define USE_ATOMIC_COMPILER_BUILTINS 1
> > -#define ATOMIC_EXCHANGE_USES_CAS 0
> > +#ifdef __x86_64__
> > +# define __HAVE_64B_ATOMICS          1
> > +# define USE_ATOMIC_COMPILER_BUILTINS        1
> > +# define SP_REG                              "rsp"
> > +# define SEG_REG                     "fs"
> > +# define BR_CONSTRAINT                       "q"
> > +# define IBR_CONSTRAINT                      "iq"
> > +#else
> > +# define __HAVE_64B_ATOMICS          0
> > +# define USE_ATOMIC_COMPILER_BUILTINS        0
> > +# define SP_REG                              "esp"
> > +# define SEG_REG                     "gs"
> > +# define BR_CONSTRAINT                       "r"
> > +# define IBR_CONSTRAINT                      "ir"
> > +#endif
> > +#define ATOMIC_EXCHANGE_USES_CAS     0
>
> Ok. As a side note, do you if we can use atomic compiler builtins for x86_32?
>

>
> The generic include/atomic.h explicit add a linker error (__atomic_link_error)
> when size is not supported. Since it is currently not used internally, I think
> we can make for x86 atomic.
>

Here is the updated patch.  The differences are

1. Define USE_ATOMIC_COMPILER_BUILTINS to 1 for x86.
2. Replace __builtin_unreachable with __atomic_link_error.

OK for master?

-- 
H.J.
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