[PATCH] powerpc: Use global register variable in <thread_pointer.h>

[Raphael M Zinsly]

LGTM

Reviewed-by: Raphael M Zinsly <rzinsly@linux.ibm.com>

On 15/12/2021 06:54, Florian Weimer via Libc-alpha wrote:
> A local register variable is merely a compiler hint, and so not
> appropriate in this context.  Move the global register variable into
> <thread_pointer.h> and include it from <tls.h>, as there can only
> be one global definition for one particular register.
> 
> Fixes commit 8dbeb0561eeb876f557ac9eef5721912ec074ea5
> ("nptl: Add <thread_pointer.h> for defining __thread_pointer").
> 
> Built with build-many-glibcs.py.
> 
> Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> 
> ---
>   sysdeps/powerpc/nptl/thread_pointer.h | 13 +++++++------
>   sysdeps/powerpc/nptl/tls.h            |  7 +------
>   2 files changed, 8 insertions(+), 12 deletions(-)
> 
> diff --git a/sysdeps/powerpc/nptl/thread_pointer.h b/sysdeps/powerpc/nptl/thread_pointer.h
> index 8fd5ba671f..4feba59610 100644
> --- a/sysdeps/powerpc/nptl/thread_pointer.h
> +++ b/sysdeps/powerpc/nptl/thread_pointer.h
> @@ -19,15 +19,16 @@
>   #ifndef _SYS_THREAD_POINTER_H
>   #define _SYS_THREAD_POINTER_H
> 
> -static inline void *
> -__thread_pointer (void)
> -{
>   #ifdef __powerpc64__
> -  register void *__result asm ("r13");
> +register void *__thread_register asm ("r13");
>   #else
> -  register void *__result asm ("r2");
> +register void *__thread_register asm ("r2");
>   #endif
> -  return __result;
> +
> +static inline void *
> +__thread_pointer (void)
> +{
> +  return __thread_register;
>   }
> 
>   #endif /* _SYS_THREAD_POINTER_H */
> diff --git a/sysdeps/powerpc/nptl/tls.h b/sysdeps/powerpc/nptl/tls.h
> index 63098f4048..d03fcb6983 100644
> --- a/sysdeps/powerpc/nptl/tls.h
> +++ b/sysdeps/powerpc/nptl/tls.h
> @@ -26,6 +26,7 @@
>   # include <stddef.h>
>   # include <stdint.h>
>   # include <dl-dtv.h>
> +# include <thread_pointer.h>
> 
>   #else /* __ASSEMBLER__ */
>   # include <tcb-offsets.h>
> @@ -36,16 +37,10 @@
>   #ifndef __powerpc64__
>   /* Register r2 (tp) is reserved by the ABI as "thread pointer". */
>   # define PT_THREAD_POINTER PT_R2
> -# ifndef __ASSEMBLER__
> -register void *__thread_register __asm__ ("r2");
> -# endif
> 
>   #else /* __powerpc64__ */
>   /* Register r13 (tp) is reserved by the ABI as "thread pointer". */
>   # define PT_THREAD_POINTER PT_R13
> -# ifndef __ASSEMBLER__
> -register void *__thread_register __asm__ ("r13");
> -# endif
>   #endif /* __powerpc64__ */
> 
>   #ifndef __ASSEMBLER__
> 

-- 
Raphael Moreira Zinsly