Re: [PATCH 06/10] powerpc: remove GCC version check for UPD_CONSTR

[Nathan Chancellor]

On 9/10/2021 4:40 PM, Nick Desaulniers wrote:
> Now that GCC 5.1 is the minimum supported version, we can drop this
> workaround for older versions of GCC. This adversely affected clang,
> too.
>
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> Cc: Paul Mackerras <paulus@xxxxxxxxx>
> Cc: Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx>
> Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
> Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> ---
>   arch/powerpc/include/asm/asm-const.h | 10 ----------
>   1 file changed, 10 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/asm-const.h b/arch/powerpc/include/asm/asm-const.h
> index 0ce2368bd20f..dbfa5e1e3198 100644
> --- a/arch/powerpc/include/asm/asm-const.h
> +++ b/arch/powerpc/include/asm/asm-const.h
> @@ -12,16 +12,6 @@
>   #  define ASM_CONST(x)		__ASM_CONST(x)
>   #endif
>   
> -/*
> - * Inline assembly memory constraint
> - *
> - * GCC 4.9 doesn't properly handle pre update memory constraint "m<>"
> - *
> - */
> -#if defined(GCC_VERSION) && GCC_VERSION < 50000
> -#define UPD_CONSTR ""
> -#else
>   #define UPD_CONSTR "<>"
> -#endif

The only reason this exists is because of commit 592bbe9c505d 
("powerpc/uaccess: Don't use "m<>" constraint with GCC 4.9"). It is 
probably just worth sinking "<>" into all of the callsites and removing
UPD_CONSTR.

>   
>   #endif /* _ASM_POWERPC_ASM_CONST_H */