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SubjectRe: [PATCH] compiler, clang: Add always_inline attribute to inline
On Mon, 19 Jun 2017, Prasad Sodagudi wrote:

> Commit abb2ea7dfd82 ("compiler, clang: suppress warning for unused
> static inline functions") re-defining the 'inline' macro but
> __attribute__((always_inline)) is missing. Some compilers may
> not honor inline hint if always_iniline attribute not there.
> So add always_inline attribute to inline as done by
> compiler-gcc.h file.
>

IIUC, __attribute__((always_inline)) was only needed for gcc versions < 4
and that the inlining decision making is improved in >= 4. To make a
change like this, I would think that we would need to show that clang is
making suboptimal decisions. I don't think there's a downside to making
CONFIG_OPTIMIZE_INLINING specific only to gcc.

If it is shown that __attribute__((always_inline)) is needed for clang as
well, this should be done as part of compiler-gcc.h to avoid duplicated
code.

> Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
> ---
> include/linux/compiler-clang.h | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
> index d614c5e..deb65b3 100644
> --- a/include/linux/compiler-clang.h
> +++ b/include/linux/compiler-clang.h
> @@ -22,4 +22,9 @@
> * directives. Suppress the warning in clang as well.
> */
> #undef inline
> +#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
> + !defined(CONFIG_OPTIMIZE_INLINING)
> +#define inline inline __attribute__((always_inline)) __attribute__((unused)) notrace
> +#else
> #define inline inline __attribute__((unused)) notrace
> +#endif

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