[PATCH] compiler, clang: Add always_inline attribute to inline
Sodagudi Prasad
psodagud at codeaurora.org
Mon Jun 19 14:14:26 PDT 2017
On 2017-06-19 13:25, David Rientjes wrote:
> 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.
Hi David,
Here is the discussion about this change -
https://lkml.org/lkml/2017/6/15/396
Please check mark and will's comments.
-Thanks, Prasad
>
>> Signed-off-by: Prasad Sodagudi <psodagud at 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
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
Forum,
Linux Foundation Collaborative Project
More information about the linux-arm-kernel
mailing list