llvm dev - Dec 2015 - MSVC warning noise on "LLVM_ATTRIBUTE_ALWAYS_INLINE inline void foo()"

On Sun, Dec 20, 2015 at 5:24 PM, Xinliang David Li via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> LLVM_ATTRIBUTE_ALWAYS_INLINE is defined to be __forceinline for MSVC. I
> wonder why you get that warning.
inline and __forceinline don't mix with MSVC -- I believe they may be
modeled with the same attribute under the hood. I'm not certain of the
best way to solve this aside from suggesting to ignore C4141 locally.

~Aaron
>
> David
>
> On Sun, Dec 20, 2015 at 8:18 AM, Johan Engelen via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>>
>> Hi all,
>>   Some functions have "inline" specified twice by use of
>> LLVM_ATTRIBUTE_ALWAYS_INLINE.
>> For example in StringRef.h:
>>   LLVM_ATTRIBUTE_ALWAYS_INLINE
>>   inline bool operator==(StringRef LHS, StringRef RHS);
>>
>> This results in warning noise when compiled with MSVC 2015:
>>   \include\llvm/ADT/StringRef.h(567): warning C4141: 'inline':
used more
>> than once
>>   \include\llvm/ADT/StringRef.h(572): warning C4141: 'inline':
used more
>> than once
>>   \include\llvm/IR/User.h(43): warning C4141: 'inline': used
more than
>> once
>>
>> Thanks very much for a fix.
>> (I hope that simply removing the "inline" after
>> LLVM_ATTRIBUTE_ALWAYS_INLINE is correct)
>>
>> Kind regards,
>>   Johan
>>
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>
>
> _______________________________________________
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> llvm-dev at lists.llvm.org
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>

On Sun, Dec 20, 2015 at 11:28 PM, Aaron Ballman <aaron at
aaronballman.com>
wrote:
> On Sun, Dec 20, 2015 at 5:24 PM, Xinliang David Li via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> > LLVM_ATTRIBUTE_ALWAYS_INLINE is defined to be __forceinline for MSVC.
I
> > wonder why you get that warning.
>
> inline and __forceinline don't mix with MSVC -- I believe they may be
> modeled with the same attribute under the hood. I'm not certain of the
> best way to solve this aside from suggesting to ignore C4141 locally.
>
Perhaps LLVM_ATTRIBUTE_ALWAYS_INLINE could be defined to "inline" if
the
compiler has no support for always_inline (currently it is set to nothing
in that case) ?
I think this would allow removal of the "inline" after
LLVM_ATTRIBUTE_ALWAYS_INLINE.
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On Sun, Dec 20, 2015 at 5:57 PM, Johan Engelen <jbc.engelen at gmail.com>
wrote:
>
> On Sun, Dec 20, 2015 at 11:28 PM, Aaron Ballman <aaron at
aaronballman.com>
> wrote:
>>
>> On Sun, Dec 20, 2015 at 5:24 PM, Xinliang David Li via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>> > LLVM_ATTRIBUTE_ALWAYS_INLINE is defined to be __forceinline for
MSVC. I
>> > wonder why you get that warning.
>>
>> inline and __forceinline don't mix with MSVC -- I believe they may
be
>> modeled with the same attribute under the hood. I'm not certain of
the
>> best way to solve this aside from suggesting to ignore C4141 locally.
>
>
> Perhaps LLVM_ATTRIBUTE_ALWAYS_INLINE could be defined to "inline"
if the
> compiler has no support for always_inline (currently it is set to nothing
in
> that case) ?
> I think this would allow removal of the "inline" after
> LLVM_ATTRIBUTE_ALWAYS_INLINE.
Wouldn't this cause functions with MSVC that are marked
LLVM_ATTRIBUTE_ALWAYS_INLINE but not 'inline' to not be inlined? I
suppose a possible way is to make a #define
LLVM_ATTRIBUTE_INLINE_ALWAYS_INLINE that combines the two when not
compiling with MSVC, and then change all the requisite function
signatures to use this new macro instead. Uncertain of the value of
that, however.

~Aaron
>