[llvm-dev] MSVC warning noise on "LLVM_ATTRIBUTE_ALWAYS_INLINE inline void foo()"

[Johan Engelen via llvm-dev]

OK, thanks for the extra explanation.
I guess LDC will have to go the same route of silencing C4141 warnings (
http://llvm.org/viewvc/llvm-project?view=revision&revision=247275).

(sorry for the maillist noise ;)

- Johan


On Mon, Dec 21, 2015 at 3:57 PM, Aaron Ballman <aaron at aaronballman.com>
wrote:

> On Mon, Dec 21, 2015 at 6:40 AM, Johan Engelen <jbc.engelen at gmail.com>
> wrote:
> > On Mon, Dec 21, 2015 at 12:08 AM, Aaron Ballman <aaron at aaronballman.com>
> > wrote:
> >>
> >> On Sun, Dec 20, 2015 at 5:57 PM, Johan Engelen <jbc.engelen at gmail.com>
> >> wrote:
> >> >
> >> > 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?
> >
> >
> > __forceinline means that MSVC will always inline that function, that is
> why
> > the extra "inline" results in a warning.
>
> __forceinline is still just a hint to the compiler to do the inline,
> but it is a stronger hint that inline
> (https://msdn.microsoft.com/en-us/library/bw1hbe6y.aspx). inline is a
> keyword in C++ that has additional semantics that __forceinline is not
> required to have, such as the fact that an inline function with
> external linkage is required to have the same address in all TUs. I am
> not comfortable assuming that inline === __forceinline for all
> versions of MSVC (including future ones).
>
> ~Aaron
>
>
> >
> > I propose:
> > in llvm/Support/Compiler.h
> >
> >   #if __has_attribute(always_inline) || LLVM_GNUC_PREREQ(4, 0, 0)
> >   #define LLVM_ATTRIBUTE_ALWAYS_INLINE __attribute__((always_inline))
> >   #elif defined(_MSC_VER)
> >   #define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline
> >   #else
> > - #define LLVM_ATTRIBUTE_ALWAYS_INLINE
> > + #define LLVM_ATTRIBUTE_ALWAYS_INLINE inline
> >   #endif
> >
> > and elsewhere
> >
> >   LLVM_ATTRIBUTE_ALWAYS_INLINE
> > - inline bool operator==(StringRef LHS, StringRef RHS) {
> > + bool operator==(StringRef LHS, StringRef RHS) {
> >     return LHS.equals(RHS);
> >   }
> >
> > As far as I can tell from online documentation, that will do the correct
> > thing on MSVC and GCC. For non-MSVC, non-GCC, this will add "inline" in
> > front of some functions that do not have it right now, notably member
> > functions that are defined in the class definition (see e.g. StringRef.h
> > empty()). I will have to test if /that/ doesn't create a warning ;)
> >
> >  -Johan
> >
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20151221/d409a1b3/attachment-0001.html>