On Tue, Jun 20, 2017 at 04:12:32PM -0700, David Rientjes wrote: > On Tue, 20 Jun 2017, Mark Rutland wrote: > > > As with my reply to David, my preference would be that we: > > > > 1) Align compiler-clang.h with the compiler-gcc.h inlining behaviour, so > > that things work by default. > > > > 2) Fix up the arm64 core code (and drivers for architected / common > > peripherals) to use __always_inline where we always require inlining. > > > > 3) Have arm64 select CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING, and have > > people test-build configurations with CONFIG_OPTIMIZE_INLINING, with > > both GCC and clang. > > > > 4) Fix up drivers, etc, as appropriate. > > > > 5) Once that's largely stable, and if there's a benefit, have arm64 > > select CONFIG_OPTIMIZE_INLINING by default. > > > > That should avoid undue breakage, while enabling this ASAP. > > > > Sounds good, but I think we should simply deal with the > __attribute__((unused)) needed for clang as part of compiler-gcc.h by > simply adding it to the inline override there to avoid duplicated code.
Agreed. That looks much better. Thanks, Mark. > > diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h > --- a/include/linux/compiler-clang.h > +++ b/include/linux/compiler-clang.h > @@ -15,11 +15,3 @@ > * with any version that can compile the kernel > */ > #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), > __COUNTER__) > - > -/* > - * GCC does not warn about unused static inline functions for > - * -Wunused-function. This turns out to avoid the need for complex #ifdef > - * directives. Suppress the warning in clang as well. > - */ > -#undef inline > -#define inline inline __attribute__((unused)) notrace > diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h > index 0efef9cf014f..71fe0994cf1a 100644 > --- a/include/linux/compiler-gcc.h > +++ b/include/linux/compiler-gcc.h > @@ -66,18 +66,22 @@ > > /* > * Force always-inline if the user requests it so via the .config, > - * or if gcc is too old: > + * or if gcc is too old. > + * GCC does not warn about unused static inline functions for > + * -Wunused-function. This turns out to avoid the need for complex #ifdef > + * directives. Suppress the warning in clang as well by using "unused" > + * function attribute, which is redundant but not harmful for gcc. > */ > #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ > !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) > -#define inline inline __attribute__((always_inline)) > notrace > -#define __inline__ __inline__ __attribute__((always_inline)) notrace > -#define __inline __inline __attribute__((always_inline)) notrace > +#define inline inline __attribute__((always_inline,unused)) > notrace > +#define __inline__ __inline__ __attribute__((always_inline,unused)) > notrace > +#define __inline __inline __attribute__((always_inline,unused)) notrace > #else > /* A lot of inline functions can cause havoc with function tracing */ > -#define inline inline notrace > -#define __inline__ __inline__ notrace > -#define __inline __inline notrace > +#define inline inline __attribute__((unused)) notrace > +#define __inline__ __inline__ __attribute__((unused)) notrace > +#define __inline __inline __attribute__((unused)) notrace > #endif > > #define __always_inline inline __attribute__((always_inline))
