Re: [PATCH 07/31] Add mips-specific parity functions

[Zeng Zhaoxiu]

å 2016å03æ29æ 01:25, David Daney åé:
> On 03/26/2016 11:06 PM, zhaoxiu.zeng wrote:
> > From: Zeng Zhaoxiu <zhaoxiu.zeng@xxxxxxxxx>
>
> There is nothing MIPS specific here.  Why not put it in asm-generic or 
> some similar place where it can be shared by all architectures?
>
> Also, are you sure __builtin_popcount() is available on all GCC 
> versions that are supported for building the kernel?
>
> David Daney

Refrence to arch_hweight.h.

In the 68th line of 
arch/mips/include/asm/mach-cavium-octeon/cpu-feature-overrides.h, we can 
see:

#ifdef __OCTEON__
/*
 * All gcc versions that have OCTEON support define __OCTEON__ and have the
 *  __builtin_popcount support.
 */
#define ARCH_HAS_USABLE_BUILTIN_POPCOUNT 1
#endif

/*
 * All gcc versions that have OCTEON support define __OCTEON__ and have the
 *  __builtin_popcount support.
 */

> > Signed-off-by: Zeng Zhaoxiu <zhaoxiu.zeng@xxxxxxxxx>
> > ---
> >   arch/mips/include/asm/arch_parity.h | 44 
> > +++++++++++++++++++++++++++++++++++++
> >   arch/mips/include/asm/bitops.h      |  3 +++
> >   2 files changed, 47 insertions(+)
> >   create mode 100644 arch/mips/include/asm/arch_parity.h
> >
> > diff --git a/arch/mips/include/asm/arch_parity.h 
> > b/arch/mips/include/asm/arch_parity.h
> > new file mode 100644
> > index 0000000..23b3c23
> > --- /dev/null
> > +++ b/arch/mips/include/asm/arch_parity.h
> > @@ -0,0 +1,44 @@
> > +/*
> > + * This file is subject to the terms and conditions of the GNU 
> > General Public
> > + * License.  See the file "COPYING" in the main directory of this 
> > archive
> > + * for more details.
> > + *
> > + */
> > +#ifndef _ASM_ARCH_PARITY_H
> > +#define _ASM_ARCH_PARITY_H
> > +
> > +#ifdef ARCH_HAS_USABLE_BUILTIN_POPCOUNT
> > +
> > +#include <asm/types.h>
> > +
> > +static inline unsigned int __arch_parity32(unsigned int w)
> > +{
> > +    return __builtin_popcount(w) & 1;
> > +}
> > +
> > +static inline unsigned int __arch_parity16(unsigned int w)
> > +{
> > +    return __arch_parity32(w & 0xffff);
> > +}
> > +
> > +static inline unsigned int __arch_parity8(unsigned int w)
> > +{
> > +    return __arch_parity32(w & 0xff);
> > +}
> > +
> > +static inline unsigned int __arch_parity4(unsigned int w)
> > +{
> > +    return __arch_parity32(w & 0xf);
> > +}
> > +
> > +static inline unsigned int __arch_parity64(__u64 w)
> > +{
> > +    return (unsigned int)__builtin_popcountll(w) & 1;
> > +}
> > +
> > +#else
> > +#include <asm-generic/bitops/arch_hweight.h>
> > +#include <asm-generic/bitops/arch_parity.h>
> > +#endif
> > +
> > +#endif /* _ASM_ARCH_PARITY_H */
> > diff --git a/arch/mips/include/asm/bitops.h 
> > b/arch/mips/include/asm/bitops.h
> > index ce9666c..0b87734 100644
> > --- a/arch/mips/include/asm/bitops.h
> > +++ b/arch/mips/include/asm/bitops.h
> > @@ -626,6 +626,9 @@ static inline int ffs(int word)
> >   #include <asm/arch_hweight.h>
> >   #include <asm-generic/bitops/const_hweight.h>
> >
> > +#include <asm/arch_parity.h>
> > +#include <asm-generic/bitops/const_parity.h>
> > +
> >   #include <asm-generic/bitops/le.h>
> >   #include <asm-generic/bitops/ext2-atomic.h>