Hi Helge,
I don't believe the compiler can implement __arch_swab64() as efficiently as the inline assembly
code. The compiler doesn't know about the permh or hsh instructions.
Dave
On 2021-09-03 4:03 a.m., Helge Deller wrote:
> No need to keep those as inline assembly functions, the compiler now
> generates the same or even better optimized code.
>
> Signed-off-by: Helge Deller <deller@xxxxxx>
>
> diff --git a/arch/parisc/include/uapi/asm/swab.h b/arch/parisc/include/uapi/asm/swab.h
> deleted file mode 100644
> index 35fb2d1bfbbd..000000000000
> --- a/arch/parisc/include/uapi/asm/swab.h
> +++ /dev/null
> @@ -1,68 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> -#ifndef _PARISC_SWAB_H
> -#define _PARISC_SWAB_H
> -
> -#include <asm/bitsperlong.h>
> -#include <linux/types.h>
> -#include <linux/compiler.h>
> -
> -#define __SWAB_64_THRU_32__
> -
> -static inline __attribute_const__ __u16 __arch_swab16(__u16 x)
> -{
> - __asm__("dep %0, 15, 8, %0\n\t" /* deposit 00ab -> 0bab */
> - "shd %%r0, %0, 8, %0" /* shift 000000ab -> 00ba */
> - : "=r" (x)
> - : "0" (x));
> - return x;
> -}
> -#define __arch_swab16 __arch_swab16
> -
> -static inline __attribute_const__ __u32 __arch_swab24(__u32 x)
> -{
> - __asm__("shd %0, %0, 8, %0\n\t" /* shift xabcxabc -> cxab */
> - "dep %0, 15, 8, %0\n\t" /* deposit cxab -> cbab */
> - "shd %%r0, %0, 8, %0" /* shift 0000cbab -> 0cba */
> - : "=r" (x)
> - : "0" (x));
> - return x;
> -}
> -
> -static inline __attribute_const__ __u32 __arch_swab32(__u32 x)
> -{
> - unsigned int temp;
> - __asm__("shd %0, %0, 16, %1\n\t" /* shift abcdabcd -> cdab */
> - "dep %1, 15, 8, %1\n\t" /* deposit cdab -> cbab */
> - "shd %0, %1, 8, %0" /* shift abcdcbab -> dcba */
> - : "=r" (x), "=&r" (temp)
> - : "0" (x));
> - return x;
> -}
> -#define __arch_swab32 __arch_swab32
> -
> -#if __BITS_PER_LONG > 32
> -/*
> -** From "PA-RISC 2.0 Architecture", HP Professional Books.
> -** See Appendix I page 8 , "Endian Byte Swapping".
> -**
> -** Pretty cool algorithm: (* == zero'd bits)
> -** PERMH 01234567 -> 67452301 into %0
> -** HSHL 67452301 -> 7*5*3*1* into %1
> -** HSHR 67452301 -> *6*4*2*0 into %0
> -** OR %0 | %1 -> 76543210 into %0 (all done!)
> -*/
> -static inline __attribute_const__ __u64 __arch_swab64(__u64 x)
> -{
> - __u64 temp;
> - __asm__("permh,3210 %0, %0\n\t"
> - "hshl %0, 8, %1\n\t"
> - "hshr,u %0, 8, %0\n\t"
> - "or %1, %0, %0"
> - : "=r" (x), "=&r" (temp)
> - : "0" (x));
> - return x;
> -}
> -#define __arch_swab64 __arch_swab64
> -#endif /* __BITS_PER_LONG > 32 */
> -
> -#endif /* _PARISC_SWAB_H */
--
John David Anglin dave.anglin@xxxxxxxx
