On Wed, May 11, 2016 at 05:16:38PM +0800, zengzhao...@163.com wrote:
> +static inline unsigned int __arch_parity4(unsigned int w)
> +{
> + unsigned int res = 0;
> +
> + asm("test $0xf, %1; setpo %b0"
> + : "+q" (res)
> + : "r" (w)
> + : "cc");
> +
> + return res;
> +}
> +
> +static inline unsigned int __arch_parity8(unsigned int w)
> +{
> + unsigned int res = 0;
> +
> + asm("test %1, %1; setpo %b0"
> + : "+q" (res)
> + : "r" (w)
> + : "cc");
> +
> + return res;
> +}
> +
> +static inline unsigned int __arch_parity16(unsigned int w)
> +{
> + unsigned int res = 0;
> +
> + asm("xor %h1, %b1; setpo %b0"
> + : "+q" (res), "+q" (w)
> + : : "cc");
> +
> + return res;
> +}
Please use the GEN_*_RMWcc() stuff to avoid the setpo where possible.
> +
> +#ifdef CONFIG_64BIT
> +/* popcnt %eax, %eax -- redundant REX prefix for alignment */
> +#define POPCNT32 ".byte 0xf3,0x40,0x0f,0xb8,0xc0"
> +/* popcnt %rax, %rax */
> +#define POPCNT64 ".byte 0xf3,0x48,0x0f,0xb8,0xc0"
> +#else
> +/* popcnt %eax, %eax */
> +#define POPCNT32 ".byte 0xf3,0x0f,0xb8,0xc0"
> +#endif
Yuck, please don't duplicate stuff like this.
> +
> +static __always_inline unsigned int __arch_parity32(unsigned int w)
> +{
> + unsigned int res;
> + unsigned int tmp;
> +
> + asm(ALTERNATIVE(
> + " mov %%eax, %1 \n"
> + " shr $16, %%eax \n"
> + " xor %1, %%eax \n"
> + " xor %%ah, %%al \n"
> + " mov $0, %%eax \n"
> + " setpo %%al \n",
> + POPCNT32 " \n"
> + " and $1, %%eax \n",
> + X86_FEATURE_POPCNT)
> + : "=a" (res), "=&r" (tmp)
> + : "a" (w)
> + : "cc");
> +
> + return res;
> +}
How many bytes does that end up being? Should we make it a call?
