Re: [PATCH 3/6] powerpc sstep: Add cnttzw, cnttzd instruction emulation

[Segher Boessenkool]

On Mon, Sep 03, 2018 at 08:49:35PM +0530, Sandipan Das wrote:
> +             case 538:       /* cnttzw */
> +                     if (!cpu_has_feature(CPU_FTR_ARCH_300))
> +                             return -1;
> +                     val = (unsigned int) regs->gpr[rd];
> +                     op->val = ( val ? __builtin_ctz(val) : 32 );
> +                     goto logical_done;
> +#ifdef __powerpc64__
> +             case 570:       /* cnttzd */
> +                     if (!cpu_has_feature(CPU_FTR_ARCH_300))
> +                             return -1;
> +                     val = regs->gpr[rd];
> +                     op->val = ( val ? __builtin_ctzl(val) : 64 );
> +                     goto logical_done;

__builtin_ctz(val) is undefined for val == 0.


Segher