Re: [PATCH] Fix x86_64 memchr for large input sizes

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

On 20/12/2016 15:07, Richard Henderson wrote:
> On 12/20/2016 06:03 AM, Adhemerval Zanella wrote:
>> +	sbb	%eax, %eax
>> +	movslq	%eax, %rax
> 
> This should be "sbb %rax, %rax" in one step.
> 
>> +	orq	%rdx, %rax
>> +	mov	%rax, %rdx
> 
> Given that the comment says you wanted the result in %rdx,
> why not "or %rax, %rdx"?

Indeed it seems the 4 instructions can be simplified to just

        sbb     %rax, %rax
        or      %rax, %rdx

Thanks for the advice.