On 12/26/22 23:25, Alejandro Colomar wrote:
> Hi Noah,
> 
> On 12/26/22 03:43, Noah Goldstein wrote:
> 
>> I see. The code you commented earlier was NULL for both.
> 
> I don't remember; maybe there was a typo...
> 
>>
>> Either way you can just make it:
>>
>> ```
>> if((dst - 1UL) >= (end - 1UL)) {
> 
> I didn't expect that would be significantly better than `(dst == end || dst == 
> NULL)`.  However, I compiled both just to see, and the assembly output for your 
> code is shorter.  I'll benchmark both to see if there are performance differences.
> 
> I wonder why the compiler doesn't generate this code if it's better; it has all 
> the information to decide that it can be transformed into that.
> 
> Both clang and GCC produce better code with your suggestion (although in the 
> case of GCC, the difference is bigger.

Self-correction:

They produce smaller code for your suggestion, but it seems to be slower code.

> 
> Cheers,
> 
> Alex
> 
>>   return dst; // either dst == NULL or dst == end.
>> }
>> ```
> 
> 

-- 
<http://www.alejandro-colomar.es/>