Re: [PATCH] elf: Replace memcmp with __memcmpeq for variable size

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 08/02/2022 19:30, Wilco Dijkstra via Libc-alpha wrote:
> Hi,
> 
>>>  My understanding is this optimization would eventually be implemented by
>>
>> What kinds of codes should compilers generate?  For glibc internal
>> usage, we can write codes in such a way that the generated codes
>> are very similar to what compilers should generate.
>>
>>>  the compiler, so maybe it would be better to let it optimize if suitable
>>>  (similar to what we are aiming for math code).
> 
> I agree with Joseph that these kind of micro-optimizations are generally counter productive -
> we've removed many similar hacks from math libraries resulting in good speedups (they
> almost always work against you, blocking compiler optimizations such as inlining, constant
> propagation etc). It's much better to improve code via algorithm or implementation
> optimizations rather than focus on these micro-optimizations.
> 
> As mentioned, codesize will increase since many applications now use both memcmp and
> __memcmpeq, and the extra I-cache misses may wipe out any savings.

This was also mine and Florian's view on this specific optimization back
on Monday's call.