[Libre-soc-dev] memcpy optimization

Jacob Lifshay programmerjake at gmail.com
Fri Dec 11 18:35:09 GMT 2020


On Fri, Dec 11, 2020, 10:26 Jacob Lifshay <programmerjake at gmail.com> wrote:

> On Fri, Dec 11, 2020, 09:26 Luke Kenneth Casson Leighton <lkcl at lkcl.net>
> wrote:
>
>> If it's just a little smaller, it can compile
>> > directly to a 64-bit load and a 64-bit store or similar code for other
>> > sizes.
>> >
>>
>> no... it really can't.  this is the dangers of the SIMD approach.
>>
>
> it *can* and *does already* when the memory block size is known at
> compile-time (assuming alignment requirements are met).
>

See https://gcc.godbolt.org/z/KrTcfY

Jacob

>


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