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Re: New optimized string routines for Intel and alignment of stack.

On 06/07/2016 02:25 PM, Zack Weinberg wrote:

On Tue, Jun 7, 2016 at 8:23 AM, Florian Weimer <fweimer@redhat.com> wrote:

On 06/07/2016 01:51 PM, Adhemerval Zanella wrote:


Also, is there any performance issue with current unaligned version


I think there is a performance penalty from not using vectorized copies for
small structs.  Even unaligned SSE loads/stores would be a win for the
example I posted, I assume.


Is the gain from using vectorized copies large enough that manually
aligning the stack in functions that want to use those instructions
would be worth it?
Probably not, using unaligned loads/stores would likely be cheaper than stack alignment (unless the function already has a frame pointer for another reason). 

Florian
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