New optimized string routines for Intel and alignment of stack.

[Florian Weimer]

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

> Besides string routines, do we have any C code that relies on stack alignment
> on 32-bit x86?

Perhaps not today, but unless we change the ABI to the original 
definition, GCC is free to exploit the stack alignment for optimization 
purposes in the future.

> Also, is there any performance issue with current unaligned version or are you
> just worry that we might remove them in the future due a better optimized version
> that assumes aligned stack?

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.

Thanks,
Florian