Re: movmem pattern and missed alignment

[Andrew Haley <aph at redhat dot com>]

On 10/08/2018 06:20 PM, Michael Matz wrote:
> Only if you somewhere visibly add accesses to *i and *j.  Without them you 
> only have the "accesses" via memcpy, and as Richi says, those don't imply 
> any alignment requirements.  The i and j pointers might validly be char* 
> pointers in disguise and hence be in fact only 1-aligned.  I.e. there's 
> nothing in your small example program from which GCC can infer that those 
> two global pointers are in fact 2-aligned.

So all you'd actually have to say is

void f1(void)
{
    *i; *j;
    __builtin_memcpy (i, j, 32);
}

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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