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Re: movmem pattern and missed alignment
On Tue, Oct 9, 2018 at 11:00 AM Alexander Monakov <amonakov@ispras.ru> wrote:
>
> On Tue, 9 Oct 2018, Richard Biener wrote:
> >
> > then we cannot set the alignment of i_1 at/after k = *i_1 because doing so would
> > affect the alignment test which we'd then optimize away. We'd need to introduce
> > a SSA copy to get a new SSA name but that would be optimized away quickly.
>
> We preserve __builtin_assume_aligned up to pass-fold-all-builtins, so would it
> work to emit it just before the memcpy
>
> i_2 = __builtin_assume_aligned(i_1, 4);
> __builtin_memcpy(j, i_2, 32);
>
> in theory?
That's still before RTL expansion so I'm not sure that is enough.
Richard.
>
> Alexander