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[Bug target/32951] missed memcpy -> movdqa optimization.
- From: "pluto at agmk dot net" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 6 Aug 2007 12:56:26 -0000
- Subject: [Bug target/32951] missed memcpy -> movdqa optimization.
- References: <bug-32951-7667@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #4 from pluto at agmk dot net 2007-08-06 12:56 -------
(In reply to comment #3)
> Subject: Re: missed memcpy -> movdqa optimization.
>
> On 6 Aug 2007 12:42:18 -0000, pluto at agmk dot net
> <gcc-bugzilla@gcc.gnu.org> wrote:
> > moreover i'm wondering why gcc uses movdqa for unaligned loads?
>
> Because __m128i is assumed to be aligned.
so, as far i can see currently there's no way to generate movdqu load
with <emmintrin.h> and __builtin_memcpy( &__m128i, unaligned_ptr, 16 )
and i must write a short inline assembly for this purpose.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32951