[opus] [PATCH] fix alignment exceptions

[Felicia Lim]

We see the MOVQ instruction but this patch deliberately uses it rather than
MOVQDA (load 128-bits aligned). We were seeing that with the trace below,
the final invocation is not 128-bit aligned but MOVQDA insists on it (the
calling function was pitch_sse4_1.c:90, in the 4-way N - i >= 4 loop).

07-31 11:00:13.469   210  2540 <(469)%20210-2540> D opus_sse1: RBE
celt_inner_prod_sse4_1: x 0xeff3deb0 y 0xeff3deb0 N 32
07-31 11:00:13.469   210  2540 <(469)%20210-2540> D opus_sse1: RBE
celt_inner_prod_sse4_1: x 0xeff3d7b0 y 0xeff3d7b0 N 32
07-31 11:00:13.469   210  2540 <(469)%20210-2540> D opus_sse1: RBE
celt_inner_prod_sse4_1: x 0xeff3df30 y 0xeff3df30 N 32
07-31 11:00:13.470   210  2540 <(470)%20210-2540> D opus_sse1: RBE
celt_inner_prod_sse4_1: x 0xeff3d850 y 0xeff3d850 N 48
07-31 11:00:13.470   210  2540 <(470)%20210-2540> D opus_sse1: RBE
celt_inner_prod_sse4_1: x 0xeff3dfd0 y 0xeff3dfd0 N 48
07-31 11:00:13.470   210  2540 <(470)%20210-2540> D opus_sse1: RBE
celt_inner_prod_sse4_1: x 0xeff3d8b0 y 0xeff3d8b0 N 64
07-31 11:00:13.470   210  2540 <(470)%20210-2540> D opus_sse1: RBE
celt_inner_prod_sse4_1: x 0xeff3e030 y 0xeff3e030 N 64
07-31 11:00:13.476   210  2540 D opus_sse1: RBE celt_inner_prod_sse4_1: x
0xeff3da38 y 0xeff3da38 N 36


On Fri, Aug 18, 2017 at 11:44 AM Jonathan Lennox <jonathan at vidyo.com> wrote:

> This would revert a patch I submitted two years ago (
> http://git.xiph.org/?p=opus.git;a=commitdiff;h=1d60b49e9d95672a17ebe5578319c59fa3963224
> ).
>
> At the time, clang produced an unnecessary MOVQ instruction when it
> compiled with the version of the code with the explicit _mm_loadl_epi64
> intrinsic.  Do you no longer see that?
>
> How does the code compile for you, and what is the issue you’re seeing?
>  (One issue might be that clang’s address sanitizer isn’t smart enough to
> know that PMOVSXWD only loads 8 bytes, despite _mm_cvtepi16_epi32’s
> argument being an __mm128i; I’ve seen it trigger incorrect out-of-bounds
> read errors.)
>
> On Aug 18, 2017, at 12:34 PM, Felicia Lim <flim at google.com> wrote:
>
> Hi,
>
> Please find attached a patch to fix alignment exceptions. Without this
> change, we were seeing occasional alignment faults when using this with
> clang.
>
> Thanks,
> Felicia
>
> <e5c277c.diff>_______________________________________________
> opus mailing list
> opus at xiph.org
> http://lists.xiph.org/mailman/listinfo/opus
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.xiph.org/pipermail/opus/attachments/20170818/55dd7ab9/attachment.html>