[Bug target/65369] [5 Regression] nettle test failure on powerpc64le-linux-gnu when built with -O3

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65369

--- Comment #30 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Alan Modra from comment #28)
> Created attachment 35024 [details]
> modified testcase without bswap optimization
> 
> This modified testcase avoids triggering the bswap optimization but still
> shows a failure at -O3.  So definitely not a problem caused by Thomas' patch.
> 
> -O3 -fno-tree-slp-vectorize is OK
> 
> -O3 slp dump shows weird offset of +12 between vector loads rather than +16
> as is usual

Well, that's the realign-load sequence.  Load ptr & ~15 and then load (ptr +
12) & ~15.  If ptr is already aligned both loads should load from the same
location.

SLP happens in md4_update only (but it's quite trivial).