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Re: [PATCH, rs6000] Fix PR83789: __builtin_altivec_lvx fails for powerpc for altivec-4.c
On 3/21/18 7:37 PM, Segher Boessenkool wrote:
> On Wed, Mar 21, 2018 at 12:47:41PM -0500, Peter Bergner wrote:
>> I'll note that GCC 7 does not need any of the changes to rs6000-p8swap.c,
>> since that file doesn't exist and doesn't need to exist in GCC 7, so I've
>> left those changes out.
>
> Did that same code live in rs6000.c in GCC 7, or is it new since
> rs6000-p8swap.c was split off from there? And what about GCC 6?
The trunk patch's changes to rs6000-p8swap.c were to rs6000_gen_lvx and
rs6000_gen_stvx and those are new to GCC 8. They are used as part of
Kelvin's optimization that changes the little endian unfriendly vsx
loads and stores that require swaps, with the altivec lvx/stvx which
do not need swaps. That optimization was new to GCC 8, so there was
no need for the rs6000-p8swap.c changes.
If you're asking about whether we also need to backport to GCC 6, I
believe Kaushik said in the bugzilla that he only encountered the
ICE on GCC 7 and trunk, so I don't think we need a GCC 6 backport.
Peter