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Re: [PATCH] Fix wrong code on aarch64 due to paradoxical subreg
- From: Bernd Edlinger <bernd dot edlinger at hotmail dot de>
- To: Jeff Law <law at redhat dot com>, Segher Boessenkool <segher at kernel dot crashing dot org>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, Eric Botcazou <ebotcazou at adacore dot com>, Bernd Schmidt <bschmidt at redhat dot com>, Andreas Schwab <schwab at linux-m68k dot org>, Tamar Christina <tamar dot christina at arm dot com>
- Date: Wed, 3 Aug 2016 14:25:14 +0000
- Subject: Re: [PATCH] Fix wrong code on aarch64 due to paradoxical subreg
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Hi,
Is it OK for the trunk?
I guess so, but need an explicit OK.
Thanks
Bernd.
On 08/01/16 20:52, Bernd Edlinger wrote:
> Hi Jeff,
>
> On 08/01/16 19:54, Jeff Law wrote:
>> Looks like you've probably nailed it. It'll be interesting see if
>> there's any fallout (though our RTL optimizer testing is pretty weak, so
>> even if there were, I doubt we'd catch it).
>>
>
> If there is, it will probably a performance regression...
>
> Anyway I'd say these two patches do just disable actually wrong
> transformations. So here are both patches as separate diffs
> with your suggestion for the comment in cse_insn.
>
> I believe that on x86_64 both patches do not change a single bit.
>
> However I think there are more paradoxical subregs generated all over,
> but the aarch64 insv code pattern did trigger more hidden bugs than
> any other port. It is certainly unfortunate that the major source
> of paradoxical subreg is in a target-dependent code path :(
>
> Please apologize that I am not able to reduce/finalize the aarch64 test
> case at this time, as I usually only work with arm and intel targets,
> but I made an exception here, because a bug like that may affect all
> targets sooner or later.
>
>
> Boot-strap and reg-testing on x86_64-linux-gnu.
> Plus aarch64 bootstrap and isl-testing by Andreas.
>
>
> Is it OK for trunk?
>
>
>
> Thanks
> Bernd.