[PATCH] D18830: [llvm] GVN.cpp: Do not swap when both LHS and RHS are arguments.

[Chandler Carruth via llvm-commits]

What Danny said here.

It feels like this patch is papering over failure to canonicalize. To make
progress we need to either:

a) Show a super clear example where there *is no canonicalization*. That
is, one usage wants one canonicalization and the other wants the other, so
we have to support both. If you can show that we cannot canonicalize this
because it is in tension with other canonicalization, that is exactly the
motivation that folks have asked for to land this patch.

or...

b) Fix everything to canonicalize so this patch isn't necessary.

On Wed, Apr 27, 2016 at 11:26 PM Daniel Berlin via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Chandler explicitly requested we take a different approach, and while I
> could overrule him, not sure it's worth it for this patch.
> I think we have spent more time on this thank it would take to track down
> every place generating it that ends up needing to be swapped and fixing it
> at the source
>
>
> On Wed, Apr 27, 2016, 12:23 PM Aditya Kumar <hiraditya at msn.com> wrote:
>
>> hiraditya added a comment.
>>
>> @dberlin
>> Please approve the patch if you are fine with it.
>>
>> Thanks,
>>
>>
>> Repository:
>>   rL LLVM
>>
>> http://reviews.llvm.org/D18830
>>
>>
>>
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