[llvm-dev] [canonicalization] GEP 0, 0

[Piotr Padlewski via llvm-dev]

On Dec 23, 2016 19:47, "Daniel Berlin" <dberlin at dberlin.org> wrote:

Define soon?
My guess is 1 year or less.
(I've already seen patches to start converting most remaining memdep uses,
like memcpy opt, licm, etc)


That's good. Anyway I already have a patch that is doing invariant group
dependence across BBs, so I guess it make sense to push it upstream to push
the bar higher.
But I think we are getting a little bit of topic - should gep 0 be
canonicalized to bitcast?

Piotr


On Fri, Dec 23, 2016 at 8:27 AM, Piotr Padlewski via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

>
>
> 2016-12-23 17:22 GMT+01:00 Davide Italiano <davide at freebsd.org>:
>
>> On Fri, Dec 23, 2016 at 8:12 AM, Piotr Padlewski via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>> > Hi everyone,
>> >
>> > I started digging into MemDep to enhance devirtualization and I found
>> out
>> > that it doesn't handle invariant.group if it will find GEP 0, 0.
>> > If I understand it correctly getelementptr with zeros is just bitcast.
>> Is
>> > there any good reason why it is not canonicalized into bitcast?
>> >
>>
>> Hi,
>> is there any particular reason why you're trying to fix this in MemDep
>> (and not in MemSSA?)
>>
>> GVN uses MemDep and  MemSSA doesn't handle invariant.group. I was told
> that MemDep won't go out soon and it is easier for me right now to fix my
> stuff there than in MemSSA. I have plans to write support for MemSSA, but
> probably not in near future.
>
>
>> --
>> Davide
>>
>> "There are no solved problems; there are only problems that are more
>> or less solved" -- Henri Poincare
>>
>
>
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