[PATCH] D40604: [GlobalISel][IRTranslator] Fix crash during translation of zero sized loads and stores

[Quentin Colombet via llvm-commits]

Sounds like the proposed patch is the right thing to do then :).

> On Nov 29, 2017, at 9:55 AM, Amara Emerson <aemerson at apple.com> wrote:
> 
> SDAGBuilder doesn’t create anything for loads and stores if the operands are zero size.
> 
> Amara
> 
>> On Nov 29, 2017, at 5:40 PM, Quentin Colombet <qcolombet at apple.com> wrote:
>> 
>> What does SDISel do in those situations?
>> 
>>> On Nov 29, 2017, at 9:27 AM, Amara Emerson via Phabricator via llvm-commits <llvm-commits at lists.llvm.org> wrote:
>>> 
>>> aemerson added inline comments.
>>> 
>>> 
>>> ================
>>> Comment at: lib/CodeGen/GlobalISel/IRTranslator.cpp:340-341
>>> 
>>> +  if (DL->getTypeStoreSize(LI.getType()) == 0)
>>> +    return true;
>>> +
>>> ----------------
>>> dsanders wrote:
>>>> I'm not sure this is correct for the load. If the load result has a use then I'd expect -verify-machineinstrs to complain about a missing def. I think we need to emit an IMPLICIT_DEF.
>>> That would require getting an LLT for a zero size type to create a vreg and running into the initial cause of the crash.
>>> 
>>> Also, is there anything meaningful you can do with the load result? You can't bitcast it to anything (I think?) and storing it won't result in a store being generated, so no instructions are emitted for the verifier.
>>> 
>>> 
>>> Repository:
>>> rL LLVM
>>> 
>>> https://reviews.llvm.org/D40604
>>> 
>>> 
>>> 
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>> 
>