[LLVMdev] [NVPTX] Backend failure in LegalizeDAG due to unimplemented expand in target lowering

[Dmitry N. Mikushin]

Hi Duncan,

Sorry I don't understand your point, could you please explain a little bit more?
Why i1 should be declared illegal? Operations on byte-wide types like
char or bool are pretty legal, according to PTX spec:

"Registers may be typed (signed integer, unsigned integer, floating
point, predicate) or untyped. Register size is restricted; aside from
predicate registers which are 1-bit, scalar registers have a width of
8-, 16-, 32-, or 64-bits, and vector registers have a width of 16-,
32-, 64-, or 128-bits. The most common use of 8-bit registers is with
ld, st, and cvt instructions, or as elements of vector tuples."

Thanks,
- D.

2012/6/30 Duncan Sands <baldrick at free.fr>:
> Hi Dmitry,
>
>>> did you declare i1 to be an illegal type?
>>
>>
>> No. How?
>
>
> I think it will be considered illegal if you don't add it to any
> register class.
>
> Ciao, Duncan.
>
>
>>
>> 2012/6/30 Duncan Sands <baldrick at free.fr>:
>>>
>>> Hi Dmitry,
>>>>
>>>> So instead of setOperationAction(ISD::STORE, MVT::i1, Expand); one
>>>> should probably do setOperationAction(ISD::STORE, MVT::i1, Custom);
>>>> and implement it in NVPTXTargetLowering::LowerOperation.
>>>>
>>>> But this issue makes a good point about the code efficiency: I suspect
>>>> such expansion will be very ugly in terms of performance. Probably we
>>>> can do much better if bool would use i32 instead of i1. I don't know
>>>> how to do that, though. Is it possible?
>>>
>>>
>>> did you declare i1 to be an illegal type?  If so, you shouldn't get any
>>> stores of i1 at this stage (you may get trunc stores to i1, but that is
>>> different).
>>>
>>> Ciao, Duncan.
>>>
>>>>
>>>> Anyway, if this is a defect, then it's a blocker for us, and we'd much
>>>> appreciate a fix.
>>>>
>>>> - D.
>>>>
>>>> 2012/6/29 Eli Friedman <eli.friedman at gmail.com>:
>>>>>
>>>>> On Fri, Jun 29, 2012 at 2:11 PM, Dmitry N. Mikushin
>>>>> <maemarcus at gmail.com> wrote:
>>>>>>
>>>>>> Hi again,
>>>>>>
>>>>>> Kind people on #llvm helped me to utilize bugpoint to reduce the
>>>>>> previously submitted test case. For record, it code be done with the
>>>>>> following command:
>>>>>>
>>>>>> $ bugpoint -llc-safe test.ll
>>>>>>
>>>>>> The resulting IR is attached, and it is crashing in the same way. Is
>>>>>> it a valid code?
>>>>>
>>>>>
>>>>> Looks like a bug in the NVPTXISelLowering.cpp: it has
>>>>> "setOperationAction(ISD::STORE, MVT::i1, Expand);", but the legalizer
>>>>> doesn't know how to handle that.
>>>>>
>>>>> -Eli
>>>>
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>>>
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>
>
>