[llvm-commits] [llvm] r140249 - in /llvm/trunk: lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp test/CodeGen/X86/2011-09-21-setcc-bug.ll

[Duncan Sands]

Hi Nadav,

>> --- llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp Wed Sep 21 09:34:38 2011
>> @@ -500,6 +500,8 @@
>>
>>    SDValue DAGTypeLegalizer::PromoteIntRes_SETCC(SDNode *N) {
>>      EVT SVT = TLI.getSetCCResultType(N->getOperand(0).getValueType());
>> +  // Vector setcc result types need to be leglized.
>> +  SVT = TLI.getTypeToTransformTo(*DAG.getContext(), SVT);
>
>> I think this is obviously wrong.  Consider a SETCC with operand type<256 x i8>
>
> Well, it was not obvious to me :)

OK :)

I think the thing to do is to only use the result of getSetCCResultType if
it is legal, and otherwise just use the usual promoted type (NVT).

> PromoteIntRes is called only when the return type needs to be IntPromoted.

Since the result type is a vector of i1 (isn't it?), this always happens.

> So the type,<256 x i8>  would be split before getting to this code. Right ?

In my example, that's the operand type not the result type.

>
> I will try to write an exhaustive test with many types and check if I can make this fail.

Thanks!

Ciao, Duncan.
>
> Thanks,
> Nadav
>
>
>> and return type<256 x i1>.  Then SVT will be<256 x i8>  on x86, but this will
>> then be turned into<128 x i8>  by your change, resulting in an invalid SETCC.
>
>> Ciao, Duncan.
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