[llvm] r185794 - Fix PromoteIntRes_BUILD_VECTOR crash with i1 vectors

[Duncan Sands]

Hi Hal,

>> That doesn't sound like a bug, since BUILD_VECTOR explicitly allows
>> the
>> operands to be bigger than the result element type (see above).
>>   However
>> your patch seems to be dealing with the opposite problem (if I read
>> it
>> right): a BUILD_VECTOR where the result element type is larger than
>> the
>> input operand type.  So I'm kind of confused by your description and
>> the
>> comment in the code, since it doesn't seem to match what the patch
>> does.
>
> Thanks for looking at this, but I don't understand why you're confused ;) -- In the situation in the test case, a (<v?i1> = BV <i32>, <i32>, ...) node is having its result promoted. The result of this promotion is (v?i16 = BV <i32>, <i32>, ...). The old code would blindly any_extend the operands to the vector element type of the result (i16 in this case), causing an assertion failure (because we can't any_extend <i32> to <i16>). All I've done in the patch is make sure that the any_extend is legal before we do it. Maybe I should remove mentioning booleans in the comment?

I read your patch wrong, sorry.  That said, if the operand type is (at least)
as big as the result type, then I guess there is no need to compute the Ops
array and create a new node, you could just mutate the return type of the
existing node in place (I don't recall if this is possible - I haven't worked
on codegen in a while).  Also, probably PromoteIntRes_SCALAR_TO_VECTOR has
exactly the same problem, because it's essentially doing the same thing as
BUILD_VECTOR.

Ciao, Duncan.

>
>   -Hal
>
>>
>> Ciao, Duncan.
>>
>>    As a result, we cannot blindly assume that we can ANY_EXTEND the
>>    operands
>>> to the result type.
>>>
>>> Added:
>>>       llvm/trunk/test/CodeGen/PowerPC/bv-pres-v8i1.ll
>>> Modified:
>>>       llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
>>>
>>> Modified:
>>> llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp?rev=185794&r1=185793&r2=185794&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
>>> (original)
>>> +++ llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
>>> Mon Jul  8 01:16:58 2013
>>> @@ -2930,7 +2930,13 @@ SDValue DAGTypeLegalizer::PromoteIntRes_
>>>      SmallVector<SDValue, 8> Ops;
>>>      Ops.reserve(NumElems);
>>>      for (unsigned i = 0; i != NumElems; ++i) {
>>> -    SDValue Op = DAG.getNode(ISD::ANY_EXTEND, dl, NOutVTElem,
>>> N->getOperand(i));
>>> +    SDValue Op;
>>> +    // It is possible for the operands to be larger than the
>>> result, for example,
>>> +    // when the operands are promoted booleans and the result was
>>> an i1 vector.
>>> +    if (N->getOperand(i).getValueType().bitsLT(NOutVTElem))
>>> +      Op = DAG.getNode(ISD::ANY_EXTEND, dl, NOutVTElem,
>>> N->getOperand(i));
>>> +    else
>>> +      Op = N->getOperand(i);
>>>        Ops.push_back(Op);
>>>      }