[llvm-commits] [llvm] r137562 - /llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

[Eli Friedman]

2011/8/13 Rotem, Nadav <nadav.rotem at intel.com>:
> Eli,
>
> You have a good point. I didn't think about it. How do you suggest we fix it ?

Maybe expand it the same way DAGTypeLegalizer::ExpandOp_BUILD_VECTOR
does?  That isn't really guaranteed to work, but it'll probably work
in practice.

Longer-term, we should probably add a ConstantVector SDNode and get
rid of BUILD_VECTOR; that would get rid of a bunch of weirdness in
SelectionDAGs.

-Eli

> Thanks,
> Nadav
>
> -----Original Message-----
> From: Eli Friedman [mailto:eli.friedman at gmail.com]
> Sent: Sunday, August 14, 2011 01:06
> To: Rotem, Nadav
> Cc: llvm-commits at cs.uiuc.edu
> Subject: Re: [llvm-commits] [llvm] r137562 - /llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
>
> On Sat, Aug 13, 2011 at 1:31 PM, Nadav Rotem <nadav.rotem at intel.com> wrote:
>> Author: nadav
>> Date: Sat Aug 13 15:31:45 2011
>> New Revision: 137562
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=137562&view=rev
>> Log:
>> Fix PR 10635. When generating integer constants, the constant element type may
>> be illegal, even if the requested vector type is legal. Testcase is one of the
>> disabled ARM tests in the vector-select patch.
>>
>>
>> Modified:
>>    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
>>
>> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp?rev=137562&r1=137561&r2=137562&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Sat Aug 13 15:31:45 2011
>> @@ -928,6 +928,13 @@
>>   assert(Val.getBitWidth() == EltVT.getSizeInBits() &&
>>          "APInt size does not match type size!");
>>
>> +  // In some cases the vector type is legal but the element type is illegal.
>> +  // In this case, promote the inserted value. The type does not need to match
>> +  // the vector element type. Any extra bits introduced will be
>> +  // truncated away.
>> +  if (VT.isVector())
>> +    EltVT = TLI.getTypeToTransformTo(*getContext(), EltVT);
>
> This doesn't appear to handle the case where the transformed type is
> narrower than the original type (consider a v2i64 constant on x86-32).
>
> -Eli
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