[llvm-commits] Buggy SelectionDAG binop vector widening

[Visa Putkinen]

On Thu, Jun 03, 2010 at 11:12:59AM -0700, Dale Johannesen wrote:
> On Jun 3, 2010, at 6:27 AMPDT, Visa Putkinen wrote:
>> The function responsible for widening vector binary operation nodes in
>> SelectionDAGs (DAGTypeLegalizer::WidenVecRes_Binary in
>> lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp, r105388) returns
>> incorrect results for many vector lengths and even triggers asserts on
>> lengths 9 and 13. I didn't find a bug report about this bug.
>>
>>
>> +        NextVT = EVT::getVectorVT(*DAG.getContext(), WidenEltVT,  
>> NextSize);
>> +      } while (!TLI.isTypeLegal(NextVT));
>
> This should be isTypeSynthesizable, not isTypeLegal.  There are probably 
> other places in here where that's also true.

Thanks for the advice. I changed all three occurances of isTypeLegal to
isTypeSynthesizable in DAGTypeLegalizer::WidenVecRes_Binary. There are
still six other isTypeLegal call sites in LegalizeVectorTypes.cpp that
probably should be updated, but I didn't touch those for now. The
updated patch is attached.

Any other thoughts about the patch? The issue is still relevant in
r105601: my patch passes http://vpu.me/v-binop-widen.ll and
http://vpu.me/v-binop-widen2.ll , which fail without the patch. The
patch doesn't seem to break any other DejaGNU tests.

-- 
Visa Putkinen // visa.putkinen at iki.fi
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