[]PATCH A bug in DAG Combiner caused by undef mask

[Hao Liu]

Hi,

 

Please consider a patch to fix PR15950:
http://llvm.org/bugs/show_bug.cgi?id=15950. 

A function partitionShuffleOfConats tries to turn a shuffle with undef mask
of two concats into a single concat, but it doesn't consider undef a masks,
whose value is -1 and will cause an overflow in an unsigned type variable. 

 

To fix this bug, we just need to consider two more situations for a
concatenated vector: all masks are undef, mixed undef and general masks. The
former situation is resolved by adding an undef vector. The latter situation
is resolved by directly bailing out.

 

Thanks,

-Hao
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