[PATCH] D14803: [AArch64] Fix a corner case in BitFeild select

[Geoff Berry via llvm-commits]

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gberry added a comment.

Hi Weiming,

I think your fix is correct, but if fixed differently it may lead to better code being generated.  The reason isBitfieldDstMask ends up with a BitWidth of 0 is because isBitfieldInsertOpFromOr has computed that the Or node in question has 0 UsefulBits, which if I understand correctly, means it is dead and could be replaced with an UNDEF node, allowing the instructions feeding to potentially be removed.


http://reviews.llvm.org/D14803