Hi All, The comment of UNDEF in ISDOpcodes.h [1] is pretty simple, /// UNDEF - An undefined node. UNDEF, The name make me think of C undefined behavior, which is ... scary. But I also see there are APIs like isBuildVectorAllOnes, isBuildVectorAllZeros, ... etc, seems UNDEF just can be any value and we don't care about what it is. The most case I see UNDEF is in BUULD_VECTOR, VECTOR_SHUFFLE, ... etc. I would like to know usually how we deal with those UNDEF nodes? Thanks. [1] http://llvm.org/doxygen/ISDOpcodes_8h_source.html Regards, chenwj -- Wei-Ren Chen (陳韋任) Homepage: https://people.cs.nctu.edu.tw/~chenwj -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170622/7e962209/attachment.html>