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Real world code sometimes has the denominator of a 'udiv' be a 'select'. LLVM can handle such cases but only when the 'select' operands are symmetric in structure (both select operands are a constant power of two or a left shift, etc.). This falls apart if we are dealt a 'udiv' where the code is not symetric or if the select operands lead us to more select instructions. Instead, we should treat the LHS and each select operand as a distinct divide operation and try to optimize them independently. If we can to simplify each operation, then we can replace the 'udiv' with, say, a 'lshr' that has a new select with a bunch of new operands for the select. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185257 91177308-0d34-0410-b5e6-96231b3b80d8
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