Even if a comparison isn't legal, we should try to prefer constants
which can be materialized with a two-instruction sequence. (Thinking
about it a bit more, there might be some more clever sequence we could
generate for certain comparisons invoving powers of two, but I'm not
sure exactly what that would look like.)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335003 91177308-0d34-0410-b5e6-96231b3b80d8
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