This patch implements getLowBitsSet/getHighBitsSet/getBitsSet in terms of the new setLowBits/setHighBits/setBits methods by making an all 0s APInt and then calling the appropriate set method.
This also adds support to setBits to allow loBits/hiBits to be in the other order to match with getBitsSet behavior.
Differential Revision: https://reviews.llvm.org/D30563
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297112 91177308-0d34-0410-b5e6-96231b3b80d8