[SelectionDAG] Simplify the ISD::SIGN_EXTEND/ZERO_EXTEND handling to use less temporary APInts by counting bits instead. NFCI

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315628 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed