[DependenceAnalysis] Refactor uses of getConstantPart. NFC.

Rather than checking for the SCEV type prior to calling
getContantPart, perform the checks in the function. This reduces
the number of places where the checks are needed.

Differential Revision: http://reviews.llvm.org/D19241


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266759 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed