Simplify the ZIV tester to the max.

As suggested by Nick Lewycky.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78277 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/LoopDependenceAnalysis.cpp b/lib/Analysis/LoopDependenceAnalysis.cpp
index 10a6a8e..eb8ea0e 100644
--- a/lib/Analysis/LoopDependenceAnalysis.cpp
+++ b/lib/Analysis/LoopDependenceAnalysis.cpp
@@ -144,9 +144,8 @@
 LoopDependenceAnalysis::analyseZIV(const SCEV *A,
                                    const SCEV *B,
                                    Subscript *S) const {
-  assert(isZIVPair(A, B));
-  const SCEV *diff = SE->getMinusSCEV(A, B);
-  return diff->isZero() ? Dependent : Independent;
+  assert(isZIVPair(A, B) && "Attempted to ZIV-test non-ZIV SCEVs!");
+  return A == B ? Dependent : Independent;
 }
 
 LoopDependenceAnalysis::DependenceResult