[SCEV] Add SCEVUnionPredicate::getUnionWith method

Author: sebpop

llvm/include/llvm/Analysis/ScalarEvolution.h

@@ -427,6 +427,15 @@ class LLVM_ABI SCEVUnionPredicate final : public SCEVPredicate {
 
   ArrayRef<const SCEVPredicate *> getPredicates() const { return Preds; }
 
+  /// Returns a new SCEVUnionPredicate that is the union of this predicate
+  /// and the given predicate \p N.
+  SCEVUnionPredicate getUnionWith(const SCEVPredicate *N,
+                                  ScalarEvolution &SE) const {
+    SCEVUnionPredicate Result(Preds, SE);
+    Result.add(N, SE);
+    return Result;
+  }
+
   /// Implementation of the SCEVPredicate interface
   bool isAlwaysTrue() const override;
   bool implies(const SCEVPredicate *N, ScalarEvolution &SE) const override;

llvm/lib/Analysis/DependenceAnalysis.cpp

@@ -1382,10 +1382,7 @@ bool DependenceInfo::strongSIVtest(const SCEV *Coeff, const SCEV *SrcConst,
         if (UnderRuntimeAssumptions) {
           const SCEVPredicate *Pred = SE->getComparePredicate(
               ICmpInst::ICMP_NE, Coeff, SE->getZero(Coeff->getType()));
-          SmallVector<const SCEVPredicate *, 4> NewPreds(
-              Result.Assumptions.getPredicates());
-          NewPreds.push_back(Pred);
-          Result.Assumptions = SCEVUnionPredicate(NewPreds, *SE);
+          Result.Assumptions = Result.Assumptions.getUnionWith(Pred, *SE);
           LLVM_DEBUG(dbgs() << "\t    Added runtime assumption: " << *Coeff
                             << " != 0\n");
         } else {