!fixup add LoopGuards class, move collect logic there.

Author: fhahn

llvm/include/llvm/Analysis/ScalarEvolution.h

@@ -1299,17 +1299,26 @@ class ScalarEvolution {
   /// sharpen it.
   void setNoWrapFlags(SCEVAddRecExpr *AddRec, SCEV::NoWrapFlags Flags);
 
-  /// Collect rewrite map for loop guards for loop \p L, together with flags
-  /// indidcating if NUW and NSW can be preserved during rewriting.
-  std::tuple<DenseMap<const SCEV *, const SCEV *>, bool, bool>
-  collectRewriteInfoFromLoopGuards(const Loop *L);
+  class LoopGuards {
+    DenseMap<const SCEV *, const SCEV *> RewriteMap;
+    bool PreserveNUW = false;
+    bool PreserveNSW = false;
+    ScalarEvolution &SE;
+
+    LoopGuards(ScalarEvolution &SE) : SE(SE) {}
+
+  public:
+    /// Collect rewrite map for loop guards for loop \p L, together with flags
+    /// indidcating if NUW and NSW can be preserved during rewriting.
+    static LoopGuards collect(const Loop *L, ScalarEvolution &SE);
+
+    /// Try to apply the collected loop guards to \p Expr
+    const SCEV *rewrite(const SCEV *Expr) const;
+  };
 
   /// Try to apply information from loop guards for \p L to \p Expr.
   const SCEV *applyLoopGuards(const SCEV *Expr, const Loop *L);
-  const SCEV *
-  applyLoopGuards(const SCEV *Expr, const Loop *L,
-                  const DenseMap<const SCEV *, const SCEV *> &RewriteMap,
-                  bool PreserveNUW, bool PreserveNSW);
+  const SCEV *applyLoopGuards(const SCEV *Expr, const LoopGuards &Gards);
 
   /// Return true if the loop has no abnormal exits. That is, if the loop
   /// is not infinite, it must exit through an explicit edge in the CFG.