[clang] [llvm] [NFC][Clang][OpenMP] Add a util to implicitly map attach-ptr-exprs on `target`, when applicable. (PR #161294)

[Alexey Bataev via llvm-commits]

================
@@ -6804,28 +6804,29 @@ class MappableExprsHandler {
   /// they were computed by collectAttachPtrExprInfo(), if they are semantically
   /// different.
   struct AttachPtrExprComparator {
-    const MappableExprsHandler *Handler = nullptr;
+    const MappableExprsHandler &Handler;
     // Cache of previous equality comparison results.
     mutable llvm::DenseMap<std::pair<const Expr *, const Expr *>, bool>
         CachedEqualityComparisons;
 
-    AttachPtrExprComparator(const MappableExprsHandler *H) : Handler(H) {}
+    AttachPtrExprComparator(const MappableExprsHandler &H) : Handler(H) {}
+    AttachPtrExprComparator() = delete;
 
     // Return true iff LHS is "less than" RHS.
     bool operator()(const Expr *LHS, const Expr *RHS) const {
       if (LHS == RHS)
         return false;
 
       // First, compare by complexity (depth)
-      const auto ItLHS = Handler->AttachPtrComponentDepthMap.find(LHS);
-      const auto ItRHS = Handler->AttachPtrComponentDepthMap.find(RHS);
+      const auto ItLHS = Handler.AttachPtrComponentDepthMap.find(LHS);
+      const auto ItRHS = Handler.AttachPtrComponentDepthMap.find(RHS);
 
       std::optional<size_t> DepthLHS =
-          (ItLHS != Handler->AttachPtrComponentDepthMap.end()) ? ItLHS->second
-                                                               : std::nullopt;
+          (ItLHS != Handler.AttachPtrComponentDepthMap.end()) ? ItLHS->second
+                                                              : std::nullopt;
       std::optional<size_t> DepthRHS =
-          (ItRHS != Handler->AttachPtrComponentDepthMap.end()) ? ItRHS->second
-                                                               : std::nullopt;
+          (ItRHS != Handler.AttachPtrComponentDepthMap.end()) ? ItRHS->second
+                                                              : std::nullopt;
----------------
alexey-bataev wrote:

All these changes must be in a separate NFC patch

https://github.com/llvm/llvm-project/pull/161294