================
@@ -6765,12 +6765,256 @@ llvm::Value 
*CGOpenMPRuntime::emitNumThreadsForTargetDirective(
 namespace {
 LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
 
+/// Utility to compare expression locations.
+/// Returns true if expr-loc of LHS is less-than that of RHS.
+/// This function asserts that both expressions have valid expr-locations.
+static bool compareExprLocs(const Expr *LHS, const Expr *RHS) {
+  // Assert that neither LHS nor RHS can be null
+  assert(LHS && "LHS expression cannot be null");
+  assert(RHS && "RHS expression cannot be null");
+
+  // Get source locations
+  SourceLocation LocLHS = LHS->getExprLoc();
+  SourceLocation LocRHS = RHS->getExprLoc();
+
+  // Assert that we have valid source locations
+  assert(LocLHS.isValid() && "LHS expression must have valid source location");
+  assert(LocRHS.isValid() && "RHS expression must have valid source location");
+
+  // Compare source locations for deterministic ordering
+  bool result = LocLHS < LocRHS;
+  return result;
+}
+
 // Utility to handle information from clauses associated with a given
 // construct that use mappable expressions (e.g. 'map' clause, 'to' clause).
 // It provides a convenient interface to obtain the information and generate
 // code for that information.
 class MappableExprsHandler {
 public:
+  /// Custom comparator for attach-pointer expressions that compares them by
+  /// complexity (i.e. their component-depth) first, then by their expr-locs if
+  /// they are semantically different.
+  struct AttachPtrExprComparator {
+    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) {}
+
+    // 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)
+      auto ItLHS = Handler->AttachPtrComponentDepthMap.find(LHS);
+      auto ItRHS = Handler->AttachPtrComponentDepthMap.find(RHS);
+
+      std::optional<size_t> DepthLHS =
+          (ItLHS != Handler->AttachPtrComponentDepthMap.end()) ? ItLHS->second
+                                                               : std::nullopt;
+      std::optional<size_t> DepthRHS =
+          (ItRHS != Handler->AttachPtrComponentDepthMap.end()) ? ItRHS->second
+                                                               : std::nullopt;
+
+      // std::nullopt (no attach pointer) has lowest complexity
+      if (!DepthLHS.has_value() && !DepthRHS.has_value()) {
+        // Both have same complexity, now check semantic equality
+        if (areEqual(LHS, RHS))
+          return false;
+        // Different semantically, compare by location
+        return compareExprLocs(LHS, RHS);
+      }
+      if (!DepthLHS.has_value())
+        return true; // LHS has lower complexity
+      if (!DepthRHS.has_value())
+        return false; // RHS has lower complexity
+
+      // Both have values, compare by depth (lower depth = lower complexity)
+      if (DepthLHS.value() != DepthRHS.value())
+        return DepthLHS.value() < DepthRHS.value();
+
+      // Same complexity, now check semantic equality
+      if (areEqual(LHS, RHS))
+        return false;
+      // Different semantically, compare by location
+      return compareExprLocs(LHS, RHS);
+    }
+
+  public:
+    /// Return true if \p LHS and \p RHS are semantically equal. Uses 
pre-cached
+    /// results, if available, otherwise does a recursive semantic comparison.
+    bool areEqual(const Expr *LHS, const Expr *RHS) const {
+      // Check cache first for faster lookup
+      auto CachedResultIt = CachedEqualityComparisons.find({LHS, RHS});
+      if (CachedResultIt != CachedEqualityComparisons.end())
+        return CachedResultIt->second;
+
+      bool ComparisonResult = areSemanticallyEqual(LHS, RHS);
+
+      // Cache the result for future lookups (both orders since semantic
+      // equality is commutative)
+      CachedEqualityComparisons[{LHS, RHS}] = ComparisonResult;
+      CachedEqualityComparisons[{RHS, LHS}] = ComparisonResult;
+      return ComparisonResult;
+    }
+
+  private:
+    /// Helper function to compare attach-pointer expressions semantically.
+    /// This function handles various expression types that can be part of an
+    /// attach-pointer.
+    /// TODO: Not urgent, but we should ideally return true when comparing
+    /// `p[10]`, `*(p + 10)`,  `*(p + 5 + 5)`, `p[10:1]` etc.
+    bool areSemanticallyEqual(const Expr *LHS, const Expr *RHS) const {
----------------
abhinavgaba wrote:

@alexey-bataev, is there a cleaner/less expensive way to compare two exprs? I 
am trying to cache the results so that we don't do this for the same two exprs 
repeatedly, but the first one comparison would involve this recursive check.

https://github.com/llvm/llvm-project/pull/155625
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits

Reply via email to