[clang] [NFC][Clang][OpenMP] Add helper functions/utils for finding/comparing attach base-ptrs. (PR #155625)

[Abhinav Gaba via cfe-commits]

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@@ -6765,12 +6765,255 @@ 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
+  return LocLHS < LocRHS;
+}
+
 // 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.
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abhinavgaba wrote:

We need a deterministic way to order two Exprs that have the same complexity but are semantically unequal. Do you have an alternative suggestion?

Using pointer comparison cannot be reliable since that can lead to build to build differences as the pointer values can change.


https://github.com/llvm/llvm-project/pull/155625