[llvm] [BOLT][DWARF] Deduplicate Foreign TU list (PR #97629)

[Maksim Panchenko via llvm-commits]

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@@ -91,6 +91,10 @@ class DWARF5AcceleratorTable {
   uint64_t CurrentUnitOffset = 0;
   const DWARFUnit *CurrentUnit = nullptr;
   std::unordered_map<uint32_t, uint32_t> AbbrevTagToIndexMap;
+  /// Contains a map of TU hashes to a Foreign TU indecies.
+  /// This is used to reduce the size of Foreign TU list since there could be
+  /// multiple TUs with the same hash.
+  std::unordered_map<uint64_t, uint32_t> TUHashToIndexMap;
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maksfb wrote:

Use `DenseMap`?

https://github.com/llvm/llvm-project/pull/97629