1 files changed, 98 insertions, 0 deletions
diff --git a/gdb/dwarf2/abbrev-table-cache.h b/gdb/dwarf2/abbrev-table-cache.h
new file mode 100644
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+++ b/gdb/dwarf2/abbrev-table-cache.h
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+/* DWARF abbrev table cache
+
+   Copyright (C) 2022-2025 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef GDB_DWARF2_ABBREV_TABLE_CACHE_H
+#define GDB_DWARF2_ABBREV_TABLE_CACHE_H
+
+#include "dwarf2/abbrev.h"
+#include "gdbsupport/unordered_set.h"
+
+/* An abbrev table cache holds abbrev tables for easier reuse.  */
+class abbrev_table_cache
+{
+public:
+  abbrev_table_cache () = default;
+  DISABLE_COPY_AND_ASSIGN (abbrev_table_cache);
+
+  abbrev_table_cache (abbrev_table_cache &&) = default;
+  abbrev_table_cache &operator= (abbrev_table_cache &&) = default;
+
+  /* Find an abbrev table coming from the abbrev section SECTION at
+     offset OFFSET.  Return the table, or nullptr if it has not yet
+     been registered.  */
+  const abbrev_table *find (dwarf2_section_info *section,
+			    sect_offset offset) const
+  {
+    abbrev_table_search_key key {section, offset};
+
+    if (auto iter = m_tables.find (key);
+	iter != m_tables.end ())
+      return iter->get ();
+
+    return nullptr;
+  }
+
+  /* Add TABLE to this cache.  Ownership of TABLE is transferred to
+     the cache.  Note that a table at a given section+offset may only
+     be registered once -- a violation of this will cause an assert.
+     To avoid this, call the 'find' method first, to see if the table
+     has already been read.  */
+  void add (abbrev_table_up table);
+
+private:
+  /* Key used to search for an existing abbrev table in M_TABLES.  */
+  struct abbrev_table_search_key
+  {
+    const dwarf2_section_info *section;
+    sect_offset sect_off;
+  };
+
+  struct abbrev_table_hash
+  {
+    using is_transparent = void;
+
+    std::size_t operator() (const abbrev_table_search_key &key) const noexcept
+    {
+      return (std::hash<const dwarf2_section_info *> () (key.section)
+	      + (std::hash<std::underlying_type_t<decltype (key.sect_off)>> ()
+		 (to_underlying (key.sect_off))));
+    }
+
+    std::size_t operator() (const abbrev_table_up &table) const noexcept
+    { return (*this) ({ table->section, table->sect_off }); }
+  };
+
+  struct abbrev_table_eq
+  {
+    using is_transparent = void;
+
+    bool operator() (const abbrev_table_search_key &key,
+		     const abbrev_table_up &table) const noexcept
+    { return key.section == table->section && key.sect_off == table->sect_off; }
+
+    bool operator() (const abbrev_table_up &lhs,
+		     const abbrev_table_up &rhs) const noexcept
+    { return (*this) ({ lhs->section, lhs->sect_off }, rhs); }
+  };
+
+  /* Hash table of abbrev tables.  */
+  gdb::unordered_set<abbrev_table_up, abbrev_table_hash, abbrev_table_eq> m_tables;
+};
+
+#endif /* GDB_DWARF2_ABBREV_TABLE_CACHE_H */