gdb/dwarf: use gdb::unordered_set for cooked_index_storage::m_reader_hash

Replace an htab with gdb::unordered_set.  I think we could also use the
dwarf2_per_cu pointer itself as the identity, basically have the
functional equivalent of:

  gdb::unordered_map<dwarf2_per_cu *, cutu_reader_up>

But I kept the existing behavior of using dwarf2_per_cu::index as the
identity.

Change-Id: Ief3df9a71ac26ca7c07a7b79ca0c26c9d031c11d
Approved-By: Tom Tromey <tom@tromey.com>

2 files changed, 53 insertions, 29 deletions

diff --git a/gdb/dwarf2/cooked-index-storage.c b/gdb/dwarf2/cooked-index-storage.c
index 820989e..9c05cf5 100644
--- a/gdb/dwarf2/cooked-index-storage.c
+++ b/gdb/dwarf2/cooked-index-storage.c
@@ -22,11 +22,7 @@
 /* See cooked-index-storage.h.  */
 
 cooked_index_storage::cooked_index_storage ()
-  : m_reader_hash (htab_create_alloc (10, hash_cutu_reader,
-				      eq_cutu_reader,
-				      htab_delete_entry<cutu_reader>,
-				      xcalloc, xfree)),
-    m_shard (new cooked_index_shard)
+  : m_shard (new cooked_index_shard)
 {
 }
 
@@ -35,9 +31,8 @@ cooked_index_storage::cooked_index_storage ()
 cutu_reader *
 cooked_index_storage::get_reader (dwarf2_per_cu *per_cu)
 {
-  int index = per_cu->index;
-  return (cutu_reader *) htab_find_with_hash (m_reader_hash.get (),
-					      &index, index);
+  auto it = m_reader_hash.find (*per_cu);
+  return it != m_reader_hash.end () ? it->get () : nullptr;
 }
 
 /* See cooked-index-storage.h.  */
@@ -47,30 +42,43 @@ cooked_index_storage::preserve (cutu_reader_up reader)
 {
   m_abbrev_table_cache.add (reader->release_abbrev_table ());
 
-  int index = reader->cu ()->per_cu->index;
-  void **slot = htab_find_slot_with_hash (m_reader_hash.get (), &index,
-					  index, INSERT);
-  gdb_assert (*slot == nullptr);
-  cutu_reader *result = reader.get ();
-  *slot = reader.release ();
-  return result;
+  auto [it, inserted] = m_reader_hash.insert (std::move (reader));
+  gdb_assert (inserted);
+
+  return it->get();
+}
+
+/* See cooked-index-storage.h.  */
+
+std::uint64_t
+cooked_index_storage::cutu_reader_hash::operator()
+  (const cutu_reader_up &reader) const noexcept
+{
+  return (*this) (*reader->cu ()->per_cu);
+}
+
+/* See cooked-index-storage.h.  */
+
+std::uint64_t
+cooked_index_storage::cutu_reader_hash::operator() (const dwarf2_per_cu &per_cu)
+  const noexcept
+{
+  return per_cu.index;
 }
 
 /* See cooked-index-storage.h.  */
 
-hashval_t
-cooked_index_storage::hash_cutu_reader (const void *a)
+bool
+cooked_index_storage::cutu_reader_eq::operator() (const cutu_reader_up &a,
+						  const cutu_reader_up &b) const noexcept
 {
-  const cutu_reader *reader = (const cutu_reader *) a;
-  return reader->cu ()->per_cu->index;
+  return (*this) (*a->cu ()->per_cu, b);
 }
 
 /* See cooked-index-storage.h.  */
 
-int
-cooked_index_storage::eq_cutu_reader (const void *a, const void *b)
+bool cooked_index_storage::cutu_reader_eq::operator()
+  (const dwarf2_per_cu &per_cu, const cutu_reader_up &reader) const noexcept
 {
-  const cutu_reader *ra = (const cutu_reader *) a;
-  const int *rb = (const int *) b;
-  return ra->cu ()->per_cu->index == *rb;
+  return per_cu.index == reader->cu ()->per_cu->index;
 }
diff --git a/gdb/dwarf2/cooked-index-storage.h b/gdb/dwarf2/cooked-index-storage.h
index 3d0b5b2..449fbe1 100644
--- a/gdb/dwarf2/cooked-index-storage.h
+++ b/gdb/dwarf2/cooked-index-storage.h
@@ -90,18 +90,34 @@ public:
   }
 
 private:
+  /* The abbrev table cache used by this indexer.  */
+  abbrev_table_cache m_abbrev_table_cache;
 
   /* Hash function for a cutu_reader.  */
-  static hashval_t hash_cutu_reader (const void *a);
+  struct cutu_reader_hash
+  {
+    using is_transparent = void;
+
+    std::uint64_t operator() (const cutu_reader_up &reader) const noexcept;
+    std::uint64_t operator() (const dwarf2_per_cu &per_cu) const noexcept;
+  };
 
   /* Equality function for cutu_reader.  */
-  static int eq_cutu_reader (const void *a, const void *b);
+  struct cutu_reader_eq
+  {
+    using is_transparent = void;
 
-  /* The abbrev table cache used by this indexer.  */
-  abbrev_table_cache m_abbrev_table_cache;
+    bool operator() (const cutu_reader_up &a,
+		     const cutu_reader_up &b) const noexcept;
+
+    bool operator() (const dwarf2_per_cu &per_cu,
+		     const cutu_reader_up &reader) const noexcept;
+  };
 
   /* A hash table of cutu_reader objects.  */
-  htab_up m_reader_hash;
+  gdb::unordered_set<cutu_reader_up, cutu_reader_hash, cutu_reader_eq>
+    m_reader_hash;
+
   /* The index shard that is being constructed.  */
   cooked_index_shard_up m_shard;