[gdb/symtab] Dump m_all_parents_map for verbose debug dwarf-read

[ This is based on "[gdb/symtab] Add parent_map::dump" [1]. ]

When building the cooked index, gdb builds up a parent map.

This map is currently only visible at user level through the effect of using
it, but it's useful to be able to inspect it as well.

Add dumping of this parent map for "set debug dwarf-read 2".

As example, take test-case gdb.dwarf2/enum-type-c++.exp with target board
debug-types.

The parent map looks like:
...
$ gdb -q -batch \
    -iex "maint set worker-threads 0" \
    -iex "set debug dwarf-read 2" \
    outputs/gdb.dwarf2/enum-type-c++/enum-type-c++
  ...
[dwarf-read] print_stats: Final m_all_parents_map:
map start:
  0x0000000000000000 0x0
  0x0000000000000037 0x20f27d30 (0x36: ec)
  0x0000000000000051 0x0
  0x000000000000008b 0x20f27dc0 (0x8a: A)
  0x00000000000000a6 0x0
...

There's no parent entry at address 0xd6, which is part of what causes this:
...
(gdb) FAIL: gdb.dwarf2/enum-type-c++.exp: val1 has a parent
...

With the series containing the proposed fix applied [2], we get instead:
...
[dwarf-read] print_stats: Final m_all_parents_map:
map start:
  0x0000000000000000 0x0
  0x0000000000000026 0x7e0bdc0 (0x25: ns)
  0x0000000000000036 0x0
  0x0000000000000037 0x7e0bdf0 (0x36: ns::ec)
  0x0000000000000051 0x0
  0x000000000000007f 0x7e0be80 (0x7e: ns)
  0x000000000000008a 0x0
  0x000000000000008b 0x7e0beb0 (0x8a: ns::A)
  0x00000000000000a6 0x0
  0x00000000000000cc 0x7e0bf10 (0xcb: ns)
  0x00000000000000d4 0x7e0bf40 (0xd3: ns::A)
  0x00000000000000dc 0x7e0bf10 (0xcb: ns)
  0x00000000000000dd 0x7e0bf40 (0xd3: ns::A)
  0x00000000000000f6 0x0
...
and find at 0xd6 parent ns::A.

Tested on x86_64-linux.

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

[1] https://sourceware.org/pipermail/gdb-patches/2023-October/202883.html
[2] https://sourceware.org/pipermail/gdb-patches/2024-September/211958.html

4 files changed, 75 insertions, 7 deletions

diff --git a/gdb/addrmap.c b/gdb/addrmap.c
index b9a0f77..696a7dc 100644
--- a/gdb/addrmap.c
+++ b/gdb/addrmap.c
@@ -354,7 +354,9 @@ addrmap_mutable::~addrmap_mutable ()
 /* See addrmap.h.  */
 
 void
-addrmap_dump (struct addrmap *map, struct ui_file *outfile, void *payload)
+addrmap_dump (struct addrmap *map, struct ui_file *outfile, void *payload,
+	      gdb::function_view<void (struct ui_file *outfile,
+				       const void *value)> annotate_value)
 {
   /* True if the previously printed addrmap entry was for PAYLOAD.
      If so, we want to print the next one as well (since the next
@@ -373,10 +375,16 @@ addrmap_dump (struct addrmap *map, struct ui_file *outfile, void *payload)
       addr_str = "<ends here>";
 
     if (matches || previous_matched)
-      gdb_printf (outfile, "  %s%s %s\n",
-		  payload != nullptr ? "  " : "",
-		  core_addr_to_string (start_addr),
-		  addr_str);
+      {
+	gdb_printf (outfile, "  %s%s %s",
+		    payload != nullptr ? "  " : "",
+		    core_addr_to_string (start_addr),
+		    addr_str);
+	if (annotate_value != nullptr)
+	  annotate_value (outfile, obj);
+
+	gdb_printf (outfile, "\n");
+      }
 
     previous_matched = matches;
 
diff --git a/gdb/addrmap.h b/gdb/addrmap.h
index abd1ee3..85d4645 100644
--- a/gdb/addrmap.h
+++ b/gdb/addrmap.h
@@ -219,8 +219,13 @@ private:
 
 /* Dump the addrmap to OUTFILE.  If PAYLOAD is non-NULL, only dump any
    components that map to PAYLOAD.  (If PAYLOAD is NULL, the entire
-   map is dumped.)  */
+   map is dumped.)  If ANNOTATE_VALUE is non-nullptr, call it for each
+   value.  */
+
 void addrmap_dump (struct addrmap *map, struct ui_file *outfile,
-		   void *payload);
+		   void *payload,
+		   gdb::function_view<void (struct ui_file *outfile,
+					    const void *value)>
+		     annotate_value = nullptr);
 
 #endif /* ADDRMAP_H */
diff --git a/gdb/dwarf2/parent-map.h b/gdb/dwarf2/parent-map.h
index 5307d4d..6cff548 100644
--- a/gdb/dwarf2/parent-map.h
+++ b/gdb/dwarf2/parent-map.h
@@ -104,6 +104,9 @@ public:
     return new (obstack) addrmap_fixed (obstack, &m_map);
   }
 
+  /* Dump a human-readable form of this map.  */
+  void dump () const;
+
 private:
 
   /* An addrmap that maps from section offsets to cooked_index_entry *.  */
@@ -141,6 +144,9 @@ public:
     return nullptr;
   }
 
+  /* Dump a human-readable form of this collection of parent_maps.  */
+  void dump () const;
+
 private:
 
   /* Storage for the convert maps.  */
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 193a52e..749e39d 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -4449,6 +4449,50 @@ cooked_index_storage::eq_cutu_reader (const void *a, const void *b)
   return ra->cu->per_cu->index == *rb;
 }
 
+/* Dump MAP as parent_map.  */
+
+static void
+dump_parent_map (const struct addrmap *map)
+{
+  auto_obstack temp_storage;
+
+  auto annotate_cooked_index_entry
+    = [&] (struct ui_file *outfile, const void *value)
+	{
+	  const cooked_index_entry *parent_entry
+	    = (const cooked_index_entry *)value;
+	  if (parent_entry == nullptr)
+	    return;
+
+	  gdb_printf (outfile, " (0x%" PRIx64 ": %s)",
+		      to_underlying (parent_entry->die_offset),
+		      parent_entry->full_name (&temp_storage, false));
+	};
+
+  addrmap_dump (const_cast<addrmap *> (map), gdb_stdlog, nullptr,
+		annotate_cooked_index_entry);
+}
+
+/* See parent-map.h.  */
+
+void
+parent_map::dump () const
+{
+  dump_parent_map (&m_map);
+}
+
+/* See parent-map.h.  */
+
+void
+parent_map_map::dump () const
+{
+  for (const auto &iter : m_maps)
+    {
+      gdb_printf (gdb_stdlog, "map start:\n");
+      dump_parent_map (iter);
+    }
+}
+
 /* An instance of this is created to index a CU.  */
 
 class cooked_indexer
@@ -4841,6 +4885,11 @@ private:
   {
     if (dwarf_read_debug > 0)
       print_tu_stats (m_per_objfile);
+    if (dwarf_read_debug > 1)
+      {
+	dwarf_read_debug_printf_v ("Final m_all_parents_map:");
+	m_all_parents_map.dump ();
+      }
   }
 
   /* After the last DWARF-reading task has finished, this function