Improve Ada support in .gdb_index

The cooked index work changed how .gdb_index is constructed, and in
the process broke .gdb_index support.  This is PR symtab/29179.

This patch partially fixes the problem.  It arranges for Ada names to
be encoded in the form expected by the index code.  In particular,
linkage names for Ada are emitted, including the "main" name; names
are Ada-encoded; and names are no longer case-folded, something that
prevented operator names from round-tripping correctly.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29179

1 files changed, 35 insertions, 9 deletions

diff --git a/gdb/dwarf2/index-write.c b/gdb/dwarf2/index-write.c
index 4f89dfb..6b4052c 100644
--- a/gdb/dwarf2/index-write.c
+++ b/gdb/dwarf2/index-write.c
@@ -1109,22 +1109,48 @@ write_cooked_index (cooked_index_vector *table,
   htab_up var_names (htab_create_alloc (10, htab_hash_string, htab_eq_string,
 					nullptr, xcalloc, xfree));
 
+  const char *main_for_ada = main_name ();
+
   for (const cooked_index_entry *entry : table->all_entries ())
     {
-      /* GDB never put C++ linkage names into .gdb_index.  The theory
-	 here is that a linkage name will normally be in the minimal
-	 symbols anyway, so including it in the index is usually
-	 redundant -- and the cases where it would not be redundant
-	 are rare and not worth supporting.  */
-      if (entry->per_cu->lang () == language_cplus
-	  && (entry->flags & IS_LINKAGE) != 0)
-	continue;
-
       const auto it = cu_index_htab.find (entry->per_cu);
       gdb_assert (it != cu_index_htab.cend ());
 
       const char *name = entry->full_name (&symtab->m_string_obstack);
 
+      if (entry->per_cu->lang () == language_ada)
+	{
+	  /* We want to ensure that the Ada main function's name
+	     appears verbatim in the index.  However, this name will
+	     be of the form "_ada_mumble", and will be rewritten by
+	     ada_decode.  So, recognize it specially here and add it
+	     to the index by hand.  */
+	  if (entry->tag == DW_TAG_subprogram
+	      && strcmp (main_for_ada, name) == 0)
+	    {
+	      /* Leave it alone.  */
+	    }
+	  else
+	    {
+	      /* In order for the index to work when read back into
+		 gdb, it has to use the encoded name, with any
+		 suffixes stripped.  */
+	      std::string encoded = ada_encode (name, false);
+	      name = obstack_strdup (&symtab->m_string_obstack,
+				     encoded.c_str ());
+	    }
+	}
+      else if (entry->per_cu->lang () == language_cplus
+	       && (entry->flags & IS_LINKAGE) != 0)
+	{
+	  /* GDB never put C++ linkage names into .gdb_index.  The
+	     theory here is that a linkage name will normally be in
+	     the minimal symbols anyway, so including it in the index
+	     is usually redundant -- and the cases where it would not
+	     be redundant are rare and not worth supporting.  */
+	  continue;
+	}
+
       gdb_index_symbol_kind kind;
       if (entry->tag == DW_TAG_subprogram)
 	kind = GDB_INDEX_SYMBOL_KIND_FUNCTION;