[binutils-gdb] Add an ad hoc version check to dwarf_scanner_base

[binutils-gdb] Add an ad hoc version check to dwarf_scanner_base

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f75a1d3a732d96ed4adadddaaeafe17732453256

commit f75a1d3a732d96ed4adadddaaeafe17732453256
Author: Tom Tromey <tom@tromey.com>
Date:   Mon Nov 22 16:53:34 2021 -0700

    Add an ad hoc version check to dwarf_scanner_base
    
    Some generic code in the DWARF reader has a special case for older
    versions of .gdb_index.  This patch adds an ad hoc version check
    method so that these spots can work without specific knowledge of
    which index is in use.

Diff:
---
 gdb/dwarf2/mapped-index.h | 8 ++++++++
 gdb/dwarf2/read.c         | 9 +++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/gdb/dwarf2/mapped-index.h b/gdb/dwarf2/mapped-index.h
index 39a9ede4896..e5d77469925 100644
--- a/gdb/dwarf2/mapped-index.h
+++ b/gdb/dwarf2/mapped-index.h
@@ -58,6 +58,14 @@ struct dwarf_scanner_base
   /* Return a quick_symbol_functions instance that refers back to this
      dwarf_scanner_base.  */
   virtual quick_symbol_functions_up make_quick_functions () const = 0;
+
+  /* An ad hoc version check.  This is needed for .gdb_index to check
+     whether a version 8 or above index is in use.  Returns true if
+     the index is usable, false otherwise.  */
+  virtual bool version_check () const
+  {
+    return true;
+  }
 };
 
 /* Base class containing bits shared by both .gdb_index and
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index f340cd68e67..aa3bf6e2f25 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -245,6 +245,11 @@ struct mapped_index final : public mapped_index_base
   { return this->symbol_table.size () / 2; }
 
   quick_symbol_functions_up make_quick_functions () const override;
+
+  bool version_check () const override
+  {
+    return version >= 8;
+  }
 };
 
 /* A description of the mapped .debug_names.
@@ -2038,7 +2043,7 @@ dw2_do_instantiate_symtab (dwarf2_per_cu_data *per_cu,
 	    && cu != NULL
 	    && cu->dwo_unit != NULL
 	    && per_objfile->per_bfd->index_table != NULL
-	    && per_objfile->per_bfd->index_table->version <= 7
+	    && !per_objfile->per_bfd->index_table->version_check ()
 	    /* DWP files aren't supported yet.  */
 	    && get_dwp_file (per_objfile) == NULL)
 	  queue_and_load_all_dwo_tus (cu);
@@ -22576,7 +22581,7 @@ follow_die_sig_1 (struct die_info *src_die, struct signatured_type *sig_type,
       /* For .gdb_index version 7 keep track of included TUs.
 	 http://sourceware.org/bugzilla/show_bug.cgi?id=15021.  */
       if (per_objfile->per_bfd->index_table != NULL
-	  && per_objfile->per_bfd->index_table->version <= 7)
+	  && !per_objfile->per_bfd->index_table->version_check ())
 	{
 	  (*ref_cu)->per_cu->imported_symtabs_push (sig_cu->per_cu);
 	}