From 17ee85fc2af74471e8c57502714a32bbeac5f1ae Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Wed, 27 May 2020 11:20:14 -0400 Subject: Share DWARF partial symtabs This changes the DWARF reader to share partial symtabs (or indices if they are available) across objfiles. This has a few parts. * If multiple objfiles backed by the same BFD can share partial symtabs (see below), a single dwarf2_per_bfd is created. It is stored in the per-bfd `dwarf2_per_bfd_bfd_data_key` registry. Multiple dwarf2_per_objfile objects will point to the same instance. The lifetime of these dwarf2_per_bfd objects is naturally handled. When all the objfiles using the BFD are destroyed, the BFD's refount drops to 0, which triggers the removal of the corresponding dwarf2_per_bfd object from the registry and its destruction. * If multiple objfiles backed by the same BFD can't share partial symtabs (see below), one dwarf2_per_bfd object is created for each objfile. Each dwarf2_per_objfile will point to their own instance of dwarf2_per_bfd. These instances of dwarf2_per_bfd are kept in a per-objfile registry, meaning that when the objfile gets destroyed, the dwarf2_per_bfd instance gets destroyed as well. * objfile::partial_symtabs is changed to be a shared_ptr again. This lets us stash a second reference in dwarf2_per_bfd; if the DWARF data is being shared, we can simply copy this value to the new objfile. * Two dwarf2_per_objfile objects backed by the same BFD may share a dwarf2_per_bfd instance if: * No other symbol reader has found symbols, and * No BFD section rqeuires relocation gdb/ChangeLog: YYYY-MM-DD Tom Tromey YYYY-MM-DD Simon Marchi * objfiles.h (struct objfile) : Now a shared_ptr. * dwarf2/read.h (struct dwarf2_per_objfile) : New member. * dwarf2/read.c (dwarf2_per_bfd_bfd_data_key, dwarf2_per_bfd_objfile_data_key>: New globals. (dwarf2_has_info): Use shared dwarf2_per_bfd if possible. (dwarf2_get_section_info): Use get_dwarf2_per_objfile. (dwarf2_initialize_objfile): Consider cases where per_bfd can be shared. (dwarf2_build_psymtabs): Set objfile::partial_symtabs and short-circuit when sharing. (dwarf2_build_psymtabs): Set dwarf2_per_objfile::partial_symtabs. (dwarf2_psymtab::expand_psymtab): Use free_cached_comp_units. Change-Id: I868c64448589102ab8cbb8f06c31a8de50a14004 --- gdb/objfiles.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'gdb/objfiles.h') diff --git a/gdb/objfiles.h b/gdb/objfiles.h index 0b47bd0c1e2..56ff52119dc 100644 --- a/gdb/objfiles.h +++ b/gdb/objfiles.h @@ -576,7 +576,7 @@ public: /* The partial symbol tables. */ - std::unique_ptr partial_symtabs; + std::shared_ptr partial_symtabs; /* The object file's BFD. Can be null if the objfile contains only minimal symbols, e.g. the run time common symbols for SunOS4. */ -- cgit v1.2.1