Introduce objfile::intern

This introduces a string cache on the per-BFD object, replacing the
macro and filename caches.  Both of these caches just store strings,
so this consolidation by itself saves a little memory (about the size
of a bcache per objfile).

Then this patch switches some allocations on the objfile obstack to
use this bcache instead.  This saves more space; and turns out to be a
bit faster as well.

Here are the before and after "maint time" + "maint space" results of
"file ./gdb":

    Command execution time: 4.664021 (cpu), 4.728518 (wall)
    Space used: 39190528 (+29212672 for this command)

    Command execution time: 4.216209 (cpu), 4.107023 (wall)
    Space used: 36667392 (+26689536 for this command)

The main interface to the string cache is a new pair of overloaded
methods, objfile::intern.

gdb/ChangeLog
2020-03-04  Tom Tromey  <tom@tromey.com>

	* symmisc.c (print_symbol_bcache_statistics)
	(print_objfile_statistics): Update.
	* symfile.c (allocate_symtab): Use intern.
	* psymtab.c (partial_symtab::partial_symtab): Use intern.
	* objfiles.h (struct objfile_per_bfd_storage) <filename_cache,
	macro_cache>: Remove.
	<string_cache>: New member.
	(struct objfile) <intern>: New methods.
	* elfread.c (elf_symtab_read): Use intern.
	* dwarf2/read.c (fixup_go_packaging): Intern package name.
	(dwarf2_compute_name, dwarf2_physname)
	(create_dwo_unit_in_dwp_v1, create_dwo_unit_in_dwp_v2): Intern
	names.
	(guess_partial_die_structure_name): Update.
	(partial_die_info::fixup): Intern name.
	(dwarf2_canonicalize_name): Change parameter to objfile.  Intern
	name.
	(dwarf2_name): Intern name.  Update.
	* buildsym.c (buildsym_compunit::get_macro_table): Use
	string_cache.

1 files changed, 3 insertions, 7 deletions

diff --git a/gdb/symmisc.c b/gdb/symmisc.c
index a6a7e72..1d7c381 100644
--- a/gdb/symmisc.c
+++ b/gdb/symmisc.c
@@ -71,9 +71,7 @@ print_symbol_bcache_statistics (void)
 			 objfile_name (objfile));
 	objfile->partial_symtabs->psymbol_cache.print_statistics
 	  ("partial symbol cache");
-	objfile->per_bfd->macro_cache.print_statistics
-	  ("preprocessor macro cache");
-	objfile->per_bfd->filename_cache.print_statistics ("file name cache");
+	objfile->per_bfd->string_cache.print_statistics ("string cache");
       }
 }
 
@@ -135,10 +133,8 @@ print_objfile_statistics (void)
       printf_filtered
 	(_("  Total memory used for psymbol cache: %d\n"),
 	 objfile->partial_symtabs->psymbol_cache.memory_used ());
-      printf_filtered (_("  Total memory used for macro cache: %d\n"),
-		       objfile->per_bfd->macro_cache.memory_used ());
-      printf_filtered (_("  Total memory used for file name cache: %d\n"),
-		       objfile->per_bfd->filename_cache.memory_used ());
+      printf_filtered (_("  Total memory used for string cache: %d\n"),
+		       objfile->per_bfd->string_cache.memory_used ());
     }
 }