Manage objfiles with shared_ptr

This changes objfiles to be managed using a shared_ptr.  shared_ptr is
chosen because it enables the use of objfiles in background threads.

The simplest way to do this was to introduce a new iterator that will
return the underlying objfile, rather than a shared_ptr.  (I also
tried changing the rest of gdb to use shared_ptr, but this was quite
large; and to using intrusive reference counting, but this also was
tricky.)

gdb/ChangeLog
2019-12-12  Tom Tromey  <tom@tromey.com>

	* progspace.h (objfile_list): New typedef.
	(class unwrapping_objfile_iterator)
	(struct unwrapping_objfile_range): Newl
	(struct program_space) <objfiles_range>: Change type.
	<objfiles>: Change return type.
	<add_objfile>: Change type of "objfile" parameter.
	<objfiles_list>: Now a list of shared_ptr.
	* progspace.c (program_space::add_objfile): Change type of
	"objfile".  Update.
	(program_space::remove_objfile): Update.
	* objfiles.h (struct objfile) <~objfile>: Make public.
	* objfiles.c (objfile::make): Update.
	(objfile::unlink): Don't call delete.

Change-Id: I6fb7fbf06efb7cb7474c525908365863eae27eb3

1 files changed, 14 insertions, 7 deletions

diff --git a/gdb/progspace.c b/gdb/progspace.c
index 3cb0d4c61e3..1d8aaea2caa 100644
--- a/gdb/progspace.c
+++ b/gdb/progspace.c
@@ -175,16 +175,20 @@ program_space::free_all_objfiles ()
 /* See progspace.h.  */
 
 void
-program_space::add_objfile (struct objfile *objfile, struct objfile *before)
+program_space::add_objfile (std::shared_ptr<objfile> &&objfile,
+			    struct objfile *before)
 {
   if (before == nullptr)
-    objfiles_list.push_back (objfile);
+    objfiles_list.push_back (std::move (objfile));
   else
     {
-      auto iter = std::find (objfiles_list.begin (), objfiles_list.end (),
-			     before);
+      auto iter = std::find_if (objfiles_list.begin (), objfiles_list.end (),
+				[=] (const std::shared_ptr<::objfile> &objf)
+				{
+				  return objf.get () == before;
+				});
       gdb_assert (iter != objfiles_list.end ());
-      objfiles_list.insert (iter, objfile);
+      objfiles_list.insert (iter, std::move (objfile));
     }
 }
 
@@ -193,8 +197,11 @@ program_space::add_objfile (struct objfile *objfile, struct objfile *before)
 void
 program_space::remove_objfile (struct objfile *objfile)
 {
-  auto iter = std::find (objfiles_list.begin (), objfiles_list.end (),
-			 objfile);
+  auto iter = std::find_if (objfiles_list.begin (), objfiles_list.end (),
+			    [=] (const std::shared_ptr<::objfile> &objf)
+			    {
+			      return objf.get () == objfile;
+			    });
   gdb_assert (iter != objfiles_list.end ());
   objfiles_list.erase (iter);