Replace solib_global_lookup with gdbarch_iterate_over_objfiles_in_search_order

All implementations of either function use it for the same purpose (except
Darwin, which is a no-op): to prefer a symbol in the current objfile over
symbols with the same name in other objfiles. There does not seem to be a
reason to have both mechanisms for that purpose.

gdb/ChangeLog:

2019-09-20  Christian Biesinger  <cbiesinger@google.com>

	* solib-darwin.c (darwin_lookup_lib_symbol): Remove.
	(_initialize_darwin_solib): Don't set
	darwin_so_ops.lookup_lib_global_symbol.
	* solib-svr4.c (set_solib_svr4_fetch_link_map_offsets): Call
	set_gdbarch_iterate_over_objfiles_in_search_order.
	(elf_lookup_lib_symbol): Rename to...
	(svr4_iterate_over_objfiles_in_search_order): this, and update
	to iterate semantics.
	(_initialize_svr4_solib): Don't set lookup_lib_global_symbol.
	* solib.c (solib_global_lookup): Remove.
	* solist.h (struct target_so_ops): Remove lookup_lib_global_symbol.
	(solib_global_lookup): Remove.
	* symtab.c (lookup_global_or_static_symbol): Remove call to
	solib_global_lookup.

1 files changed, 37 insertions, 19 deletions

diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index e04fde9..dc63549 100644
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -51,6 +51,10 @@ static int svr4_have_link_map_offsets (void);
 static void svr4_relocate_main_executable (void);
 static void svr4_free_library_list (void *p_list);
 static void probes_table_remove_objfile_probes (struct objfile *objfile);
+static void svr4_iterate_over_objfiles_in_search_order (
+  struct gdbarch *gdbarch, iterate_over_objfiles_in_search_order_cb_ftype *cb,
+  void *cb_data, struct objfile *objfile);
+
 
 /* On SVR4 systems, a list of symbols in the dynamic linker where
    GDB can try to place a breakpoint to monitor shared library
@@ -3102,6 +3106,8 @@ set_solib_svr4_fetch_link_map_offsets (struct gdbarch *gdbarch,
   ops->fetch_link_map_offsets = flmo;
 
   set_solib_ops (gdbarch, &svr4_so_ops);
+  set_gdbarch_iterate_over_objfiles_in_search_order
+    (gdbarch, svr4_iterate_over_objfiles_in_search_order);
 }
 
 /* Fetch a link_map_offsets structure using the architecture-specific
@@ -3200,32 +3206,45 @@ svr4_lp64_fetch_link_map_offsets (void)
 
 struct target_so_ops svr4_so_ops;
 
-/* Lookup global symbol for ELF DSOs linked with -Bsymbolic.  Those DSOs have a
+/* Search order for ELF DSOs linked with -Bsymbolic.  Those DSOs have a
    different rule for symbol lookup.  The lookup begins here in the DSO, not in
    the main executable.  */
 
-static struct block_symbol
-elf_lookup_lib_symbol (struct objfile *objfile,
-		       const char *name,
-		       const domain_enum domain)
+static void
+svr4_iterate_over_objfiles_in_search_order
+  (struct gdbarch *gdbarch,
+   iterate_over_objfiles_in_search_order_cb_ftype *cb,
+   void *cb_data, struct objfile *current_objfile)
 {
-  bfd *abfd;
-
-  if (objfile == symfile_objfile)
-    abfd = exec_bfd;
-  else
+  bool checked_current_objfile = false;
+  if (current_objfile != nullptr)
     {
-      /* OBJFILE should have been passed as the non-debug one.  */
-      gdb_assert (objfile->separate_debug_objfile_backlink == NULL);
+      bfd *abfd;
 
-      abfd = objfile->obfd;
-    }
+      if (current_objfile->separate_debug_objfile_backlink != nullptr)
+        current_objfile = current_objfile->separate_debug_objfile_backlink;
 
-  if (abfd == NULL || scan_dyntag (DT_SYMBOLIC, abfd, NULL, NULL) != 1)
-    return {};
+      if (current_objfile == symfile_objfile)
+	abfd = exec_bfd;
+      else
+	abfd = current_objfile->obfd;
+
+      if (abfd != nullptr &&
+	  scan_dyntag (DT_SYMBOLIC, abfd, nullptr, nullptr) == 1)
+	{
+	  checked_current_objfile = true;
+	  if (cb (current_objfile, cb_data) != 0)
+	    return;
+	}
+    }
 
-  return lookup_global_symbol_from_objfile (objfile, GLOBAL_BLOCK, name,
-					    domain);
+  for (objfile *objfile : current_program_space->objfiles ())
+    {
+      if (checked_current_objfile && objfile == current_objfile)
+	continue;
+      if (cb (objfile, cb_data) != 0)
+	return;
+    }
 }
 
 void
@@ -3242,7 +3261,6 @@ _initialize_svr4_solib (void)
   svr4_so_ops.open_symbol_file_object = open_symbol_file_object;
   svr4_so_ops.in_dynsym_resolve_code = svr4_in_dynsym_resolve_code;
   svr4_so_ops.bfd_open = solib_bfd_open;
-  svr4_so_ops.lookup_lib_global_symbol = elf_lookup_lib_symbol;
   svr4_so_ops.same = svr4_same;
   svr4_so_ops.keep_data_in_core = svr4_keep_data_in_core;
   svr4_so_ops.update_breakpoints = svr4_update_solib_event_breakpoints;