[PATCH v4] Replace solib_global_lookup with gdbarch_iterate_over_objfiles_in_search_order

["Christian Biesinger via gdb-patches" <gdb-patches@sourceware.org>]

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:

2019-08-27  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.
---
 gdb/solib-darwin.c |  9 --------
 gdb/solib-svr4.c   | 56 ++++++++++++++++++++++++++++++----------------
 gdb/solib.c        | 15 -------------
 gdb/solist.h       | 11 ---------
 gdb/symtab.c       |  6 +----
 5 files changed, 38 insertions(+), 59 deletions(-)

diff --git a/gdb/solib-darwin.c b/gdb/solib-darwin.c
index 778c6d9f61..286e38558f 100644
--- a/gdb/solib-darwin.c
+++ b/gdb/solib-darwin.c
@@ -638,14 +638,6 @@ darwin_relocate_section_addresses (struct so_list *so,
     so->addr_low = sec->addr;
 }
 \f
-static struct block_symbol
-darwin_lookup_lib_symbol (struct objfile *objfile,
-			  const char *name,
-			  const domain_enum domain)
-{
-  return {};
-}
-
 static gdb_bfd_ref_ptr
 darwin_bfd_open (const char *pathname)
 {
@@ -687,6 +679,5 @@ _initialize_darwin_solib (void)
   darwin_so_ops.current_sos = darwin_current_sos;
   darwin_so_ops.open_symbol_file_object = open_symbol_file_object;
   darwin_so_ops.in_dynsym_resolve_code = darwin_in_dynsym_resolve_code;
-  darwin_so_ops.lookup_lib_global_symbol = darwin_lookup_lib_symbol;
   darwin_so_ops.bfd_open = darwin_bfd_open;
 }
diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index e04fde942d..dc63549105 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;
diff --git a/gdb/solib.c b/gdb/solib.c
index 86000f6d61..60cad2122f 100644
--- a/gdb/solib.c
+++ b/gdb/solib.c
@@ -1441,21 +1441,6 @@ show_auto_solib_add (struct ui_file *file, int from_tty,
 }
 
 
-/* Handler for library-specific lookup of global symbol NAME in OBJFILE.  Call
-   the library-specific handler if it is installed for the current target.  */
-
-struct block_symbol
-solib_global_lookup (struct objfile *objfile,
-		     const char *name,
-		     const domain_enum domain)
-{
-  const struct target_so_ops *ops = solib_ops (target_gdbarch ());
-
-  if (ops->lookup_lib_global_symbol != NULL)
-    return ops->lookup_lib_global_symbol (objfile, name, domain);
-  return {};
-}
-
 /* Lookup the value for a specific symbol from dynamic symbol table.  Look
    up symbol from ABFD.  MATCH_SYM is a callback function to determine
    whether to pick up a symbol.  DATA is the input of this callback
diff --git a/gdb/solist.h b/gdb/solist.h
index e1410c2b79..ee99fc815b 100644
--- a/gdb/solist.h
+++ b/gdb/solist.h
@@ -139,12 +139,6 @@ struct target_so_ops
 			      unsigned o_flags,
 			      gdb::unique_xmalloc_ptr<char> *temp_pathname);
 
-  /* Hook for looking up global symbols in a library-specific way.  */
-  struct block_symbol (*lookup_lib_global_symbol)
-    (struct objfile *objfile,
-     const char *name,
-     const domain_enum domain);
-
   /* Given two so_list objects, one from the GDB thread list
      and another from the list returned by current_sos, return 1
      if they represent the same library.
@@ -209,9 +203,4 @@ extern gdb_bfd_ref_ptr solib_bfd_open (const char *in_pathname);
 /* FIXME: gdbarch needs to control this variable.  */
 extern struct target_so_ops *current_target_so_ops;
 
-/* Handler for library-specific global symbol lookup in solib.c.  */
-struct block_symbol solib_global_lookup (struct objfile *objfile,
-					    const char *name,
-					    const domain_enum domain);
-
 #endif
diff --git a/gdb/symtab.c b/gdb/symtab.c
index 35eab08cb3..54c7ed9c7c 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -2634,11 +2634,7 @@ lookup_global_or_static_symbol (const char *name,
       return result;
     }
 
-  /* Call library-specific lookup procedure.  */
-  if (objfile != NULL)
-    result = solib_global_lookup (objfile, name, domain);
-
-  /* If that didn't work go a global search (of global blocks, heh).  */
+  /* Do a global search (of global blocks, heh).  */
   if (result.symbol == NULL)
     {
       memset (&lookup_data, 0, sizeof (lookup_data));
-- 
2.23.0.351.gc4317032e6-goog