Windows-specific iterate_over_objfiles_in_search_order

This patch sets the windows target to use their own version of
the iterate_over_objfiles_in_search_order gdbarch method, in
order to make global symbol searches sensitive to the current
objfile.

gdb/ChangeLog:

        * windows-tdep.h (windows_iterate_over_objfiles_in_search_order):
        Add declaration.
        * windows-tdep.c: #include "objfiles.h".
        (windows_iterate_over_objfiles_in_search_order): New function.
        * amd64-windows-tdep.c (amd64_windows_init_abi): Set
        iterate_over_objfiles_in_search_order gdbarch method to
        windows_iterate_over_objfiles_in_search_order.
        * i386-cygwin-tdep.c (i386_cygwin_init_abi): Likewise.

1 files changed, 46 insertions, 0 deletions

diff --git a/gdb/windows-tdep.c b/gdb/windows-tdep.c
index a704599..116525c 100644
--- a/gdb/windows-tdep.c
+++ b/gdb/windows-tdep.c
@@ -26,6 +26,7 @@
 #include "command.h"
 #include "gdbcmd.h"
 #include "gdbthread.h"
+#include "objfiles.h"
 
 struct cmd_list_element *info_w32_cmdlist;
 
@@ -398,6 +399,51 @@ windows_xfer_shared_library (const char* so_name, CORE_ADDR load_addr,
   obstack_grow_str (obstack, "\"/></library>");
 }
 
+/* Implement the "iterate_over_objfiles_in_search_order" gdbarch
+   method.  It searches all objfiles, starting with CURRENT_OBJFILE
+   first (if not NULL).
+
+   On Windows, the system behaves a little differently when two
+   objfiles each define a global symbol using the same name, compared
+   to other platforms such as GNU/Linux for instance.  On GNU/Linux,
+   all instances of the symbol effectively get merged into a single
+   one, but on Windows, they remain distinct.
+
+   As a result, it usually makes sense to start global symbol searches
+   with the current objfile before expanding it to all other objfiles.
+   This helps for instance when a user debugs some code in a DLL that
+   refers to a global variable defined inside that DLL.  When trying
+   to print the value of that global variable, it would be unhelpful
+   to print the value of another global variable defined with the same
+   name, but in a different DLL.  */
+
+void
+windows_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)
+{
+  int stop;
+  struct objfile *objfile;
+
+  if (current_objfile)
+    {
+      stop = cb (current_objfile, cb_data);
+      if (stop)
+	return;
+    }
+
+  ALL_OBJFILES (objfile)
+    {
+      if (objfile != current_objfile)
+	{
+	  stop = cb (objfile, cb_data);
+	  if (stop)
+	    return;
+	}
+    }
+}
+
 static void
 show_maint_show_all_tib (struct ui_file *file, int from_tty,
 		struct cmd_list_element *c, const char *value)