GDB: set correct data model for x86_64-nacl

gdb/nacl-tdep.c

 /* Target-dependent code for NaCl.
 
    Copyright (C) 2001, 2003-2012 Free Software Foundation, Inc.
 
    This file is part of GDB.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.
@@ skipping 63 matching lines @@
 static void
 amd64_nacl_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 {
   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
   linux_init_abi (info, gdbarch);
   amd64_init_abi (info, gdbarch);
   tdep->tdesc = tdesc_amd64_linux;
   set_solib_svr4_fetch_link_map_offsets (gdbarch,
                                          svr4_lp64_fetch_link_map_offsets);
   nacl_init_abi (info, gdbarch);
+
+  /* NaCl data model.
+
+     WARNING! This might confuse a lot of code, as it uses
+       if (set_gdbarch_ptr_bit (gdbarch) == <bits>)
+     to distinguish between i386 and x86_64 (lame!).  Luckily, most of that
+     code is about native debugging and syscalls, so it is not used for NaCl.
+
+     TODO(eaeltsin): find better way to distinguish between i386 and x86_64!  */
+  set_gdbarch_long_bit (gdbarch, 32);
+  set_gdbarch_ptr_bit (gdbarch, 32);
+
+  /* TODO(eaeltsin): we might use address size instead of pointer size to
+     distinguish between i386 and x86_64...  At least address size is not
+     a property of the data model.  */
+  set_gdbarch_addr_bit (gdbarch, 64);
+
+  /* How to extract addresses from registers.  */
   set_gdbarch_addr_bits_remove (gdbarch, amd64_nacl_addr_bits_remove);
   set_gdbarch_unwind_pc (gdbarch, amd64_nacl_unwind_pc);
   set_gdbarch_unwind_sp (gdbarch, amd64_nacl_unwind_sp);
 }
 
 /* Provide a prototype to silence -Wmissing-prototypes.  */
 extern void _initialize_nacl_tdep (void);
 
 void
 _initialize_nacl_tdep (void)
 {
   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
                           GDB_OSABI_NACL, amd64_nacl_init_abi);
 
   gdbarch_register_osabi (bfd_arch_i386, 0,
                           GDB_OSABI_NACL, i386_nacl_init_abi);
 }