Check for valid PC when stepping in the ARM sim debugger.

src/arm/simulator-arm.cc

-// Copyright 2011 the V8 project authors. All rights reserved.
+// Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
 //       with the distribution.
@@ skipping 257 matching lines @@
 
   // make sure to have a proper terminating character if reaching the limit
   cmd[COMMAND_SIZE] = 0;
   arg1[ARG_SIZE] = 0;
   arg2[ARG_SIZE] = 0;
 
   // Undo all set breakpoints while running in the debugger shell. This will
   // make them invisible to all commands.
   UndoBreakpoints();
 
-  while (!done) {
+  while (!done && !sim_->has_bad_pc()) {
     if (last_pc != sim_->get_pc()) {
       disasm::NameConverter converter;
       disasm::Disassembler dasm(converter);
       // use a reasonably large buffer
       v8::internal::EmbeddedVector<char, 256> buffer;
       dasm.InstructionDecode(buffer,
                              reinterpret_cast<byte*>(sim_->get_pc()));
       PrintF("  0x%08x  %s\n", sim_->get_pc(), buffer.start());
       last_pc = sim_->get_pc();
     }
@@ skipping 3136 matching lines @@
   uintptr_t address = *stack_slot;
   set_register(sp, current_sp + sizeof(uintptr_t));
   return address;
 }
 
 } }  // namespace v8::internal
 
 #endif  // USE_SIMULATOR
 
 #endif  // V8_TARGET_ARCH_ARM