Non-SFI NaCl: Do not create unwind tables for libc_free.c

chrome/test/data/nacl/nonsfi/libc_free.c

 /*
  * Copyright 2014 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /*
  * This is a minimal NaCl program without libc. It uses NaCl's stable IRT ABI.
  */
 
@@ skipping 192 matching lines @@
     // Reply back with what we received.
     ppb_messaging->PostMessage(instance, message);
   } else if (!my_strncmp("random", message_string, message_len)) {
     TestRandom(instance);
   } else {
     // Unknown message came.
     PostStringMessage(instance, "Unknown message type");
   }
 }
 
+#if defined(__arm__)
+// ARM GCC emits references to them. They should not be called unless

[Mark Seaborn, 2014/07/21 22:49:33]

Hmm, where in the code do the references come from?

[hamaji, 2014/07/22 08:17:23]

They are in exidx section. Ah, -funwind-tables is set and dropping this flag
seems to be a better solution.

[Mark Seaborn, 2014/07/22 15:19:48]

Yes, that's what we do for nacl_helper_bootstrap, which also avoids using
libc/libgcc.

+// an exception occurs. We exit with a unique exit code just in case.
+static const int kUnwindExitCode = 2;
+void __aeabi_unwind_cpp_pr0() { __libnacl_irt_basic.exit(kUnwindExitCode); }

[Mark Seaborn, 2014/07/21 22:49:33]

Nit: the function body should be on a separate line.

Just calling __builtin_trap() to exit would also be simpler.

[hamaji, 2014/07/22 08:17:23]

It seems ARM GCC uses abort() to implement __builtin_trap, but anyway, this code
was removed.

+void __aeabi_unwind_cpp_pr1() { __libnacl_irt_basic.exit(kUnwindExitCode); }
+#endif
+
 void _start(uintptr_t info[]) {
   Elf_auxv_t* auxv = nacl_startup_auxv(info);
   grok_auxv(auxv);
   DO_QUERY(NACL_IRT_BASIC_v0_1, __libnacl_irt_basic);
   DO_QUERY(NACL_IRT_RANDOM_v0_1, __libnacl_irt_random);
 
   struct nacl_irt_ppapihook ppapihook;
   DO_QUERY(NACL_IRT_PPAPIHOOK_v0_1, ppapihook);
 
   /* This is local as a workaround to avoid having to apply
    * relocations to global variables. */
   struct PP_StartFunctions start_funcs;
   start_funcs.PPP_InitializeModule = MyPPP_InitializeModule;
   start_funcs.PPP_ShutdownModule = MyPPP_ShutdownModule;
   start_funcs.PPP_GetInterface = MyPPP_GetInterface;
   /* Similarly, initialize some global variables, avoiding relocations. */
   ppp_instance.DidCreate = DidCreate;
   ppp_instance.DidDestroy = DidDestroy;
   ppp_instance.DidChangeView = DidChangeView;
   ppp_instance.DidChangeFocus = DidChangeFocus;
   ppp_instance.HandleDocumentLoad = HandleDocumentLoad;
   ppp_messaging.HandleMessage = HandleMessage;
 
   ppapihook.ppapi_start(&start_funcs);
 
   __libnacl_irt_basic.exit(0);
 }