Pass -mtls-use-call when building libraries used in IRT.

src/shared/srpc/nacl.scons

 # -*- python -*-
-# Copyright 2008 The Native Client Authors.  All rights reserved.
-# Use of this source code is governed by a BSD-style license that can
-# be found in the LICENSE file.
+# Copyright (c) 2011 The Native Client Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
 
 
 Import('env')
 
 # TODO(robertm): get rid of this if possible
 env.Append(CCFLAGS=['-fno-strict-aliasing'])
 
+# This library is linked into irt.nexe (see src/untrusted/irt/).
+# All IRT code must avoid direct use of the TLS ABI register, which
+# is reserved for user TLS.  Instead, ensure all TLS accesses use a
+# call to __nacl_read_tp, which the IRT code overrides to segregate
+# IRT-private TLS from user TLS.
+if not env.Bit('bitcode'):
+  env.Append(CCFLAGS=['-mtls-use-call'])
+
 
 # NOTE: keep this sync'ed with build.scons
 trusted_untrusted_shared = [
     'invoke.c',
     'module_init_fini.c',
     'nacl_srpc.c',
     'nacl_srpc_message.c',
     'rpc_serialize.c',
     'rpc_service.c',
     'rpc_server_loop.c',
     'utility.c',
 ]
 
 # NOTE: these files maybe candidates for a separate library
 untrusted_only = [
     'accept.c',
     'accept_threaded.c']
 
 env.ComponentLibrary('libsrpc',
                      trusted_untrusted_shared + untrusted_only)
 
 
 env.AddLibraryToSdk(['libsrpc'])
 header_install = env.AddHeaderToSdk(['nacl_srpc.h'])
 env.Requires('libsrpc', header_install)