Adds tls_edit utility which patches irt_core.nexe's TLS usage.

src/untrusted/irt/nacl.scons

 # -*- python -*-
 # Copyright (c) 2012 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(mseaborn): Enable -Wstrict-prototypes here.  Currently
 # dlmalloc/malloc.c does not build with this warning.
@@ skipping 74 matching lines @@
                   'irt_core_resource.c',
                   ]
 
 irt_libs = ['srpc',
             'imc_syscalls',
             'platform',
             'gio',
             'm',
             ]
 
-irt_core_library = blob_env.ComponentProgram(
-    'irt_core', irt_support_objs + irt_nonbrowser, EXTRA_LIBS=irt_libs)
+irt_core_raw = blob_env.ComponentProgram(
+    'irt_core_raw', irt_support_objs + irt_nonbrowser, EXTRA_LIBS=irt_libs)
+
+irt_core_nexe = blob_env.ApplyTLSEdit(
+    'irt_core.nexe',
+    irt_core_raw)
+
+irt_core_library = blob_env.Install('${STAGING_DIR}', irt_core_nexe)
+blob_env.Alias('irt_core', irt_core_library)
+blob_env.ComponentProgramAlias(irt_core_library)
+
 env.SDKInstallBin('irt_core.nexe', irt_core_library)
 
 # TODO(mcgrathr): these should be installed, but scons is a mystery
 #env.AddHeaderToSdk(['irt.h'])
 #env.AddHeaderToSdk(['irt_ppapi.h'])
 
 # Make sure that the linked IRT nexe never uses TLS via the TLS ABI
 # register (e.g., %gs on x86-32).  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 (or __aeabi_read_tp
 # for ARM), which the IRT code overrides to segregate IRT-private TLS
 # from user TLS.
 if ((env.Bit('build_arm') or env.Bit('build_x86_32'))
     # Do not try to run OBJDUMP if 'built_elsewhere', since that *might*
     # mean that a toolchain is not even present. E.g., the arm buildbots
     # do not have the pnacl toolchain, since that is built for x86 hosts.
     and not env.Bit('built_elsewhere')):
   check_tls_arch = '${TARGET_FULLARCH}'
   if env.Bit('build_arm'):
     check_tls_arch = 'arm'
   node = env.CommandTest('irt_core_tls_test.out',
                          ['${PYTHON}', env.File('check_tls.py'),
                           check_tls_arch, '${OBJDUMP}', irt_core_library],
                          # don't run ${PYTHON} under the emulator.
                          direct_emulation=False)
   env.AddNodeToTestSuite(node, ['small_tests'], 'run_irt_core_tls_test')