Build the IRT with nacl-clang for x86

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 #! -*- 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 atexit
 import json
 import os
 import platform
 import re
@@ skipping 3450 matching lines @@
 
 
 # The IRT-building environment was cloned from nacl_env, but it should
 # ignore the --nacl_glibc, nacl_pic=1 and bitcode=1 switches.
 # We have to reinstantiate the naclsdk.py magic after clearing those flags,
 # so it regenerates the tool paths right.
 # TODO(mcgrathr,bradnelson): could get cleaner if naclsdk.py got folded back in.
 nacl_irt_env.ClearBits('nacl_glibc')
 nacl_irt_env.ClearBits('nacl_pic')
 nacl_irt_env.ClearBits('nacl_clang')
+
 # The choice of toolchain used to build the IRT does not depend on the toolchain
-# used to build user/test code. The PNaCl toolchain is used on x86, except on
-# Windows (because pnacl-clang doesn't run on Windows XP. If we stop supporting
-# building on XP, we can remove this exception).  See
-# https://code.google.com/p/nativeclient/issues/detail?id=3936
-if (nacl_irt_env.Bit('build_mips32') or nacl_irt_env.Bit('build_x86_64') or
-    (nacl_irt_env.Bit('build_x86_32') and
-     not nacl_irt_env.Bit('host_windows'))):
+# used to build user/test code. PNaCl is used on mips because that's currently
+# the only compiler for mips. nacl-clang is used on x86.
+if nacl_irt_env.Bit('build_mips32'):
   nacl_irt_env.SetBits('bitcode')
 else:
   nacl_irt_env.ClearBits('bitcode')
+if nacl_irt_env.Bit('build_x86_64') or nacl_irt_env.Bit('build_x86_32'):
+  nacl_irt_env.SetBits('nacl_clang')
+  # The IRT must be built using LLVM's assembler on x86-64 to preserve sandbox
+  # base address hiding. It's also use on x86-32 for consistency.

[jvoung (off chromium), 2015/03/19 17:36:25]

"It's also use on" -> "It's also used on"
or something

[Derek Schuff, 2015/03/19 18:36:16]

Done.

+  nacl_irt_env.Append(CCFLAGS=['-integrated-as'])

[jvoung (off chromium), 2015/03/19 17:36:25]

Might want to check with Nick about the GN build.

I see a "nacl_toolchain("irt_x64")", but I don't know if it's using the
integrated-as.

Also not sure if it's doing the appropriate mstackrealign, etc. for
nacl_toolchain("irt_x86")

[Derek Schuff, 2015/03/19 18:36:16]

Yeah, my plan was to get this landed for gyp and ensure it works before circling
back to GN, since they've always been doing their own thing anyway.

+  if nacl_irt_env.Bit('build_x86_32'):
+    # The x86-32 IRT needs to be callable with an under-aligned stack.
+    # See  https://code.google.com/p/nativeclient/issues/detail?id=3935
+    nacl_irt_env.Append(CCFLAGS=['-mstackrealign', '-mno-sse'])
+
 nacl_irt_env.ClearBits('pnacl_generate_pexe')

[jvoung (off chromium), 2015/03/19 17:36:25]

Maybe these last couple of ClearBits('...') should be moved up to be with the
rest of the ClearBits.

[Derek Schuff, 2015/03/19 18:36:16]

Done.

 nacl_irt_env.ClearBits('use_sandboxed_translator')
 nacl_irt_env.Tool('naclsdk')
 # These are unfortunately clobbered by running Tool, which
 # we needed to do to get the destination directory reset.
 # We want all the same values from nacl_env.
 nacl_irt_env.Replace(EXTRA_CFLAGS=nacl_env['EXTRA_CFLAGS'],
                      EXTRA_CXXFLAGS=nacl_env['EXTRA_CXXFLAGS'],
                      CCFLAGS=nacl_env['CCFLAGS'],
                      CFLAGS=nacl_env['CFLAGS'],
                      CXXFLAGS=nacl_env['CXXFLAGS'])
 FixWindowsAssembler(nacl_irt_env)
 # Make it find the libraries it builds, rather than the SDK ones.
 nacl_irt_env.Replace(LIBPATH='${LIB_DIR}')
 
 if nacl_irt_env.Bit('bitcode'):
   if nacl_irt_env.Bit('build_x86_64'):

[jvoung (off chromium), 2015/03/19 17:36:25]

this case isn't possible anymore?

[Derek Schuff, 2015/03/19 18:36:16]

Done.

     nacl_irt_env.Append(CCFLAGS=['--target=x86_64-unknown-nacl'])
     nacl_irt_env.Append(LINKFLAGS=['--target=x86_64-unknown-nacl',
                                    '--pnacl-allow-translate',
                                    '-arch', 'x86-64'])
   elif nacl_irt_env.Bit('build_x86_32'):

[jvoung (off chromium), 2015/03/19 17:36:25]

same

[Derek Schuff, 2015/03/19 18:36:16]

Done.

     nacl_irt_env.Append(CCFLAGS=['--target=i686-unknown-nacl'])
     # X86-32 IRT needs to be callable with an under-aligned stack, so we disable
     # SSE instructions, which can fault on misaligned addresses: see
     # https://code.google.com/p/nativeclient/issues/detail?id=3935
     nacl_irt_env.Append(LINKFLAGS=['--target=i686-unknown-nacl',
                                    '--pnacl-allow-translate',
                                    '-arch', 'x86-32',
                                    '-Wt,-mattr=-sse'])
   elif nacl_irt_env.Bit('build_mips32'):
     # Disable the PNaCl IRT verifier since it will complain about
     # __executable_start symbol not being a valid external symbol.
     nacl_irt_env.Append(LINKFLAGS=['--pnacl-disable-abi-check'])
 
 # The IRT is C only, don't link with the C++ linker so that it doesn't
 # start depending on the C++ standard library and (in the case of
 # libc++) pthread.
 nacl_irt_env.Replace(LINK=(nacl_irt_env['LINK'].
                            replace('pnacl-clang++', 'pnacl-clang')))
+nacl_irt_env.Replace(LINK=(nacl_irt_env['LINK'].
+                           replace('nacl-clang++', 'nacl-clang')))
 
 if nacl_irt_env.Bit('bitcode'):
   nacl_irt_env.Append(LINKFLAGS=['--pnacl-allow-native'])

[jvoung (off chromium), 2015/03/19 17:36:24]

Could put this under the "3504 if nacl_irt_env.Bit('bitcode'):" to consolidate.

[Derek Schuff, 2015/03/19 18:36:16]

Done.

 
 # 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. This only applies to mips now, on
 # other platforms we modify the TLS register through tls_edit as a
 # post process.
 if nacl_irt_env.Bit('build_mips32'):
   nacl_irt_env.Append(LINKFLAGS=['-Wt,-mtls-use-call'])
 
@@ skipping 474 matching lines @@
   nacl_env.ValidateSdk()
 
 if BROKEN_TEST_COUNT > 0:
   msg = "There are %d broken tests." % BROKEN_TEST_COUNT
   if GetOption('brief_comstr'):
     msg += " Add --verbose to the command line for more information."
   print msg
 
 # separate warnings from actual build output
 Banner('B U I L D - O U T P U T:')