PNaCl driver: Add libgcc to mixed native/bitcode links

pnacl/driver/pnacl-driver.py

Index: pnacl/driver/pnacl-driver.py
diff --git a/pnacl/driver/pnacl-driver.py b/pnacl/driver/pnacl-driver.py
index f6412d84950605698ef130a2e69d05252838205e..069fceee5593026c0a6d8a4f1f1b4a9c9827eb4a 100755
--- a/pnacl/driver/pnacl-driver.py
+++ b/pnacl/driver/pnacl-driver.py
@@ -123,6 +123,7 @@ EXTRA_ENV = {
   # linker will know if an opt level was explicitly set or not.
   'LD_FLAGS' : '${#OPT_LEVEL ? -O${OPT_LEVEL}} -static ' +
                '${PIC ? -fPIC} ${@AddPrefix:-L:SEARCH_DIRS} ' +
+               '${ALLOW_NATIVE ? -L${LIBS_NATIVE_ARCH}} ' +

[Mark Seaborn, 2014/08/09 07:11:51]

Might an alternative be to do this below:

if env.getbool('ALLOW_NATIVE'):
  env.append('LD_FLAGS', env.eval('-L${LIBS_NATIVE_ARCH}'))
  env.append('STDLIBS', '-lgcc')

In some of my recent changes to the driver scripts, I've been trying to move
away from the string interpolation that driver_env does, because the evaluation
order is a bit hard to understand.  (See SetUpArch and SetUpLinkOptions in
pnacl-translate.py.)

If you do that, the change is OK with me.  Otherwise I'd need to stare at the
driver_env.py change some more to understand it...

[Derek Schuff, 2014/08/11 17:54:17]

Done.

                '--pnacl-exceptions=${CXX_EH_MODE}',
 
   'SEARCH_DIRS' : '', # Directories specified using -L
@@ -151,13 +152,17 @@ EXTRA_ENV = {
   'TRANSLATE_FLAGS' : '-O${#OPT_LEVEL ? ${OPT_LEVEL} : 0}',
 
   'STDLIBS'   : '${DEFAULTLIBS ? '
-                '${LIBSTDCPP} ${LIBPTHREAD} ${LIBNACL} ${LIBC} ${LIBPNACLMM}}',
+                '${LIBSTDCPP} ${LIBPTHREAD} ${LIBNACL} ${LIBC} ${LIBPNACLMM} '
+                '${ALLOW_NATIVE ? ${NATIVELIBS}}}',
   'LIBSTDCPP' : '${IS_CXX ? -l${STDLIB_TRUNC} -lm }',
   'LIBC'      : '-lc',
   'LIBNACL'   : '-lnacl',
   'LIBPNACLMM': '-lpnaclmm',
   # Enabled/disabled by -pthreads
   'LIBPTHREAD': '${PTHREAD ? -lpthread}',
+  # For native/mixed links, also bring in the native libgcc to avoid link
+  # failure if pre-translated native code needs functions from it.
+  'NATIVELIBS': '-lgcc',
 
   # IS_CXX is set by pnacl-clang and pnacl-clang++ programmatically
   'CC' : '${IS_CXX ? ${CLANGXX} : ${CLANG}}',