Use llvm-opt's LTO pass list instead of generic O2/O3 pass list for LTO

pnacl/driver/pnacl-ld.py

Index: pnacl/driver/pnacl-ld.py
diff --git a/pnacl/driver/pnacl-ld.py b/pnacl/driver/pnacl-ld.py
index f8e9e7a313723be88da82eff355b842378cf5b1c..509c178c44b007390bf825e85ce7000d210129c7 100755
--- a/pnacl/driver/pnacl-ld.py
+++ b/pnacl/driver/pnacl-ld.py
@@ -40,7 +40,8 @@ EXTRA_ENV = {
   'OPT_LEVEL': '',  # Default opt is 0, but we need to know if it's explicitly
                     # requested or not, since we don't want to propagate
                     # the value to TRANSLATE_FLAGS if it wasn't explicitly set.
-  'OPT_FLAGS': '-O${#OPT_LEVEL ? ${OPT_LEVEL} : 0} ${OPT_STRIP_%STRIP_MODE%} ' +
+  'OPT_LTO_FLAGS': '-std-link-opts -disable-internalize',

[jvoung - send to chromium..., 2013/03/21 21:23:37]

might also want to leave a comment on why -disable-internalize is used

+  'OPT_FLAGS': '${#OPT_LEVEL && !OPT_LEVEL == 0 ? ${OPT_LTO_FLAGS}} ${OPT_STRIP_%STRIP_MODE%} ' +

[jvoung - send to chromium..., 2013/03/21 21:17:05]

80 cols

                '-inline-threshold=${OPT_INLINE_THRESHOLD} ' +
                '--do-not-wrap',
   'OPT_STRIP_none': '',
@@ -331,7 +332,7 @@ def main(argv):
     if env.getbool('STATIC') and len(native_objects) == 0:
       chain.add(DoExpandCtorsAndTls, 'expand_ctors_and_tls.' + bitcode_type)
     if env.getone('OPT_LEVEL') != '' and env.getone('OPT_LEVEL') != '0':
-      chain.add(DoOPT, 'opt.' + bitcode_type)
+      chain.add(DoLTO, 'opt.' + bitcode_type)
     elif env.getone('STRIP_MODE') != 'none':
       chain.add(DoStrip, 'stripped.' + bitcode_type)
   else:
@@ -434,9 +435,10 @@ def CheckInputsArch(inputs):
 def DoExpandCtorsAndTls(infile, outfile):
   RunDriver('opt', ['-nacl-expand-ctors',
                     '-nacl-expand-tls',
+                    '--do-not-wrap',
                     infile, '-o', outfile])
 
-def DoOPT(infile, outfile):
+def DoLTO(infile, outfile):
   opt_flags = env.get('OPT_FLAGS')
   RunDriver('opt', opt_flags + [ infile, '-o', outfile ])