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

pnacl/driver/pnacl-ld.py

 #!/usr/bin/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.
 #
 # IMPORTANT NOTE: If you make local mods to this file, you must run:
 #   %  pnacl/build.sh driver
 # in order for them to take effect in the scons build.  This command
 # updates the copy in the toolchain/ tree.
 #
@@ skipping 22 matching lines @@
   'STRIP_MODE' : 'none',
 
   'STRIP_FLAGS'      : '--do-not-wrap ${STRIP_FLAGS_%STRIP_MODE%}',
   'STRIP_FLAGS_all'  : '-s',
   'STRIP_FLAGS_debug': '-S',
 
   'OPT_INLINE_THRESHOLD': '100',
   '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} ${OPT_STRIP_%STRIP_MODE%} ' +
+  'OPT_LTO_FLAGS': '-std-link-opts -disable-internalize',
+  'OPT_FLAGS': '${#OPT_LEVEL && !OPT_LEVEL == 0 ? ${OPT_LTO_FLAGS}} ${OPT_STRIP_%STRIP_MODE%} ' +
                '-inline-threshold=${OPT_INLINE_THRESHOLD} ' +
                '--do-not-wrap',
   'OPT_STRIP_none': '',
   'OPT_STRIP_all': '-disable-opt --strip',
   'OPT_STRIP_debug': '-disable-opt --strip-debug',
 
   'TRANSLATE_FLAGS': '${PIC ? -fPIC} ${!STDLIB ? -nostdlib} ' +
                      '${STATIC ? -static} ' +
                      '${SHARED ? -shared} ' +
                      '${#SONAME ? -Wl,--soname=${SONAME}} ' +
@@ skipping 288 matching lines @@
     # program is available and should not be used if we are linking .o
     # files, otherwise:
     #  * -nacl-expand-ctors will drop constructors;
     #  * -nacl-expand-tls leave TLS variables unconverted.
     if env.getbool('STATIC') and len(native_objects) == 0:
       passes = ['-nacl-expand-ctors',
                 '-nacl-expand-tls']
       chain.add(DoLLVMPasses(passes), 'expand_features.' + 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)
 
     if env.getbool('STATIC'):
       # ABI simplification pass.  This should come last because other
       # LLVM passes might reintroduce ConstantExprs.
       chain.add(DoLLVMPasses(['-expand-constant-expr']),
                 'expand_constant_exprs.' + bitcode_type)
   else:
     chain = DriverChain('', output, tng)
@@ skipping 89 matching lines @@
                 pathtools.touser(f), FileType(f))
     count += 1
 
   if count == 0:
     Log.Fatal("no input files")
 
 def DoLLVMPasses(pass_list):
   def Func(infile, outfile):
     filtered_list = [pass_option for pass_option in pass_list
                      if pass_option not in env.get('LLVM_PASSES_TO_DISABLE')]
-    RunDriver('opt', filtered_list + [infile, '-o', outfile])
+    RunDriver('opt', filtered_list + [infile, '-o', outfile, '--do-not-wrap'])
   return Func
 
-def DoOPT(infile, outfile):
+def DoLTO(infile, outfile):
   opt_flags = env.get('OPT_FLAGS')
   RunDriver('opt', opt_flags + [ infile, '-o', outfile ])
 
 def DoStrip(infile, outfile):
   strip_flags = env.get('STRIP_FLAGS')
   RunDriver('strip', strip_flags + [ infile, '-o', outfile ])
 
 def DoTranslate(infile, outfile):
   args = env.get('TRANSLATE_FLAGS')
   args += ['-Wl,'+s for s in env.get('LD_FLAGS_NATIVE')]
@@ skipping 31 matching lines @@
   -O<opt-level>               Optimize output file
   -M, --print-map             Print map file on standard output
   --whole-archive             Include all objects from following archives
   --no-whole-archive          Turn off --whole-archive
   -s, --strip-all             Strip all symbols
   -S, --strip-debug           Strip debugging symbols
   --undefined SYMBOL          Start with undefined reference to SYMBOL
 
   -help | -h                  Output this help.
 """