Update pnacl/DEPS to bring in stricter ABI checks for metadata

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 360 matching lines @@
       chain.add(DoLTO, 'opt.' + bitcode_type)
     elif env.getone('STRIP_MODE') != 'none':
       chain.add(DoStrip, 'stripped.' + bitcode_type)
 
     if env.getbool('STATIC'):
       # ABI simplification passes.  We should not place arbitrary
       # passes after '-expand-constant-expr' because they might
       # reintroduce ConstantExprs.  However, '-expand-getelementptr'
       # must follow '-expand-constant-expr' to expand the
       # getelementptr instructions it creates.
-      passes = ['-expand-constant-expr',
+      # We place '-strip-metadata' after optimization passes are run

[Mark Seaborn, 2013/04/26 21:36:45]

It would be clearer to omit "are run"

[jvoung (off chromium), 2013/04/26 22:54:51]

Done.

+      # since optimizations depend on the metadata.
+      passes = ['-strip-metadata',
+                '-expand-constant-expr',
                 '-expand-getelementptr']
       if (not env.getbool('DISABLE_ABI_CHECK') and
           not env.getbool('ALLOW_CXX_EXCEPTIONS') and
           len(native_objects) == 0):
         passes += ['-verify-pnaclabi-module',
-                   '-verify-pnaclabi-functions']
+                   '-verify-pnaclabi-functions',
+                   '-pnaclabi-allow-debug-metadata']

[Mark Seaborn, 2013/04/26 21:36:45]

Maybe comment "This option modifies the behaviour of -verify-pnaclabi-*".  It's
odd having it in a list called "passes" otherwise.

[jvoung (off chromium), 2013/04/26 22:54:51]

Done.

       chain.add(DoLLVMPasses(passes),
                 'expand_features_after_opt.' + bitcode_type)
   else:
     chain = DriverChain('', output, tng)
 
   # If -arch is also specified, invoke pnacl-translate afterwards.
   if arch_flag_given:
     env.set('NATIVE_OBJECTS', *native_objects)
     chain.add(DoTranslate, native_type)
 
@@ skipping 136 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.
 """