Merge branch 'incoming' of https://github.com/ddcc/emscripten into incoming

Author: kripken

AUTHORS

@@ -254,3 +254,4 @@ a license to everyone to use it as detailed in LICENSE.)
 * Dustin VanLerberghe <[email protected]>
 * Philip Bielby <[email protected]> (copyright owned by Jagex Ltd.)
 * Régis Fénéon <[email protected]>
+* Dominic Chen <[email protected]> (copyright owned by Google, Inc.)

emcc.py

@@ -436,6 +436,7 @@ def log_time(name):
     default_object_extension = '.o'
     valid_abspaths = []
     separate_asm = False
+    cfi = False
 
     def is_valid_abspath(path_name):
       # Any path that is underneath the emscripten repository root must be ok.
@@ -724,6 +725,8 @@ def detect_fixed_language_mode(args):
         newargs.append('-D__SSSE3__=1')
         newargs.append('-D__SSE4_1__=1')
         newargs[i] = ''
+      elif newargs[i].startswith("-fsanitize=cfi"):
+        cfi = True
 
     if should_exit:
       sys.exit(0)
@@ -1443,6 +1446,11 @@ def save_intermediate(name=None, suffix='js'):
         # At minimum remove dead functions etc., this potentially saves a lot in the size of the generated code (and the time to compile it)
         link_opts += shared.Building.get_safe_internalize() + ['-globaldce']
 
+      if cfi:
+        if use_cxx:
+           link_opts.append("-wholeprogramdevirt")
+        link_opts.append("-lowertypetests")
+
       if AUTODEBUG:
         # let llvm opt directly emit ll, to skip writing and reading all the bitcode
         link_opts += ['-S']

site/build/text/docs/tools_reference/emcc.txt

@@ -546,6 +546,15 @@ Options that are modified or new in *emcc* are listed below:
    load during startup. See Avoid memory spikes by separating out
    asm.js.
 
+"-fsanitize=<check>"
+   Instructs the compiler to turn on runtime checks for various forms
+   of undefined or suspicious behavior. For more information, refer
+   to the appropriate compiler documentation. Only the following have
+   been tested:
+
+     * "cfi": Enable [control flow integrity](http://clang.llvm.org/docs/ControlFlowIntegrity.html)
+       checks. Note that this is only supported by Clang/LLVM, and
+       indirect function call checking requires Clang/LLVM 3.9+.
 
 Environment variables
 =====================