Instrumented malloc and free with dummy functions.

docs/ASAN.rst

+Using AddressSanitizer in Subzero
+=================================
+
+AddressSanitizer is a powerful compile-time tool used to detect and report
+illegal memory accesses. For a full description of the tool, see the original
+`paper
+<https://www.usenix.org/system/files/conference/atc12/atc12-final39.pdf>`_.
+AddressSanitizer is only supported on native builds of .pexe files and cannot be
+used in production.
+
+In Subzero, AddressSanitizer depends on being able to find and instrument calls
+to various functions such as malloc() and free(), and as such the .pexe file
+being translated must not have had those symbols stripped. Subzero will not
+complain if it is told to translate a .pexe file with its symbols stripped, but
+it will not be able to find calls to malloc() and free(), so AddressSanitizer
+will not work correctly in the final executable.
+
+These are the steps to compile hello.c to an instrumented object file::
+
+    pnacl-clang -o hello.nonfinal.pexe hello.c
+    pnacl-finalize --no-strip-syms -o hello.pexe hello.nonfinal.pexe
+    pnacl-sz -fsanitize-address -filetype=obj -o hello.o hello.pexe
+
+The resulting object file must be linked with the Subzero-specific
+AddressSanitizer runtime to work correctly. A .pexe file can be compiled with
+AddressSanitizer and properly linked into a final executable using
+subzero/pydir/szbuild.py with the --fsanitize-address flag, i.e.::
+
+    pydir/szbuild.py --fsanitize-address hello.pexe
+

[Jim Stichnoth, 2016/06/17 22:39:24]

Remove trailing "whitespace" (i.e. newlines) to keep git happy.

[tlively, 2016/06/17 23:03:58]

I didn't see this comment until after I landed, but it will be in my next CL.

+
+
+