[MS Demangler] Fix several crashes and demangling bugs.

These bugs were found by writing a Python script which spidered
the entire Chromium build directory tree demangling every symbol
in every object file.  At the start, the tool printed:

  Processed 27443 object files.
  2926377/2936108 symbols successfully demangled (99.6686%)
  9731 symbols could not be demangled (0.3314%)
  14589 files crashed while demangling (53.1611%)

After this patch, it prints:

  Processed 27443 object files.
  41295518/41295617 symbols successfully demangled (99.9998%)
  99 symbols could not be demangled (0.0002%)
  0 files crashed while demangling (0.0000%)

The issues fixed in this patch are:

  * Ignore empty parameter packs.  Previously we would encounter
    a mangling for an empty parameter pack and add a null node
    to the AST.  Since we don't print these anyway, we now just
    don't add anything to the AST and ignore it entirely.  This
    fixes some of the crashes.

  * Account for "incorrect" string literal demanglings.  Apparently
    an older version of clang would not truncate mangled string
    literals to 32 bytes of encoded character data.  The demangling
    code however would allocate a 32 byte buffer thinking that it
    would not encounter more than this, and overrun the buffer.
    We now demangle up to 128 bytes of data, since the buggy
    clang would encode up to 32 *characters* of data.

  * Extended support for demangling init-fini stubs.  If you had
    something like
      struct Foo {
        static vector<string> S;
      };
    this would generate a dynamic atexit initializer *for the
    variable*.  We didn't handle this, but now we print something
    nice.  This is actually an improvement over undname, which will
    fail to demangle this at all.

  * Fixed one case of static this adjustment.  We weren't handling
    several thunk codes so we didn't recognize the mangling.  These
    are now handled.

  * Fixed a back-referencing problem.  Member pointer templates
    should have their components considered for back-referencing

The remaining 99 symbols which can't be demangled are all symbols
which are compiler-generated and undname can't demangle either.

llvm-svn: 341000

0 files changed, 0 insertions, 0 deletions