Add an c++ itanium demangler to llvm.

This adds a copy of the demangler in libcxxabi.

The code also has no dependencies on anything else in LLVM. To enforce
that I added it as another library. That way a BUILD_SHARED_LIBS will
fail if anyone adds an use of StringRef for example.

The no llvm dependency combined with the fact that this has to build
on linux, OS X and Windows required a few changes to the code. In
particular:

    No constexpr.
    No alignas

On OS X at least this library has only one global symbol:
__ZN4llvm16itanium_demangleEPKcPcPmPi

My current plan is:

    Commit something like this
    Change lld to use it
    Change lldb to use it as the fallback

    Add a few #ifdefs so that exactly the same file can be used in
    libcxxabi to export abi::__cxa_demangle.

Once the fast demangler in lldb can handle any names this
implementation can be replaced with it and we will have the one true
demangler.

llvm-svn: 280732

1 files changed, 2 insertions, 8 deletions

diff --git a/llvm/lib/Support/Unix/Signals.inc b/llvm/lib/Support/Unix/Signals.inc
index 961f32b4603..4661fd68657 100644
--- a/llvm/lib/Support/Unix/Signals.inc
+++ b/llvm/lib/Support/Unix/Signals.inc
@@ -14,6 +14,7 @@
 
 #include "Unix.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/Demangle/Demangle.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/FileUtilities.h"
@@ -33,9 +34,6 @@
 #if HAVE_SYS_STAT_H
 #include <sys/stat.h>
 #endif
-#if HAVE_CXXABI_H
-#include <cxxabi.h>
-#endif
 #if HAVE_DLFCN_H
 #include <dlfcn.h>
 #endif
@@ -443,12 +441,8 @@ void llvm::sys::PrintStackTrace(raw_ostream &OS) {
 
     if (dlinfo.dli_sname != nullptr) {
       OS << ' ';
-#  if HAVE_CXXABI_H
       int res;
-      char* d = abi::__cxa_demangle(dlinfo.dli_sname, nullptr, nullptr, &res);
-#  else
-      char* d = NULL;
-#  endif
+      char* d = itaniumDemangle(dlinfo.dli_sname, nullptr, nullptr, &res);
       if (!d) OS << dlinfo.dli_sname;
       else    OS << d;
       free(d);