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

2 files changed, 36 insertions, 0 deletions

diff --git a/llvm/tools/llvm-cxxfilt/CMakeLists.txt b/llvm/tools/llvm-cxxfilt/CMakeLists.txt
new file mode 100644
index 00000000000..4d0e5b01028
--- /dev/null
+++ b/llvm/tools/llvm-cxxfilt/CMakeLists.txt
@@ -0,0 +1,7 @@
+set(LLVM_LINK_COMPONENTS
+  Demangle
+  )
+
+add_llvm_tool(llvm-cxxfilt
+  llvm-cxxfilt.cpp
+  )
diff --git a/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp b/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp
new file mode 100644
index 00000000000..d2c1ba37420
--- /dev/null
+++ b/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp
@@ -0,0 +1,29 @@
+//===-- llvm-c++filt.cpp --------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Demangle/Demangle.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+
+using namespace llvm;
+
+int main(int argc, char **argv) {
+  for (int I = 1; I < argc; ++I) {
+    const char *Mangled = argv[I];
+    int Status;
+    char *Demangled = itaniumDemangle(Mangled, nullptr, nullptr, &Status);
+    if (Demangled)
+      printf("%s\n", Demangled);
+    else
+      printf("%s\n", Mangled);
+    free(Demangled);
+  }
+  return 0;
+}