sys: Updated llvm demangler, now supports D-Lang and Rust symbols

lib/external/llvm-demangle/source/Demangle.cpp

@@ -0,0 +1,64 @@
+//===-- Demangle.cpp - Common demangling functions ------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file This file contains definitions of common demangling functions.
+///
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Demangle/Demangle.h"
+#include <cstdlib>
+#include <cstring>
+
+static bool isItaniumEncoding(const char *S) {
+  // Itanium encoding requires 1 or 3 leading underscores, followed by 'Z'.
+  return std::strncmp(S, "_Z", 2) == 0 || std::strncmp(S, "___Z", 4) == 0;
+}
+
+static bool isRustEncoding(const char *S) { return S[0] == '_' && S[1] == 'R'; }
+
+static bool isDLangEncoding(const std::string &MangledName) {
+  return MangledName.size() >= 2 && MangledName[0] == '_' &&
+         MangledName[1] == 'D';
+}
+
+std::string llvm::demangle(const std::string &MangledName) {
+  std::string Result;
+  const char *S = MangledName.c_str();
+
+  if (nonMicrosoftDemangle(S, Result))
+    return Result;
+
+  if (S[0] == '_' && nonMicrosoftDemangle(S + 1, Result))
+    return Result;
+
+  if (char *Demangled =
+          microsoftDemangle(S, nullptr, nullptr, nullptr, nullptr)) {
+    Result = Demangled;
+    std::free(Demangled);
+    return Result;
+  }
+
+  return MangledName;
+}
+
+bool llvm::nonMicrosoftDemangle(const char *MangledName, std::string &Result) {
+  char *Demangled = nullptr;
+  if (isItaniumEncoding(MangledName))
+    Demangled = itaniumDemangle(MangledName, nullptr, nullptr, nullptr);
+  else if (isRustEncoding(MangledName))
+    Demangled = rustDemangle(MangledName);
+  else if (isDLangEncoding(MangledName))
+    Demangled = dlangDemangle(MangledName);
+
+  if (!Demangled)
+    return false;
+
+  Result = Demangled;
+  std::free(Demangled);
+  return true;
+}