Let llvm-demangle-fuzzer fuzz microsoftDemangle as well

[thakis]

Summary

PR39582.

[erik.pilkington]

Isn't this already being done in https://reviews.llvm.org/D54780? Have you coordinated with @morehouse?

[thakis]

I have not. PR39582 didn't say they were looking at this, and D54780 hasn't landed in weeks. But yeah, this is a dupe, thanks for pointing it out.

tools/llvm-demangle-fuzzer/llvm-demangle-fuzzer.cpp

 //===--- llvm-demangle-fuzzer.cpp - Fuzzer for the Itanium Demangler ------===//
 //
 //                     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 <cstdint>
 #include <cstdlib>
 #include <string>
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
-  std::string NullTerminatedString((const char *)Data, Size);
-  int status = 0;
-  if (char *demangle = llvm::itaniumDemangle(NullTerminatedString.c_str(), nullptr,
-                                         nullptr, &status))
-    free(demangle);
+  if (Size == 0)
+    return 0;
+
+  bool UseItanium = Data[0] < 128;
+  std::string NullTerminatedString((const char *)Data + 1, Size - 1);
+
+  if (UseItanium) {
+    free(llvm::itaniumDemangle(NullTerminatedString.c_str(), nullptr, nullptr,
+                               nullptr));
+  } else {
+    free(llvm::microsoftDemangle(NullTerminatedString.c_str(), nullptr, nullptr,
+                                 nullptr));
+  }
 
   return 0;
 }