c++filt: support COFF import thunks

The synthetic thunk for the import is prefixed with __imp_.  Attempt to
undecorate the names when they begin with the __imp_ prefix.

llvm-svn: 298550

2 files changed, 11 insertions, 0 deletions

diff --git a/llvm/test/tools/llvm-cxxfilt/coff-import.test b/llvm/test/tools/llvm-cxxfilt/coff-import.test
new file mode 100644
index 00000000000..35494d7a832
--- /dev/null
+++ b/llvm/test/tools/llvm-cxxfilt/coff-import.test
@@ -0,0 +1,5 @@
+RUN: llvm-cxxfilt -_ ___imp__ZSt6futureIvE | FileCheck %s
+RUN: llvm-cxxfilt __imp__ZSt6futureIvE | FileCheck %s
+
+CHECK: import thunk for std::future<void>
+
diff --git a/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp b/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp
index 8be2a6d3b45..13024fbeaea 100644
--- a/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp
+++ b/llvm/tools/llvm-cxxfilt/llvm-cxxfilt.cpp
@@ -68,6 +68,12 @@ static void demangle(llvm::raw_ostream &OS, const std::string &Mangled) {
                 (DecoratedLength >= 4 && strncmp(Decorated, "___Z", 4) == 0)))
     Undecorated = itaniumDemangle(Decorated, nullptr, nullptr, &Status);
 
+  if (!Undecorated &&
+      (DecoratedLength > 6 && strncmp(Decorated, "__imp_", 6) == 0)) {
+    OS << "import thunk for ";
+    Undecorated = itaniumDemangle(Decorated + 6, nullptr, nullptr, &Status);
+  }
+
   OS << (Undecorated ? Undecorated : Mangled) << '\n';
 
   free(Undecorated);