[libunwind] Provide placement new definition

While Clang automatically generates the code for placement new,
g++ doesn't do that so we need to provide our own definition.

Differential Revision: https://reviews.llvm.org/D57455

llvm-svn: 352966

Author: petrhosek

libunwind/src/Unwind-seh.cpp

@@ -442,20 +442,23 @@ _Unwind_GetRegionStart(struct _Unwind_Context *context) {
 static int
 _unw_init_seh(unw_cursor_t *cursor, CONTEXT *context) {
 #ifdef _LIBUNWIND_TARGET_X86_64
-  new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_x86_64>(
-      context, LocalAddressSpace::sThisAddressSpace);
+  new (reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_x86_64> *>(cursor))
+      UnwindCursor<LocalAddressSpace, Registers_x86_64>(
+          context, LocalAddressSpace::sThisAddressSpace);
   auto *co = reinterpret_cast<AbstractUnwindCursor *>(cursor);
   co->setInfoBasedOnIPRegister();
   return UNW_ESUCCESS;
 #elif defined(_LIBUNWIND_TARGET_ARM)
-  new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_arm>(
-      context, LocalAddressSpace::sThisAddressSpace);
+  new (reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_arm> *>(cursor))
+      UnwindCursor<LocalAddressSpace, Registers_arm>(
+          context, LocalAddressSpace::sThisAddressSpace);
   auto *co = reinterpret_cast<AbstractUnwindCursor *>(cursor);
   co->setInfoBasedOnIPRegister();
   return UNW_ESUCCESS;
 #elif defined(_LIBUNWIND_TARGET_AARCH64)
-  new ((void *)cursor) UnwindCursor<LocalAddressSpace, Registers_arm64>(
-      context, LocalAddressSpace::sThisAddressSpace);
+  new (reinterpret_cast<UnwindCursor<LocalAddressSpace, Registers_arm64> *>(cursor))
+      UnwindCursor<LocalAddressSpace, Registers_arm64>(
+          context, LocalAddressSpace::sThisAddressSpace);
   auto *co = reinterpret_cast<AbstractUnwindCursor *>(cursor);
   co->setInfoBasedOnIPRegister();
   return UNW_ESUCCESS;

libunwind/src/UnwindCursor.hpp

@@ -892,6 +892,10 @@ class UnwindCursor : public AbstractUnwindCursor{
   virtual void        saveVFPAsX();
 #endif
 
+  // libunwind does not and should not depend on C++ library which means that we
+  // need our own defition of inline placement new.
+  static void *operator new(size_t, UnwindCursor<A, R> *p) { return p; }
+
 private:
 
 #if defined(_LIBUNWIND_ARM_EHABI)

libunwind/src/libunwind.cpp

@@ -71,8 +71,9 @@ _LIBUNWIND_EXPORT int unw_init_local(unw_cursor_t *cursor,
 # error Architecture not supported
 #endif
   // Use "placement new" to allocate UnwindCursor in the cursor buffer.
-  new ((void *)cursor) UnwindCursor<LocalAddressSpace, REGISTER_KIND>(
-                                 context, LocalAddressSpace::sThisAddressSpace);
+  new (reinterpret_cast<UnwindCursor<LocalAddressSpace, REGISTER_KIND> *>(cursor))
+      UnwindCursor<LocalAddressSpace, REGISTER_KIND>(
+          context, LocalAddressSpace::sThisAddressSpace);
 #undef REGISTER_KIND
   AbstractUnwindCursor *co = (AbstractUnwindCursor *)cursor;
   co->setInfoBasedOnIPRegister();