ExecutionEngine::clearGlobalMappingsFromModule failed to remove reverse

mappings, which could cause errors and assert-failures.  This patch fixes that,
adds a test, and refactors the global-mapping-removal code into a single place.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83678 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ExecutionEngine/ExecutionEngine.h

@@ -61,6 +61,9 @@ public:
   getGlobalAddressReverseMap(const MutexGuard &) {
     return GlobalAddressReverseMap;
   }
+
+  // Returns the address ToUnmap was mapped to.
+  void *RemoveMapping(const MutexGuard &, const GlobalValue *ToUnmap);
 };