IR: Introduce Module::global_objects().

This is a convenience iterator that allows clients to enumerate the
GlobalObjects within a Module.

Also start using it in a few places where it is obviously the right thing
to use.

Differential Revision: http://reviews.llvm.org/D21580

llvm-svn: 273470

llvm/lib/ExecutionEngine/ExecutionEngine.cpp

@@ -235,10 +235,8 @@ void ExecutionEngine::clearAllGlobalMappings() {
 void ExecutionEngine::clearGlobalMappingsFromModule(Module *M) {
   MutexGuard locked(lock);
 
-  for (Function &FI : *M)
-    EEState.RemoveMapping(getMangledName(&FI));
-  for (GlobalVariable &GI : M->globals())
-    EEState.RemoveMapping(getMangledName(&GI));
+  for (GlobalObject &GO : M->global_objects())
+    EEState.RemoveMapping(getMangledName(&GO));
 }
 
 uint64_t ExecutionEngine::updateGlobalMapping(const GlobalValue *GV,