[Bugpoint redesign] Added Pass to Remove Global Variables

Summary:
This pass tries to remove Global Variables, as well as their derived uses. For example if a variable `@x` is used by `%call1` and `%call2`, both these uses and the definition of `@x` are deleted. Moreover if `%call1` or `%call2` are used elsewhere those uses are also deleted, and so on recursively.

I'm still uncertain if this pass should remove derived uses, I'm open to suggestions.

Subscribers: mgorny, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64176

> llvm-svn: 368918

llvm-svn: 369061
diff --git a/llvm/tools/llvm-reduce/DeltaManager.h b/llvm/tools/llvm-reduce/DeltaManager.h
index 28d1cd9..8033d76 100644
--- a/llvm/tools/llvm-reduce/DeltaManager.h
+++ b/llvm/tools/llvm-reduce/DeltaManager.h
@@ -14,11 +14,16 @@
 #include "TestRunner.h"
 #include "deltas/Delta.h"
 #include "deltas/ReduceFunctions.h"
+#include "deltas/ReduceGlobalVars.h"
 
 namespace llvm {
 
+// TODO: Add CLI option to run only specified Passes (for unit tests)
 inline void runDeltaPasses(TestRunner &Tester) {
+  outs() << "Reducing functions...\n";
   reduceFunctionsDeltaPass(Tester);
+  outs() << "Reducing GVs...\n";
+  reduceGlobalsDeltaPass(Tester);
   // TODO: Implement the remaining Delta Passes
 }