teach various passes about blockaddress.  We no longer
crash on any clang tests.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85465 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/GlobalDCE.cpp b/lib/Transforms/IPO/GlobalDCE.cpp
index af4711e..cfab6b2 100644
--- a/lib/Transforms/IPO/GlobalDCE.cpp
+++ b/lib/Transforms/IPO/GlobalDCE.cpp
@@ -191,13 +191,13 @@
 
 void GlobalDCE::MarkUsedGlobalsAsNeeded(Constant *C) {
   if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
-    GlobalIsNeeded(GV);
-  else {
-    // Loop over all of the operands of the constant, adding any globals they
-    // use to the list of needed globals.
-    for (User::op_iterator I = C->op_begin(), E = C->op_end(); I != E; ++I)
-      MarkUsedGlobalsAsNeeded(cast<Constant>(*I));
-  }
+    return GlobalIsNeeded(GV);
+  
+  // Loop over all of the operands of the constant, adding any globals they
+  // use to the list of needed globals.
+  for (User::op_iterator I = C->op_begin(), E = C->op_end(); I != E; ++I)
+    if (Constant *OpC = dyn_cast<Constant>(*I))
+      MarkUsedGlobalsAsNeeded(OpC);
 }
 
 // RemoveUnusedGlobalValue - Loop over all of the uses of the specified