Use cast<> instead of dyn_cast<> for things that are known to be
Instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73002 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 2c01cc3..5f12825 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -932,8 +932,7 @@
                                                       GlobalVariable *GV,
                                               SmallPtrSet<PHINode*, 8> &PHIs) {
   for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
-    Instruction *Inst = dyn_cast<Instruction>(*UI);
-    if (Inst == 0) return false;
+    Instruction *Inst = cast<Instruction>(*UI);
     
     if (isa<LoadInst>(Inst) || isa<CmpInst>(Inst)) {
       continue; // Fine, ignore.