[InstrProfiling] Avoid unnecessary bitcast (NFC)

Not needed with opaque pointers.

Author: nikic

llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp

@@ -1495,13 +1495,11 @@ static inline bool shouldRecordVTableAddr(GlobalVariable *GV) {
 // FIXME: Introduce an internal alias like what's done for functions to reduce
 // the number of relocation entries.
 static inline Constant *getVTableAddrForProfData(GlobalVariable *GV) {
-  auto *Int8PtrTy = PointerType::getUnqual(GV->getContext());
-
   // Store a nullptr in __profvt_ if a real address shouldn't be used.
   if (!shouldRecordVTableAddr(GV))
-    return ConstantPointerNull::get(Int8PtrTy);
+    return ConstantPointerNull::get(PointerType::getUnqual(GV->getContext()));
 
-  return ConstantExpr::getBitCast(GV, Int8PtrTy);
+  return GV;
 }
 
 void InstrLowerer::getOrCreateVTableProfData(GlobalVariable *GV) {