ART: Enable more Clang warnings

Change-Id: Ie6aba02f4223b1de02530e1515c63505f37e184c
diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index f5e4df1..cfc798a 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -562,7 +562,6 @@
     case Primitive::kPrimLong:
     case Primitive::kPrimDouble:
       return Location::DoubleStackSlot(GetStackSlot(load->GetLocal()));
-      break;
 
     case Primitive::kPrimInt:
     case Primitive::kPrimNot:
@@ -575,10 +574,11 @@
     case Primitive::kPrimShort:
     case Primitive::kPrimVoid:
       LOG(FATAL) << "Unexpected type " << load->GetType();
+      UNREACHABLE();
   }
 
   LOG(FATAL) << "Unreachable";
-  return Location();
+  UNREACHABLE();
 }
 
 Location InvokeDexCallingConventionVisitor::GetNextLocation(Primitive::Type type) {
@@ -683,7 +683,6 @@
       return Location();
   }
   UNREACHABLE();
-  return Location();
 }
 
 void CodeGeneratorARM::Move32(Location destination, Location source) {