Some code clean-up.

Change-Id: I4b745fd5298cd61c793e3b57514b48347bd66c0e
diff --git a/compiler/trampolines/trampoline_compiler.cc b/compiler/trampolines/trampoline_compiler.cc
index 6da375a..e793c6b 100644
--- a/compiler/trampolines/trampoline_compiler.cc
+++ b/compiler/trampolines/trampoline_compiler.cc
@@ -166,7 +166,7 @@
       return x86_64::CreateTrampoline(offset);
     default:
       LOG(FATAL) << "Unexpected InstructionSet: " << isa;
-      return nullptr;
+      UNREACHABLE();
   }
 }
 
@@ -182,7 +182,7 @@
       return x86::CreateTrampoline(offset);
     default:
       LOG(FATAL) << "Unexpected InstructionSet: " << isa;
-      return nullptr;
+      UNREACHABLE();
   }
 }