Fix compilation errors with gcc.

Change-Id: If88d4f639658db2d6d71f5abcad563211138fc4a
diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index 696f5a8..04952be 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -707,6 +707,7 @@
     case Primitive::kPrimVoid:
       return Location();
   }
+
   UNREACHABLE();
 }
 
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index 4c4fbd9..8a7b52e 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -576,6 +576,8 @@
     case Primitive::kPrimFloat:
       return Location::FpuRegisterLocation(XMM0);
   }
+
+  UNREACHABLE();
 }
 
 Location InvokeDexCallingConventionVisitorX86::GetMethodLocation() const {
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index febe2bc..a2a3cf5 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -1263,6 +1263,8 @@
     case Primitive::kPrimFloat:
       return Location::FpuRegisterLocation(XMM0);
   }
+
+  UNREACHABLE();
 }
 
 Location InvokeDexCallingConventionVisitorX86_64::GetMethodLocation() const {