diff --git a/compiler/common_compiler_test.cc b/compiler/common_compiler_test.cc
index 359d6af..7e19e15 100644
--- a/compiler/common_compiler_test.cc
+++ b/compiler/common_compiler_test.cc
@@ -111,7 +111,7 @@
 #else
   // Only warn if not Intel as Intel doesn't have cache flush instructions.
 #if !defined(__i386__) && !defined(__x86_64__)
-  LOG(WARNING) << "UNIMPLEMENTED: cache flush";
+  UNIMPLEMENTED(WARNING) << "cache flush";
 #endif
 #endif
 }
diff --git a/compiler/compiler.cc b/compiler/compiler.cc
index fbfd8e6..36213ca 100644
--- a/compiler/compiler.cc
+++ b/compiler/compiler.cc
@@ -75,8 +75,8 @@
 
     default:
       LOG(FATAL) << "UNREACHABLE";
+      UNREACHABLE();
   }
-  return nullptr;
 }
 
 }  // namespace art
diff --git a/compiler/dex/quick/arm64/utility_arm64.cc b/compiler/dex/quick/arm64/utility_arm64.cc
index 0883694..6985b73 100644
--- a/compiler/dex/quick/arm64/utility_arm64.cc
+++ b/compiler/dex/quick/arm64/utility_arm64.cc
@@ -768,8 +768,8 @@
       opcode = kA64Sub4RRre;
       break;
     default:
-      LOG(FATAL) << "Unimplemented opcode: " << op;
-      break;
+      UNIMPLEMENTED(FATAL) << "Unimplemented opcode: " << op;
+      UNREACHABLE();
   }
   A64Opcode widened_opcode = r_dest.Is64Bit() ? WIDE(opcode) : opcode;
 
diff --git a/compiler/image_writer.cc b/compiler/image_writer.cc
index 35a3d4b..235aba8 100644
--- a/compiler/image_writer.cc
+++ b/compiler/image_writer.cc
@@ -206,7 +206,7 @@
       break;
     default:
       LOG(FATAL) << "Unreachable.";
-      break;
+      UNREACHABLE();
   }
   object->SetLockWord(LockWord::FromForwardingAddress(offset), false);
   DCHECK(IsImageOffsetAssigned(object));
diff --git a/compiler/jni/portable/jni_compiler.cc b/compiler/jni/portable/jni_compiler.cc
index d2f54f8..ff37d85 100644
--- a/compiler/jni/portable/jni_compiler.cc
+++ b/compiler/jni/portable/jni_compiler.cc
@@ -298,6 +298,7 @@
     case 'D': ret_type =  irb_.getJDoubleTy(); break;
     case 'L': ret_type =  irb_.getJObjectTy(); break;
     default: LOG(FATAL)  << "Unreachable: unexpected return type in shorty " << shorty;
+      UNREACHABLE();
   }
   // Get argument type
   std::vector< ::llvm::Type*> args_type;
diff --git a/compiler/utils/arena_object.h b/compiler/utils/arena_object.h
index 50909f75..8f6965e 100644
--- a/compiler/utils/arena_object.h
+++ b/compiler/utils/arena_object.h
@@ -31,6 +31,7 @@
 
   void operator delete(void*, size_t) {
     LOG(FATAL) << "UNREACHABLE";
+    UNREACHABLE();
   }
 };
 
diff --git a/compiler/utils/arm/assembler_arm.cc b/compiler/utils/arm/assembler_arm.cc
index b430c7e..db42b46 100644
--- a/compiler/utils/arm/assembler_arm.cc
+++ b/compiler/utils/arm/assembler_arm.cc
@@ -324,7 +324,7 @@
       return IsAbsoluteUint(10, offset);  // VFP addressing mode.
     default:
       LOG(FATAL) << "UNREACHABLE";
-      return false;
+      UNREACHABLE();
   }
 }
 
@@ -342,7 +342,7 @@
       return IsAbsoluteUint(10, offset);  // VFP addressing mode.
     default:
       LOG(FATAL) << "UNREACHABLE";
-      return false;
+      UNREACHABLE();
   }
 }
 
@@ -359,9 +359,9 @@
       return IsAbsoluteUint(10, offset);  // VFP addressing mode.
     case kLoadWordPair:
       return IsAbsoluteUint(10, offset);
-  default:
+    default:
       LOG(FATAL) << "UNREACHABLE";
-      return false;
+      UNREACHABLE();
   }
 }
 
@@ -377,9 +377,9 @@
       return IsAbsoluteUint(10, offset);  // VFP addressing mode.
     case kStoreWordPair:
       return IsAbsoluteUint(10, offset);
-  default:
+    default:
       LOG(FATAL) << "UNREACHABLE";
-      return false;
+      UNREACHABLE();
   }
 }
 
diff --git a/compiler/utils/arm/assembler_arm32.cc b/compiler/utils/arm/assembler_arm32.cc
index 6af69c8..3d46617 100644
--- a/compiler/utils/arm/assembler_arm32.cc
+++ b/compiler/utils/arm/assembler_arm32.cc
@@ -1356,6 +1356,7 @@
       break;
     default:
       LOG(FATAL) << "UNREACHABLE";
+      UNREACHABLE();
   }
 }
 
@@ -1427,6 +1428,7 @@
       break;
     default:
       LOG(FATAL) << "UNREACHABLE";
+      UNREACHABLE();
   }
 }
 
diff --git a/compiler/utils/arm/assembler_thumb2.cc b/compiler/utils/arm/assembler_thumb2.cc
index 7968a77..37478c4 100644
--- a/compiler/utils/arm/assembler_thumb2.cc
+++ b/compiler/utils/arm/assembler_thumb2.cc
@@ -2406,6 +2406,7 @@
       break;
     default:
       LOG(FATAL) << "UNREACHABLE";
+      UNREACHABLE();
   }
 }
 
@@ -2477,6 +2478,7 @@
       break;
     default:
       LOG(FATAL) << "UNREACHABLE";
+      UNREACHABLE();
   }
 }
 
diff --git a/disassembler/disassembler_x86.cc b/disassembler/disassembler_x86.cc
index e12559f..b9e98f6 100644
--- a/disassembler/disassembler_x86.cc
+++ b/disassembler/disassembler_x86.cc
@@ -508,7 +508,7 @@
           case 0x5D: opcode << "min"; break;
           case 0x5E: opcode << "div"; break;
           case 0x5F: opcode << "max"; break;
-          default: LOG(FATAL) << "Unreachable";
+          default: LOG(FATAL) << "Unreachable"; UNREACHABLE();
         }
         if (prefix[2] == 0x66) {
           opcode << "pd";
@@ -1239,7 +1239,7 @@
     case 0xF2: prefixed_opcode << "repne "; break;
     case 0xF3: prefixed_opcode << "repe "; break;
     case 0: break;
-    default: LOG(FATAL) << "Unreachable";
+    default: LOG(FATAL) << "Unreachable"; UNREACHABLE();
   }
   prefixed_opcode << opcode.str();
   os << FormatInstructionPointer(begin_instr)
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index f6717fb..854effd 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -5284,6 +5284,7 @@
       break;
     default:
       LOG(FATAL) << "Unreachable - invocation type: " << type;
+      UNREACHABLE();
   }
   if (resolved == nullptr) {
     // Search by name, which works across dex files.
diff --git a/runtime/dex_file.cc b/runtime/dex_file.cc
index 78cbe58..761441e 100644
--- a/runtime/dex_file.cc
+++ b/runtime/dex_file.cc
@@ -1182,13 +1182,14 @@
   case kArray:
   case kAnnotation:
     UNIMPLEMENTED(FATAL) << ": type " << type_;
-    break;
+    UNREACHABLE();
   case kNull:
     jval_.l = NULL;
     width = 0;
     break;
   default:
     LOG(FATAL) << "Unreached";
+    UNREACHABLE();
   }
   ptr_ += width;
 }
diff --git a/runtime/dex_instruction.cc b/runtime/dex_instruction.cc
index af38433..a802759 100644
--- a/runtime/dex_instruction.cc
+++ b/runtime/dex_instruction.cc
@@ -113,7 +113,7 @@
         return 1;  // NOP.
       } else {
         LOG(FATAL) << "Unreachable: " << DumpString(nullptr);
-        return 0;
+        UNREACHABLE();
       }
   }
 }
diff --git a/runtime/entrypoints/entrypoint_utils-inl.h b/runtime/entrypoints/entrypoint_utils-inl.h
index 9fb9a3b..ccc5d83 100644
--- a/runtime/entrypoints/entrypoint_utils-inl.h
+++ b/runtime/entrypoints/entrypoint_utils-inl.h
@@ -499,11 +499,8 @@
     case StaticPrimitiveRead:    is_primitive = true;  is_set = false; is_static = true;  break;
     case StaticPrimitiveWrite:   is_primitive = true;  is_set = true;  is_static = true;  break;
     default:
-      LOG(FATAL) << "UNREACHABLE";  // Assignment below to avoid GCC warnings.
-      is_primitive = true;
-      is_set = true;
-      is_static = true;
-      break;
+      LOG(FATAL) << "UNREACHABLE";
+      UNREACHABLE();
   }
   if (UNLIKELY(resolved_field->IsStatic() != is_static)) {
     // Incompatible class change.
diff --git a/runtime/entrypoints/portable/portable_trampoline_entrypoints.cc b/runtime/entrypoints/portable/portable_trampoline_entrypoints.cc
index c3664bf..61d66ba 100644
--- a/runtime/entrypoints/portable/portable_trampoline_entrypoints.cc
+++ b/runtime/entrypoints/portable/portable_trampoline_entrypoints.cc
@@ -172,7 +172,7 @@
         break;
       case Primitive::kPrimVoid:
         LOG(FATAL) << "UNREACHABLE";
-        break;
+        UNREACHABLE();
     }
     ++cur_reg_;
   }
@@ -261,8 +261,7 @@
         break;
       case Primitive::kPrimVoid:
         LOG(FATAL) << "UNREACHABLE";
-        val.j = 0;
-        break;
+        UNREACHABLE();
     }
     args_.push_back(val);
   }
diff --git a/runtime/entrypoints/quick/quick_alloc_entrypoints.cc b/runtime/entrypoints/quick/quick_alloc_entrypoints.cc
index a2869ec..7dbfdd5 100644
--- a/runtime/entrypoints/quick/quick_alloc_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_alloc_entrypoints.cc
@@ -248,7 +248,8 @@
     }
 #endif
     default: {
-      LOG(FATAL) << "Unimplemented";
+      UNIMPLEMENTED(FATAL);
+      UNREACHABLE();
     }
   }
 }
diff --git a/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc b/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
index af341bb..2e38c3a 100644
--- a/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
@@ -456,7 +456,7 @@
       break;
     case Primitive::kPrimVoid:
       LOG(FATAL) << "UNREACHABLE";
-      break;
+      UNREACHABLE();
   }
   ++cur_reg_;
 }
@@ -564,8 +564,7 @@
       break;
     case Primitive::kPrimVoid:
       LOG(FATAL) << "UNREACHABLE";
-      val.j = 0;
-      break;
+      UNREACHABLE();
   }
   args_->push_back(val);
 }
@@ -1557,7 +1556,7 @@
       break;
     case Primitive::kPrimVoid:
       LOG(FATAL) << "UNREACHABLE";
-      break;
+      UNREACHABLE();
   }
 }
 
diff --git a/runtime/gc/collector/mark_sweep.cc b/runtime/gc/collector/mark_sweep.cc
index 83da063..ad3bb11 100644
--- a/runtime/gc/collector/mark_sweep.cc
+++ b/runtime/gc/collector/mark_sweep.cc
@@ -813,6 +813,7 @@
           break;
         default:
           LOG(FATAL) << "Unreachable";
+          UNREACHABLE();
         }
         TimingLogger::ScopedTiming t(name, GetTimings());
         ScanObjectVisitor visitor(this);
diff --git a/runtime/gc/gc_cause.cc b/runtime/gc/gc_cause.cc
index f0e1512..6be683d 100644
--- a/runtime/gc/gc_cause.cc
+++ b/runtime/gc/gc_cause.cc
@@ -35,8 +35,8 @@
     case kGcCauseTrim: return "HeapTrim";
     default:
       LOG(FATAL) << "Unreachable";
+      UNREACHABLE();
   }
-  return "";
 }
 
 std::ostream& operator<<(std::ostream& os, const GcCause& gc_cause) {
diff --git a/runtime/gc/heap.cc b/runtime/gc/heap.cc
index bceac44..c0008aa 100644
--- a/runtime/gc/heap.cc
+++ b/runtime/gc/heap.cc
@@ -1325,8 +1325,9 @@
               // Throw OOM by default.
               break;
             default: {
-              LOG(FATAL) << "Unimplemented homogeneous space compaction result "
-                         << static_cast<size_t>(result);
+              UNIMPLEMENTED(FATAL) << "homogeneous space compaction result: "
+                  << static_cast<size_t>(result);
+              UNREACHABLE();
             }
           }
           // Always print that we ran homogeneous space compation since this can cause jank.
@@ -1761,7 +1762,8 @@
         break;
       }
       default: {
-        LOG(FATAL) << "Unimplemented";
+        UNIMPLEMENTED(FATAL);
+        UNREACHABLE();
       }
     }
     if (IsGcConcurrent()) {
diff --git a/runtime/gc/space/bump_pointer_space.cc b/runtime/gc/space/bump_pointer_space.cc
index 8f42642..0a55b52 100644
--- a/runtime/gc/space/bump_pointer_space.cc
+++ b/runtime/gc/space/bump_pointer_space.cc
@@ -201,8 +201,8 @@
 }
 
 accounting::ContinuousSpaceBitmap::SweepCallback* BumpPointerSpace::GetSweepCallback() {
-  LOG(FATAL) << "Unimplemented";
-  return nullptr;
+  UNIMPLEMENTED(FATAL);
+  UNREACHABLE();
 }
 
 uint64_t BumpPointerSpace::GetBytesAllocated() {
diff --git a/runtime/gc/space/space.cc b/runtime/gc/space/space.cc
index bff28f6..b233805 100644
--- a/runtime/gc/space/space.cc
+++ b/runtime/gc/space/space.cc
@@ -39,33 +39,33 @@
 }
 
 DlMallocSpace* Space::AsDlMallocSpace() {
-  LOG(FATAL) << "Unreachable";
-  return nullptr;
+  UNIMPLEMENTED(FATAL) << "Unreachable";
+  UNREACHABLE();
 }
 
 RosAllocSpace* Space::AsRosAllocSpace() {
-  LOG(FATAL) << "Unreachable";
-  return nullptr;
+  UNIMPLEMENTED(FATAL) << "Unreachable";
+  UNREACHABLE();
 }
 
 ZygoteSpace* Space::AsZygoteSpace() {
-  LOG(FATAL) << "Unreachable";
-  return nullptr;
+  UNIMPLEMENTED(FATAL) << "Unreachable";
+  UNREACHABLE();
 }
 
 BumpPointerSpace* Space::AsBumpPointerSpace() {
-  LOG(FATAL) << "Unreachable";
-  return nullptr;
+  UNIMPLEMENTED(FATAL) << "Unreachable";
+  UNREACHABLE();
 }
 
 AllocSpace* Space::AsAllocSpace() {
-  LOG(FATAL) << "Unimplemented";
-  return nullptr;
+  UNIMPLEMENTED(FATAL) << "Unreachable";
+  UNREACHABLE();
 }
 
 ContinuousMemMapAllocSpace* Space::AsContinuousMemMapAllocSpace() {
-  LOG(FATAL) << "Unimplemented";
-  return nullptr;
+  UNIMPLEMENTED(FATAL) << "Unreachable";
+  UNREACHABLE();
 }
 
 DiscontinuousSpace::DiscontinuousSpace(const std::string& name,
diff --git a/runtime/gc/space/zygote_space.cc b/runtime/gc/space/zygote_space.cc
index 51d84f5..9de0548 100644
--- a/runtime/gc/space/zygote_space.cc
+++ b/runtime/gc/space/zygote_space.cc
@@ -58,7 +58,8 @@
 }
 
 void ZygoteSpace::Clear() {
-  LOG(FATAL) << "Unimplemented";
+  UNIMPLEMENTED(FATAL);
+  UNREACHABLE();
 }
 
 ZygoteSpace::ZygoteSpace(const std::string& name, MemMap* mem_map, size_t objects_allocated)
diff --git a/runtime/interpreter/interpreter.cc b/runtime/interpreter/interpreter.cc
index dfb03cd..9de12f2 100644
--- a/runtime/interpreter/interpreter.cc
+++ b/runtime/interpreter/interpreter.cc
@@ -325,7 +325,7 @@
 JValue ExecuteGotoImpl(Thread* self, MethodHelper& mh, const DexFile::CodeItem* code_item,
                        ShadowFrame& shadow_frame, JValue result_register) {
   LOG(FATAL) << "UNREACHABLE";
-  exit(0);
+  UNREACHABLE();
 }
 // Explicit definitions of ExecuteGotoImpl.
 template<> SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
diff --git a/runtime/interpreter/interpreter_common.cc b/runtime/interpreter/interpreter_common.cc
index 3ccdd03..c887a88 100644
--- a/runtime/interpreter/interpreter_common.cc
+++ b/runtime/interpreter/interpreter_common.cc
@@ -80,6 +80,7 @@
       break;
     default:
       LOG(FATAL) << "Unreachable: " << field_type;
+      UNREACHABLE();
   }
   return true;
 }
@@ -153,6 +154,7 @@
       break;
     default:
       LOG(FATAL) << "Unreachable: " << field_type;
+      UNREACHABLE();
   }
   return true;
 }
@@ -195,7 +197,7 @@
       break;
     default:
       LOG(FATAL) << "Unreachable: " << field_type;
-      break;
+      UNREACHABLE();
   }
   return field_value;
 }
@@ -285,6 +287,7 @@
     }
     default:
       LOG(FATAL) << "Unreachable: " << field_type;
+      UNREACHABLE();
   }
   return true;
 }
@@ -369,6 +372,7 @@
       break;
     default:
       LOG(FATAL) << "Unreachable: " << field_type;
+      UNREACHABLE();
   }
   return true;
 }
diff --git a/runtime/mirror/art_method-inl.h b/runtime/mirror/art_method-inl.h
index 664a412..d262fd5 100644
--- a/runtime/mirror/art_method-inl.h
+++ b/runtime/mirror/art_method-inl.h
@@ -171,7 +171,7 @@
     }
     default:
       LOG(FATAL) << "Unreachable - invocation type: " << type;
-      return true;
+      UNREACHABLE();
   }
 }
 
@@ -223,9 +223,7 @@
 }
 
 inline const uint8_t* ArtMethod::GetVmapTable(const void* code_pointer) {
-  if (IsOptimized()) {
-    LOG(FATAL) << "Unimplemented vmap table for optimized compiler";
-  }
+  CHECK(!IsOptimized()) << "Unimplemented vmap table for optimized compiler";
   DCHECK(code_pointer != nullptr);
   DCHECK(code_pointer == GetQuickOatCodePointer());
   uint32_t offset =
diff --git a/runtime/mirror/object-inl.h b/runtime/mirror/object-inl.h
index b89da9d..c9e60bc 100644
--- a/runtime/mirror/object-inl.h
+++ b/runtime/mirror/object-inl.h
@@ -121,7 +121,7 @@
       OFFSET_OF_OBJECT_MEMBER(Object, x_rb_ptr_));
 #else
   LOG(FATAL) << "Unreachable";
-  return nullptr;
+  UNREACHABLE();
 #endif
 }
 
@@ -134,6 +134,7 @@
       OFFSET_OF_OBJECT_MEMBER(Object, x_rb_ptr_), rb_ptr);
 #else
   LOG(FATAL) << "Unreachable";
+  UNREACHABLE();
 #endif
 }
 
@@ -156,7 +157,7 @@
   return true;
 #else
   LOG(FATAL) << "Unreachable";
-  return false;
+  UNREACHABLE();
 #endif
 }
 
@@ -166,13 +167,12 @@
     DCHECK(obj->GetReadBarrierPointer() == nullptr)
         << "Bad Baker pointer: obj=" << reinterpret_cast<void*>(obj)
         << " ptr=" << reinterpret_cast<void*>(obj->GetReadBarrierPointer());
-  } else if (kUseBrooksReadBarrier) {
+  } else {
+    CHECK(kUseBrooksReadBarrier);
     Object* obj = const_cast<Object*>(this);
     DCHECK_EQ(obj, obj->GetReadBarrierPointer())
         << "Bad Brooks pointer: obj=" << reinterpret_cast<void*>(obj)
         << " ptr=" << reinterpret_cast<void*>(obj->GetReadBarrierPointer());
-  } else {
-    LOG(FATAL) << "Unreachable";
   }
 }
 
diff --git a/runtime/monitor.cc b/runtime/monitor.cc
index 6123934..5020ced 100644
--- a/runtime/monitor.cc
+++ b/runtime/monitor.cc
@@ -877,7 +877,7 @@
     }
     default: {
       LOG(FATAL) << "Unreachable";
-      return ThreadList::kInvalidThreadId;
+      UNREACHABLE();
     }
   }
 }
@@ -1032,7 +1032,7 @@
       return true;
     default:
       LOG(FATAL) << "Unreachable";
-      return false;
+      UNREACHABLE();
   }
 }
 
diff --git a/runtime/native/dalvik_system_VMRuntime.cc b/runtime/native/dalvik_system_VMRuntime.cc
index ec7d82d..c35bb30 100644
--- a/runtime/native/dalvik_system_VMRuntime.cc
+++ b/runtime/native/dalvik_system_VMRuntime.cc
@@ -326,6 +326,7 @@
       break;
     default:
       LOG(FATAL) << "Unreachable - invocation type: " << invoke_type;
+      UNREACHABLE();
   }
   if (method == NULL) {
     return;
diff --git a/runtime/native/java_lang_System.cc b/runtime/native/java_lang_System.cc
index ee99e78..43681a7 100644
--- a/runtime/native/java_lang_System.cc
+++ b/runtime/native/java_lang_System.cc
@@ -93,7 +93,7 @@
     switch (dstComponentPrimitiveType) {
       case Primitive::kPrimVoid:
         LOG(FATAL) << "Unreachable, cannot have arrays of type void";
-        return;
+        UNREACHABLE();
       case Primitive::kPrimBoolean:
       case Primitive::kPrimByte:
         DCHECK_EQ(Primitive::ComponentSize(dstComponentPrimitiveType), 1U);
@@ -122,7 +122,7 @@
       }
       default:
         LOG(FATAL) << "Unknown array type: " << PrettyTypeOf(srcArray);
-        return;
+        UNREACHABLE();
     }
   }
   // If one of the arrays holds a primitive type the other array must hold the exact same type.
diff --git a/runtime/quick_exception_handler.h b/runtime/quick_exception_handler.h
index b93769c..cf1ecbf 100644
--- a/runtime/quick_exception_handler.h
+++ b/runtime/quick_exception_handler.h
@@ -40,6 +40,7 @@
 
   ~QuickExceptionHandler() {
     LOG(FATAL) << "UNREACHABLE";  // Expected to take long jump.
+    UNREACHABLE();
   }
 
   void FindCatch(const ThrowLocation& throw_location, mirror::Throwable* exception,
diff --git a/runtime/stack.cc b/runtime/stack.cc
index 0cdc984..0adf031 100644
--- a/runtime/stack.cc
+++ b/runtime/stack.cc
@@ -127,7 +127,8 @@
     }
   } else if (m->IsOptimized()) {
     // TODO: Implement, currently only used for exceptions when jdwp is enabled.
-    LOG(WARNING) << "StackVisitor::GetThisObject is unimplemented with the optimizing compiler";
+    UNIMPLEMENTED(WARNING)
+        << "StackVisitor::GetThisObject is unimplemented with the optimizing compiler";
     return nullptr;
   } else {
     const DexFile::CodeItem* code_item = m->GetCodeItem();
diff --git a/runtime/stack_map.h b/runtime/stack_map.h
index b1c46a9..a58ecab 100644
--- a/runtime/stack_map.h
+++ b/runtime/stack_map.h
@@ -286,7 +286,7 @@
       }
     }
     LOG(FATAL) << "Unreachable";
-    return StackMap(MemoryRegion());
+    UNREACHABLE();
   }
 
   StackMap GetStackMapForNativePcOffset(uint32_t native_pc_offset) {
@@ -298,7 +298,7 @@
       }
     }
     LOG(FATAL) << "Unreachable";
-    return StackMap(MemoryRegion());
+    UNREACHABLE();
   }
 
  private:
diff --git a/runtime/thread.cc b/runtime/thread.cc
index 9c04133..da82c76 100644
--- a/runtime/thread.cc
+++ b/runtime/thread.cc
@@ -1971,6 +1971,7 @@
   exception_handler.UpdateInstrumentationStack();
   exception_handler.DoLongJump();
   LOG(FATAL) << "UNREACHABLE";
+  UNREACHABLE();
 }
 
 Context* Thread::GetLongJumpContext() {