diff --git a/compiler/compiled_method.cc b/compiler/compiled_method.cc
index ef9d919..58f7e4f 100644
--- a/compiler/compiled_method.cc
+++ b/compiler/compiled_method.cc
@@ -73,7 +73,7 @@
     }
     default:
       LOG(FATAL) << "Unknown InstructionSet: " << instruction_set;
-      return 0;
+      UNREACHABLE();
   }
 }
 
@@ -94,7 +94,7 @@
     }
     default:
       LOG(FATAL) << "Unknown InstructionSet: " << instruction_set;
-      return nullptr;
+      UNREACHABLE();
   }
 }
 
diff --git a/compiler/jni/quick/arm/calling_convention_arm.cc b/compiler/jni/quick/arm/calling_convention_arm.cc
index 54f193b..8b4bab7 100644
--- a/compiler/jni/quick/arm/calling_convention_arm.cc
+++ b/compiler/jni/quick/arm/calling_convention_arm.cc
@@ -173,7 +173,7 @@
 
 ManagedRegister ArmManagedRuntimeCallingConvention::CurrentParamRegister() {
   LOG(FATAL) << "Should not reach here";
-  return ManagedRegister::NoRegister();
+  UNREACHABLE();
 }
 
 FrameOffset ArmManagedRuntimeCallingConvention::CurrentParamStackOffset() {
diff --git a/compiler/jni/quick/arm64/calling_convention_arm64.cc b/compiler/jni/quick/arm64/calling_convention_arm64.cc
index 328ecbb..4e6221e 100644
--- a/compiler/jni/quick/arm64/calling_convention_arm64.cc
+++ b/compiler/jni/quick/arm64/calling_convention_arm64.cc
@@ -181,7 +181,7 @@
 
 ManagedRegister Arm64ManagedRuntimeCallingConvention::CurrentParamRegister() {
   LOG(FATAL) << "Should not reach here";
-  return ManagedRegister::NoRegister();
+  UNREACHABLE();
 }
 
 FrameOffset Arm64ManagedRuntimeCallingConvention::CurrentParamStackOffset() {
diff --git a/compiler/jni/quick/mips/calling_convention_mips.cc b/compiler/jni/quick/mips/calling_convention_mips.cc
index 5ec1add..d3d489e 100644
--- a/compiler/jni/quick/mips/calling_convention_mips.cc
+++ b/compiler/jni/quick/mips/calling_convention_mips.cc
@@ -124,7 +124,7 @@
 
 ManagedRegister MipsManagedRuntimeCallingConvention::CurrentParamRegister() {
   LOG(FATAL) << "Should not reach here";
-  return ManagedRegister::NoRegister();
+  UNREACHABLE();
 }
 
 FrameOffset MipsManagedRuntimeCallingConvention::CurrentParamStackOffset() {
diff --git a/compiler/jni/quick/mips64/calling_convention_mips64.cc b/compiler/jni/quick/mips64/calling_convention_mips64.cc
index a7012ae..3c7cee6 100644
--- a/compiler/jni/quick/mips64/calling_convention_mips64.cc
+++ b/compiler/jni/quick/mips64/calling_convention_mips64.cc
@@ -109,7 +109,7 @@
 
 ManagedRegister Mips64ManagedRuntimeCallingConvention::CurrentParamRegister() {
   LOG(FATAL) << "Should not reach here";
-  return ManagedRegister::NoRegister();
+  UNREACHABLE();
 }
 
 FrameOffset Mips64ManagedRuntimeCallingConvention::CurrentParamStackOffset() {
diff --git a/compiler/jni/quick/x86/calling_convention_x86.cc b/compiler/jni/quick/x86/calling_convention_x86.cc
index ad58e38..71e6019 100644
--- a/compiler/jni/quick/x86/calling_convention_x86.cc
+++ b/compiler/jni/quick/x86/calling_convention_x86.cc
@@ -257,7 +257,7 @@
 
 ManagedRegister X86JniCallingConvention::CurrentParamRegister() {
   LOG(FATAL) << "Should not reach here";
-  return ManagedRegister::NoRegister();
+  UNREACHABLE();
 }
 
 FrameOffset X86JniCallingConvention::CurrentParamStackOffset() {
diff --git a/compiler/optimizing/code_generator.cc b/compiler/optimizing/code_generator.cc
index c2e83cd..2184f99 100644
--- a/compiler/optimizing/code_generator.cc
+++ b/compiler/optimizing/code_generator.cc
@@ -1662,7 +1662,7 @@
     case 3: return kQuickAllocArrayResolved64;
   }
   LOG(FATAL) << "Unreachable";
-  return kQuickAllocArrayResolved;
+  UNREACHABLE();
 }
 
 }  // namespace art
diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index 48b50ea..bbf167d 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -3046,7 +3046,7 @@
 
   if (!DataType::IsIntegralType(type)) {
     LOG(FATAL) << "Unexpected type " << type << " for DivZeroCheck.";
-    return;
+    UNREACHABLE();
   }
 
   if (value.IsConstant()) {
diff --git a/compiler/optimizing/code_generator_arm_vixl.cc b/compiler/optimizing/code_generator_arm_vixl.cc
index d5b734d..dad1813 100644
--- a/compiler/optimizing/code_generator_arm_vixl.cc
+++ b/compiler/optimizing/code_generator_arm_vixl.cc
@@ -1037,26 +1037,26 @@
 size_t CodeGeneratorARMVIXL::SaveCoreRegister(size_t stack_index ATTRIBUTE_UNUSED,
                                               uint32_t reg_id ATTRIBUTE_UNUSED) {
   TODO_VIXL32(FATAL);
-  return 0;
+  UNREACHABLE();
 }
 
 // Restores the register from the stack. Returns the size taken on stack.
 size_t CodeGeneratorARMVIXL::RestoreCoreRegister(size_t stack_index ATTRIBUTE_UNUSED,
                                                  uint32_t reg_id ATTRIBUTE_UNUSED) {
   TODO_VIXL32(FATAL);
-  return 0;
+  UNREACHABLE();
 }
 
 size_t CodeGeneratorARMVIXL::SaveFloatingPointRegister(size_t stack_index ATTRIBUTE_UNUSED,
                                                        uint32_t reg_id ATTRIBUTE_UNUSED) {
   TODO_VIXL32(FATAL);
-  return 0;
+  UNREACHABLE();
 }
 
 size_t CodeGeneratorARMVIXL::RestoreFloatingPointRegister(size_t stack_index ATTRIBUTE_UNUSED,
                                                           uint32_t reg_id ATTRIBUTE_UNUSED) {
   TODO_VIXL32(FATAL);
-  return 0;
+  UNREACHABLE();
 }
 
 static void GenerateDataProcInstruction(HInstruction::InstructionKind kind,
@@ -2268,7 +2268,7 @@
     case DataType::Type::kUint64:
     case DataType::Type::kVoid:
       LOG(FATAL) << "Unexpected parameter type " << type;
-      break;
+      UNREACHABLE();
   }
   return Location::NoLocation();
 }
diff --git a/compiler/optimizing/code_generator_mips.cc b/compiler/optimizing/code_generator_mips.cc
index c6d0f3f..c536dd3 100644
--- a/compiler/optimizing/code_generator_mips.cc
+++ b/compiler/optimizing/code_generator_mips.cc
@@ -147,7 +147,7 @@
     case DataType::Type::kUint64:
     case DataType::Type::kVoid:
       LOG(FATAL) << "Unexpected parameter type " << type;
-      break;
+      UNREACHABLE();
   }
 
   // Space on the stack is reserved for all arguments.
diff --git a/compiler/optimizing/code_generator_mips64.cc b/compiler/optimizing/code_generator_mips64.cc
index 039b3ca..016aac7 100644
--- a/compiler/optimizing/code_generator_mips64.cc
+++ b/compiler/optimizing/code_generator_mips64.cc
@@ -3642,7 +3642,7 @@
 
   if (!DataType::IsIntegralType(type)) {
     LOG(FATAL) << "Unexpected type " << type << " for DivZeroCheck.";
-    return;
+    UNREACHABLE();
   }
 
   if (value.IsConstant()) {
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index fba4da6..1b74d22 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -1228,7 +1228,7 @@
     case DataType::Type::kUint64:
     case DataType::Type::kVoid:
       LOG(FATAL) << "Unexpected parameter type " << type;
-      break;
+      UNREACHABLE();
   }
   return Location::NoLocation();
 }
@@ -2989,7 +2989,7 @@
 
     default:
       LOG(FATAL) << "Unexpected add type " << add->GetResultType();
-      break;
+      UNREACHABLE();
   }
 }
 
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index e7212cd..781f272 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -2425,7 +2425,7 @@
     case DataType::Type::kUint64:
     case DataType::Type::kVoid:
       LOG(FATAL) << "Unexpected parameter type " << type;
-      break;
+      UNREACHABLE();
   }
   return Location::NoLocation();
 }
diff --git a/compiler/optimizing/induction_var_analysis.cc b/compiler/optimizing/induction_var_analysis.cc
index a4d638f..3a10d58 100644
--- a/compiler/optimizing/induction_var_analysis.cc
+++ b/compiler/optimizing/induction_var_analysis.cc
@@ -1074,8 +1074,8 @@
           && lower_value >= upper_value;
     default:
       LOG(FATAL) << "CONDITION UNREACHABLE";
+      UNREACHABLE();
   }
-  return false;  // not certain, may be untaken
 }
 
 bool HInductionVarAnalysis::IsFinite(InductionInfo* upper_expr,
@@ -1099,8 +1099,8 @@
       return (IsAtLeast(upper_expr, &value) && value >= (min - stride_value));
     default:
       LOG(FATAL) << "CONDITION UNREACHABLE";
+      UNREACHABLE();
   }
-  return false;  // not certain, may be infinite
 }
 
 bool HInductionVarAnalysis::FitsNarrowerControl(InductionInfo* lower_expr,
diff --git a/compiler/optimizing/instruction_simplifier.cc b/compiler/optimizing/instruction_simplifier.cc
index 2b6ae20..4c6d6ba 100644
--- a/compiler/optimizing/instruction_simplifier.cc
+++ b/compiler/optimizing/instruction_simplifier.cc
@@ -749,8 +749,8 @@
       return new (allocator) HBelowOrEqual(rhs, lhs);
     default:
       LOG(FATAL) << "Unknown ConditionType " << cond->GetKind();
+      UNREACHABLE();
   }
-  return nullptr;
 }
 
 static bool CmpHasBoolType(HInstruction* input, HInstruction* cmp) {
diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index 3f225f3..d1fba31 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -1231,7 +1231,7 @@
     }
   }
   LOG(FATAL) << "Did not find an order between two instructions of the same block.";
-  return true;
+  UNREACHABLE();
 }
 
 bool HInstruction::StrictlyDominates(HInstruction* other_instruction) const {
@@ -1254,7 +1254,7 @@
       } else {
         // There is no order among phis.
         LOG(FATAL) << "There is no dominance between phis of a same block.";
-        return false;
+        UNREACHABLE();
       }
     } else {
       // `this` is not a phi.
diff --git a/dex2oat/linker/image_writer.cc b/dex2oat/linker/image_writer.cc
index 75b3555..20606fc 100644
--- a/dex2oat/linker/image_writer.cc
+++ b/dex2oat/linker/image_writer.cc
@@ -895,7 +895,7 @@
         oss << ". Lock owner:" << lw.ThinLockOwner();
       }
       LOG(FATAL) << oss.str();
-      break;
+      UNREACHABLE();
     }
     case LockWord::kUnlocked:
       // No hash, don't need to save it.
diff --git a/disassembler/disassembler.cc b/disassembler/disassembler.cc
index aee690e..0662334 100644
--- a/disassembler/disassembler.cc
+++ b/disassembler/disassembler.cc
@@ -75,7 +75,7 @@
 #endif
     default:
       UNIMPLEMENTED(FATAL) << static_cast<uint32_t>(instruction_set);
-      return nullptr;
+      UNREACHABLE();
   }
 }
 
diff --git a/libartbase/base/file_utils.cc b/libartbase/base/file_utils.cc
index 1d106b2..f8d6016 100644
--- a/libartbase/base/file_utils.cc
+++ b/libartbase/base/file_utils.cc
@@ -157,7 +157,7 @@
     return dir;
   } else {
     LOG(FATAL) << error_msg;
-    return nullptr;
+    UNREACHABLE();
   }
 }
 
diff --git a/libdexfile/dex/dex_instruction.cc b/libdexfile/dex/dex_instruction.cc
index 8378211..83663c5 100644
--- a/libdexfile/dex/dex_instruction.cc
+++ b/libdexfile/dex/dex_instruction.cc
@@ -85,7 +85,7 @@
     default: LOG(FATAL) << "Tried to access the branch offset of an instruction " << Name() <<
         " which does not have a target operand.";
   }
-  return 0;
+  UNREACHABLE();
 }
 
 bool Instruction::CanFlowThrough() const {
diff --git a/openjdkjvm/OpenjdkJvm.cc b/openjdkjvm/OpenjdkJvm.cc
index 8d0200c..7a388c9 100644
--- a/openjdkjvm/OpenjdkJvm.cc
+++ b/openjdkjvm/OpenjdkJvm.cc
@@ -434,36 +434,37 @@
   }
 }
 
-JNIEXPORT jint JVM_IHashCode(JNIEnv* env ATTRIBUTE_UNUSED,
+JNIEXPORT __attribute__((noreturn)) jint JVM_IHashCode(JNIEnv* env ATTRIBUTE_UNUSED,
                              jobject javaObject ATTRIBUTE_UNUSED) {
   UNIMPLEMENTED(FATAL) << "JVM_IHashCode is not implemented";
-  return 0;
+  UNREACHABLE();
 }
 
-JNIEXPORT jlong JVM_NanoTime(JNIEnv* env ATTRIBUTE_UNUSED, jclass unused ATTRIBUTE_UNUSED) {
+JNIEXPORT __attribute__((noreturn)) jlong JVM_NanoTime(JNIEnv* env ATTRIBUTE_UNUSED, jclass unused ATTRIBUTE_UNUSED) {
   UNIMPLEMENTED(FATAL) << "JVM_NanoTime is not implemented";
-  return 0L;
+  UNREACHABLE();
 }
 
-JNIEXPORT void JVM_ArrayCopy(JNIEnv* /* env */, jclass /* unused */, jobject /* javaSrc */,
+JNIEXPORT __attribute__((noreturn)) void JVM_ArrayCopy(JNIEnv* /* env */, jclass /* unused */, jobject /* javaSrc */,
                              jint /* srcPos */, jobject /* javaDst */, jint /* dstPos */,
                              jint /* length */) {
   UNIMPLEMENTED(FATAL) << "JVM_ArrayCopy is not implemented";
+  UNREACHABLE();
 }
 
-JNIEXPORT jint JVM_FindSignal(const char* name ATTRIBUTE_UNUSED) {
+JNIEXPORT __attribute__((noreturn)) jint JVM_FindSignal(const char* name ATTRIBUTE_UNUSED) {
   LOG(FATAL) << "JVM_FindSignal is not implemented";
-  return 0;
+  UNREACHABLE();
 }
 
-JNIEXPORT void* JVM_RegisterSignal(jint signum ATTRIBUTE_UNUSED, void* handler ATTRIBUTE_UNUSED) {
+JNIEXPORT __attribute__((noreturn)) void* JVM_RegisterSignal(jint signum ATTRIBUTE_UNUSED, void* handler ATTRIBUTE_UNUSED) {
   LOG(FATAL) << "JVM_RegisterSignal is not implemented";
-  return nullptr;
+  UNREACHABLE();
 }
 
-JNIEXPORT jboolean JVM_RaiseSignal(jint signum ATTRIBUTE_UNUSED) {
+JNIEXPORT __attribute__((noreturn)) jboolean JVM_RaiseSignal(jint signum ATTRIBUTE_UNUSED) {
   LOG(FATAL) << "JVM_RaiseSignal is not implemented";
-  return JNI_FALSE;
+  UNREACHABLE();
 }
 
 JNIEXPORT __attribute__((noreturn))  void JVM_Halt(jint code) {
diff --git a/openjdkjvmti/events.cc b/openjdkjvmti/events.cc
index a96436e..7fb6a15 100644
--- a/openjdkjvmti/events.cc
+++ b/openjdkjvmti/events.cc
@@ -960,7 +960,7 @@
       return art::instrumentation::Instrumentation::kExceptionHandled;
     default:
       LOG(FATAL) << "Unknown event ";
-      return 0;
+      UNREACHABLE();
   }
 }
 
diff --git a/runtime/common_runtime_test.cc b/runtime/common_runtime_test.cc
index fcf6bb2..7388c2e 100644
--- a/runtime/common_runtime_test.cc
+++ b/runtime/common_runtime_test.cc
@@ -139,7 +139,7 @@
   PreRuntimeCreate();
   if (!Runtime::Create(options, false)) {
     LOG(FATAL) << "Failed to create runtime";
-    return;
+    UNREACHABLE();
   }
   PostRuntimeCreate();
   runtime_.reset(Runtime::Current());
diff --git a/runtime/common_throws.cc b/runtime/common_throws.cc
index 0dc0723..62788b1 100644
--- a/runtime/common_throws.cc
+++ b/runtime/common_throws.cc
@@ -717,7 +717,7 @@
                  << instr.DumpString(dex_file)
                  << " in "
                  << method->PrettyMethod();
-      break;
+      UNREACHABLE();
     }
   }
 }
diff --git a/runtime/debugger.cc b/runtime/debugger.cc
index 4af97f0..80140b3 100644
--- a/runtime/debugger.cc
+++ b/runtime/debugger.cc
@@ -1228,7 +1228,7 @@
     return 8;
   default:
     LOG(FATAL) << "Unknown tag " << tag;
-    return -1;
+    UNREACHABLE();
   }
 }
 
@@ -2266,7 +2266,7 @@
       // Don't add a 'default' here so the compiler can spot incompatible enum changes.
   }
   LOG(FATAL) << "Unknown thread state: " << state;
-  return JDWP::TS_ZOMBIE;
+  UNREACHABLE();
 }
 
 JDWP::JdwpError Dbg::GetThreadStatus(JDWP::ObjectId thread_id, JDWP::JdwpThreadStatus* pThreadStatus,
@@ -3155,7 +3155,7 @@
       break;
     default:
       LOG(FATAL) << "Unsupported deoptimization request kind " << request.GetKind();
-      break;
+      UNREACHABLE();
   }
 }
 
@@ -3233,7 +3233,7 @@
     }
     default: {
       LOG(FATAL) << "Unknown deoptimization request kind " << req.GetKind();
-      break;
+      UNREACHABLE();
     }
   }
 }
diff --git a/runtime/dex/dex_file_annotations.cc b/runtime/dex/dex_file_annotations.cc
index 6434828..9127a27 100644
--- a/runtime/dex/dex_file_annotations.cc
+++ b/runtime/dex/dex_file_annotations.cc
@@ -240,7 +240,7 @@
       break;
     default:
       LOG(FATAL) << StringPrintf("Bad annotation element value byte 0x%02x", value_type);
-      return false;
+      UNREACHABLE();
   }
 
   annotation += width;
diff --git a/runtime/entrypoints/quick/quick_jni_entrypoints.cc b/runtime/entrypoints/quick/quick_jni_entrypoints.cc
index 3c41a8c..5c86bbb 100644
--- a/runtime/entrypoints/quick/quick_jni_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_jni_entrypoints.cc
@@ -252,7 +252,7 @@
         return 0;
       default:
         LOG(FATAL) << "Unexpected return shorty character " << return_shorty_char;
-        return 0;
+        UNREACHABLE();
     }
   }
 }
diff --git a/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc b/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
index 8737f3f..6deb509 100644
--- a/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
@@ -297,7 +297,7 @@
       case 4: return (6 * GetBytesPerGprSpillLocation(kRuntimeISA));
       default:
       LOG(FATAL) << "Unexpected GPR index: " << gpr_index;
-      return 0;
+      UNREACHABLE();
     }
   }
 #else
diff --git a/runtime/gc/allocator/rosalloc.cc b/runtime/gc/allocator/rosalloc.cc
index b90a95d..d4b9fab 100644
--- a/runtime/gc/allocator/rosalloc.cc
+++ b/runtime/gc/allocator/rosalloc.cc
@@ -286,7 +286,7 @@
       break;
     default:
       LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(page_map_type);
-      break;
+      UNREACHABLE();
     }
     if (kIsDebugBuild) {
       // Clear the first page since it is not madvised due to the magic number.
@@ -325,7 +325,7 @@
     LOG(FATAL) << "Unreachable - " << __PRETTY_FUNCTION__ << " : " << "pm_idx=" << pm_idx << ", pm_type="
                << static_cast<int>(pm_type) << ", ptr=" << std::hex
                << reinterpret_cast<intptr_t>(ptr);
-    return 0;
+    UNREACHABLE();
   }
   // Update the page map and count the number of pages.
   size_t num_pages = 1;
@@ -514,7 +514,7 @@
         return FreePages(self, ptr, false);
       case kPageMapLargeObjectPart:
         LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(page_map_[pm_idx]);
-        return 0;
+        UNREACHABLE();
       case kPageMapRunPart: {
         // Find the beginning of the run.
         do {
@@ -529,11 +529,11 @@
       case kPageMapReleased:
       case kPageMapEmpty:
         LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(page_map_[pm_idx]);
-        return 0;
+        UNREACHABLE();
       }
       default:
         LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(page_map_[pm_idx]);
-        return 0;
+        UNREACHABLE();
     }
   }
   DCHECK(run != nullptr);
@@ -1307,7 +1307,7 @@
     case kPageMapEmpty:
       LOG(FATAL) << "Unreachable - " << __PRETTY_FUNCTION__ << ": pm_idx=" << pm_idx << ", ptr="
                  << std::hex << reinterpret_cast<intptr_t>(ptr);
-      break;
+      UNREACHABLE();
     case kPageMapLargeObject: {
       size_t num_pages = 1;
       size_t idx = pm_idx + 1;
@@ -1321,7 +1321,7 @@
     case kPageMapLargeObjectPart:
       LOG(FATAL) << "Unreachable - " << __PRETTY_FUNCTION__ << ": pm_idx=" << pm_idx << ", ptr="
                  << std::hex << reinterpret_cast<intptr_t>(ptr);
-      break;
+      UNREACHABLE();
     case kPageMapRun:
     case kPageMapRunPart: {
       // Find the beginning of the run.
@@ -1340,10 +1340,9 @@
     }
     default: {
       LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(page_map_[pm_idx]);
-      break;
+      UNREACHABLE();
     }
   }
-  return 0;
 }
 
 bool RosAlloc::Trim() {
@@ -1456,7 +1455,7 @@
       }
       case kPageMapLargeObjectPart:
         LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(pm);
-        break;
+        UNREACHABLE();
       case kPageMapRun: {
         // The start of a run.
         Run* run = reinterpret_cast<Run*>(base_ + i * kPageSize);
@@ -1476,10 +1475,10 @@
       }
       case kPageMapRunPart:
         LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(pm);
-        break;
+        UNREACHABLE();
       default:
         LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(pm);
-        break;
+        UNREACHABLE();
     }
   }
 }
@@ -1809,7 +1808,7 @@
         }
         case kPageMapLargeObjectPart:
           LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(pm) << std::endl << DumpPageMap();
-          break;
+          UNREACHABLE();
         case kPageMapRun: {
           // The start of a run.
           Run* run = reinterpret_cast<Run*>(base_ + i * kPageSize);
@@ -1837,7 +1836,7 @@
           // Fall-through.
         default:
           LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(pm) << std::endl << DumpPageMap();
-          break;
+          UNREACHABLE();
       }
     }
   }
@@ -2030,7 +2029,7 @@
         break;  // Skip.
       default:
         LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(pm);
-        break;
+        UNREACHABLE();
     }
   }
   return reclaimed_bytes;
@@ -2138,7 +2137,7 @@
       case kPageMapLargeObjectPart:
         LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(pm) << std::endl
                    << DumpPageMap();
-        break;
+        UNREACHABLE();
       case kPageMapRun: {
         Run* run = reinterpret_cast<Run*>(base_ + i * kPageSize);
         size_t idx = run->size_bracket_idx_;
@@ -2157,7 +2156,7 @@
       default:
         LOG(FATAL) << "Unreachable - page map type: " << static_cast<int>(pm) << std::endl
                    << DumpPageMap();
-        break;
+        UNREACHABLE();
     }
   }
   os << "RosAlloc stats:\n";
diff --git a/runtime/gc/heap.cc b/runtime/gc/heap.cc
index 4359bea..f767360 100644
--- a/runtime/gc/heap.cc
+++ b/runtime/gc/heap.cc
@@ -2169,7 +2169,7 @@
       default: {
         LOG(FATAL) << "Attempted to transition to invalid collector type "
                    << static_cast<size_t>(collector_type);
-        break;
+        UNREACHABLE();
       }
     }
     ChangeCollector(collector_type);
diff --git a/runtime/gc/space/space.cc b/runtime/gc/space/space.cc
index a8bd7b8..e7961eb 100644
--- a/runtime/gc/space/space.cc
+++ b/runtime/gc/space/space.cc
@@ -63,7 +63,7 @@
 
 RegionSpace* Space::AsRegionSpace() {
   LOG(FATAL) << "Unreachable";
-  return nullptr;
+  UNREACHABLE();
 }
 
 AllocSpace* Space::AsAllocSpace() {
diff --git a/runtime/hprof/hprof.cc b/runtime/hprof/hprof.cc
index 832bacb..3abe4c5 100644
--- a/runtime/hprof/hprof.cc
+++ b/runtime/hprof/hprof.cc
@@ -1051,7 +1051,7 @@
     case HPROF_ROOT_REFERENCE_CLEANUP:
     case HPROF_UNREACHABLE:
       LOG(FATAL) << "obsolete tag " << static_cast<int>(heap_tag);
-      break;
+      UNREACHABLE();
   }
 
   ++objects_in_segment_;
diff --git a/runtime/interpreter/interpreter_common.cc b/runtime/interpreter/interpreter_common.cc
index fe61547..e52a1c9 100644
--- a/runtime/interpreter/interpreter_common.cc
+++ b/runtime/interpreter/interpreter_common.cc
@@ -1876,7 +1876,7 @@
     default:
       LOG(FATAL) << "Unsupported primitive type " << primitive_component_type
                  << " in fill-array-data";
-      break;
+      UNREACHABLE();
   }
 }
 
diff --git a/runtime/jdwp/jdwp_event.cc b/runtime/jdwp/jdwp_event.cc
index 0353ea7..7ce70cb 100644
--- a/runtime/jdwp/jdwp_event.cc
+++ b/runtime/jdwp/jdwp_event.cc
@@ -554,7 +554,7 @@
       break;
     default:
       LOG(FATAL) << "unknown mod kind " << pMod->modKind;
-      break;
+      UNREACHABLE();
     }
   }
   return true;
diff --git a/runtime/jdwp/jdwp_request.cc b/runtime/jdwp/jdwp_request.cc
index 6af267e..a77962e 100644
--- a/runtime/jdwp/jdwp_request.cc
+++ b/runtime/jdwp/jdwp_request.cc
@@ -70,7 +70,7 @@
     case 2: value = Read2BE(); break;
     case 4: value = Read4BE(); break;
     case 8: value = Read8BE(); break;
-    default: LOG(FATAL) << width; break;
+    default: LOG(FATAL) << width;
   }
   return value;
 }
diff --git a/runtime/jni/check_jni.cc b/runtime/jni/check_jni.cc
index 48f9981..7279299 100644
--- a/runtime/jni/check_jni.cc
+++ b/runtime/jni/check_jni.cc
@@ -880,7 +880,7 @@
       break;
     case kDirectByteBuffer:
       UNIMPLEMENTED(FATAL);
-      break;
+      UNREACHABLE();
     case kString:
       okay = obj->GetClass()->IsStringClass();
       break;
@@ -2945,7 +2945,7 @@
           break;
         case Primitive::kPrimVoid:
           LOG(FATAL) << "Unexpected type: " << type;
-          break;
+          UNREACHABLE();
       }
       if (sc.Check(soa, false, result_check, &result)) {
         return result;
@@ -3031,7 +3031,7 @@
           break;
         case Primitive::kPrimVoid:
           LOG(FATAL) << "Unexpected type: " << type;
-          break;
+          UNREACHABLE();
       }
       JniValueType result;
       result.V = nullptr;
diff --git a/runtime/mirror/object.cc b/runtime/mirror/object.cc
index 9b38576..f6adc80 100644
--- a/runtime/mirror/object.cc
+++ b/runtime/mirror/object.cc
@@ -225,11 +225,10 @@
       }
       default: {
         LOG(FATAL) << "Invalid state during hashcode " << lw.GetState();
-        break;
+        UNREACHABLE();
       }
     }
   }
-  UNREACHABLE();
 }
 
 void Object::CheckFieldAssignmentImpl(MemberOffset field_offset, ObjPtr<Object> new_value) {
diff --git a/runtime/monitor.cc b/runtime/monitor.cc
index 6479283..7240357 100644
--- a/runtime/monitor.cc
+++ b/runtime/monitor.cc
@@ -168,11 +168,11 @@
     }
     case LockWord::kUnlocked: {
       LOG(FATAL) << "Inflating unlocked lock word";
-      break;
+      UNREACHABLE();
     }
     default: {
       LOG(FATAL) << "Invalid monitor state " << lw.GetState();
-      return false;
+      UNREACHABLE();
     }
   }
   LockWord fat(this, lw.GCState());
@@ -1236,7 +1236,7 @@
       }
       default: {
         LOG(FATAL) << "Invalid monitor state " << lock_word.GetState();
-        return false;
+        UNREACHABLE();
       }
     }
   }
@@ -1280,7 +1280,7 @@
       case LockWord::kFatLocked:  // Unreachable given the loop condition above. Fall-through.
       default: {
         LOG(FATAL) << "Invalid monitor state " << lock_word.GetState();
-        return;
+        UNREACHABLE();
       }
     }
   }
@@ -1320,7 +1320,7 @@
     }
     default: {
       LOG(FATAL) << "Invalid monitor state " << lock_word.GetState();
-      return;
+      UNREACHABLE();
     }
   }
 }
diff --git a/runtime/oat_file.cc b/runtime/oat_file.cc
index c1ccd33..5c5523d 100644
--- a/runtime/oat_file.cc
+++ b/runtime/oat_file.cc
@@ -1920,7 +1920,7 @@
       }
       case kOatClassMax: {
         LOG(FATAL) << "Invalid OatClassType " << type_;
-        break;
+        UNREACHABLE();
       }
     }
 }
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index 9cbbd41..ab79b9e 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -1241,7 +1241,6 @@
     }
     case JdwpProvider::kUnset: {
       LOG(FATAL) << "Illegal jdwp provider " << jdwp_provider_ << " was not filtered out!";
-      break;
     }
   }
   callbacks_->AddThreadLifecycleCallback(Dbg::GetThreadLifecycleCallback());
@@ -1856,7 +1855,7 @@
     return 0;  // backward compatibility
   default:
     LOG(FATAL) << "Unknown statistic " << kind;
-    return -1;  // unreachable
+    UNREACHABLE();
   }
 }
 
diff --git a/runtime/thread_list.cc b/runtime/thread_list.cc
index 23e57a2..4bbd81a 100644
--- a/runtime/thread_list.cc
+++ b/runtime/thread_list.cc
@@ -1561,7 +1561,7 @@
     }
   }
   LOG(FATAL) << "Out of internal thread ids";
-  return 0;
+  UNREACHABLE();
 }
 
 void ThreadList::ReleaseThreadId(Thread* self, uint32_t id) {
diff --git a/runtime/transaction.cc b/runtime/transaction.cc
index e4bf447..62482fd 100644
--- a/runtime/transaction.cc
+++ b/runtime/transaction.cc
@@ -531,7 +531,7 @@
       break;
     default:
       LOG(FATAL) << "Unknown value kind " << static_cast<int>(field_value.kind);
-      break;
+      UNREACHABLE();
   }
 }
 
@@ -558,7 +558,7 @@
           break;
         default:
           LOG(FATAL) << "Unknown interned string kind";
-          break;
+          UNREACHABLE();
       }
       break;
     }
@@ -572,13 +572,13 @@
           break;
         default:
           LOG(FATAL) << "Unknown interned string kind";
-          break;
+          UNREACHABLE();
       }
       break;
     }
     default:
       LOG(FATAL) << "Unknown interned string op";
-      break;
+      UNREACHABLE();
   }
 }
 
@@ -669,9 +669,10 @@
       break;
     case Primitive::kPrimNot:
       LOG(FATAL) << "ObjectArray should be treated as Object";
-      break;
+      UNREACHABLE();
     default:
       LOG(FATAL) << "Unsupported type " << array_type;
+      UNREACHABLE();
   }
 }
 
diff --git a/runtime/well_known_classes.cc b/runtime/well_known_classes.cc
index 5300e2d..cde885c 100644
--- a/runtime/well_known_classes.cc
+++ b/runtime/well_known_classes.cc
@@ -276,7 +276,7 @@
       STRING_INIT_LIST(TO_STRING_FACTORY)
   #undef TO_STRING_FACTORY
   LOG(FATAL) << "Could not find StringFactory method for String.<init>";
-  return nullptr;
+  UNREACHABLE();
 }
 
 uint32_t WellKnownClasses::StringInitToEntryPoint(ArtMethod* string_init) {
@@ -288,7 +288,7 @@
       STRING_INIT_LIST(TO_ENTRY_POINT)
   #undef TO_ENTRY_POINT
   LOG(FATAL) << "Could not find StringFactory method for String.<init>";
-  return 0;
+  UNREACHABLE();
 }
 #undef STRING_INIT_LIST
 
diff --git a/test/ti-agent/common_helper.cc b/test/ti-agent/common_helper.cc
index f5e1e1b..3be48a3 100644
--- a/test/ti-agent/common_helper.cc
+++ b/test/ti-agent/common_helper.cc
@@ -24,6 +24,7 @@
 #include "jvmti.h"
 
 #include "jvmti_helper.h"
+#include "ti_macros.h"
 
 namespace art {
 
@@ -87,7 +88,7 @@
       break;
     default:
       LOG(FATAL) << "Unable to figure out type!";
-      return nullptr;
+      UNREACHABLE();
   }
   std::ostringstream oss;
   oss << "(" << type << ")L" << name << ";";
diff --git a/tools/timeout_dumper/timeout_dumper.cc b/tools/timeout_dumper/timeout_dumper.cc
index 30e194c..96d165c 100644
--- a/tools/timeout_dumper/timeout_dumper.cc
+++ b/tools/timeout_dumper/timeout_dumper.cc
@@ -432,7 +432,7 @@
     LOG(ERROR) << prefix << "(failed to create Backtrace for thread " << tid << ")";
     return;
   }
-  backtrace->SetSkipFrames(0);
+  backtrace->SetSkipFrames(false);
   if (!backtrace->Unwind(0, nullptr)) {
     LOG(ERROR) << prefix << "(backtrace::Unwind failed for thread " << tid
                << ": " <<  backtrace->GetErrorString(backtrace->GetError()) << ")";
diff --git a/tools/titrace/instruction_decoder.cc b/tools/titrace/instruction_decoder.cc
index 89904b3..6f497b3 100644
--- a/tools/titrace/instruction_decoder.cc
+++ b/tools/titrace/instruction_decoder.cc
@@ -456,9 +456,10 @@
         case kBreakpoint: return "breakpoint";
         case kImpdep1: return "impdep1";
         case kImpdep2: return "impdep2";
-        default: LOG(FATAL) << "Unknown opcode " << op;
+        default:
+          LOG(FATAL) << "Unknown opcode " << op;
+          __builtin_unreachable();
        }
-       return "";
      }
   };
 };
@@ -500,7 +501,7 @@
 #undef MAKE_ENUM_DEFINITION
         default: LOG(FATAL) << "Unknown opcode " << op;
       }
-      return "";
+      __builtin_unreachable();
     }
   };
 };