Compiler changes for bitstring based type checks.

We guard the use of this feature with a compile-time flag,
set to true in this CL.

Boot image size for aosp_taimen-userdebug in AOSP master:
  - before:
    arm boot*.oat: 63604740
    arm64 boot*.oat: 74237864
  - after:
    arm boot*.oat: 63531172 (-72KiB, -0.1%)
    arm64 boot*.oat: 74135008 (-100KiB, -0.1%)

The new TypeCheckBenchmark yields the following changes
using the little cores of taimen fixed at 1.4016GHz:
                               32-bit        64-bit
  timeCheckCastLevel1ToLevel1  11.48->15.80 11.47->15.78
  timeCheckCastLevel2ToLevel1  15.08->15.79 15.08->15.79
  timeCheckCastLevel3ToLevel1  19.01->15.82 17.94->15.81
  timeCheckCastLevel9ToLevel1  42.55->15.79 42.63->15.81
  timeCheckCastLevel9ToLevel2  39.70->14.36 39.70->14.35
  timeInstanceOfLevel1ToLevel1 13.74->17.93 13.76->17.95
  timeInstanceOfLevel2ToLevel1 17.02->17.95 16.99->17.93
  timeInstanceOfLevel3ToLevel1 24.03->17.95 24.45->17.95
  timeInstanceOfLevel9ToLevel1 47.13->17.95 47.14->18.00
  timeInstanceOfLevel9ToLevel2 44.19->16.52 44.27->16.51
This suggests that the bitstring typecheck should not be
used for exact type checks which would be equivalent to the
"Level1ToLevel1" benchmark. Whether the implementation is
a beneficial replacement for the kClassHierarchyCheck and
kAbstractClassCheck on average depends on how many levels
from the target class (or Object for a negative result) is
a typical object's class.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing --jit
Test: testrunner.py --host -t 670-bitstring-type-check
Test: Pixel 2 XL boots.
Test: testrunner.py --target --optimizing --jit
Test: testrunner.py --target -t 670-bitstring-type-check
Bug: 64692057
Bug: 71853552
Bug: 26687569
Change-Id: I538d7e036b5a8ae2cc3fe77662a5903d74854562

45 files changed, 1529 insertions, 238 deletions

diff --git a/benchmark/type-check/info.txt b/benchmark/type-check/info.txt
new file mode 100644
index 0000000000..d14fb9685b
--- /dev/null
+++ b/benchmark/type-check/info.txt
@@ -0,0 +1 @@
+Benchmarks for repeating check-cast and instance-of instructions in a loop.
diff --git a/benchmark/type-check/src/TypeCheckBenchmark.java b/benchmark/type-check/src/TypeCheckBenchmark.java
new file mode 100644
index 0000000000..96904d99b6
--- /dev/null
+++ b/benchmark/type-check/src/TypeCheckBenchmark.java
@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+public class TypeCheckBenchmark {
+    public void timeCheckCastLevel1ToLevel1(int count) {
+        Object[] arr = arr1;
+        for (int i = 0; i < count; ++i) {
+            Level1 l1 = (Level1) arr[i & 1023];
+        }
+    }
+
+    public void timeCheckCastLevel2ToLevel1(int count) {
+        Object[] arr = arr2;
+        for (int i = 0; i < count; ++i) {
+            Level1 l1 = (Level1) arr[i & 1023];
+        }
+    }
+
+    public void timeCheckCastLevel3ToLevel1(int count) {
+        Object[] arr = arr3;
+        for (int i = 0; i < count; ++i) {
+            Level1 l1 = (Level1) arr[i & 1023];
+        }
+    }
+
+    public void timeCheckCastLevel9ToLevel1(int count) {
+        Object[] arr = arr9;
+        for (int i = 0; i < count; ++i) {
+            Level1 l1 = (Level1) arr[i & 1023];
+        }
+    }
+
+    public void timeCheckCastLevel9ToLevel2(int count) {
+        Object[] arr = arr9;
+        for (int i = 0; i < count; ++i) {
+            Level2 l2 = (Level2) arr[i & 1023];
+        }
+    }
+
+    public void timeInstanceOfLevel1ToLevel1(int count) {
+        int sum = 0;
+        Object[] arr = arr1;
+        for (int i = 0; i < count; ++i) {
+            if (arr[i & 1023] instanceof Level1) {
+              ++sum;
+            }
+        }
+        result = sum;
+    }
+
+    public void timeInstanceOfLevel2ToLevel1(int count) {
+        int sum = 0;
+        Object[] arr = arr2;
+        for (int i = 0; i < count; ++i) {
+            if (arr[i & 1023] instanceof Level1) {
+              ++sum;
+            }
+        }
+        result = sum;
+    }
+
+    public void timeInstanceOfLevel3ToLevel1(int count) {
+        int sum = 0;
+        Object[] arr = arr3;
+        for (int i = 0; i < count; ++i) {
+            if (arr[i & 1023] instanceof Level1) {
+              ++sum;
+            }
+        }
+        result = sum;
+    }
+
+    public void timeInstanceOfLevel9ToLevel1(int count) {
+        int sum = 0;
+        Object[] arr = arr9;
+        for (int i = 0; i < count; ++i) {
+            if (arr[i & 1023] instanceof Level1) {
+              ++sum;
+            }
+        }
+        result = sum;
+    }
+
+    public void timeInstanceOfLevel9ToLevel2(int count) {
+        int sum = 0;
+        Object[] arr = arr9;
+        for (int i = 0; i < count; ++i) {
+            if (arr[i & 1023] instanceof Level2) {
+              ++sum;
+            }
+        }
+        result = sum;
+    }
+
+    public static Object[] createArray(int level) {
+        try {
+            Class<?>[] ls = {
+                    null,
+                    Level1.class,
+                    Level2.class,
+                    Level3.class,
+                    Level4.class,
+                    Level5.class,
+                    Level6.class,
+                    Level7.class,
+                    Level8.class,
+                    Level9.class,
+            };
+            Class<?> l = ls[level];
+            Object[] array = new Object[1024];
+            for (int i = 0; i < array.length; ++i) {
+                array[i] = l.newInstance();
+            }
+            return array;
+        } catch (Exception unexpected) {
+            throw new Error("Initialization failure!");
+        }
+    }
+    Object[] arr1 = createArray(1);
+    Object[] arr2 = createArray(2);
+    Object[] arr3 = createArray(3);
+    Object[] arr9 = createArray(9);
+    int result;
+}
+
+class Level1 { }
+class Level2 extends Level1 { }
+class Level3 extends Level2 { }
+class Level4 extends Level3 { }
+class Level5 extends Level4 { }
+class Level6 extends Level5 { }
+class Level7 extends Level6 { }
+class Level8 extends Level7 { }
+class Level9 extends Level8 { }
diff --git a/compiler/driver/compiler_driver.cc b/compiler/driver/compiler_driver.cc
index 869865956c..407a53d4eb 100644
--- a/compiler/driver/compiler_driver.cc
+++ b/compiler/driver/compiler_driver.cc
@@ -697,7 +697,8 @@ void CompilerDriver::Resolve(jobject class_loader,
 // TODO: Collect the relevant string indices in parallel, then allocate them sequentially in a
 //       stable order.
 
-static void ResolveConstStrings(Handle<mirror::DexCache> dex_cache,
+static void ResolveConstStrings(ClassLinker* class_linker,
+                                Handle<mirror::DexCache> dex_cache,
                                 const DexFile& dex_file,
                                 const DexFile::CodeItem* code_item)
       REQUIRES_SHARED(Locks::mutator_lock_) {
@@ -706,7 +707,6 @@ static void ResolveConstStrings(Handle<mirror::DexCache> dex_cache,
     return;
   }
 
-  ClassLinker* const class_linker = Runtime::Current()->GetClassLinker();
   for (const DexInstructionPcPair& inst : CodeItemInstructionAccessor(dex_file, code_item)) {
     switch (inst->Opcode()) {
       case Instruction::CONST_STRING:
@@ -754,22 +754,105 @@ static void ResolveConstStrings(CompilerDriver* driver,
           dex_file->StringByTypeIdx(class_def.class_idx_));
       if (!compilation_enabled) {
         // Compilation is skipped, do not resolve const-string in code of this class.
-        // TODO: Make sure that inlining honors this.
+        // FIXME: Make sure that inlining honors this. b/26687569
         continue;
       }
 
       // Direct and virtual methods.
-      int64_t previous_method_idx = -1;
       while (it.HasNextMethod()) {
-        uint32_t method_idx = it.GetMemberIndex();
-        if (method_idx == previous_method_idx) {
-          // smali can create dex files with two encoded_methods sharing the same method_idx
-          // http://code.google.com/p/smali/issues/detail?id=119
-          it.Next();
-          continue;
+        ResolveConstStrings(class_linker, dex_cache, *dex_file, it.GetMethodCodeItem());
+        it.Next();
+      }
+      DCHECK(!it.HasNext());
+    }
+  }
+}
+
+// Initialize type check bit strings for check-cast and instance-of in the code. Done to have
+// deterministic allocation behavior. Right now this is single-threaded for simplicity.
+// TODO: Collect the relevant type indices in parallel, then process them sequentially in a
+//       stable order.
+
+static void InitializeTypeCheckBitstrings(CompilerDriver* driver,
+                                          ClassLinker* class_linker,
+                                          Handle<mirror::DexCache> dex_cache,
+                                          const DexFile& dex_file,
+                                          const DexFile::CodeItem* code_item)
+      REQUIRES_SHARED(Locks::mutator_lock_) {
+  if (code_item == nullptr) {
+    // Abstract or native method.
+    return;
+  }
+
+  for (const DexInstructionPcPair& inst : CodeItemInstructionAccessor(dex_file, code_item)) {
+    switch (inst->Opcode()) {
+      case Instruction::CHECK_CAST:
+      case Instruction::INSTANCE_OF: {
+        dex::TypeIndex type_index(
+            (inst->Opcode() == Instruction::CHECK_CAST) ? inst->VRegB_21c() : inst->VRegC_22c());
+        const char* descriptor = dex_file.StringByTypeIdx(type_index);
+        // We currently do not use the bitstring type check for array or final (including
+        // primitive) classes. We may reconsider this in future if it's deemed to be beneficial.
+        // And we cannot use it for classes outside the boot image as we do not know the runtime
+        // value of their bitstring when compiling (it may not even get assigned at runtime).
+        if (descriptor[0] == 'L' && driver->IsImageClass(descriptor)) {
+          ObjPtr<mirror::Class> klass =
+              class_linker->LookupResolvedType(type_index,
+                                               dex_cache.Get(),
+                                               /* class_loader */ nullptr);
+          CHECK(klass != nullptr) << descriptor << " should have been previously resolved.";
+          // Now assign the bitstring if the class is not final. Keep this in sync with sharpening.
+          if (!klass->IsFinal()) {
+            MutexLock subtype_check_lock(Thread::Current(), *Locks::subtype_check_lock_);
+            SubtypeCheck<ObjPtr<mirror::Class>>::EnsureAssigned(klass);
+          }
         }
-        previous_method_idx = method_idx;
-        ResolveConstStrings(dex_cache, *dex_file, it.GetMethodCodeItem());
+        break;
+      }
+
+      default:
+        break;
+    }
+  }
+}
+
+static void InitializeTypeCheckBitstrings(CompilerDriver* driver,
+                                          const std::vector<const DexFile*>& dex_files,
+                                          TimingLogger* timings) {
+  ScopedObjectAccess soa(Thread::Current());
+  StackHandleScope<1> hs(soa.Self());
+  ClassLinker* const class_linker = Runtime::Current()->GetClassLinker();
+  MutableHandle<mirror::DexCache> dex_cache(hs.NewHandle<mirror::DexCache>(nullptr));
+
+  for (const DexFile* dex_file : dex_files) {
+    dex_cache.Assign(class_linker->FindDexCache(soa.Self(), *dex_file));
+    TimingLogger::ScopedTiming t("Initialize type check bitstrings", timings);
+
+    size_t class_def_count = dex_file->NumClassDefs();
+    for (size_t class_def_index = 0; class_def_index < class_def_count; ++class_def_index) {
+      const DexFile::ClassDef& class_def = dex_file->GetClassDef(class_def_index);
+
+      const uint8_t* class_data = dex_file->GetClassData(class_def);
+      if (class_data == nullptr) {
+        // empty class, probably a marker interface
+        continue;
+      }
+
+      ClassDataItemIterator it(*dex_file, class_data);
+      it.SkipAllFields();
+
+      bool compilation_enabled = driver->IsClassToCompile(
+          dex_file->StringByTypeIdx(class_def.class_idx_));
+      if (!compilation_enabled) {
+        // Compilation is skipped, do not look for type checks in code of this class.
+        // FIXME: Make sure that inlining honors this. b/26687569
+        continue;
+      }
+
+      // Direct and virtual methods.
+      while (it.HasNextMethod()) {
+        InitializeTypeCheckBitstrings(
+            driver, class_linker, dex_cache, *dex_file, it.GetMethodCodeItem());
         it.Next();
       }
       DCHECK(!it.HasNext());
@@ -871,6 +954,13 @@ void CompilerDriver::PreCompile(jobject class_loader,
 
   UpdateImageClasses(timings);
   VLOG(compiler) << "UpdateImageClasses: " << GetMemoryUsageString(false);
+
+  if (GetCompilerOptions().IsForceDeterminism() && GetCompilerOptions().IsBootImage()) {
+    // Initialize type check bit string used by check-cast and instanceof.
+    // Do this now to have a deterministic image.
+    // Note: This is done after UpdateImageClasses() at it relies on the image classes to be final.
+    InitializeTypeCheckBitstrings(this, dex_files, timings);
+  }
 }
 
 bool CompilerDriver::IsImageClass(const char* descriptor) const {
diff --git a/compiler/driver/compiler_driver.h b/compiler/driver/compiler_driver.h
index ef16212fb7..134b5695b9 100644
--- a/compiler/driver/compiler_driver.h
+++ b/compiler/driver/compiler_driver.h
@@ -76,6 +76,9 @@ class VdexFile;
 class VerificationResults;
 class VerifiedMethod;
 
+// Compile-time flag to enable/disable bitstring type checks.
+static constexpr bool kUseBitstringTypeCheck = true;
+
 enum EntryPointCallingConvention {
   // ABI of invocations to a method's interpreter entry point.
   kInterpreterAbi,
diff --git a/compiler/optimizing/code_generator.h b/compiler/optimizing/code_generator.h
index 3c5a37f958..2dafbf7f6d 100644
--- a/compiler/optimizing/code_generator.h
+++ b/compiler/optimizing/code_generator.h
@@ -438,6 +438,8 @@ class CodeGenerator : public DeletableArenaObject<kArenaAllocCodeGenerator> {
       case TypeCheckKind::kArrayCheck:
       case TypeCheckKind::kUnresolvedCheck:
         return false;
+      case TypeCheckKind::kBitstringCheck:
+        return true;
     }
     LOG(FATAL) << "Unreachable";
     UNREACHABLE();
diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index 13bbffa1e3..b47a5cf3c4 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -2112,6 +2112,26 @@ void InstructionCodeGeneratorARM64::GenerateClassInitializationCheck(SlowPathCod
   __ Bind(slow_path->GetExitLabel());
 }
 
+void InstructionCodeGeneratorARM64::GenerateBitstringTypeCheckCompare(
+    HTypeCheckInstruction* check, vixl::aarch64::Register temp) {
+  uint32_t path_to_root = check->GetBitstringPathToRoot();
+  uint32_t mask = check->GetBitstringMask();
+  DCHECK(IsPowerOfTwo(mask + 1));
+  size_t mask_bits = WhichPowerOf2(mask + 1);
+
+  if (mask_bits == 16u) {
+    // Load only the bitstring part of the status word.
+    __ Ldrh(temp, HeapOperand(temp, mirror::Class::StatusOffset()));
+  } else {
+    // /* uint32_t */ temp = temp->status_
+    __ Ldr(temp, HeapOperand(temp, mirror::Class::StatusOffset()));
+    // Extract the bitstring bits.
+    __ Ubfx(temp, temp, 0, mask_bits);
+  }
+  // Compare the bitstring bits to `path_to_root`.
+  __ Cmp(temp, path_to_root);
+}
+
 void CodeGeneratorARM64::GenerateMemoryBarrier(MemBarrierKind kind) {
   BarrierType type = BarrierAll;
 
@@ -3840,6 +3860,8 @@ void LocationsBuilderARM64::VisitInstanceOf(HInstanceOf* instruction) {
     case TypeCheckKind::kInterfaceCheck:
       call_kind = LocationSummary::kCallOnSlowPath;
       break;
+    case TypeCheckKind::kBitstringCheck:
+      break;
   }
 
   LocationSummary* locations =
@@ -3848,7 +3870,13 @@ void LocationsBuilderARM64::VisitInstanceOf(HInstanceOf* instruction) {
     locations->SetCustomSlowPathCallerSaves(RegisterSet::Empty());  // No caller-save registers.
   }
   locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RequiresRegister());
+  if (type_check_kind == TypeCheckKind::kBitstringCheck) {
+    locations->SetInAt(1, Location::ConstantLocation(instruction->InputAt(1)->AsConstant()));
+    locations->SetInAt(2, Location::ConstantLocation(instruction->InputAt(2)->AsConstant()));
+    locations->SetInAt(3, Location::ConstantLocation(instruction->InputAt(3)->AsConstant()));
+  } else {
+    locations->SetInAt(1, Location::RequiresRegister());
+  }
   // The "out" register is used as a temporary, so it overlaps with the inputs.
   // Note that TypeCheckSlowPathARM64 uses this register too.
   locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
@@ -3861,7 +3889,9 @@ void InstructionCodeGeneratorARM64::VisitInstanceOf(HInstanceOf* instruction) {
   LocationSummary* locations = instruction->GetLocations();
   Location obj_loc = locations->InAt(0);
   Register obj = InputRegisterAt(instruction, 0);
-  Register cls = InputRegisterAt(instruction, 1);
+  Register cls = (type_check_kind == TypeCheckKind::kBitstringCheck)
+      ? Register()
+      : InputRegisterAt(instruction, 1);
   Location out_loc = locations->Out();
   Register out = OutputRegister(instruction);
   const size_t num_temps = NumberOfInstanceOfTemps(type_check_kind);
@@ -4047,6 +4077,23 @@ void InstructionCodeGeneratorARM64::VisitInstanceOf(HInstanceOf* instruction) {
       }
       break;
     }
+
+    case TypeCheckKind::kBitstringCheck: {
+      // /* HeapReference<Class> */ temp = obj->klass_
+      GenerateReferenceLoadTwoRegisters(instruction,
+                                        out_loc,
+                                        obj_loc,
+                                        class_offset,
+                                        maybe_temp_loc,
+                                        kWithoutReadBarrier);
+
+      GenerateBitstringTypeCheckCompare(instruction, out);
+      __ Cset(out, eq);
+      if (zero.IsLinked()) {
+        __ B(&done);
+      }
+      break;
+    }
   }
 
   if (zero.IsLinked()) {
@@ -4069,7 +4116,13 @@ void LocationsBuilderARM64::VisitCheckCast(HCheckCast* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetAllocator()) LocationSummary(instruction, call_kind);
   locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RequiresRegister());
+  if (type_check_kind == TypeCheckKind::kBitstringCheck) {
+    locations->SetInAt(1, Location::ConstantLocation(instruction->InputAt(1)->AsConstant()));
+    locations->SetInAt(2, Location::ConstantLocation(instruction->InputAt(2)->AsConstant()));
+    locations->SetInAt(3, Location::ConstantLocation(instruction->InputAt(3)->AsConstant()));
+  } else {
+    locations->SetInAt(1, Location::RequiresRegister());
+  }
   // Add temps for read barriers and other uses. One is used by TypeCheckSlowPathARM64.
   locations->AddRegisterTemps(NumberOfCheckCastTemps(type_check_kind));
 }
@@ -4079,7 +4132,9 @@ void InstructionCodeGeneratorARM64::VisitCheckCast(HCheckCast* instruction) {
   LocationSummary* locations = instruction->GetLocations();
   Location obj_loc = locations->InAt(0);
   Register obj = InputRegisterAt(instruction, 0);
-  Register cls = InputRegisterAt(instruction, 1);
+  Register cls = (type_check_kind == TypeCheckKind::kBitstringCheck)
+      ? Register()
+      : InputRegisterAt(instruction, 1);
   const size_t num_temps = NumberOfCheckCastTemps(type_check_kind);
   DCHECK_GE(num_temps, 1u);
   DCHECK_LE(num_temps, 3u);
@@ -4260,6 +4315,20 @@ void InstructionCodeGeneratorARM64::VisitCheckCast(HCheckCast* instruction) {
       __ B(ne, &start_loop);
       break;
     }
+
+    case TypeCheckKind::kBitstringCheck: {
+      // /* HeapReference<Class> */ temp = obj->klass_
+      GenerateReferenceLoadTwoRegisters(instruction,
+                                        temp_loc,
+                                        obj_loc,
+                                        class_offset,
+                                        maybe_temp2_loc,
+                                        kWithoutReadBarrier);
+
+      GenerateBitstringTypeCheckCompare(instruction, temp);
+      __ B(ne, type_check_slow_path->GetEntryLabel());
+      break;
+    }
   }
   __ Bind(&done);
 
diff --git a/compiler/optimizing/code_generator_arm64.h b/compiler/optimizing/code_generator_arm64.h
index f92c94fda7..cc369de983 100644
--- a/compiler/optimizing/code_generator_arm64.h
+++ b/compiler/optimizing/code_generator_arm64.h
@@ -264,6 +264,8 @@ class InstructionCodeGeneratorARM64 : public InstructionCodeGenerator {
  private:
   void GenerateClassInitializationCheck(SlowPathCodeARM64* slow_path,
                                         vixl::aarch64::Register class_reg);
+  void GenerateBitstringTypeCheckCompare(HTypeCheckInstruction* check,
+                                         vixl::aarch64::Register temp);
   void GenerateSuspendCheck(HSuspendCheck* instruction, HBasicBlock* successor);
   void HandleBinaryOp(HBinaryOperation* instr);
 
diff --git a/compiler/optimizing/code_generator_arm_vixl.cc b/compiler/optimizing/code_generator_arm_vixl.cc
index 577fe00dcd..84ba178f7b 100644
--- a/compiler/optimizing/code_generator_arm_vixl.cc
+++ b/compiler/optimizing/code_generator_arm_vixl.cc
@@ -7191,6 +7191,67 @@ void InstructionCodeGeneratorARMVIXL::GenerateClassInitializationCheck(
   __ Bind(slow_path->GetExitLabel());
 }
 
+void InstructionCodeGeneratorARMVIXL::GenerateBitstringTypeCheckCompare(
+    HTypeCheckInstruction* check,
+    vixl32::Register temp,
+    vixl32::FlagsUpdate flags_update) {
+  uint32_t path_to_root = check->GetBitstringPathToRoot();
+  uint32_t mask = check->GetBitstringMask();
+  DCHECK(IsPowerOfTwo(mask + 1));
+  size_t mask_bits = WhichPowerOf2(mask + 1);
+
+  // Note that HInstanceOf shall check for zero value in `temp` but HCheckCast needs
+  // the Z flag for BNE. This is indicated by the `flags_update` parameter.
+  if (mask_bits == 16u) {
+    // Load only the bitstring part of the status word.
+    __ Ldrh(temp, MemOperand(temp, mirror::Class::StatusOffset().Int32Value()));
+    // Check if the bitstring bits are equal to `path_to_root`.
+    if (flags_update == SetFlags) {
+      __ Cmp(temp, path_to_root);
+    } else {
+      __ Sub(temp, temp, path_to_root);
+    }
+  } else {
+    // /* uint32_t */ temp = temp->status_
+    __ Ldr(temp, MemOperand(temp, mirror::Class::StatusOffset().Int32Value()));
+    if (GetAssembler()->ShifterOperandCanHold(SUB, path_to_root)) {
+      // Compare the bitstring bits using SUB.
+      __ Sub(temp, temp, path_to_root);
+      // Shift out bits that do not contribute to the comparison.
+      __ Lsl(flags_update, temp, temp, dchecked_integral_cast<uint32_t>(32u - mask_bits));
+    } else if (IsUint<16>(path_to_root)) {
+      if (temp.IsLow()) {
+        // Note: Optimized for size but contains one more dependent instruction than necessary.
+        //       MOVW+SUB(register) would be 8 bytes unless we find a low-reg temporary but the
+        //       macro assembler would use the high reg IP for the constant by default.
+        // Compare the bitstring bits using SUB.
+        __ Sub(temp, temp, path_to_root & 0x00ffu);  // 16-bit SUB (immediate) T2
+        __ Sub(temp, temp, path_to_root & 0xff00u);  // 32-bit SUB (immediate) T3
+        // Shift out bits that do not contribute to the comparison.
+        __ Lsl(flags_update, temp, temp, dchecked_integral_cast<uint32_t>(32u - mask_bits));
+      } else {
+        // Extract the bitstring bits.
+        __ Ubfx(temp, temp, 0, mask_bits);
+        // Check if the bitstring bits are equal to `path_to_root`.
+        if (flags_update == SetFlags) {
+          __ Cmp(temp, path_to_root);
+        } else {
+          __ Sub(temp, temp, path_to_root);
+        }
+      }
+    } else {
+      // Shift out bits that do not contribute to the comparison.
+      __ Lsl(temp, temp, dchecked_integral_cast<uint32_t>(32u - mask_bits));
+      // Check if the shifted bitstring bits are equal to `path_to_root << (32u - mask_bits)`.
+      if (flags_update == SetFlags) {
+        __ Cmp(temp, path_to_root << (32u - mask_bits));
+      } else {
+        __ Sub(temp, temp, path_to_root << (32u - mask_bits));
+      }
+    }
+  }
+}
+
 HLoadString::LoadKind CodeGeneratorARMVIXL::GetSupportedLoadStringKind(
     HLoadString::LoadKind desired_string_load_kind) {
   switch (desired_string_load_kind) {
@@ -7382,6 +7443,8 @@ void LocationsBuilderARMVIXL::VisitInstanceOf(HInstanceOf* instruction) {
     case TypeCheckKind::kInterfaceCheck:
       call_kind = LocationSummary::kCallOnSlowPath;
       break;
+    case TypeCheckKind::kBitstringCheck:
+      break;
   }
 
   LocationSummary* locations =
@@ -7390,7 +7453,13 @@ void LocationsBuilderARMVIXL::VisitInstanceOf(HInstanceOf* instruction) {
     locations->SetCustomSlowPathCallerSaves(RegisterSet::Empty());  // No caller-save registers.
   }
   locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RequiresRegister());
+  if (type_check_kind == TypeCheckKind::kBitstringCheck) {
+    locations->SetInAt(1, Location::ConstantLocation(instruction->InputAt(1)->AsConstant()));
+    locations->SetInAt(2, Location::ConstantLocation(instruction->InputAt(2)->AsConstant()));
+    locations->SetInAt(3, Location::ConstantLocation(instruction->InputAt(3)->AsConstant()));
+  } else {
+    locations->SetInAt(1, Location::RequiresRegister());
+  }
   // The "out" register is used as a temporary, so it overlaps with the inputs.
   // Note that TypeCheckSlowPathARM uses this register too.
   locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
@@ -7405,7 +7474,9 @@ void InstructionCodeGeneratorARMVIXL::VisitInstanceOf(HInstanceOf* instruction)
   LocationSummary* locations = instruction->GetLocations();
   Location obj_loc = locations->InAt(0);
   vixl32::Register obj = InputRegisterAt(instruction, 0);
-  vixl32::Register cls = InputRegisterAt(instruction, 1);
+  vixl32::Register cls = (type_check_kind == TypeCheckKind::kBitstringCheck)
+      ? vixl32::Register()
+      : InputRegisterAt(instruction, 1);
   Location out_loc = locations->Out();
   vixl32::Register out = OutputRegister(instruction);
   const size_t num_temps = NumberOfInstanceOfTemps(type_check_kind);
@@ -7645,6 +7716,26 @@ void InstructionCodeGeneratorARMVIXL::VisitInstanceOf(HInstanceOf* instruction)
       __ B(slow_path->GetEntryLabel());
       break;
     }
+
+    case TypeCheckKind::kBitstringCheck: {
+      // /* HeapReference<Class> */ temp = obj->klass_
+      GenerateReferenceLoadTwoRegisters(instruction,
+                                        out_loc,
+                                        obj_loc,
+                                        class_offset,
+                                        maybe_temp_loc,
+                                        kWithoutReadBarrier);
+
+      GenerateBitstringTypeCheckCompare(instruction, out, DontCare);
+      // If `out` is a low reg and we would have another low reg temp, we could
+      // optimize this as RSBS+ADC, see GenerateConditionWithZero().
+      //
+      // Also, in some cases when `out` is a low reg and we're loading a constant to IP
+      // it would make sense to use CMP+MOV+IT+MOV instead of SUB+CLZ+LSR as the code size
+      // would be the same and we would have fewer direct data dependencies.
+      codegen_->GenerateConditionWithZero(kCondEQ, out, out);  // CLZ+LSR
+      break;
+    }
   }
 
   if (done.IsReferenced()) {
@@ -7662,7 +7753,13 @@ void LocationsBuilderARMVIXL::VisitCheckCast(HCheckCast* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetAllocator()) LocationSummary(instruction, call_kind);
   locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RequiresRegister());
+  if (type_check_kind == TypeCheckKind::kBitstringCheck) {
+    locations->SetInAt(1, Location::ConstantLocation(instruction->InputAt(1)->AsConstant()));
+    locations->SetInAt(2, Location::ConstantLocation(instruction->InputAt(2)->AsConstant()));
+    locations->SetInAt(3, Location::ConstantLocation(instruction->InputAt(3)->AsConstant()));
+  } else {
+    locations->SetInAt(1, Location::RequiresRegister());
+  }
   locations->AddRegisterTemps(NumberOfCheckCastTemps(type_check_kind));
 }
 
@@ -7671,7 +7768,9 @@ void InstructionCodeGeneratorARMVIXL::VisitCheckCast(HCheckCast* instruction) {
   LocationSummary* locations = instruction->GetLocations();
   Location obj_loc = locations->InAt(0);
   vixl32::Register obj = InputRegisterAt(instruction, 0);
-  vixl32::Register cls = InputRegisterAt(instruction, 1);
+  vixl32::Register cls = (type_check_kind == TypeCheckKind::kBitstringCheck)
+      ? vixl32::Register()
+      : InputRegisterAt(instruction, 1);
   Location temp_loc = locations->GetTemp(0);
   vixl32::Register temp = RegisterFrom(temp_loc);
   const size_t num_temps = NumberOfCheckCastTemps(type_check_kind);
@@ -7856,6 +7955,20 @@ void InstructionCodeGeneratorARMVIXL::VisitCheckCast(HCheckCast* instruction) {
       __ B(ne, &start_loop, /* far_target */ false);
       break;
     }
+
+    case TypeCheckKind::kBitstringCheck: {
+      // /* HeapReference<Class> */ temp = obj->klass_
+      GenerateReferenceLoadTwoRegisters(instruction,
+                                        temp_loc,
+                                        obj_loc,
+                                        class_offset,
+                                        maybe_temp2_loc,
+                                        kWithoutReadBarrier);
+
+      GenerateBitstringTypeCheckCompare(instruction, temp, SetFlags);
+      __ B(ne, type_check_slow_path->GetEntryLabel());
+      break;
+    }
   }
   if (done.IsReferenced()) {
     __ Bind(&done);
diff --git a/compiler/optimizing/code_generator_arm_vixl.h b/compiler/optimizing/code_generator_arm_vixl.h
index 38570bb0fe..bd815f45b3 100644
--- a/compiler/optimizing/code_generator_arm_vixl.h
+++ b/compiler/optimizing/code_generator_arm_vixl.h
@@ -322,6 +322,9 @@ class InstructionCodeGeneratorARMVIXL : public InstructionCodeGenerator {
   void GenerateSuspendCheck(HSuspendCheck* instruction, HBasicBlock* successor);
   void GenerateClassInitializationCheck(LoadClassSlowPathARMVIXL* slow_path,
                                         vixl32::Register class_reg);
+  void GenerateBitstringTypeCheckCompare(HTypeCheckInstruction* check,
+                                         vixl::aarch32::Register temp,
+                                         vixl::aarch32::FlagsUpdate flags_update);
   void GenerateAndConst(vixl::aarch32::Register out, vixl::aarch32::Register first, uint32_t value);
   void GenerateOrrConst(vixl::aarch32::Register out, vixl::aarch32::Register first, uint32_t value);
   void GenerateEorConst(vixl::aarch32::Register out, vixl::aarch32::Register first, uint32_t value);
diff --git a/compiler/optimizing/code_generator_mips.cc b/compiler/optimizing/code_generator_mips.cc
index 5c8e46ed19..2ed0ab79a1 100644
--- a/compiler/optimizing/code_generator_mips.cc
+++ b/compiler/optimizing/code_generator_mips.cc
@@ -1929,6 +1929,34 @@ void InstructionCodeGeneratorMIPS::GenerateClassInitializationCheck(SlowPathCode
   __ Bind(slow_path->GetExitLabel());
 }
 
+void InstructionCodeGeneratorMIPS::GenerateBitstringTypeCheckCompare(HTypeCheckInstruction* check,
+                                                                     Register temp) {
+  uint32_t path_to_root = check->GetBitstringPathToRoot();
+  uint32_t mask = check->GetBitstringMask();
+  DCHECK(IsPowerOfTwo(mask + 1));
+  size_t mask_bits = WhichPowerOf2(mask + 1);
+
+  if (mask_bits == 16u) {
+    // Load only the bitstring part of the status word.
+    __ LoadFromOffset(
+        kLoadUnsignedHalfword, temp, temp, mirror::Class::StatusOffset().Int32Value());
+    // Compare the bitstring bits using XOR.
+    __ Xori(temp, temp, dchecked_integral_cast<uint16_t>(path_to_root));
+  } else {
+    // /* uint32_t */ temp = temp->status_
+    __ LoadFromOffset(kLoadWord, temp, temp, mirror::Class::StatusOffset().Int32Value());
+    // Compare the bitstring bits using XOR.
+    if (IsUint<16>(path_to_root)) {
+      __ Xori(temp, temp, dchecked_integral_cast<uint16_t>(path_to_root));
+    } else {
+      __ LoadConst32(TMP, path_to_root);
+      __ Xor(temp, temp, TMP);
+    }
+    // Shift out bits that do not contribute to the comparison.
+    __ Sll(temp, temp, 32 - mask_bits);
+  }
+}
+
 void InstructionCodeGeneratorMIPS::GenerateMemoryBarrier(MemBarrierKind kind ATTRIBUTE_UNUSED) {
   __ Sync(0);  // Only stype 0 is supported.
 }
@@ -3289,12 +3317,20 @@ void LocationsBuilderMIPS::VisitCheckCast(HCheckCast* instruction) {
     case TypeCheckKind::kInterfaceCheck:
       call_kind = LocationSummary::kCallOnSlowPath;
       break;
+    case TypeCheckKind::kBitstringCheck:
+      break;
   }
 
   LocationSummary* locations =
       new (GetGraph()->GetAllocator()) LocationSummary(instruction, call_kind);
   locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RequiresRegister());
+  if (type_check_kind == TypeCheckKind::kBitstringCheck) {
+    locations->SetInAt(1, Location::ConstantLocation(instruction->InputAt(1)->AsConstant()));
+    locations->SetInAt(2, Location::ConstantLocation(instruction->InputAt(2)->AsConstant()));
+    locations->SetInAt(3, Location::ConstantLocation(instruction->InputAt(3)->AsConstant()));
+  } else {
+    locations->SetInAt(1, Location::RequiresRegister());
+  }
   locations->AddRegisterTemps(NumberOfCheckCastTemps(type_check_kind));
 }
 
@@ -3303,7 +3339,7 @@ void InstructionCodeGeneratorMIPS::VisitCheckCast(HCheckCast* instruction) {
   LocationSummary* locations = instruction->GetLocations();
   Location obj_loc = locations->InAt(0);
   Register obj = obj_loc.AsRegister<Register>();
-  Register cls = locations->InAt(1).AsRegister<Register>();
+  Location cls = locations->InAt(1);
   Location temp_loc = locations->GetTemp(0);
   Register temp = temp_loc.AsRegister<Register>();
   const size_t num_temps = NumberOfCheckCastTemps(type_check_kind);
@@ -3353,7 +3389,7 @@ void InstructionCodeGeneratorMIPS::VisitCheckCast(HCheckCast* instruction) {
                                         kWithoutReadBarrier);
       // Jump to slow path for throwing the exception or doing a
       // more involved array check.
-      __ Bne(temp, cls, slow_path->GetEntryLabel());
+      __ Bne(temp, cls.AsRegister<Register>(), slow_path->GetEntryLabel());
       break;
     }
 
@@ -3379,7 +3415,7 @@ void InstructionCodeGeneratorMIPS::VisitCheckCast(HCheckCast* instruction) {
       // exception.
       __ Beqz(temp, slow_path->GetEntryLabel());
       // Otherwise, compare the classes.
-      __ Bne(temp, cls, &loop);
+      __ Bne(temp, cls.AsRegister<Register>(), &loop);
       break;
     }
 
@@ -3394,7 +3430,7 @@ void InstructionCodeGeneratorMIPS::VisitCheckCast(HCheckCast* instruction) {
       // Walk over the class hierarchy to find a match.
       MipsLabel loop;
       __ Bind(&loop);
-      __ Beq(temp, cls, &done);
+      __ Beq(temp, cls.AsRegister<Register>(), &done);
       // /* HeapReference<Class> */ temp = temp->super_class_
       GenerateReferenceLoadOneRegister(instruction,
                                        temp_loc,
@@ -3417,7 +3453,7 @@ void InstructionCodeGeneratorMIPS::VisitCheckCast(HCheckCast* instruction) {
                                         maybe_temp2_loc,
                                         kWithoutReadBarrier);
       // Do an exact check.
-      __ Beq(temp, cls, &done);
+      __ Beq(temp, cls.AsRegister<Register>(), &done);
       // Otherwise, we need to check that the object's class is a non-primitive array.
       // /* HeapReference<Class> */ temp = temp->component_type_
       GenerateReferenceLoadOneRegister(instruction,
@@ -3476,7 +3512,21 @@ void InstructionCodeGeneratorMIPS::VisitCheckCast(HCheckCast* instruction) {
       // Go to next interface.
       __ Addiu(TMP, TMP, -2);
       // Compare the classes and continue the loop if they do not match.
-      __ Bne(AT, cls, &loop);
+      __ Bne(AT, cls.AsRegister<Register>(), &loop);
+      break;
+    }
+
+    case TypeCheckKind::kBitstringCheck: {
+      // /* HeapReference<Class> */ temp = obj->klass_
+      GenerateReferenceLoadTwoRegisters(instruction,
+                                        temp_loc,
+                                        obj_loc,
+                                        class_offset,
+                                        maybe_temp2_loc,
+                                        kWithoutReadBarrier);
+
+      GenerateBitstringTypeCheckCompare(instruction, temp);
+      __ Bnez(temp, slow_path->GetEntryLabel());
       break;
     }
   }
@@ -7207,6 +7257,8 @@ void LocationsBuilderMIPS::VisitInstanceOf(HInstanceOf* instruction) {
     case TypeCheckKind::kInterfaceCheck:
       call_kind = LocationSummary::kCallOnSlowPath;
       break;
+    case TypeCheckKind::kBitstringCheck:
+      break;
   }
 
   LocationSummary* locations =
@@ -7215,7 +7267,13 @@ void LocationsBuilderMIPS::VisitInstanceOf(HInstanceOf* instruction) {
     locations->SetCustomSlowPathCallerSaves(RegisterSet::Empty());  // No caller-save registers.
   }
   locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RequiresRegister());
+  if (type_check_kind == TypeCheckKind::kBitstringCheck) {
+    locations->SetInAt(1, Location::ConstantLocation(instruction->InputAt(1)->AsConstant()));
+    locations->SetInAt(2, Location::ConstantLocation(instruction->InputAt(2)->AsConstant()));
+    locations->SetInAt(3, Location::ConstantLocation(instruction->InputAt(3)->AsConstant()));
+  } else {
+    locations->SetInAt(1, Location::RequiresRegister());
+  }
   // The output does overlap inputs.
   // Note that TypeCheckSlowPathMIPS uses this register too.
   locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
@@ -7227,7 +7285,7 @@ void InstructionCodeGeneratorMIPS::VisitInstanceOf(HInstanceOf* instruction) {
   LocationSummary* locations = instruction->GetLocations();
   Location obj_loc = locations->InAt(0);
   Register obj = obj_loc.AsRegister<Register>();
-  Register cls = locations->InAt(1).AsRegister<Register>();
+  Location cls = locations->InAt(1);
   Location out_loc = locations->Out();
   Register out = out_loc.AsRegister<Register>();
   const size_t num_temps = NumberOfInstanceOfTemps(type_check_kind);
@@ -7257,7 +7315,7 @@ void InstructionCodeGeneratorMIPS::VisitInstanceOf(HInstanceOf* instruction) {
                                         maybe_temp_loc,
                                         kCompilerReadBarrierOption);
       // Classes must be equal for the instanceof to succeed.
-      __ Xor(out, out, cls);
+      __ Xor(out, out, cls.AsRegister<Register>());
       __ Sltiu(out, out, 1);
       break;
     }
@@ -7282,7 +7340,7 @@ void InstructionCodeGeneratorMIPS::VisitInstanceOf(HInstanceOf* instruction) {
                                        kCompilerReadBarrierOption);
       // If `out` is null, we use it for the result, and jump to `done`.
       __ Beqz(out, &done);
-      __ Bne(out, cls, &loop);
+      __ Bne(out, cls.AsRegister<Register>(), &loop);
       __ LoadConst32(out, 1);
       break;
     }
@@ -7298,7 +7356,7 @@ void InstructionCodeGeneratorMIPS::VisitInstanceOf(HInstanceOf* instruction) {
       // Walk over the class hierarchy to find a match.
       MipsLabel loop, success;
       __ Bind(&loop);
-      __ Beq(out, cls, &success);
+      __ Beq(out, cls.AsRegister<Register>(), &success);
       // /* HeapReference<Class> */ out = out->super_class_
       GenerateReferenceLoadOneRegister(instruction,
                                        out_loc,
@@ -7323,7 +7381,7 @@ void InstructionCodeGeneratorMIPS::VisitInstanceOf(HInstanceOf* instruction) {
                                         kCompilerReadBarrierOption);
       // Do an exact check.
       MipsLabel success;
-      __ Beq(out, cls, &success);
+      __ Beq(out, cls.AsRegister<Register>(), &success);
       // Otherwise, we need to check that the object's class is a non-primitive array.
       // /* HeapReference<Class> */ out = out->component_type_
       GenerateReferenceLoadOneRegister(instruction,
@@ -7355,7 +7413,7 @@ void InstructionCodeGeneratorMIPS::VisitInstanceOf(HInstanceOf* instruction) {
       slow_path = new (codegen_->GetScopedAllocator()) TypeCheckSlowPathMIPS(
           instruction, /* is_fatal */ false);
       codegen_->AddSlowPath(slow_path);
-      __ Bne(out, cls, slow_path->GetEntryLabel());
+      __ Bne(out, cls.AsRegister<Register>(), slow_path->GetEntryLabel());
       __ LoadConst32(out, 1);
       break;
     }
@@ -7387,6 +7445,20 @@ void InstructionCodeGeneratorMIPS::VisitInstanceOf(HInstanceOf* instruction) {
       __ B(slow_path->GetEntryLabel());
       break;
     }
+
+    case TypeCheckKind::kBitstringCheck: {
+      // /* HeapReference<Class> */ temp = obj->klass_
+      GenerateReferenceLoadTwoRegisters(instruction,
+                                        out_loc,
+                                        obj_loc,
+                                        class_offset,
+                                        maybe_temp_loc,
+                                        kWithoutReadBarrier);
+
+      GenerateBitstringTypeCheckCompare(instruction, out);
+      __ Sltiu(out, out, 1);
+      break;
+    }
   }
 
   __ Bind(&done);
diff --git a/compiler/optimizing/code_generator_mips.h b/compiler/optimizing/code_generator_mips.h
index 32b3e4221f..ffeb3b00a7 100644
--- a/compiler/optimizing/code_generator_mips.h
+++ b/compiler/optimizing/code_generator_mips.h
@@ -237,6 +237,7 @@ class InstructionCodeGeneratorMIPS : public InstructionCodeGenerator {
  private:
   void GenerateClassInitializationCheck(SlowPathCodeMIPS* slow_path, Register class_reg);
   void GenerateSuspendCheck(HSuspendCheck* check, HBasicBlock* successor);
+  void GenerateBitstringTypeCheckCompare(HTypeCheckInstruction* check, Register temp);
   void HandleBinaryOp(HBinaryOperation* operation);
   void HandleCondition(HCondition* instruction);
   void HandleShift(HBinaryOperation* operation);
diff --git a/compiler/optimizing/code_generator_mips64.cc b/compiler/optimizing/code_generator_mips64.cc
index bcfe051c90..3ae8a30754 100644
--- a/compiler/optimizing/code_generator_mips64.cc
+++ b/compiler/optimizing/code_generator_mips64.cc
@@ -1775,6 +1775,34 @@ void InstructionCodeGeneratorMIPS64::GenerateClassInitializationCheck(SlowPathCo
   __ Bind(slow_path->GetExitLabel());
 }
 
+void InstructionCodeGeneratorMIPS64::GenerateBitstringTypeCheckCompare(HTypeCheckInstruction* check,
+                                                                       GpuRegister temp) {
+  uint32_t path_to_root = check->GetBitstringPathToRoot();
+  uint32_t mask = check->GetBitstringMask();
+  DCHECK(IsPowerOfTwo(mask + 1));
+  size_t mask_bits = WhichPowerOf2(mask + 1);
+
+  if (mask_bits == 16u) {
+    // Load only the bitstring part of the status word.
+    __ LoadFromOffset(
+        kLoadUnsignedHalfword, temp, temp, mirror::Class::StatusOffset().Int32Value());
+    // Compare the bitstring bits using XOR.
+    __ Xori(temp, temp, dchecked_integral_cast<uint16_t>(path_to_root));
+  } else {
+    // /* uint32_t */ temp = temp->status_
+    __ LoadFromOffset(kLoadWord, temp, temp, mirror::Class::StatusOffset().Int32Value());
+    // Compare the bitstring bits using XOR.
+    if (IsUint<16>(path_to_root)) {
+      __ Xori(temp, temp, dchecked_integral_cast<uint16_t>(path_to_root));
+    } else {
+      __ LoadConst32(TMP, path_to_root);
+      __ Xor(temp, temp, TMP);
+    }
+    // Shift out bits that do not contribute to the comparison.
+    __ Sll(temp, temp, 32 - mask_bits);
+  }
+}
+
 void InstructionCodeGeneratorMIPS64::GenerateMemoryBarrier(MemBarrierKind kind ATTRIBUTE_UNUSED) {
   __ Sync(0);  // only stype 0 is supported
 }
@@ -2844,12 +2872,20 @@ void LocationsBuilderMIPS64::VisitCheckCast(HCheckCast* instruction) {
     case TypeCheckKind::kInterfaceCheck:
       call_kind = LocationSummary::kCallOnSlowPath;
       break;
+    case TypeCheckKind::kBitstringCheck:
+      break;
   }
 
   LocationSummary* locations =
       new (GetGraph()->GetAllocator()) LocationSummary(instruction, call_kind);
   locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RequiresRegister());
+  if (type_check_kind == TypeCheckKind::kBitstringCheck) {
+    locations->SetInAt(1, Location::ConstantLocation(instruction->InputAt(1)->AsConstant()));
+    locations->SetInAt(2, Location::ConstantLocation(instruction->InputAt(2)->AsConstant()));
+    locations->SetInAt(3, Location::ConstantLocation(instruction->InputAt(3)->AsConstant()));
+  } else {
+    locations->SetInAt(1, Location::RequiresRegister());
+  }
   locations->AddRegisterTemps(NumberOfCheckCastTemps(type_check_kind));
 }
 
@@ -2858,7 +2894,7 @@ void InstructionCodeGeneratorMIPS64::VisitCheckCast(HCheckCast* instruction) {
   LocationSummary* locations = instruction->GetLocations();
   Location obj_loc = locations->InAt(0);
   GpuRegister obj = obj_loc.AsRegister<GpuRegister>();
-  GpuRegister cls = locations->InAt(1).AsRegister<GpuRegister>();
+  Location cls = locations->InAt(1);
   Location temp_loc = locations->GetTemp(0);
   GpuRegister temp = temp_loc.AsRegister<GpuRegister>();
   const size_t num_temps = NumberOfCheckCastTemps(type_check_kind);
@@ -2908,7 +2944,7 @@ void InstructionCodeGeneratorMIPS64::VisitCheckCast(HCheckCast* instruction) {
                                         kWithoutReadBarrier);
       // Jump to slow path for throwing the exception or doing a
       // more involved array check.
-      __ Bnec(temp, cls, slow_path->GetEntryLabel());
+      __ Bnec(temp, cls.AsRegister<GpuRegister>(), slow_path->GetEntryLabel());
       break;
     }
 
@@ -2934,7 +2970,7 @@ void InstructionCodeGeneratorMIPS64::VisitCheckCast(HCheckCast* instruction) {
       // exception.
       __ Beqzc(temp, slow_path->GetEntryLabel());
       // Otherwise, compare the classes.
-      __ Bnec(temp, cls, &loop);
+      __ Bnec(temp, cls.AsRegister<GpuRegister>(), &loop);
       break;
     }
 
@@ -2949,7 +2985,7 @@ void InstructionCodeGeneratorMIPS64::VisitCheckCast(HCheckCast* instruction) {
       // Walk over the class hierarchy to find a match.
       Mips64Label loop;
       __ Bind(&loop);
-      __ Beqc(temp, cls, &done);
+      __ Beqc(temp, cls.AsRegister<GpuRegister>(), &done);
       // /* HeapReference<Class> */ temp = temp->super_class_
       GenerateReferenceLoadOneRegister(instruction,
                                        temp_loc,
@@ -2972,7 +3008,7 @@ void InstructionCodeGeneratorMIPS64::VisitCheckCast(HCheckCast* instruction) {
                                         maybe_temp2_loc,
                                         kWithoutReadBarrier);
       // Do an exact check.
-      __ Beqc(temp, cls, &done);
+      __ Beqc(temp, cls.AsRegister<GpuRegister>(), &done);
       // Otherwise, we need to check that the object's class is a non-primitive array.
       // /* HeapReference<Class> */ temp = temp->component_type_
       GenerateReferenceLoadOneRegister(instruction,
@@ -3031,7 +3067,21 @@ void InstructionCodeGeneratorMIPS64::VisitCheckCast(HCheckCast* instruction) {
       __ Daddiu(temp, temp, 2 * kHeapReferenceSize);
       __ Addiu(TMP, TMP, -2);
       // Compare the classes and continue the loop if they do not match.
-      __ Bnec(AT, cls, &loop);
+      __ Bnec(AT, cls.AsRegister<GpuRegister>(), &loop);
+      break;
+    }
+
+    case TypeCheckKind::kBitstringCheck: {
+      // /* HeapReference<Class> */ temp = obj->klass_
+      GenerateReferenceLoadTwoRegisters(instruction,
+                                        temp_loc,
+                                        obj_loc,
+                                        class_offset,
+                                        maybe_temp2_loc,
+                                        kWithoutReadBarrier);
+
+      GenerateBitstringTypeCheckCompare(instruction, temp);
+      __ Bnezc(temp, slow_path->GetEntryLabel());
       break;
     }
   }
@@ -5524,6 +5574,8 @@ void LocationsBuilderMIPS64::VisitInstanceOf(HInstanceOf* instruction) {
     case TypeCheckKind::kInterfaceCheck:
       call_kind = LocationSummary::kCallOnSlowPath;
       break;
+    case TypeCheckKind::kBitstringCheck:
+      break;
   }
 
   LocationSummary* locations =
@@ -5532,7 +5584,13 @@ void LocationsBuilderMIPS64::VisitInstanceOf(HInstanceOf* instruction) {
     locations->SetCustomSlowPathCallerSaves(RegisterSet::Empty());  // No caller-save registers.
   }
   locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::RequiresRegister());
+  if (type_check_kind == TypeCheckKind::kBitstringCheck) {
+    locations->SetInAt(1, Location::ConstantLocation(instruction->InputAt(1)->AsConstant()));
+    locations->SetInAt(2, Location::ConstantLocation(instruction->InputAt(2)->AsConstant()));
+    locations->SetInAt(3, Location::ConstantLocation(instruction->InputAt(3)->AsConstant()));
+  } else {
+    locations->SetInAt(1, Location::RequiresRegister());
+  }
   // The output does overlap inputs.
   // Note that TypeCheckSlowPathMIPS64 uses this register too.
   locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
@@ -5544,7 +5602,7 @@ void InstructionCodeGeneratorMIPS64::VisitInstanceOf(HInstanceOf* instruction) {
   LocationSummary* locations = instruction->GetLocations();
   Location obj_loc = locations->InAt(0);
   GpuRegister obj = obj_loc.AsRegister<GpuRegister>();
-  GpuRegister cls = locations->InAt(1).AsRegister<GpuRegister>();
+  Location cls = locations->InAt(1);
   Location out_loc = locations->Out();
   GpuRegister out = out_loc.AsRegister<GpuRegister>();
   const size_t num_temps = NumberOfInstanceOfTemps(type_check_kind);
@@ -5574,7 +5632,7 @@ void InstructionCodeGeneratorMIPS64::VisitInstanceOf(HInstanceOf* instruction) {
                                         maybe_temp_loc,
                                         kCompilerReadBarrierOption);
       // Classes must be equal for the instanceof to succeed.
-      __ Xor(out, out, cls);
+      __ Xor(out, out, cls.AsRegister<GpuRegister>());
       __ Sltiu(out, out, 1);
       break;
     }
@@ -5599,7 +5657,7 @@ void InstructionCodeGeneratorMIPS64::VisitInstanceOf(HInstanceOf* instruction) {
                                        kCompilerReadBarrierOption);
       // If `out` is null, we use it for the result, and jump to `done`.
       __ Beqzc(out, &done);
-      __ Bnec(out, cls, &loop);
+      __ Bnec(out, cls.AsRegister<GpuRegister>(), &loop);
       __ LoadConst32(out, 1);
       break;
     }
@@ -5615,7 +5673,7 @@ void InstructionCodeGeneratorMIPS64::VisitInstanceOf(HInstanceOf* instruction) {
       // Walk over the class hierarchy to find a match.
       Mips64Label loop, success;
       __ Bind(&loop);
-      __ Beqc(out, cls, &success);
+      __ Beqc(out, cls.AsRegister<GpuRegister>(), &success);
       // /* HeapReference<Class> */ out = out->super_class_
       GenerateReferenceLoadOneRegister(instruction,
                                        out_loc,
@@ -5640,7 +5698,7 @@ void InstructionCodeGeneratorMIPS64::VisitInstanceOf(HInstanceOf* instruction) {
                                         kCompilerReadBarrierOption);
       // Do an exact check.
       Mips64Label success;
-      __ Beqc(out, cls, &success);
+      __ Beqc(out, cls.AsRegister<GpuRegister>(), &success);
       // Otherwise, we need to check that the object's class is a non-primitive array.
       // /* HeapReference<Class> */ out = out->component_type_
       GenerateReferenceLoadOneRegister(instruction,
@@ -5672,7 +5730,7 @@ void InstructionCodeGeneratorMIPS64::VisitInstanceOf(HInstanceOf* instruction) {
       slow_path = new (codegen_->GetScopedAllocator()) TypeCheckSlowPathMIPS64(
           instruction, /* is_fatal */ false);
       codegen_->AddSlowPath(slow_path);
-      __ Bnec(out, cls, slow_path->GetEntryLabel());
+      __ Bnec(out, cls.AsRegister<GpuRegister>(), slow_path->GetEntryLabel());
       __ LoadConst32(out, 1);
       break;
     }
@@ -5704,6 +5762,20 @@ void InstructionCodeGeneratorMIPS64::VisitInstanceOf(HInstanceOf* instruction) {
       __ Bc(slow_path->GetEntryLabel());
       break;
     }
+
+    case TypeCheckKind::kBitstringCheck: {
+      // /* HeapReference<Class> */ temp = obj->klass_
+      GenerateReferenceLoadTwoRegisters(instruction,
+                                        out_loc,
+                                        obj_loc,
+                                        class_offset,
+                                        maybe_temp_loc,
+                                        kWithoutReadBarrier);
+
+      GenerateBitstringTypeCheckCompare(instruction, out);
+      __ Sltiu(out, out, 1);
+      break;
+    }
   }
 
   __ Bind(&done);
diff --git a/compiler/optimizing/code_generator_mips64.h b/compiler/optimizing/code_generator_mips64.h
index d479410f07..87d5a9c15a 100644
--- a/compiler/optimizing/code_generator_mips64.h
+++ b/compiler/optimizing/code_generator_mips64.h
@@ -233,6 +233,7 @@ class InstructionCodeGeneratorMIPS64 : public InstructionCodeGenerator {
 
  private:
   void GenerateClassInitializationCheck(SlowPathCodeMIPS64* slow_path, GpuRegister class_reg);
+  void GenerateBitstringTypeCheckCompare(HTypeCheckInstruction* check, GpuRegister temp);
   void GenerateSuspendCheck(HSuspendCheck* check, HBasicBlock* successor);
   void HandleBinaryOp(HBinaryOperation* operation);
   void HandleCondition(HCondition* instruction);
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index cbe9e0a35c..e85f9001b1 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -6234,6 +6234,27 @@ void InstructionCodeGeneratorX86::GenerateClassInitializationCheck(
   // No need for memory fence, thanks to the X86 memory model.
 }
 
+void InstructionCodeGeneratorX86::GenerateBitstringTypeCheckCompare(HTypeCheckInstruction* check,
+                                                                    Register temp) {
+  uint32_t path_to_root = check->GetBitstringPathToRoot();
+  uint32_t mask = check->GetBitstringMask();
+  DCHECK(IsPowerOfTwo(mask + 1));
+  size_t mask_bits = WhichPowerOf2(mask + 1);
+
+  if ((false) && mask_bits == 16u) {
+    // FIXME: cmpw() erroneously emits the constant as 32 bits instead of 16 bits. b/71853552
+    // Compare the bitstring in memory.
+    __ cmpw(Address(temp, mirror::Class::StatusOffset()), Immediate(path_to_root));
+  } else {
+    // /* uint32_t */ temp = temp->status_
+    __ movl(temp, Address(temp, mirror::Class::StatusOffset()));
+    // Compare the bitstring bits using SUB.
+    __ subl(temp, Immediate(path_to_root));
+    // Shift out bits that do not contribute to the comparison.
+    __ shll(temp, Immediate(32u - mask_bits));
+  }
+}
+
 HLoadString::LoadKind CodeGeneratorX86::GetSupportedLoadStringKind(
     HLoadString::LoadKind desired_string_load_kind) {
   switch (desired_string_load_kind) {
@@ -6426,6 +6447,8 @@ void LocationsBuilderX86::VisitInstanceOf(HInstanceOf* instruction) {
     case TypeCheckKind::kInterfaceCheck:
       call_kind = LocationSummary::kCallOnSlowPath;
       break;
+    case TypeCheckKind::kBitstringCheck:
+      break;
   }
 
   LocationSummary* locations =
@@ -6434,7 +6457,13 @@ void LocationsBuilderX86::VisitInstanceOf(HInstanceOf* instruction) {
     locations->SetCustomSlowPathCallerSaves(RegisterSet::Empty());  // No caller-save registers.
   }
   locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::Any());
+  if (type_check_kind == TypeCheckKind::kBitstringCheck) {
+    locations->SetInAt(1, Location::ConstantLocation(instruction->InputAt(1)->AsConstant()));
+    locations->SetInAt(2, Location::ConstantLocation(instruction->InputAt(2)->AsConstant()));
+    locations->SetInAt(3, Location::ConstantLocation(instruction->InputAt(3)->AsConstant()));
+  } else {
+    locations->SetInAt(1, Location::Any());
+  }
   // Note that TypeCheckSlowPathX86 uses this "out" register too.
   locations->SetOut(Location::RequiresRegister());
   // When read barriers are enabled, we need a temporary register for some cases.
@@ -6655,6 +6684,21 @@ void InstructionCodeGeneratorX86::VisitInstanceOf(HInstanceOf* instruction) {
       }
       break;
     }
+
+    case TypeCheckKind::kBitstringCheck: {
+      // /* HeapReference<Class> */ temp = obj->klass_
+      GenerateReferenceLoadTwoRegisters(instruction,
+                                        out_loc,
+                                        obj_loc,
+                                        class_offset,
+                                        kWithoutReadBarrier);
+
+      GenerateBitstringTypeCheckCompare(instruction, out);
+      __ j(kNotEqual, &zero);
+      __ movl(out, Immediate(1));
+      __ jmp(&done);
+      break;
+    }
   }
 
   if (zero.IsLinked()) {
@@ -6681,6 +6725,10 @@ void LocationsBuilderX86::VisitCheckCast(HCheckCast* instruction) {
     // Require a register for the interface check since there is a loop that compares the class to
     // a memory address.
     locations->SetInAt(1, Location::RequiresRegister());
+  } else if (type_check_kind == TypeCheckKind::kBitstringCheck) {
+    locations->SetInAt(1, Location::ConstantLocation(instruction->InputAt(1)->AsConstant()));
+    locations->SetInAt(2, Location::ConstantLocation(instruction->InputAt(2)->AsConstant()));
+    locations->SetInAt(3, Location::ConstantLocation(instruction->InputAt(3)->AsConstant()));
   } else {
     locations->SetInAt(1, Location::Any());
   }
@@ -6900,6 +6948,19 @@ void InstructionCodeGeneratorX86::VisitCheckCast(HCheckCast* instruction) {
       __ MaybeUnpoisonHeapReference(cls.AsRegister<Register>());
       break;
     }
+
+    case TypeCheckKind::kBitstringCheck: {
+      // /* HeapReference<Class> */ temp = obj->klass_
+      GenerateReferenceLoadTwoRegisters(instruction,
+                                        temp_loc,
+                                        obj_loc,
+                                        class_offset,
+                                        kWithoutReadBarrier);
+
+      GenerateBitstringTypeCheckCompare(instruction, temp);
+      __ j(kNotEqual, type_check_slow_path->GetEntryLabel());
+      break;
+    }
   }
   __ Bind(&done);
 
diff --git a/compiler/optimizing/code_generator_x86.h b/compiler/optimizing/code_generator_x86.h
index 0082853184..2d14d4cdc2 100644
--- a/compiler/optimizing/code_generator_x86.h
+++ b/compiler/optimizing/code_generator_x86.h
@@ -211,6 +211,7 @@ class InstructionCodeGeneratorX86 : public InstructionCodeGenerator {
   // the suspend call.
   void GenerateSuspendCheck(HSuspendCheck* check, HBasicBlock* successor);
   void GenerateClassInitializationCheck(SlowPathCode* slow_path, Register class_reg);
+  void GenerateBitstringTypeCheckCompare(HTypeCheckInstruction* check, Register temp);
   void HandleBitwiseOperation(HBinaryOperation* instruction);
   void GenerateDivRemIntegral(HBinaryOperation* instruction);
   void DivRemOneOrMinusOne(HBinaryOperation* instruction);
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index 510eec4f30..9f8b1bb038 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -5440,6 +5440,27 @@ void InstructionCodeGeneratorX86_64::GenerateClassInitializationCheck(
   // No need for memory fence, thanks to the x86-64 memory model.
 }
 
+void InstructionCodeGeneratorX86_64::GenerateBitstringTypeCheckCompare(HTypeCheckInstruction* check,
+                                                                       CpuRegister temp) {
+  uint32_t path_to_root = check->GetBitstringPathToRoot();
+  uint32_t mask = check->GetBitstringMask();
+  DCHECK(IsPowerOfTwo(mask + 1));
+  size_t mask_bits = WhichPowerOf2(mask + 1);
+
+  if ((false) && mask_bits == 16u) {
+    // FIXME: cmpw() erroneously emits the constant as 32 bits instead of 16 bits. b/71853552
+    // Compare the bitstring in memory.
+    __ cmpw(Address(temp, mirror::Class::StatusOffset()), Immediate(path_to_root));
+  } else {
+    // /* uint32_t */ temp = temp->status_
+    __ movl(temp, Address(temp, mirror::Class::StatusOffset()));
+    // Compare the bitstring bits using SUB.
+    __ subl(temp, Immediate(path_to_root));
+    // Shift out bits that do not contribute to the comparison.
+    __ shll(temp, Immediate(32u - mask_bits));
+  }
+}
+
 HLoadClass::LoadKind CodeGeneratorX86_64::GetSupportedLoadClassKind(
     HLoadClass::LoadKind desired_class_load_kind) {
   switch (desired_class_load_kind) {
@@ -5812,6 +5833,8 @@ void LocationsBuilderX86_64::VisitInstanceOf(HInstanceOf* instruction) {
     case TypeCheckKind::kInterfaceCheck:
       call_kind = LocationSummary::kCallOnSlowPath;
       break;
+    case TypeCheckKind::kBitstringCheck:
+      break;
   }
 
   LocationSummary* locations =
@@ -5820,7 +5843,13 @@ void LocationsBuilderX86_64::VisitInstanceOf(HInstanceOf* instruction) {
     locations->SetCustomSlowPathCallerSaves(RegisterSet::Empty());  // No caller-save registers.
   }
   locations->SetInAt(0, Location::RequiresRegister());
-  locations->SetInAt(1, Location::Any());
+  if (type_check_kind == TypeCheckKind::kBitstringCheck) {
+    locations->SetInAt(1, Location::ConstantLocation(instruction->InputAt(1)->AsConstant()));
+    locations->SetInAt(2, Location::ConstantLocation(instruction->InputAt(2)->AsConstant()));
+    locations->SetInAt(3, Location::ConstantLocation(instruction->InputAt(3)->AsConstant()));
+  } else {
+    locations->SetInAt(1, Location::Any());
+  }
   // Note that TypeCheckSlowPathX86_64 uses this "out" register too.
   locations->SetOut(Location::RequiresRegister());
   // When read barriers are enabled, we need a temporary register for
@@ -6049,6 +6078,27 @@ void InstructionCodeGeneratorX86_64::VisitInstanceOf(HInstanceOf* instruction) {
       }
       break;
     }
+
+    case TypeCheckKind::kBitstringCheck: {
+      // /* HeapReference<Class> */ temp = obj->klass_
+      GenerateReferenceLoadTwoRegisters(instruction,
+                                        out_loc,
+                                        obj_loc,
+                                        class_offset,
+                                        kWithoutReadBarrier);
+
+      GenerateBitstringTypeCheckCompare(instruction, out);
+      if (zero.IsLinked()) {
+        __ j(kNotEqual, &zero);
+        __ movl(out, Immediate(1));
+        __ jmp(&done);
+      } else {
+        __ setcc(kEqual, out);
+        // setcc only sets the low byte.
+        __ andl(out, Immediate(1));
+      }
+      break;
+    }
   }
 
   if (zero.IsLinked()) {
@@ -6075,6 +6125,10 @@ void LocationsBuilderX86_64::VisitCheckCast(HCheckCast* instruction) {
     // Require a register for the interface check since there is a loop that compares the class to
     // a memory address.
     locations->SetInAt(1, Location::RequiresRegister());
+  } else if (type_check_kind == TypeCheckKind::kBitstringCheck) {
+    locations->SetInAt(1, Location::ConstantLocation(instruction->InputAt(1)->AsConstant()));
+    locations->SetInAt(2, Location::ConstantLocation(instruction->InputAt(2)->AsConstant()));
+    locations->SetInAt(3, Location::ConstantLocation(instruction->InputAt(3)->AsConstant()));
   } else {
     locations->SetInAt(1, Location::Any());
   }
@@ -6261,7 +6315,7 @@ void InstructionCodeGeneratorX86_64::VisitCheckCast(HCheckCast* instruction) {
       break;
     }
 
-    case TypeCheckKind::kInterfaceCheck:
+    case TypeCheckKind::kInterfaceCheck: {
       // Fast path for the interface check. Try to avoid read barriers to improve the fast path.
       // We can not get false positives by doing this.
       // /* HeapReference<Class> */ temp = obj->klass_
@@ -6297,6 +6351,20 @@ void InstructionCodeGeneratorX86_64::VisitCheckCast(HCheckCast* instruction) {
       // If `cls` was poisoned above, unpoison it.
       __ MaybeUnpoisonHeapReference(cls.AsRegister<CpuRegister>());
       break;
+    }
+
+    case TypeCheckKind::kBitstringCheck: {
+      // /* HeapReference<Class> */ temp = obj->klass_
+      GenerateReferenceLoadTwoRegisters(instruction,
+                                        temp_loc,
+                                        obj_loc,
+                                        class_offset,
+                                        kWithoutReadBarrier);
+
+      GenerateBitstringTypeCheckCompare(instruction, temp);
+      __ j(kNotEqual, type_check_slow_path->GetEntryLabel());
+      break;
+    }
   }
 
   if (done.IsLinked()) {
diff --git a/compiler/optimizing/code_generator_x86_64.h b/compiler/optimizing/code_generator_x86_64.h
index e86123ef01..97f8ec7ae0 100644
--- a/compiler/optimizing/code_generator_x86_64.h
+++ b/compiler/optimizing/code_generator_x86_64.h
@@ -208,6 +208,7 @@ class InstructionCodeGeneratorX86_64 : public InstructionCodeGenerator {
   // the suspend call.
   void GenerateSuspendCheck(HSuspendCheck* instruction, HBasicBlock* successor);
   void GenerateClassInitializationCheck(SlowPathCode* slow_path, CpuRegister class_reg);
+  void GenerateBitstringTypeCheckCompare(HTypeCheckInstruction* check, CpuRegister temp);
   void HandleBitwiseOperation(HBinaryOperation* operation);
   void GenerateRemFP(HRem* rem);
   void DivRemOneOrMinusOne(HBinaryOperation* instruction);
diff --git a/compiler/optimizing/graph_checker.cc b/compiler/optimizing/graph_checker.cc
index c88baa8610..fbcbe3608e 100644
--- a/compiler/optimizing/graph_checker.cc
+++ b/compiler/optimizing/graph_checker.cc
@@ -25,6 +25,11 @@
 #include "base/bit_vector-inl.h"
 #include "base/scoped_arena_allocator.h"
 #include "base/scoped_arena_containers.h"
+#include "handle.h"
+#include "mirror/class.h"
+#include "obj_ptr-inl.h"
+#include "scoped_thread_state_change-inl.h"
+#include "subtype_check.h"
 
 namespace art {
 
@@ -548,30 +553,85 @@ void GraphChecker::VisitReturnVoid(HReturnVoid* ret) {
   }
 }
 
-void GraphChecker::VisitCheckCast(HCheckCast* check) {
-  VisitInstruction(check);
-  HInstruction* input = check->InputAt(1);
-  if (!input->IsLoadClass()) {
-    AddError(StringPrintf("%s:%d expects a HLoadClass as second input, not %s:%d.",
+void GraphChecker::CheckTypeCheckBitstringInput(HTypeCheckInstruction* check,
+                                                size_t input_pos,
+                                                bool check_value,
+                                                uint32_t expected_value,
+                                                const char* name) {
+  if (!check->InputAt(input_pos)->IsIntConstant()) {
+    AddError(StringPrintf("%s:%d (bitstring) expects a HIntConstant input %zu (%s), not %s:%d.",
                           check->DebugName(),
                           check->GetId(),
-                          input->DebugName(),
-                          input->GetId()));
+                          input_pos,
+                          name,
+                          check->InputAt(2)->DebugName(),
+                          check->InputAt(2)->GetId()));
+  } else if (check_value) {
+    uint32_t actual_value =
+        static_cast<uint32_t>(check->InputAt(input_pos)->AsIntConstant()->GetValue());
+    if (actual_value != expected_value) {
+      AddError(StringPrintf("%s:%d (bitstring) has %s 0x%x, not 0x%x as expected.",
+                            check->DebugName(),
+                            check->GetId(),
+                            name,
+                            actual_value,
+                            expected_value));
+    }
   }
 }
 
-void GraphChecker::VisitInstanceOf(HInstanceOf* instruction) {
-  VisitInstruction(instruction);
-  HInstruction* input = instruction->InputAt(1);
-  if (!input->IsLoadClass()) {
-    AddError(StringPrintf("%s:%d expects a HLoadClass as second input, not %s:%d.",
-                          instruction->DebugName(),
-                          instruction->GetId(),
-                          input->DebugName(),
-                          input->GetId()));
+void GraphChecker::HandleTypeCheckInstruction(HTypeCheckInstruction* check) {
+  VisitInstruction(check);
+  HInstruction* input = check->InputAt(1);
+  if (check->GetTypeCheckKind() == TypeCheckKind::kBitstringCheck) {
+    if (!input->IsNullConstant()) {
+      AddError(StringPrintf("%s:%d (bitstring) expects a HNullConstant as second input, not %s:%d.",
+                            check->DebugName(),
+                            check->GetId(),
+                            input->DebugName(),
+                            input->GetId()));
+    }
+    bool check_values = false;
+    BitString::StorageType expected_path_to_root = 0u;
+    BitString::StorageType expected_mask = 0u;
+    {
+      ScopedObjectAccess soa(Thread::Current());
+      ObjPtr<mirror::Class> klass = check->GetClass().Get();
+      MutexLock subtype_check_lock(Thread::Current(), *Locks::subtype_check_lock_);
+      SubtypeCheckInfo::State state = SubtypeCheck<ObjPtr<mirror::Class>>::GetState(klass);
+      if (state == SubtypeCheckInfo::kAssigned) {
+        expected_path_to_root =
+            SubtypeCheck<ObjPtr<mirror::Class>>::GetEncodedPathToRootForTarget(klass);
+        expected_mask = SubtypeCheck<ObjPtr<mirror::Class>>::GetEncodedPathToRootMask(klass);
+        check_values = true;
+      } else {
+        AddError(StringPrintf("%s:%d (bitstring) references a class with unassigned bitstring.",
+                              check->DebugName(),
+                              check->GetId()));
+      }
+    }
+    CheckTypeCheckBitstringInput(
+        check, /* input_pos */ 2, check_values, expected_path_to_root, "path_to_root");
+    CheckTypeCheckBitstringInput(check, /* input_pos */ 3, check_values, expected_mask, "mask");
+  } else {
+    if (!input->IsLoadClass()) {
+      AddError(StringPrintf("%s:%d (classic) expects a HLoadClass as second input, not %s:%d.",
+                            check->DebugName(),
+                            check->GetId(),
+                            input->DebugName(),
+                            input->GetId()));
+    }
   }
 }
 
+void GraphChecker::VisitCheckCast(HCheckCast* check) {
+  HandleTypeCheckInstruction(check);
+}
+
+void GraphChecker::VisitInstanceOf(HInstanceOf* instruction) {
+  HandleTypeCheckInstruction(instruction);
+}
+
 void GraphChecker::HandleLoop(HBasicBlock* loop_header) {
   int id = loop_header->GetBlockId();
   HLoopInformation* loop_information = loop_header->GetLoopInformation();
diff --git a/compiler/optimizing/graph_checker.h b/compiler/optimizing/graph_checker.h
index 0f0b49d240..dbedc40518 100644
--- a/compiler/optimizing/graph_checker.h
+++ b/compiler/optimizing/graph_checker.h
@@ -71,6 +71,12 @@ class GraphChecker : public HGraphDelegateVisitor {
   void VisitTryBoundary(HTryBoundary* try_boundary) OVERRIDE;
   void VisitTypeConversion(HTypeConversion* instruction) OVERRIDE;
 
+  void CheckTypeCheckBitstringInput(HTypeCheckInstruction* check,
+                                    size_t input_pos,
+                                    bool check_value,
+                                    uint32_t expected_value,
+                                    const char* name);
+  void HandleTypeCheckInstruction(HTypeCheckInstruction* instruction);
   void HandleLoop(HBasicBlock* loop_header);
   void HandleBooleanInput(HInstruction* instruction, size_t input_index);
 
diff --git a/compiler/optimizing/graph_visualizer.cc b/compiler/optimizing/graph_visualizer.cc
index 12c69889ab..55191214a6 100644
--- a/compiler/optimizing/graph_visualizer.cc
+++ b/compiler/optimizing/graph_visualizer.cc
@@ -389,16 +389,23 @@ class HGraphVisualizerPrinter : public HGraphDelegateVisitor {
     StartAttributeStream("load_kind") << load_string->GetLoadKind();
   }
 
-  void VisitCheckCast(HCheckCast* check_cast) OVERRIDE {
-    StartAttributeStream("check_kind") << check_cast->GetTypeCheckKind();
+  void HandleTypeCheckInstruction(HTypeCheckInstruction* check) {
+    StartAttributeStream("check_kind") << check->GetTypeCheckKind();
     StartAttributeStream("must_do_null_check") << std::boolalpha
-        << check_cast->MustDoNullCheck() << std::noboolalpha;
+        << check->MustDoNullCheck() << std::noboolalpha;
+    if (check->GetTypeCheckKind() == TypeCheckKind::kBitstringCheck) {
+      StartAttributeStream("path_to_root") << std::hex
+          << "0x" << check->GetBitstringPathToRoot() << std::dec;
+      StartAttributeStream("mask") << std::hex << "0x" << check->GetBitstringMask() << std::dec;
+    }
+  }
+
+  void VisitCheckCast(HCheckCast* check_cast) OVERRIDE {
+    HandleTypeCheckInstruction(check_cast);
   }
 
   void VisitInstanceOf(HInstanceOf* instance_of) OVERRIDE {
-    StartAttributeStream("check_kind") << instance_of->GetTypeCheckKind();
-    StartAttributeStream("must_do_null_check") << std::boolalpha
-        << instance_of->MustDoNullCheck() << std::noboolalpha;
+    HandleTypeCheckInstruction(instance_of);
   }
 
   void VisitArrayLength(HArrayLength* array_length) OVERRIDE {
@@ -648,20 +655,32 @@ class HGraphVisualizerPrinter : public HGraphDelegateVisitor {
           << std::boolalpha << loop_info->IsIrreducible() << std::noboolalpha;
     }
 
+    // For the builder and the inliner, we want to add extra information on HInstructions
+    // that have reference types, and also HInstanceOf/HCheckcast.
     if ((IsPass(HGraphBuilder::kBuilderPassName)
         || IsPass(HInliner::kInlinerPassName))
-        && (instruction->GetType() == DataType::Type::kReference)) {
-      ReferenceTypeInfo info = instruction->IsLoadClass()
-        ? instruction->AsLoadClass()->GetLoadedClassRTI()
-        : instruction->GetReferenceTypeInfo();
+        && (instruction->GetType() == DataType::Type::kReference ||
+            instruction->IsInstanceOf() ||
+            instruction->IsCheckCast())) {
+      ReferenceTypeInfo info = (instruction->GetType() == DataType::Type::kReference)
+          ? instruction->IsLoadClass()
+              ? instruction->AsLoadClass()->GetLoadedClassRTI()
+              : instruction->GetReferenceTypeInfo()
+          : instruction->IsInstanceOf()
+              ? instruction->AsInstanceOf()->GetTargetClassRTI()
+              : instruction->AsCheckCast()->GetTargetClassRTI();
       ScopedObjectAccess soa(Thread::Current());
       if (info.IsValid()) {
         StartAttributeStream("klass")
             << mirror::Class::PrettyDescriptor(info.GetTypeHandle().Get());
-        StartAttributeStream("can_be_null")
-            << std::boolalpha << instruction->CanBeNull() << std::noboolalpha;
+        if (instruction->GetType() == DataType::Type::kReference) {
+          StartAttributeStream("can_be_null")
+              << std::boolalpha << instruction->CanBeNull() << std::noboolalpha;
+        }
         StartAttributeStream("exact") << std::boolalpha << info.IsExact() << std::noboolalpha;
-      } else if (instruction->IsLoadClass()) {
+      } else if (instruction->IsLoadClass() ||
+                 instruction->IsInstanceOf() ||
+                 instruction->IsCheckCast()) {
         StartAttributeStream("klass") << "unresolved";
       } else {
         // The NullConstant may be added to the graph during other passes that happen between
diff --git a/compiler/optimizing/instruction_builder.cc b/compiler/optimizing/instruction_builder.cc
index 64a1eccf60..0205c6a4d3 100644
--- a/compiler/optimizing/instruction_builder.cc
+++ b/compiler/optimizing/instruction_builder.cc
@@ -1811,29 +1811,6 @@ void HInstructionBuilder::BuildFillWideArrayData(HInstruction* object,
   }
 }
 
-static TypeCheckKind ComputeTypeCheckKind(Handle<mirror::Class> cls)
-    REQUIRES_SHARED(Locks::mutator_lock_) {
-  if (cls == nullptr) {
-    return TypeCheckKind::kUnresolvedCheck;
-  } else if (cls->IsInterface()) {
-    return TypeCheckKind::kInterfaceCheck;
-  } else if (cls->IsArrayClass()) {
-    if (cls->GetComponentType()->IsObjectClass()) {
-      return TypeCheckKind::kArrayObjectCheck;
-    } else if (cls->CannotBeAssignedFromOtherTypes()) {
-      return TypeCheckKind::kExactCheck;
-    } else {
-      return TypeCheckKind::kArrayCheck;
-    }
-  } else if (cls->IsFinal()) {
-    return TypeCheckKind::kExactCheck;
-  } else if (cls->IsAbstract()) {
-    return TypeCheckKind::kAbstractClassCheck;
-  } else {
-    return TypeCheckKind::kClassHierarchyCheck;
-  }
-}
-
 void HInstructionBuilder::BuildLoadString(dex::StringIndex string_index, uint32_t dex_pc) {
   HLoadString* load_string =
       new (allocator_) HLoadString(graph_->GetCurrentMethod(), string_index, *dex_file_, dex_pc);
@@ -1848,22 +1825,8 @@ void HInstructionBuilder::BuildLoadString(dex::StringIndex string_index, uint32_
 HLoadClass* HInstructionBuilder::BuildLoadClass(dex::TypeIndex type_index, uint32_t dex_pc) {
   ScopedObjectAccess soa(Thread::Current());
   const DexFile& dex_file = *dex_compilation_unit_->GetDexFile();
-  Handle<mirror::ClassLoader> class_loader = dex_compilation_unit_->GetClassLoader();
-  Handle<mirror::Class> klass = handles_->NewHandle(compiler_driver_->ResolveClass(
-      soa, dex_compilation_unit_->GetDexCache(), class_loader, type_index, dex_compilation_unit_));
-
-  bool needs_access_check = true;
-  if (klass != nullptr) {
-    if (klass->IsPublic()) {
-      needs_access_check = false;
-    } else {
-      ObjPtr<mirror::Class> compiling_class = GetCompilingClass();
-      if (compiling_class != nullptr && compiling_class->CanAccess(klass.Get())) {
-        needs_access_check = false;
-      }
-    }
-  }
-
+  Handle<mirror::Class> klass = ResolveClass(soa, type_index);
+  bool needs_access_check = LoadClassNeedsAccessCheck(klass);
   return BuildLoadClass(type_index, dex_file, klass, dex_pc, needs_access_check);
 }
 
@@ -1908,25 +1871,83 @@ HLoadClass* HInstructionBuilder::BuildLoadClass(dex::TypeIndex type_index,
   return load_class;
 }
 
+Handle<mirror::Class> HInstructionBuilder::ResolveClass(ScopedObjectAccess& soa,
+                                                        dex::TypeIndex type_index) {
+  Handle<mirror::ClassLoader> class_loader = dex_compilation_unit_->GetClassLoader();
+  ObjPtr<mirror::Class> klass = compiler_driver_->ResolveClass(
+      soa, dex_compilation_unit_->GetDexCache(), class_loader, type_index, dex_compilation_unit_);
+  // TODO: Avoid creating excessive handles if the method references the same class repeatedly.
+  // (Use a map on the local_allocator_.)
+  return handles_->NewHandle(klass);
+}
+
+bool HInstructionBuilder::LoadClassNeedsAccessCheck(Handle<mirror::Class> klass) {
+  if (klass == nullptr) {
+    return true;
+  } else if (klass->IsPublic()) {
+    return false;
+  } else {
+    ObjPtr<mirror::Class> compiling_class = GetCompilingClass();
+    return compiling_class == nullptr || !compiling_class->CanAccess(klass.Get());
+  }
+}
+
 void HInstructionBuilder::BuildTypeCheck(const Instruction& instruction,
                                          uint8_t destination,
                                          uint8_t reference,
                                          dex::TypeIndex type_index,
                                          uint32_t dex_pc) {
   HInstruction* object = LoadLocal(reference, DataType::Type::kReference);
-  HLoadClass* cls = BuildLoadClass(type_index, dex_pc);
 
   ScopedObjectAccess soa(Thread::Current());
-  TypeCheckKind check_kind = ComputeTypeCheckKind(cls->GetClass());
+  const DexFile& dex_file = *dex_compilation_unit_->GetDexFile();
+  Handle<mirror::Class> klass = ResolveClass(soa, type_index);
+  bool needs_access_check = LoadClassNeedsAccessCheck(klass);
+  TypeCheckKind check_kind = HSharpening::ComputeTypeCheckKind(
+      klass.Get(), code_generator_, compiler_driver_, needs_access_check);
+
+  HInstruction* class_or_null = nullptr;
+  HIntConstant* bitstring_path_to_root = nullptr;
+  HIntConstant* bitstring_mask = nullptr;
+  if (check_kind == TypeCheckKind::kBitstringCheck) {
+    // TODO: Allow using the bitstring check also if we need an access check.
+    DCHECK(!needs_access_check);
+    class_or_null = graph_->GetNullConstant(dex_pc);
+    MutexLock subtype_check_lock(Thread::Current(), *Locks::subtype_check_lock_);
+    uint32_t path_to_root =
+        SubtypeCheck<ObjPtr<mirror::Class>>::GetEncodedPathToRootForTarget(klass.Get());
+    uint32_t mask = SubtypeCheck<ObjPtr<mirror::Class>>::GetEncodedPathToRootMask(klass.Get());
+    bitstring_path_to_root = graph_->GetIntConstant(static_cast<int32_t>(path_to_root), dex_pc);
+    bitstring_mask = graph_->GetIntConstant(static_cast<int32_t>(mask), dex_pc);
+  } else {
+    class_or_null = BuildLoadClass(type_index, dex_file, klass, dex_pc, needs_access_check);
+  }
+  DCHECK(class_or_null != nullptr);
+
   if (instruction.Opcode() == Instruction::INSTANCE_OF) {
-    AppendInstruction(new (allocator_) HInstanceOf(object, cls, check_kind, dex_pc));
+    AppendInstruction(new (allocator_) HInstanceOf(object,
+                                                   class_or_null,
+                                                   check_kind,
+                                                   klass,
+                                                   dex_pc,
+                                                   allocator_,
+                                                   bitstring_path_to_root,
+                                                   bitstring_mask));
     UpdateLocal(destination, current_block_->GetLastInstruction());
   } else {
     DCHECK_EQ(instruction.Opcode(), Instruction::CHECK_CAST);
     // We emit a CheckCast followed by a BoundType. CheckCast is a statement
     // which may throw. If it succeeds BoundType sets the new type of `object`
     // for all subsequent uses.
-    AppendInstruction(new (allocator_) HCheckCast(object, cls, check_kind, dex_pc));
+    AppendInstruction(
+        new (allocator_) HCheckCast(object,
+                                    class_or_null,
+                                    check_kind,
+                                    klass,
+                                    dex_pc,
+                                    allocator_,
+                                    bitstring_path_to_root,
+                                    bitstring_mask));
     AppendInstruction(new (allocator_) HBoundType(object, dex_pc));
     UpdateLocal(reference, current_block_->GetLastInstruction());
   }
diff --git a/compiler/optimizing/instruction_builder.h b/compiler/optimizing/instruction_builder.h
index 4428c53277..f78829232d 100644
--- a/compiler/optimizing/instruction_builder.h
+++ b/compiler/optimizing/instruction_builder.h
@@ -39,6 +39,7 @@ class DexCompilationUnit;
 class HBasicBlockBuilder;
 class Instruction;
 class OptimizingCompilerStats;
+class ScopedObjectAccess;
 class SsaBuilder;
 class VariableSizedHandleScope;
 
@@ -232,6 +233,12 @@ class HInstructionBuilder : public ValueObject {
                              bool needs_access_check)
       REQUIRES_SHARED(Locks::mutator_lock_);
 
+  Handle<mirror::Class> ResolveClass(ScopedObjectAccess& soa, dex::TypeIndex type_index)
+      REQUIRES_SHARED(Locks::mutator_lock_);
+
+  bool LoadClassNeedsAccessCheck(Handle<mirror::Class> klass)
+      REQUIRES_SHARED(Locks::mutator_lock_);
+
   // Returns the outer-most compiling method's class.
   ObjPtr<mirror::Class> GetOutermostCompilingClass() const;
 
diff --git a/compiler/optimizing/instruction_simplifier.cc b/compiler/optimizing/instruction_simplifier.cc
index a42a85dc1d..2538fa38f1 100644
--- a/compiler/optimizing/instruction_simplifier.cc
+++ b/compiler/optimizing/instruction_simplifier.cc
@@ -576,7 +576,9 @@ bool InstructionSimplifierVisitor::CanEnsureNotNullAt(HInstruction* input, HInst
 
 // Returns whether doing a type test between the class of `object` against `klass` has
 // a statically known outcome. The result of the test is stored in `outcome`.
-static bool TypeCheckHasKnownOutcome(HLoadClass* klass, HInstruction* object, bool* outcome) {
+static bool TypeCheckHasKnownOutcome(ReferenceTypeInfo class_rti,
+                                     HInstruction* object,
+                                     /*out*/bool* outcome) {
   DCHECK(!object->IsNullConstant()) << "Null constants should be special cased";
   ReferenceTypeInfo obj_rti = object->GetReferenceTypeInfo();
   ScopedObjectAccess soa(Thread::Current());
@@ -586,7 +588,6 @@ static bool TypeCheckHasKnownOutcome(HLoadClass* klass, HInstruction* object, bo
     return false;
   }
 
-  ReferenceTypeInfo class_rti = klass->GetLoadedClassRTI();
   if (!class_rti.IsValid()) {
     // Happens when the loaded class is unresolved.
     return false;
@@ -611,8 +612,8 @@ static bool TypeCheckHasKnownOutcome(HLoadClass* klass, HInstruction* object, bo
 
 void InstructionSimplifierVisitor::VisitCheckCast(HCheckCast* check_cast) {
   HInstruction* object = check_cast->InputAt(0);
-  HLoadClass* load_class = check_cast->InputAt(1)->AsLoadClass();
-  if (load_class->NeedsAccessCheck()) {
+  if (check_cast->GetTypeCheckKind() != TypeCheckKind::kBitstringCheck &&
+      check_cast->GetTargetClass()->NeedsAccessCheck()) {
     // If we need to perform an access check we cannot remove the instruction.
     return;
   }
@@ -630,15 +631,18 @@ void InstructionSimplifierVisitor::VisitCheckCast(HCheckCast* check_cast) {
   // Note: The `outcome` is initialized to please valgrind - the compiler can reorder
   // the return value check with the `outcome` check, b/27651442 .
   bool outcome = false;
-  if (TypeCheckHasKnownOutcome(load_class, object, &outcome)) {
+  if (TypeCheckHasKnownOutcome(check_cast->GetTargetClassRTI(), object, &outcome)) {
     if (outcome) {
       check_cast->GetBlock()->RemoveInstruction(check_cast);
       MaybeRecordStat(stats_, MethodCompilationStat::kRemovedCheckedCast);
-      if (!load_class->HasUses()) {
-        // We cannot rely on DCE to remove the class because the `HLoadClass` thinks it can throw.
-        // However, here we know that it cannot because the checkcast was successfull, hence
-        // the class was already loaded.
-        load_class->GetBlock()->RemoveInstruction(load_class);
+      if (check_cast->GetTypeCheckKind() != TypeCheckKind::kBitstringCheck) {
+        HLoadClass* load_class = check_cast->GetTargetClass();
+        if (!load_class->HasUses()) {
+          // We cannot rely on DCE to remove the class because the `HLoadClass` thinks it can throw.
+          // However, here we know that it cannot because the checkcast was successfull, hence
+          // the class was already loaded.
+          load_class->GetBlock()->RemoveInstruction(load_class);
+        }
       }
     } else {
       // Don't do anything for exceptional cases for now. Ideally we should remove
@@ -649,8 +653,8 @@ void InstructionSimplifierVisitor::VisitCheckCast(HCheckCast* check_cast) {
 
 void InstructionSimplifierVisitor::VisitInstanceOf(HInstanceOf* instruction) {
   HInstruction* object = instruction->InputAt(0);
-  HLoadClass* load_class = instruction->InputAt(1)->AsLoadClass();
-  if (load_class->NeedsAccessCheck()) {
+  if (instruction->GetTypeCheckKind() != TypeCheckKind::kBitstringCheck &&
+      instruction->GetTargetClass()->NeedsAccessCheck()) {
     // If we need to perform an access check we cannot remove the instruction.
     return;
   }
@@ -673,7 +677,7 @@ void InstructionSimplifierVisitor::VisitInstanceOf(HInstanceOf* instruction) {
   // Note: The `outcome` is initialized to please valgrind - the compiler can reorder
   // the return value check with the `outcome` check, b/27651442 .
   bool outcome = false;
-  if (TypeCheckHasKnownOutcome(load_class, object, &outcome)) {
+  if (TypeCheckHasKnownOutcome(instruction->GetTargetClassRTI(), object, &outcome)) {
     MaybeRecordStat(stats_, MethodCompilationStat::kRemovedInstanceOf);
     if (outcome && can_be_null) {
       // Type test will succeed, we just need a null test.
@@ -686,11 +690,14 @@ void InstructionSimplifierVisitor::VisitInstanceOf(HInstanceOf* instruction) {
     }
     RecordSimplification();
     instruction->GetBlock()->RemoveInstruction(instruction);
-    if (outcome && !load_class->HasUses()) {
-      // We cannot rely on DCE to remove the class because the `HLoadClass` thinks it can throw.
-      // However, here we know that it cannot because the instanceof check was successfull, hence
-      // the class was already loaded.
-      load_class->GetBlock()->RemoveInstruction(load_class);
+    if (outcome && instruction->GetTypeCheckKind() != TypeCheckKind::kBitstringCheck) {
+      HLoadClass* load_class = instruction->GetTargetClass();
+      if (!load_class->HasUses()) {
+        // We cannot rely on DCE to remove the class because the `HLoadClass` thinks it can throw.
+        // However, here we know that it cannot because the instanceof check was successfull, hence
+        // the class was already loaded.
+        load_class->GetBlock()->RemoveInstruction(load_class);
+      }
     }
   }
 }
diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index 727431a493..29a98701f8 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -3096,6 +3096,8 @@ std::ostream& operator<<(std::ostream& os, TypeCheckKind rhs) {
       return os << "array_object_check";
     case TypeCheckKind::kArrayCheck:
       return os << "array_check";
+    case TypeCheckKind::kBitstringCheck:
+      return os << "bitstring_check";
     default:
       LOG(FATAL) << "Unknown TypeCheckKind: " << static_cast<int>(rhs);
       UNREACHABLE();
diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 2047954207..331757fdcb 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -5929,8 +5929,7 @@ class HLoadClass FINAL : public HInstruction {
         special_input_(HUserRecord<HInstruction*>(current_method)),
         type_index_(type_index),
         dex_file_(dex_file),
-        klass_(klass),
-        loaded_class_rti_(ReferenceTypeInfo::CreateInvalid()) {
+        klass_(klass) {
     // Referrers class should not need access check. We never inline unverified
     // methods so we can't possibly end up in this situation.
     DCHECK(!is_referrers_class || !needs_access_check);
@@ -5940,6 +5939,7 @@ class HLoadClass FINAL : public HInstruction {
     SetPackedFlag<kFlagNeedsAccessCheck>(needs_access_check);
     SetPackedFlag<kFlagIsInBootImage>(false);
     SetPackedFlag<kFlagGenerateClInitCheck>(false);
+    SetPackedFlag<kFlagValidLoadedClassRTI>(false);
   }
 
   bool IsClonable() const OVERRIDE { return true; }
@@ -5988,13 +5988,18 @@ class HLoadClass FINAL : public HInstruction {
   }
 
   ReferenceTypeInfo GetLoadedClassRTI() {
-    return loaded_class_rti_;
+    if (GetPackedFlag<kFlagValidLoadedClassRTI>()) {
+      // Note: The is_exact flag from the return value should not be used.
+      return ReferenceTypeInfo::CreateUnchecked(klass_, /* is_exact */ true);
+    } else {
+      return ReferenceTypeInfo::CreateInvalid();
+    }
   }
 
-  void SetLoadedClassRTI(ReferenceTypeInfo rti) {
-    // Make sure we only set exact types (the loaded class should never be merged).
-    DCHECK(rti.IsExact());
-    loaded_class_rti_ = rti;
+  // Loaded class RTI is marked as valid by RTP if the klass_ is admissible.
+  void SetValidLoadedClassRTI() REQUIRES_SHARED(Locks::mutator_lock_) {
+    DCHECK(klass_ != nullptr);
+    SetPackedFlag<kFlagValidLoadedClassRTI>(true);
   }
 
   dex::TypeIndex GetTypeIndex() const { return type_index_; }
@@ -6047,7 +6052,8 @@ class HLoadClass FINAL : public HInstruction {
   static constexpr size_t kFieldLoadKind           = kFlagGenerateClInitCheck + 1;
   static constexpr size_t kFieldLoadKindSize =
       MinimumBitsToStore(static_cast<size_t>(LoadKind::kLast));
-  static constexpr size_t kNumberOfLoadClassPackedBits = kFieldLoadKind + kFieldLoadKindSize;
+  static constexpr size_t kFlagValidLoadedClassRTI = kFieldLoadKind + kFieldLoadKindSize;
+  static constexpr size_t kNumberOfLoadClassPackedBits = kFlagValidLoadedClassRTI + 1;
   static_assert(kNumberOfLoadClassPackedBits < kMaxNumberOfPackedBits, "Too many packed fields.");
   using LoadKindField = BitField<LoadKind, kFieldLoadKind, kFieldLoadKindSize>;
 
@@ -6075,8 +6081,6 @@ class HLoadClass FINAL : public HInstruction {
   const DexFile& dex_file_;
 
   Handle<mirror::Class> klass_;
-
-  ReferenceTypeInfo loaded_class_rti_;
 };
 std::ostream& operator<<(std::ostream& os, HLoadClass::LoadKind rhs);
 
@@ -6604,71 +6608,156 @@ enum class TypeCheckKind {
   kInterfaceCheck,        // No optimization yet when checking against an interface.
   kArrayObjectCheck,      // Can just check if the array is not primitive.
   kArrayCheck,            // No optimization yet when checking against a generic array.
+  kBitstringCheck,        // Compare the type check bitstring.
   kLast = kArrayCheck
 };
 
 std::ostream& operator<<(std::ostream& os, TypeCheckKind rhs);
 
-class HInstanceOf FINAL : public HExpression<2> {
+// Note: HTypeCheckInstruction is just a helper class, not an abstract instruction with an
+// `IsTypeCheckInstruction()`. (New virtual methods in the HInstruction class have a high cost.)
+class HTypeCheckInstruction : public HVariableInputSizeInstruction {
  public:
-  HInstanceOf(HInstruction* object,
-              HLoadClass* target_class,
-              TypeCheckKind check_kind,
-              uint32_t dex_pc)
-      : HExpression(DataType::Type::kBool,
-                    SideEffectsForArchRuntimeCalls(check_kind),
-                    dex_pc) {
+  HTypeCheckInstruction(HInstruction* object,
+                        HInstruction* target_class_or_null,
+                        TypeCheckKind check_kind,
+                        Handle<mirror::Class> klass,
+                        uint32_t dex_pc,
+                        ArenaAllocator* allocator,
+                        HIntConstant* bitstring_path_to_root,
+                        HIntConstant* bitstring_mask,
+                        SideEffects side_effects)
+      : HVariableInputSizeInstruction(
+          side_effects,
+          dex_pc,
+          allocator,
+          /* number_of_inputs */ check_kind == TypeCheckKind::kBitstringCheck ? 4u : 2u,
+          kArenaAllocTypeCheckInputs),
+        klass_(klass) {
     SetPackedField<TypeCheckKindField>(check_kind);
     SetPackedFlag<kFlagMustDoNullCheck>(true);
+    SetPackedFlag<kFlagValidTargetClassRTI>(false);
     SetRawInputAt(0, object);
-    SetRawInputAt(1, target_class);
+    SetRawInputAt(1, target_class_or_null);
+    DCHECK_EQ(check_kind == TypeCheckKind::kBitstringCheck, bitstring_path_to_root != nullptr);
+    DCHECK_EQ(check_kind == TypeCheckKind::kBitstringCheck, bitstring_mask != nullptr);
+    if (check_kind == TypeCheckKind::kBitstringCheck) {
+      DCHECK(target_class_or_null->IsNullConstant());
+      SetRawInputAt(2, bitstring_path_to_root);
+      SetRawInputAt(3, bitstring_mask);
+    } else {
+      DCHECK(target_class_or_null->IsLoadClass());
+    }
   }
 
   HLoadClass* GetTargetClass() const {
+    DCHECK_NE(GetTypeCheckKind(), TypeCheckKind::kBitstringCheck);
     HInstruction* load_class = InputAt(1);
     DCHECK(load_class->IsLoadClass());
     return load_class->AsLoadClass();
   }
 
-  bool IsClonable() const OVERRIDE { return true; }
-  bool CanBeMoved() const OVERRIDE { return true; }
+  uint32_t GetBitstringPathToRoot() const {
+    DCHECK_EQ(GetTypeCheckKind(), TypeCheckKind::kBitstringCheck);
+    HInstruction* path_to_root = InputAt(2);
+    DCHECK(path_to_root->IsIntConstant());
+    return static_cast<uint32_t>(path_to_root->AsIntConstant()->GetValue());
+  }
 
-  bool InstructionDataEquals(const HInstruction* other ATTRIBUTE_UNUSED) const OVERRIDE {
-    return true;
+  uint32_t GetBitstringMask() const {
+    DCHECK_EQ(GetTypeCheckKind(), TypeCheckKind::kBitstringCheck);
+    HInstruction* mask = InputAt(3);
+    DCHECK(mask->IsIntConstant());
+    return static_cast<uint32_t>(mask->AsIntConstant()->GetValue());
   }
 
-  bool NeedsEnvironment() const OVERRIDE {
-    return CanCallRuntime(GetTypeCheckKind());
+  bool IsClonable() const OVERRIDE { return true; }
+  bool CanBeMoved() const OVERRIDE { return true; }
+
+  bool InstructionDataEquals(const HInstruction* other) const OVERRIDE {
+    DCHECK(other->IsInstanceOf() || other->IsCheckCast()) << other->DebugName();
+    return GetPackedFields() == down_cast<const HTypeCheckInstruction*>(other)->GetPackedFields();
   }
 
-  // Used only in code generation.
   bool MustDoNullCheck() const { return GetPackedFlag<kFlagMustDoNullCheck>(); }
   void ClearMustDoNullCheck() { SetPackedFlag<kFlagMustDoNullCheck>(false); }
   TypeCheckKind GetTypeCheckKind() const { return GetPackedField<TypeCheckKindField>(); }
   bool IsExactCheck() const { return GetTypeCheckKind() == TypeCheckKind::kExactCheck; }
 
-  static bool CanCallRuntime(TypeCheckKind check_kind) {
-    // Mips currently does runtime calls for any other checks.
-    return check_kind != TypeCheckKind::kExactCheck;
+  ReferenceTypeInfo GetTargetClassRTI() {
+    if (GetPackedFlag<kFlagValidTargetClassRTI>()) {
+      // Note: The is_exact flag from the return value should not be used.
+      return ReferenceTypeInfo::CreateUnchecked(klass_, /* is_exact */ true);
+    } else {
+      return ReferenceTypeInfo::CreateInvalid();
+    }
   }
 
-  static SideEffects SideEffectsForArchRuntimeCalls(TypeCheckKind check_kind) {
-    return CanCallRuntime(check_kind) ? SideEffects::CanTriggerGC() : SideEffects::None();
+  // Target class RTI is marked as valid by RTP if the klass_ is admissible.
+  void SetValidTargetClassRTI() REQUIRES_SHARED(Locks::mutator_lock_) {
+    DCHECK(klass_ != nullptr);
+    SetPackedFlag<kFlagValidTargetClassRTI>(true);
   }
 
-  DECLARE_INSTRUCTION(InstanceOf);
+  Handle<mirror::Class> GetClass() const {
+    return klass_;
+  }
 
  protected:
-  DEFAULT_COPY_CONSTRUCTOR(InstanceOf);
+  DEFAULT_COPY_CONSTRUCTOR(TypeCheckInstruction);
 
  private:
-  static constexpr size_t kFieldTypeCheckKind = kNumberOfExpressionPackedBits;
+  static constexpr size_t kFieldTypeCheckKind = kNumberOfGenericPackedBits;
   static constexpr size_t kFieldTypeCheckKindSize =
       MinimumBitsToStore(static_cast<size_t>(TypeCheckKind::kLast));
   static constexpr size_t kFlagMustDoNullCheck = kFieldTypeCheckKind + kFieldTypeCheckKindSize;
-  static constexpr size_t kNumberOfInstanceOfPackedBits = kFlagMustDoNullCheck + 1;
+  static constexpr size_t kFlagValidTargetClassRTI = kFlagMustDoNullCheck + 1;
+  static constexpr size_t kNumberOfInstanceOfPackedBits = kFlagValidTargetClassRTI + 1;
   static_assert(kNumberOfInstanceOfPackedBits <= kMaxNumberOfPackedBits, "Too many packed fields.");
   using TypeCheckKindField = BitField<TypeCheckKind, kFieldTypeCheckKind, kFieldTypeCheckKindSize>;
+
+  Handle<mirror::Class> klass_;
+};
+
+class HInstanceOf FINAL : public HTypeCheckInstruction {
+ public:
+  HInstanceOf(HInstruction* object,
+              HInstruction* target_class_or_null,
+              TypeCheckKind check_kind,
+              Handle<mirror::Class> klass,
+              uint32_t dex_pc,
+              ArenaAllocator* allocator,
+              HIntConstant* bitstring_path_to_root,
+              HIntConstant* bitstring_mask)
+      : HTypeCheckInstruction(object,
+                              target_class_or_null,
+                              check_kind,
+                              klass,
+                              dex_pc,
+                              allocator,
+                              bitstring_path_to_root,
+                              bitstring_mask,
+                              SideEffectsForArchRuntimeCalls(check_kind)) {}
+
+  DataType::Type GetType() const OVERRIDE { return DataType::Type::kBool; }
+
+  bool NeedsEnvironment() const OVERRIDE {
+    return CanCallRuntime(GetTypeCheckKind());
+  }
+
+  static bool CanCallRuntime(TypeCheckKind check_kind) {
+    // Mips currently does runtime calls for any other checks.
+    return check_kind != TypeCheckKind::kExactCheck;
+  }
+
+  static SideEffects SideEffectsForArchRuntimeCalls(TypeCheckKind check_kind) {
+    return CanCallRuntime(check_kind) ? SideEffects::CanTriggerGC() : SideEffects::None();
+  }
+
+  DECLARE_INSTRUCTION(InstanceOf);
+
+ protected:
+  DEFAULT_COPY_CONSTRUCTOR(InstanceOf);
 };
 
 class HBoundType FINAL : public HExpression<1> {
@@ -6718,31 +6807,25 @@ class HBoundType FINAL : public HExpression<1> {
   ReferenceTypeInfo upper_bound_;
 };
 
-class HCheckCast FINAL : public HTemplateInstruction<2> {
+class HCheckCast FINAL : public HTypeCheckInstruction {
  public:
   HCheckCast(HInstruction* object,
-             HLoadClass* target_class,
+             HInstruction* target_class_or_null,
              TypeCheckKind check_kind,
-             uint32_t dex_pc)
-      : HTemplateInstruction(SideEffects::CanTriggerGC(), dex_pc) {
-    SetPackedField<TypeCheckKindField>(check_kind);
-    SetPackedFlag<kFlagMustDoNullCheck>(true);
-    SetRawInputAt(0, object);
-    SetRawInputAt(1, target_class);
-  }
-
-  HLoadClass* GetTargetClass() const {
-    HInstruction* load_class = InputAt(1);
-    DCHECK(load_class->IsLoadClass());
-    return load_class->AsLoadClass();
-  }
-
-  bool IsClonable() const OVERRIDE { return true; }
-  bool CanBeMoved() const OVERRIDE { return true; }
-
-  bool InstructionDataEquals(const HInstruction* other ATTRIBUTE_UNUSED) const OVERRIDE {
-    return true;
-  }
+             Handle<mirror::Class> klass,
+             uint32_t dex_pc,
+             ArenaAllocator* allocator,
+             HIntConstant* bitstring_path_to_root,
+             HIntConstant* bitstring_mask)
+      : HTypeCheckInstruction(object,
+                              target_class_or_null,
+                              check_kind,
+                              klass,
+                              dex_pc,
+                              allocator,
+                              bitstring_path_to_root,
+                              bitstring_mask,
+                              SideEffects::CanTriggerGC()) {}
 
   bool NeedsEnvironment() const OVERRIDE {
     // Instruction may throw a CheckCastError.
@@ -6751,24 +6834,10 @@ class HCheckCast FINAL : public HTemplateInstruction<2> {
 
   bool CanThrow() const OVERRIDE { return true; }
 
-  bool MustDoNullCheck() const { return GetPackedFlag<kFlagMustDoNullCheck>(); }
-  void ClearMustDoNullCheck() { SetPackedFlag<kFlagMustDoNullCheck>(false); }
-  TypeCheckKind GetTypeCheckKind() const { return GetPackedField<TypeCheckKindField>(); }
-  bool IsExactCheck() const { return GetTypeCheckKind() == TypeCheckKind::kExactCheck; }
-
   DECLARE_INSTRUCTION(CheckCast);
 
  protected:
   DEFAULT_COPY_CONSTRUCTOR(CheckCast);
-
- private:
-  static constexpr size_t kFieldTypeCheckKind = kNumberOfGenericPackedBits;
-  static constexpr size_t kFieldTypeCheckKindSize =
-      MinimumBitsToStore(static_cast<size_t>(TypeCheckKind::kLast));
-  static constexpr size_t kFlagMustDoNullCheck = kFieldTypeCheckKind + kFieldTypeCheckKindSize;
-  static constexpr size_t kNumberOfCheckCastPackedBits = kFlagMustDoNullCheck + 1;
-  static_assert(kNumberOfCheckCastPackedBits <= kMaxNumberOfPackedBits, "Too many packed fields.");
-  using TypeCheckKindField = BitField<TypeCheckKind, kFieldTypeCheckKind, kFieldTypeCheckKindSize>;
 };
 
 /**
diff --git a/compiler/optimizing/optimizing_compiler_stats.h b/compiler/optimizing/optimizing_compiler_stats.h
index 0023265e50..a6a2f46d2e 100644
--- a/compiler/optimizing/optimizing_compiler_stats.h
+++ b/compiler/optimizing/optimizing_compiler_stats.h
@@ -99,6 +99,7 @@ enum class MethodCompilationStat {
   kConstructorFenceRemovedLSE,
   kConstructorFenceRemovedPFRA,
   kConstructorFenceRemovedCFRE,
+  kBitstringTypeCheck,
   kJitOutOfMemoryForCommit,
   kLastStat
 };
diff --git a/compiler/optimizing/prepare_for_register_allocation.cc b/compiler/optimizing/prepare_for_register_allocation.cc
index f843c008d8..59733397bf 100644
--- a/compiler/optimizing/prepare_for_register_allocation.cc
+++ b/compiler/optimizing/prepare_for_register_allocation.cc
@@ -34,6 +34,20 @@ void PrepareForRegisterAllocation::Run() {
   }
 }
 
+void PrepareForRegisterAllocation::VisitCheckCast(HCheckCast* check_cast) {
+  // Record only those bitstring type checks that make it to the codegen stage.
+  if (check_cast->GetTypeCheckKind() == TypeCheckKind::kBitstringCheck) {
+    MaybeRecordStat(stats_, MethodCompilationStat::kBitstringTypeCheck);
+  }
+}
+
+void PrepareForRegisterAllocation::VisitInstanceOf(HInstanceOf* instance_of) {
+  // Record only those bitstring type checks that make it to the codegen stage.
+  if (instance_of->GetTypeCheckKind() == TypeCheckKind::kBitstringCheck) {
+    MaybeRecordStat(stats_, MethodCompilationStat::kBitstringTypeCheck);
+  }
+}
+
 void PrepareForRegisterAllocation::VisitNullCheck(HNullCheck* check) {
   check->ReplaceWith(check->InputAt(0));
 }
diff --git a/compiler/optimizing/prepare_for_register_allocation.h b/compiler/optimizing/prepare_for_register_allocation.h
index 2c64f016c1..f6e4d3ef99 100644
--- a/compiler/optimizing/prepare_for_register_allocation.h
+++ b/compiler/optimizing/prepare_for_register_allocation.h
@@ -40,6 +40,8 @@ class PrepareForRegisterAllocation : public HGraphDelegateVisitor {
       "prepare_for_register_allocation";
 
  private:
+  void VisitCheckCast(HCheckCast* check_cast) OVERRIDE;
+  void VisitInstanceOf(HInstanceOf* instance_of) OVERRIDE;
   void VisitNullCheck(HNullCheck* check) OVERRIDE;
   void VisitDivZeroCheck(HDivZeroCheck* check) OVERRIDE;
   void VisitBoundsCheck(HBoundsCheck* check) OVERRIDE;
diff --git a/compiler/optimizing/reference_type_propagation.cc b/compiler/optimizing/reference_type_propagation.cc
index 8bb124e066..178d7fd0f0 100644
--- a/compiler/optimizing/reference_type_propagation.cc
+++ b/compiler/optimizing/reference_type_propagation.cc
@@ -87,6 +87,7 @@ class ReferenceTypePropagation::RTPVisitor : public HGraphDelegateVisitor {
   void VisitDeoptimize(HDeoptimize* deopt) OVERRIDE;
   void VisitNewInstance(HNewInstance* new_instance) OVERRIDE;
   void VisitLoadClass(HLoadClass* load_class) OVERRIDE;
+  void VisitInstanceOf(HInstanceOf* load_class) OVERRIDE;
   void VisitClinitCheck(HClinitCheck* clinit_check) OVERRIDE;
   void VisitLoadString(HLoadString* instr) OVERRIDE;
   void VisitLoadException(HLoadException* instr) OVERRIDE;
@@ -171,6 +172,12 @@ void ReferenceTypePropagation::ValidateTypes() {
                 << "NullCheck " << instr->GetReferenceTypeInfo()
                 << "Input(0) " << instr->InputAt(0)->GetReferenceTypeInfo();
           }
+        } else if (instr->IsInstanceOf()) {
+          HInstanceOf* iof = instr->AsInstanceOf();
+          DCHECK(!iof->GetTargetClassRTI().IsValid() || iof->GetTargetClassRTI().IsExact());
+        } else if (instr->IsCheckCast()) {
+          HCheckCast* check = instr->AsCheckCast();
+          DCHECK(!check->GetTargetClassRTI().IsValid() || check->GetTargetClassRTI().IsExact());
         }
       }
     }
@@ -499,8 +506,7 @@ void ReferenceTypePropagation::RTPVisitor::BoundTypeForIfInstanceOf(HBasicBlock*
     return;
   }
 
-  HLoadClass* load_class = instanceOf->InputAt(1)->AsLoadClass();
-  ReferenceTypeInfo class_rti = load_class->GetLoadedClassRTI();
+  ReferenceTypeInfo class_rti = instanceOf->GetTargetClassRTI();
   if (!class_rti.IsValid()) {
     // He have loaded an unresolved class. Don't bother bounding the type.
     return;
@@ -644,15 +650,20 @@ void ReferenceTypePropagation::RTPVisitor::VisitUnresolvedStaticFieldGet(
 
 void ReferenceTypePropagation::RTPVisitor::VisitLoadClass(HLoadClass* instr) {
   ScopedObjectAccess soa(Thread::Current());
-  Handle<mirror::Class> resolved_class = instr->GetClass();
-  if (IsAdmissible(resolved_class.Get())) {
-    instr->SetLoadedClassRTI(ReferenceTypeInfo::Create(
-        resolved_class, /* is_exact */ true));
+  if (IsAdmissible(instr->GetClass().Get())) {
+    instr->SetValidLoadedClassRTI();
   }
   instr->SetReferenceTypeInfo(
       ReferenceTypeInfo::Create(handle_cache_->GetClassClassHandle(), /* is_exact */ true));
 }
 
+void ReferenceTypePropagation::RTPVisitor::VisitInstanceOf(HInstanceOf* instr) {
+  ScopedObjectAccess soa(Thread::Current());
+  if (IsAdmissible(instr->GetClass().Get())) {
+    instr->SetValidTargetClassRTI();
+  }
+}
+
 void ReferenceTypePropagation::RTPVisitor::VisitClinitCheck(HClinitCheck* instr) {
   instr->SetReferenceTypeInfo(instr->InputAt(0)->GetReferenceTypeInfo());
 }
@@ -720,8 +731,6 @@ void ReferenceTypePropagation::RTPVisitor::VisitBoundType(HBoundType* instr) {
 }
 
 void ReferenceTypePropagation::RTPVisitor::VisitCheckCast(HCheckCast* check_cast) {
-  HLoadClass* load_class = check_cast->InputAt(1)->AsLoadClass();
-  ReferenceTypeInfo class_rti = load_class->GetLoadedClassRTI();
   HBoundType* bound_type = check_cast->GetNext()->AsBoundType();
   if (bound_type == nullptr || bound_type->GetUpperBound().IsValid()) {
     // The next instruction is not an uninitialized BoundType. This must be
@@ -730,12 +739,14 @@ void ReferenceTypePropagation::RTPVisitor::VisitCheckCast(HCheckCast* check_cast
   }
   DCHECK_EQ(bound_type->InputAt(0), check_cast->InputAt(0));
 
-  if (class_rti.IsValid()) {
+  ScopedObjectAccess soa(Thread::Current());
+  Handle<mirror::Class> klass = check_cast->GetClass();
+  if (IsAdmissible(klass.Get())) {
     DCHECK(is_first_run_);
-    ScopedObjectAccess soa(Thread::Current());
+    check_cast->SetValidTargetClassRTI();
     // This is the first run of RTP and class is resolved.
-    bool is_exact = class_rti.GetTypeHandle()->CannotBeAssignedFromOtherTypes();
-    bound_type->SetUpperBound(ReferenceTypeInfo::Create(class_rti.GetTypeHandle(), is_exact),
+    bool is_exact = klass->CannotBeAssignedFromOtherTypes();
+    bound_type->SetUpperBound(ReferenceTypeInfo::Create(klass, is_exact),
                               /* CheckCast succeeds for nulls. */ true);
   } else {
     // This is the first run of RTP and class is unresolved. Remove the binding.
diff --git a/compiler/optimizing/sharpening.cc b/compiler/optimizing/sharpening.cc
index 1e49411c72..dffef17587 100644
--- a/compiler/optimizing/sharpening.cc
+++ b/compiler/optimizing/sharpening.cc
@@ -236,6 +236,75 @@ HLoadClass::LoadKind HSharpening::ComputeLoadClassKind(
   return load_kind;
 }
 
+static inline bool CanUseTypeCheckBitstring(ObjPtr<mirror::Class> klass,
+                                            CodeGenerator* codegen,
+                                            CompilerDriver* compiler_driver)
+    REQUIRES_SHARED(Locks::mutator_lock_) {
+  DCHECK(!klass->IsProxyClass());
+  DCHECK(!klass->IsArrayClass());
+
+  if (Runtime::Current()->UseJitCompilation()) {
+    // If we're JITting, try to assign a type check bitstring (fall through).
+  } else if (codegen->GetCompilerOptions().IsBootImage()) {
+    const char* descriptor = klass->GetDexFile().StringByTypeIdx(klass->GetDexTypeIndex());
+    if (!compiler_driver->IsImageClass(descriptor)) {
+      return false;
+    }
+    // If the target is a boot image class, try to assign a type check bitstring (fall through).
+    // (If --force-determinism, this was already done; repeating is OK and yields the same result.)
+  } else {
+    // TODO: Use the bitstring also for AOT app compilation if the target class has a bitstring
+    // already assigned in the boot image.
+    return false;
+  }
+
+  // Try to assign a type check bitstring.
+  MutexLock subtype_check_lock(Thread::Current(), *Locks::subtype_check_lock_);
+  if ((false) &&  // FIXME: Inliner does not respect compiler_driver->IsClassToCompile()
+                  // and we're hitting an unassigned bitstring in dex2oat_image_test. b/26687569
+      kIsDebugBuild &&
+      codegen->GetCompilerOptions().IsBootImage() &&
+      codegen->GetCompilerOptions().IsForceDeterminism()) {
+    SubtypeCheckInfo::State old_state = SubtypeCheck<ObjPtr<mirror::Class>>::GetState(klass);
+    CHECK(old_state == SubtypeCheckInfo::kAssigned || old_state == SubtypeCheckInfo::kOverflowed)
+        << klass->PrettyDescriptor() << "/" << old_state
+        << " in " << codegen->GetGraph()->PrettyMethod();
+  }
+  SubtypeCheckInfo::State state = SubtypeCheck<ObjPtr<mirror::Class>>::EnsureAssigned(klass);
+  return state == SubtypeCheckInfo::kAssigned;
+}
+
+TypeCheckKind HSharpening::ComputeTypeCheckKind(ObjPtr<mirror::Class> klass,
+                                                CodeGenerator* codegen,
+                                                CompilerDriver* compiler_driver,
+                                                bool needs_access_check) {
+  if (klass == nullptr) {
+    return TypeCheckKind::kUnresolvedCheck;
+  } else if (klass->IsInterface()) {
+    return TypeCheckKind::kInterfaceCheck;
+  } else if (klass->IsArrayClass()) {
+    if (klass->GetComponentType()->IsObjectClass()) {
+      return TypeCheckKind::kArrayObjectCheck;
+    } else if (klass->CannotBeAssignedFromOtherTypes()) {
+      return TypeCheckKind::kExactCheck;
+    } else {
+      return TypeCheckKind::kArrayCheck;
+    }
+  } else if (klass->IsFinal()) {  // TODO: Consider using bitstring for final classes.
+    return TypeCheckKind::kExactCheck;
+  } else if (kUseBitstringTypeCheck &&
+             !needs_access_check &&
+             CanUseTypeCheckBitstring(klass, codegen, compiler_driver)) {
+    // TODO: We should not need the `!needs_access_check` check but getting rid of that
+    // requires rewriting some optimizations in instruction simplifier.
+    return TypeCheckKind::kBitstringCheck;
+  } else if (klass->IsAbstract()) {
+    return TypeCheckKind::kAbstractClassCheck;
+  } else {
+    return TypeCheckKind::kClassHierarchyCheck;
+  }
+}
+
 void HSharpening::ProcessLoadString(
     HLoadString* load_string,
     CodeGenerator* codegen,
diff --git a/compiler/optimizing/sharpening.h b/compiler/optimizing/sharpening.h
index 6df7d6d91e..fa3e948eeb 100644
--- a/compiler/optimizing/sharpening.h
+++ b/compiler/optimizing/sharpening.h
@@ -44,12 +44,10 @@ class HSharpening : public HOptimization {
 
   static constexpr const char* kSharpeningPassName = "sharpening";
 
-  // Used by the builder.
-  static void ProcessLoadString(HLoadString* load_string,
-                                CodeGenerator* codegen,
-                                CompilerDriver* compiler_driver,
-                                const DexCompilationUnit& dex_compilation_unit,
-                                VariableSizedHandleScope* handles);
+  // Used by Sharpening and InstructionSimplifier.
+  static void SharpenInvokeStaticOrDirect(HInvokeStaticOrDirect* invoke,
+                                          CodeGenerator* codegen,
+                                          CompilerDriver* compiler_driver);
 
   // Used by the builder and the inliner.
   static HLoadClass::LoadKind ComputeLoadClassKind(HLoadClass* load_class,
@@ -58,10 +56,19 @@ class HSharpening : public HOptimization {
                                                    const DexCompilationUnit& dex_compilation_unit)
       REQUIRES_SHARED(Locks::mutator_lock_);
 
-  // Used by Sharpening and InstructionSimplifier.
-  static void SharpenInvokeStaticOrDirect(HInvokeStaticOrDirect* invoke,
-                                          CodeGenerator* codegen,
-                                          CompilerDriver* compiler_driver);
+  // Used by the builder.
+  static TypeCheckKind ComputeTypeCheckKind(ObjPtr<mirror::Class> klass,
+                                            CodeGenerator* codegen,
+                                            CompilerDriver* compiler_driver,
+                                            bool needs_access_check)
+      REQUIRES_SHARED(Locks::mutator_lock_);
+
+  // Used by the builder.
+  static void ProcessLoadString(HLoadString* load_string,
+                                CodeGenerator* codegen,
+                                CompilerDriver* compiler_driver,
+                                const DexCompilationUnit& dex_compilation_unit,
+                                VariableSizedHandleScope* handles);
 
  private:
   CodeGenerator* codegen_;
diff --git a/runtime/arch/arm/quick_entrypoints_arm.S b/runtime/arch/arm/quick_entrypoints_arm.S
index 737d2a86a1..1671a243c9 100644
--- a/runtime/arch/arm/quick_entrypoints_arm.S
+++ b/runtime/arch/arm/quick_entrypoints_arm.S
@@ -794,6 +794,9 @@ END art_quick_unlock_object_no_inline
     .extern artInstanceOfFromCode
     .extern artThrowClassCastExceptionForObject
 ENTRY art_quick_check_instance_of
+    // Type check using the bit string passes null as the target class. In that case just throw.
+    cbz r1, .Lthrow_class_cast_exception_for_bitstring_check
+
     push {r0-r2, lr}                    @ save arguments, padding (r2) and link register
     .cfi_adjust_cfa_offset 16
     .cfi_rel_offset r0, 0
@@ -812,6 +815,7 @@ ENTRY art_quick_check_instance_of
     .cfi_restore r2
     .cfi_restore lr
 
+.Lthrow_class_cast_exception_for_bitstring_check:
     SETUP_SAVE_ALL_CALLEE_SAVES_FRAME r2       @ save all registers as basis for long jump context
     mov r2, r9                      @ pass Thread::Current
     bl  artThrowClassCastExceptionForObject  @ (Object*, Class*, Thread*)
diff --git a/runtime/arch/arm64/quick_entrypoints_arm64.S b/runtime/arch/arm64/quick_entrypoints_arm64.S
index b0e7b0a964..06141184f6 100644
--- a/runtime/arch/arm64/quick_entrypoints_arm64.S
+++ b/runtime/arch/arm64/quick_entrypoints_arm64.S
@@ -1333,6 +1333,9 @@ END art_quick_unlock_object_no_inline
     .extern artInstanceOfFromCode
     .extern artThrowClassCastExceptionForObject
 ENTRY art_quick_check_instance_of
+    // Type check using the bit string passes null as the target class. In that case just throw.
+    cbz x1, .Lthrow_class_cast_exception_for_bitstring_check
+
     // Store arguments and link register
     // Stack needs to be 16B aligned on calls.
     SAVE_TWO_REGS_INCREASE_FRAME x0, x1, 32
@@ -1358,6 +1361,7 @@ ENTRY art_quick_check_instance_of
     // Restore
     RESTORE_TWO_REGS_DECREASE_FRAME x0, x1, 32
 
+.Lthrow_class_cast_exception_for_bitstring_check:
     SETUP_SAVE_ALL_CALLEE_SAVES_FRAME // save all registers as basis for long jump context
     mov x2, xSELF                     // pass Thread::Current
     bl artThrowClassCastExceptionForObject     // (Object*, Class*, Thread*)
diff --git a/runtime/arch/mips/quick_entrypoints_mips.S b/runtime/arch/mips/quick_entrypoints_mips.S
index b2f7e10f52..d8fe480719 100644
--- a/runtime/arch/mips/quick_entrypoints_mips.S
+++ b/runtime/arch/mips/quick_entrypoints_mips.S
@@ -1423,6 +1423,10 @@ END art_quick_unlock_object_no_inline
     .extern artInstanceOfFromCode
     .extern artThrowClassCastExceptionForObject
 ENTRY art_quick_check_instance_of
+    // Type check using the bit string passes null as the target class. In that case just throw.
+    beqz   $a1, .Lthrow_class_cast_exception_for_bitstring_check
+    nop
+
     addiu  $sp, $sp, -32
     .cfi_adjust_cfa_offset 32
     sw     $gp, 16($sp)
@@ -1441,12 +1445,15 @@ ENTRY art_quick_check_instance_of
     jalr   $zero, $ra
     addiu  $sp, $sp, 32
     .cfi_adjust_cfa_offset -32
+
 .Lthrow_class_cast_exception:
     lw     $t9, 8($sp)
     lw     $a1, 4($sp)
     lw     $a0, 0($sp)
     addiu  $sp, $sp, 32
     .cfi_adjust_cfa_offset -32
+
+.Lthrow_class_cast_exception_for_bitstring_check:
     SETUP_SAVE_ALL_CALLEE_SAVES_FRAME
     la   $t9, artThrowClassCastExceptionForObject
     jalr $zero, $t9                 # artThrowClassCastException (Object*, Class*, Thread*)
diff --git a/runtime/arch/mips64/quick_entrypoints_mips64.S b/runtime/arch/mips64/quick_entrypoints_mips64.S
index 63f4f6cb8c..a5edc1fc2d 100644
--- a/runtime/arch/mips64/quick_entrypoints_mips64.S
+++ b/runtime/arch/mips64/quick_entrypoints_mips64.S
@@ -1364,6 +1364,9 @@ END art_quick_unlock_object_no_inline
     .extern artInstanceOfFromCode
     .extern artThrowClassCastExceptionForObject
 ENTRY art_quick_check_instance_of
+    // Type check using the bit string passes null as the target class. In that case just throw.
+    beqzc  $a1, .Lthrow_class_cast_exception_for_bitstring_check
+
     daddiu $sp, $sp, -32
     .cfi_adjust_cfa_offset 32
     sd     $ra, 24($sp)
@@ -1379,12 +1382,15 @@ ENTRY art_quick_check_instance_of
     jalr   $zero, $ra
     daddiu $sp, $sp, 32
     .cfi_adjust_cfa_offset -32
+
 .Lthrow_class_cast_exception:
     ld     $t9, 16($sp)
     ld     $a1, 8($sp)
     ld     $a0, 0($sp)
     daddiu $sp, $sp, 32
     .cfi_adjust_cfa_offset -32
+
+.Lthrow_class_cast_exception_for_bitstring_check:
     SETUP_GP
     SETUP_SAVE_ALL_CALLEE_SAVES_FRAME
     dla  $t9, artThrowClassCastExceptionForObject
diff --git a/runtime/arch/x86/quick_entrypoints_x86.S b/runtime/arch/x86/quick_entrypoints_x86.S
index 5a28120b30..d64e2fd99f 100644
--- a/runtime/arch/x86/quick_entrypoints_x86.S
+++ b/runtime/arch/x86/quick_entrypoints_x86.S
@@ -1431,6 +1431,10 @@ DEFINE_FUNCTION art_quick_instance_of
 END_FUNCTION art_quick_instance_of
 
 DEFINE_FUNCTION art_quick_check_instance_of
+    // Type check using the bit string passes null as the target class. In that case just throw.
+    testl %ecx, %ecx
+    jz .Lthrow_class_cast_exception_for_bitstring_check
+
     PUSH eax                              // alignment padding
     PUSH ecx                              // pass arg2 - checked class
     PUSH eax                              // pass arg1 - obj
@@ -1448,6 +1452,7 @@ DEFINE_FUNCTION art_quick_check_instance_of
     addl LITERAL(4), %esp
     CFI_ADJUST_CFA_OFFSET(-4)
 
+.Lthrow_class_cast_exception_for_bitstring_check:
     SETUP_SAVE_ALL_CALLEE_SAVES_FRAME ebx, ebx // save all registers as basis for long jump context
     // Outgoing argument set up
     PUSH eax                              // alignment padding
diff --git a/runtime/arch/x86_64/quick_entrypoints_x86_64.S b/runtime/arch/x86_64/quick_entrypoints_x86_64.S
index 781ade99ce..81ad7806dd 100644
--- a/runtime/arch/x86_64/quick_entrypoints_x86_64.S
+++ b/runtime/arch/x86_64/quick_entrypoints_x86_64.S
@@ -1402,6 +1402,10 @@ DEFINE_FUNCTION art_quick_unlock_object_no_inline
 END_FUNCTION art_quick_unlock_object_no_inline
 
 DEFINE_FUNCTION art_quick_check_instance_of
+    // Type check using the bit string passes null as the target class. In that case just throw.
+    testl %esi, %esi
+    jz .Lthrow_class_cast_exception_for_bitstring_check
+
     // We could check the super classes here but that is usually already checked in the caller.
     PUSH rdi                          // Save args for exc
     PUSH rsi
@@ -1425,6 +1429,7 @@ DEFINE_FUNCTION art_quick_check_instance_of
     POP rsi                           // Pop arguments
     POP rdi
 
+.Lthrow_class_cast_exception_for_bitstring_check:
     SETUP_SAVE_ALL_CALLEE_SAVES_FRAME // save all registers as basis for long jump context
     mov %gs:THREAD_SELF_OFFSET, %rdx  // pass Thread::Current()
     call SYMBOL(artThrowClassCastExceptionForObject)  // (Object* src, Class* dest, Thread*)
diff --git a/runtime/base/arena_allocator.cc b/runtime/base/arena_allocator.cc
index cc413c5ab9..6b66173627 100644
--- a/runtime/base/arena_allocator.cc
+++ b/runtime/base/arena_allocator.cc
@@ -56,6 +56,7 @@ const char* const ArenaAllocatorStatsImpl<kCount>::kAllocNames[] = {
   "CtorFenceIns ",
   "InvokeInputs ",
   "PhiInputs    ",
+  "TypeCheckIns ",
   "LoopInfo     ",
   "LIBackEdges  ",
   "TryCatchInf  ",
diff --git a/runtime/base/arena_allocator.h b/runtime/base/arena_allocator.h
index 9e03658aef..d720e977dd 100644
--- a/runtime/base/arena_allocator.h
+++ b/runtime/base/arena_allocator.h
@@ -62,6 +62,7 @@ enum ArenaAllocKind {
   kArenaAllocConstructorFenceInputs,
   kArenaAllocInvokeInputs,
   kArenaAllocPhiInputs,
+  kArenaAllocTypeCheckInputs,
   kArenaAllocLoopInfo,
   kArenaAllocLoopInfoBackEdges,
   kArenaAllocTryCatchInfo,
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index b61fb4afe9..fb4690235d 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -4483,6 +4483,14 @@ mirror::Class* ClassLinker::CreateProxyClass(ScopedObjectAccessAlreadyRunnable&
 
   Runtime::Current()->GetRuntimeCallbacks()->ClassPrepare(temp_klass, klass);
 
+  // SubtypeCheckInfo::Initialized must happen-before any new-instance for that type.
+  // See also ClassLinker::EnsureInitialized().
+  {
+    MutexLock subtype_check_lock(Thread::Current(), *Locks::subtype_check_lock_);
+    SubtypeCheck<ObjPtr<mirror::Class>>::EnsureInitialized(klass.Get());
+    // TODO: Avoid taking subtype_check_lock_ if SubtypeCheck for j.l.r.Proxy is already assigned.
+  }
+
   {
     // Lock on klass is released. Lock new class object.
     ObjectLock<mirror::Class> initialization_lock(self, klass);
diff --git a/runtime/entrypoints/quick/quick_throw_entrypoints.cc b/runtime/entrypoints/quick/quick_throw_entrypoints.cc
index 565b4edcc3..4b26beece3 100644
--- a/runtime/entrypoints/quick/quick_throw_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_throw_entrypoints.cc
@@ -15,8 +15,11 @@
  */
 
 #include "callee_save_frame.h"
+#include "dex/code_item_accessors-inl.h"
+#include "dex/dex_instruction-inl.h"
 #include "common_throws.h"
 #include "mirror/object-inl.h"
+#include "nth_caller_visitor.h"
 #include "thread.h"
 #include "well_known_classes.h"
 
@@ -111,6 +114,21 @@ extern "C" NO_RETURN void artThrowClassCastException(mirror::Class* dest_type,
                                                      Thread* self)
     REQUIRES_SHARED(Locks::mutator_lock_) {
   ScopedQuickEntrypointChecks sqec(self);
+  if (dest_type == nullptr) {
+    // Find the target class for check cast using the bitstring check (dest_type == null).
+    NthCallerVisitor visitor(self, 0u);
+    visitor.WalkStack();
+    DCHECK(visitor.caller != nullptr);
+    uint32_t dex_pc = visitor.GetDexPc();
+    CodeItemDataAccessor accessor(visitor.caller);
+    const Instruction& check_cast = accessor.InstructionAt(dex_pc);
+    DCHECK_EQ(check_cast.Opcode(), Instruction::CHECK_CAST);
+    dex::TypeIndex type_index(check_cast.VRegB_21c());
+    ClassLinker* linker = Runtime::Current()->GetClassLinker();
+    dest_type = linker->LookupResolvedType(type_index, visitor.caller).Ptr();
+    CHECK(dest_type != nullptr) << "Target class should have been previously resolved: "
+        << visitor.caller->GetDexFile()->PrettyType(type_index);
+  }
   DCHECK(!dest_type->IsAssignableFrom(src_type));
   ThrowClassCastException(dest_type, src_type);
   self->QuickDeliverException();
diff --git a/runtime/subtype_check.h b/runtime/subtype_check.h
index 54d2f00106..03a6d9caee 100644
--- a/runtime/subtype_check.h
+++ b/runtime/subtype_check.h
@@ -283,6 +283,17 @@ struct SubtypeCheck {
     return SubtypeCheckInfo::kUninitialized;
   }
 
+  // Retrieve the state of this class's SubtypeCheckInfo.
+  //
+  // Cost: O(Depth(Class)).
+  //
+  // Returns: The precise SubtypeCheckInfo::State.
+  static SubtypeCheckInfo::State GetState(ClassPtr klass)
+      REQUIRES(Locks::subtype_check_lock_)
+      REQUIRES_SHARED(Locks::mutator_lock_) {
+    return GetSubtypeCheckInfo(klass).GetState();
+  }
+
   // Retrieve the path to root bitstring as a plain uintN_t value that is amenable to
   // be used by a fast check "encoded_src & mask_target == encoded_target".
   //
@@ -305,8 +316,9 @@ struct SubtypeCheck {
   static BitString::StorageType GetEncodedPathToRootForTarget(ClassPtr klass)
       REQUIRES(Locks::subtype_check_lock_)
       REQUIRES_SHARED(Locks::mutator_lock_) {
-    DCHECK_EQ(SubtypeCheckInfo::kAssigned, GetSubtypeCheckInfo(klass).GetState());
-    return GetSubtypeCheckInfo(klass).GetEncodedPathToRoot();
+    SubtypeCheckInfo sci = GetSubtypeCheckInfo(klass);
+    DCHECK_EQ(SubtypeCheckInfo::kAssigned, sci.GetState());
+    return sci.GetEncodedPathToRoot();
   }
 
   // Retrieve the path to root bitstring mask as a plain uintN_t value that is amenable to
@@ -318,8 +330,9 @@ struct SubtypeCheck {
   static BitString::StorageType GetEncodedPathToRootMask(ClassPtr klass)
       REQUIRES(Locks::subtype_check_lock_)
       REQUIRES_SHARED(Locks::mutator_lock_) {
-    DCHECK_EQ(SubtypeCheckInfo::kAssigned, GetSubtypeCheckInfo(klass).GetState());
-    return GetSubtypeCheckInfo(klass).GetEncodedPathToRootMask();
+    SubtypeCheckInfo sci = GetSubtypeCheckInfo(klass);
+    DCHECK_EQ(SubtypeCheckInfo::kAssigned, sci.GetState());
+    return sci.GetEncodedPathToRootMask();
   }
 
   // Is the source class a subclass of the target?
diff --git a/test/670-bitstring-type-check/build b/test/670-bitstring-type-check/build
new file mode 100644
index 0000000000..38307f2c0f
--- /dev/null
+++ b/test/670-bitstring-type-check/build
@@ -0,0 +1,216 @@
+#!/bin/bash
+#
+# Copyright (C) 2018 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Stop if something fails.
+set -e
+
+# Write out the source file.
+
+mkdir src
+cat >src/Main.java <<EOF
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+EOF
+
+for i in {0..8192}; do echo "class Level1Class$i { }" >>src/Main.java; done
+for i in {0..1024}; do echo "class Level2Class$i extends Level1Class0 { }" >>src/Main.java; done
+
+cat >>src/Main.java <<EOF
+class Level3Class0 extends Level2Class0 { }
+class Level4Class0 extends Level3Class0 { }
+class Level5Class0 extends Level4Class0 { }
+class Level6Class0 extends Level5Class0 { }
+class Level7Class0 extends Level6Class0 { }
+class Level8Class0 extends Level7Class0 { }
+class Level9Class0 extends Level8Class0 { }
+
+public class Main {
+  public static void main(String[] args) throws Exception {
+    // 8193 classes at level 1 make sure we shall have an overflow if there are 13 or
+    // less bits for the level 1 character. 1025 classes at level 2 similarly guarantees
+    // an overflow if the number of bits for level 2 character is 10 or less. To test
+    // type checks also for the depth overflow, we provide a hierarchy 9 levels deep.
+
+    // Make sure the bitstrings are initialized.
+    for (int i = 0; i <= 8192; ++i) {
+      Class.forName("Level1Class" + i).newInstance();
+    }
+    for (int i = 0; i <= 1024; ++i) {
+      Class.forName("Level2Class" + i).newInstance();
+    }
+
+    // Note: Using a different class for tests so that verification of Main.main() does
+    // not try to resolve classes used by the tests. This guarantees uninitialized type
+    // check bitstrings when we enter Main.main() and start initializing them above.
+    Helper.testInstanceOf();
+    Helper.testCheckCast();
+  }
+}
+
+class Helper {
+  public static void testInstanceOf() throws Exception {
+    for (int i = 1; i <= 9; ++i) {
+      Object o = createInstance("Level" + i + "Class0");
+      assertTrue(o instanceof Level1Class0);
+      if (o instanceof Level2Class0) {
+        assertFalse(i < 2);
+      } else {
+        assertTrue(i < 2);
+      }
+      if (o instanceof Level3Class0) {
+        assertFalse(i < 3);
+      } else {
+        assertTrue(i < 3);
+      }
+      if (o instanceof Level4Class0) {
+        assertFalse(i < 4);
+      } else {
+        assertTrue(i < 4);
+      }
+      if (o instanceof Level5Class0) {
+        assertFalse(i < 5);
+      } else {
+        assertTrue(i < 5);
+      }
+      if (o instanceof Level6Class0) {
+        assertFalse(i < 6);
+      } else {
+        assertTrue(i < 6);
+      }
+      if (o instanceof Level7Class0) {
+        assertFalse(i < 7);
+      } else {
+        assertTrue(i < 7);
+      }
+      if (o instanceof Level8Class0) {
+        assertFalse(i < 8);
+      } else {
+        assertTrue(i < 8);
+      }
+      if (o instanceof Level9Class0) {
+        assertFalse(i < 9);
+      } else {
+        assertTrue(i < 9);
+      }
+    }
+
+    assertTrue(createInstance("Level1Class8192") instanceof Level1Class8192);
+    assertFalse(createInstance("Level1Class8192") instanceof Level1Class0);
+    assertTrue(createInstance("Level2Class1024") instanceof Level2Class1024);
+    assertTrue(createInstance("Level2Class1024") instanceof Level1Class0);
+    assertFalse(createInstance("Level2Class1024") instanceof Level2Class0);
+  }
+
+  public static void testCheckCast() throws Exception {
+    for (int i = 1; i <= 9; ++i) {
+      Object o = createInstance("Level" + i + "Class0");
+      Level1Class0 l1c0 = (Level1Class0) o;
+      try {
+        Level2Class0 l2c0 = (Level2Class0) o;
+        assertFalse(i < 2);
+      } catch (ClassCastException cce) {
+        assertTrue(i < 2);
+      }
+      try {
+        Level3Class0 l3c0 = (Level3Class0) o;
+        assertFalse(i < 3);
+      } catch (ClassCastException cce) {
+        assertTrue(i < 3);
+      }
+      try {
+        Level4Class0 l4c0 = (Level4Class0) o;
+        assertFalse(i < 4);
+      } catch (ClassCastException cce) {
+        assertTrue(i < 4);
+      }
+      try {
+        Level5Class0 l5c0 = (Level5Class0) o;
+        assertFalse(i < 5);
+      } catch (ClassCastException cce) {
+        assertTrue(i < 5);
+      }
+      try {
+        Level6Class0 l6c0 = (Level6Class0) o;
+        assertFalse(i < 6);
+      } catch (ClassCastException cce) {
+        assertTrue(i < 6);
+      }
+      try {
+        Level7Class0 l7c0 = (Level7Class0) o;
+        assertFalse(i < 7);
+      } catch (ClassCastException cce) {
+        assertTrue(i < 7);
+      }
+      try {
+        Level8Class0 l8c0 = (Level8Class0) o;
+        assertFalse(i < 8);
+      } catch (ClassCastException cce) {
+        assertTrue(i < 8);
+      }
+      try {
+        Level9Class0 l9c0 = (Level9Class0) o;
+        assertFalse(i < 9);
+      } catch (ClassCastException cce) {
+        assertTrue(i < 9);
+      }
+    }
+
+    Level1Class8192 l1c8192 = (Level1Class8192) createInstance("Level1Class8192");
+    try {
+      Level1Class0 l1c0 = (Level1Class0) createInstance("Level1Class8192");
+      throw new AssertionError("Unexpected");
+    } catch (ClassCastException expected) {}
+    Level2Class1024 l2c1024 = (Level2Class1024) createInstance("Level2Class1024");
+    Level1Class0 l1c0 = (Level1Class0) createInstance("Level2Class1024");
+    try {
+      Level2Class0 l2c0 = (Level2Class0) createInstance("Level2Class1024");
+      throw new AssertionError("Unexpected");
+    } catch (ClassCastException expected) {}
+  }
+
+  public static Object createInstance(String className) throws Exception {
+    return Class.forName(className).newInstance();
+  }
+
+  public static void assertTrue(boolean value) throws Exception {
+    if (!value) {
+      throw new AssertionError();
+    }
+  }
+
+  public static void assertFalse(boolean value) throws Exception {
+    if (value) {
+      throw new AssertionError();
+    }
+  }
+}
+EOF
+
+./default-build "$@"
diff --git a/test/670-bitstring-type-check/expected.txt b/test/670-bitstring-type-check/expected.txt
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/test/670-bitstring-type-check/expected.txt
diff --git a/test/670-bitstring-type-check/info.txt b/test/670-bitstring-type-check/info.txt
new file mode 100644
index 0000000000..a34ba86171
--- /dev/null
+++ b/test/670-bitstring-type-check/info.txt
@@ -0,0 +1 @@
+Tests for the bitstring type checks.