Revert "Revert "Deoptimization-based bce.""

This reverts commit 0ba627337274ccfb8c9cb9bf23fffb1e1b9d1430.

Change-Id: I1ca10d15bbb49897a0cf541ab160431ec180a006
diff --git a/compiler/oat_test.cc b/compiler/oat_test.cc
index 503068c..989b04f 100644
--- a/compiler/oat_test.cc
+++ b/compiler/oat_test.cc
@@ -176,7 +176,7 @@
   EXPECT_EQ(72U, sizeof(OatHeader));
   EXPECT_EQ(4U, sizeof(OatMethodOffsets));
   EXPECT_EQ(28U, sizeof(OatQuickMethodHeader));
-  EXPECT_EQ(91 * GetInstructionSetPointerSize(kRuntimeISA), sizeof(QuickEntryPoints));
+  EXPECT_EQ(92 * GetInstructionSetPointerSize(kRuntimeISA), sizeof(QuickEntryPoints));
 }
 
 TEST_F(OatTest, OatHeaderIsValid) {
diff --git a/compiler/optimizing/bounds_check_elimination.cc b/compiler/optimizing/bounds_check_elimination.cc
index 1d16794..01f7e91 100644
--- a/compiler/optimizing/bounds_check_elimination.cc
+++ b/compiler/optimizing/bounds_check_elimination.cc
@@ -443,9 +443,31 @@
 
 class BCEVisitor : public HGraphVisitor {
  public:
+  // The least number of bounds checks that should be eliminated by triggering
+  // the deoptimization technique.
+  static constexpr size_t kThresholdForAddingDeoptimize = 2;
+
+  // Very large constant index is considered as an anomaly. This is a threshold
+  // beyond which we don't bother to apply the deoptimization technique since
+  // it's likely some AIOOBE will be thrown.
+  static constexpr int32_t kMaxConstantForAddingDeoptimize = INT_MAX - 1024 * 1024;
+
   explicit BCEVisitor(HGraph* graph)
       : HGraphVisitor(graph),
-        maps_(graph->GetBlocks().Size()) {}
+        maps_(graph->GetBlocks().Size()),
+        need_to_revisit_block_(false) {}
+
+  void VisitBasicBlock(HBasicBlock* block) OVERRIDE {
+    first_constant_index_bounds_check_map_.clear();
+    HGraphVisitor::VisitBasicBlock(block);
+    if (need_to_revisit_block_) {
+      AddComparesWithDeoptimization(block);
+      need_to_revisit_block_ = false;
+      first_constant_index_bounds_check_map_.clear();
+      GetValueRangeMap(block)->clear();
+      HGraphVisitor::VisitBasicBlock(block);
+    }
+  }
 
  private:
   // Return the map of proven value ranges at the beginning of a basic block.
@@ -701,9 +723,26 @@
         }
       }
 
+      if (first_constant_index_bounds_check_map_.find(array_length->GetId()) ==
+          first_constant_index_bounds_check_map_.end()) {
+        // Remember the first bounds check against array_length of a constant index.
+        // That bounds check instruction has an associated HEnvironment where we
+        // may add an HDeoptimize to eliminate bounds checks of constant indices
+        // against array_length.
+        first_constant_index_bounds_check_map_.Put(array_length->GetId(), bounds_check);
+      } else {
+        // We've seen it at least twice. It's beneficial to introduce a compare with
+        // deoptimization fallback to eliminate the bounds checks.
+        need_to_revisit_block_ = true;
+      }
+
       // Once we have an array access like 'array[5] = 1', we record array.length >= 6.
       // We currently don't do it for non-constant index since a valid array[i] can't prove
       // a valid array[i-1] yet due to the lower bound side.
+      if (constant == INT_MAX) {
+        // INT_MAX as an index will definitely throw AIOOBE.
+        return;
+      }
       ValueBound lower = ValueBound(nullptr, constant + 1);
       ValueBound upper = ValueBound::Max();
       ValueRange* range = new (GetGraph()->GetArena())
@@ -938,8 +977,90 @@
     }
   }
 
+  void VisitDeoptimize(HDeoptimize* deoptimize) {
+    // Right now it's only HLessThanOrEqual.
+    DCHECK(deoptimize->InputAt(0)->IsLessThanOrEqual());
+    HLessThanOrEqual* less_than_or_equal = deoptimize->InputAt(0)->AsLessThanOrEqual();
+    HInstruction* instruction = less_than_or_equal->InputAt(0);
+    if (instruction->IsArrayLength()) {
+      HInstruction* constant = less_than_or_equal->InputAt(1);
+      DCHECK(constant->IsIntConstant());
+      DCHECK(constant->AsIntConstant()->GetValue() <= kMaxConstantForAddingDeoptimize);
+      ValueBound lower = ValueBound(nullptr, constant->AsIntConstant()->GetValue() + 1);
+      ValueRange* range = new (GetGraph()->GetArena())
+          ValueRange(GetGraph()->GetArena(), lower, ValueBound::Max());
+      GetValueRangeMap(deoptimize->GetBlock())->Overwrite(instruction->GetId(), range);
+    }
+  }
+
+  void AddCompareWithDeoptimization(HInstruction* array_length,
+                                    HIntConstant* const_instr,
+                                    HBasicBlock* block) {
+    DCHECK(array_length->IsArrayLength());
+    ValueRange* range = LookupValueRange(array_length, block);
+    ValueBound lower_bound = range->GetLower();
+    DCHECK(lower_bound.IsConstant());
+    DCHECK(const_instr->GetValue() <= kMaxConstantForAddingDeoptimize);
+    DCHECK_EQ(lower_bound.GetConstant(), const_instr->GetValue() + 1);
+
+    // If array_length is less than lower_const, deoptimize.
+    HBoundsCheck* bounds_check = first_constant_index_bounds_check_map_.Get(
+        array_length->GetId())->AsBoundsCheck();
+    HCondition* cond = new (GetGraph()->GetArena()) HLessThanOrEqual(array_length, const_instr);
+    HDeoptimize* deoptimize = new (GetGraph()->GetArena())
+        HDeoptimize(cond, bounds_check->GetDexPc());
+    block->InsertInstructionBefore(cond, bounds_check);
+    block->InsertInstructionBefore(deoptimize, bounds_check);
+    deoptimize->SetEnvironment(bounds_check->GetEnvironment());
+  }
+
+  void AddComparesWithDeoptimization(HBasicBlock* block) {
+    for (ArenaSafeMap<int, HBoundsCheck*>::iterator it =
+             first_constant_index_bounds_check_map_.begin();
+         it != first_constant_index_bounds_check_map_.end();
+         ++it) {
+      HBoundsCheck* bounds_check = it->second;
+      HArrayLength* array_length = bounds_check->InputAt(1)->AsArrayLength();
+      HIntConstant* lower_bound_const_instr = nullptr;
+      int32_t lower_bound_const = INT_MIN;
+      size_t counter = 0;
+      // Count the constant indexing for which bounds checks haven't
+      // been removed yet.
+      for (HUseIterator<HInstruction*> it2(array_length->GetUses());
+           !it2.Done();
+           it2.Advance()) {
+        HInstruction* user = it2.Current()->GetUser();
+        if (user->GetBlock() == block &&
+            user->IsBoundsCheck() &&
+            user->AsBoundsCheck()->InputAt(0)->IsIntConstant()) {
+          DCHECK_EQ(array_length, user->AsBoundsCheck()->InputAt(1));
+          HIntConstant* const_instr = user->AsBoundsCheck()->InputAt(0)->AsIntConstant();
+          if (const_instr->GetValue() > lower_bound_const) {
+            lower_bound_const = const_instr->GetValue();
+            lower_bound_const_instr = const_instr;
+          }
+          counter++;
+        }
+      }
+      if (counter >= kThresholdForAddingDeoptimize &&
+          lower_bound_const_instr->GetValue() <= kMaxConstantForAddingDeoptimize) {
+        AddCompareWithDeoptimization(array_length, lower_bound_const_instr, block);
+      }
+    }
+  }
+
   std::vector<std::unique_ptr<ArenaSafeMap<int, ValueRange*>>> maps_;
 
+  // Map an HArrayLength instruction's id to the first HBoundsCheck instruction in
+  // a block that checks a constant index against that HArrayLength.
+  SafeMap<int, HBoundsCheck*> first_constant_index_bounds_check_map_;
+
+  // For the block, there is at least one HArrayLength instruction for which there
+  // is more than one bounds check instruction with constant indexing. And it's
+  // beneficial to add a compare instruction that has deoptimization fallback and
+  // eliminate those bounds checks.
+  bool need_to_revisit_block_;
+
   DISALLOW_COPY_AND_ASSIGN(BCEVisitor);
 };
 
diff --git a/compiler/optimizing/bounds_check_elimination_test.cc b/compiler/optimizing/bounds_check_elimination_test.cc
index b3653fe..75cf1cf 100644
--- a/compiler/optimizing/bounds_check_elimination_test.cc
+++ b/compiler/optimizing/bounds_check_elimination_test.cc
@@ -284,9 +284,9 @@
   ASSERT_FALSE(IsRemoved(bounds_check));
 }
 
-// array[5] = 1; // Can't eliminate.
-// array[4] = 1; // Can eliminate.
 // array[6] = 1; // Can't eliminate.
+// array[5] = 1; // Can eliminate.
+// array[4] = 1; // Can eliminate.
 TEST(BoundsCheckEliminationTest, ConstantArrayBoundsElimination) {
   ArenaPool pool;
   ArenaAllocator allocator(&pool);
@@ -311,9 +311,20 @@
 
   HNullCheck* null_check = new (&allocator) HNullCheck(parameter, 0);
   HArrayLength* array_length = new (&allocator) HArrayLength(null_check);
+  HBoundsCheck* bounds_check6 = new (&allocator)
+      HBoundsCheck(constant_6, array_length, 0);
+  HInstruction* array_set = new (&allocator) HArraySet(
+    null_check, bounds_check6, constant_1, Primitive::kPrimInt, 0);
+  block->AddInstruction(null_check);
+  block->AddInstruction(array_length);
+  block->AddInstruction(bounds_check6);
+  block->AddInstruction(array_set);
+
+  null_check = new (&allocator) HNullCheck(parameter, 0);
+  array_length = new (&allocator) HArrayLength(null_check);
   HBoundsCheck* bounds_check5 = new (&allocator)
       HBoundsCheck(constant_5, array_length, 0);
-  HInstruction* array_set = new (&allocator) HArraySet(
+  array_set = new (&allocator) HArraySet(
     null_check, bounds_check5, constant_1, Primitive::kPrimInt, 0);
   block->AddInstruction(null_check);
   block->AddInstruction(array_length);
@@ -331,17 +342,6 @@
   block->AddInstruction(bounds_check4);
   block->AddInstruction(array_set);
 
-  null_check = new (&allocator) HNullCheck(parameter, 0);
-  array_length = new (&allocator) HArrayLength(null_check);
-  HBoundsCheck* bounds_check6 = new (&allocator)
-      HBoundsCheck(constant_6, array_length, 0);
-  array_set = new (&allocator) HArraySet(
-    null_check, bounds_check6, constant_1, Primitive::kPrimInt, 0);
-  block->AddInstruction(null_check);
-  block->AddInstruction(array_length);
-  block->AddInstruction(bounds_check6);
-  block->AddInstruction(array_set);
-
   block->AddInstruction(new (&allocator) HGoto());
 
   HBasicBlock* exit = new (&allocator) HBasicBlock(graph);
@@ -353,9 +353,9 @@
   RunSimplifierAndGvn(graph);
   BoundsCheckElimination bounds_check_elimination(graph);
   bounds_check_elimination.Run();
-  ASSERT_FALSE(IsRemoved(bounds_check5));
-  ASSERT_TRUE(IsRemoved(bounds_check4));
   ASSERT_FALSE(IsRemoved(bounds_check6));
+  ASSERT_TRUE(IsRemoved(bounds_check5));
+  ASSERT_TRUE(IsRemoved(bounds_check4));
 }
 
 // for (int i=initial; i<array.length; i+=increment) { array[i] = 10; }
diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index 1f95041..f5e4df1 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -287,6 +287,26 @@
   DISALLOW_COPY_AND_ASSIGN(TypeCheckSlowPathARM);
 };
 
+class DeoptimizationSlowPathARM : public SlowPathCodeARM {
+ public:
+  explicit DeoptimizationSlowPathARM(HInstruction* instruction)
+    : instruction_(instruction) {}
+
+  void EmitNativeCode(CodeGenerator* codegen) OVERRIDE {
+    __ Bind(GetEntryLabel());
+    SaveLiveRegisters(codegen, instruction_->GetLocations());
+    DCHECK(instruction_->IsDeoptimize());
+    HDeoptimize* deoptimize = instruction_->AsDeoptimize();
+    uint32_t dex_pc = deoptimize->GetDexPc();
+    CodeGeneratorARM* arm_codegen = down_cast<CodeGeneratorARM*>(codegen);
+    arm_codegen->InvokeRuntime(QUICK_ENTRY_POINT(pDeoptimize), instruction_, dex_pc, this);
+  }
+
+ private:
+  HInstruction* const instruction_;
+  DISALLOW_COPY_AND_ASSIGN(DeoptimizationSlowPathARM);
+};
+
 #undef __
 
 #undef __
@@ -887,24 +907,17 @@
   UNUSED(exit);
 }
 
-void LocationsBuilderARM::VisitIf(HIf* if_instr) {
-  LocationSummary* locations =
-      new (GetGraph()->GetArena()) LocationSummary(if_instr, LocationSummary::kNoCall);
-  HInstruction* cond = if_instr->InputAt(0);
-  if (!cond->IsCondition() || cond->AsCondition()->NeedsMaterialization()) {
-    locations->SetInAt(0, Location::RequiresRegister());
-  }
-}
-
-void InstructionCodeGeneratorARM::VisitIf(HIf* if_instr) {
-  HInstruction* cond = if_instr->InputAt(0);
+void InstructionCodeGeneratorARM::GenerateTestAndBranch(HInstruction* instruction,
+                                                        Label* true_target,
+                                                        Label* false_target,
+                                                        Label* always_true_target) {
+  HInstruction* cond = instruction->InputAt(0);
   if (cond->IsIntConstant()) {
     // Constant condition, statically compared against 1.
     int32_t cond_value = cond->AsIntConstant()->GetValue();
     if (cond_value == 1) {
-      if (!codegen_->GoesToNextBlock(if_instr->GetBlock(),
-                                     if_instr->IfTrueSuccessor())) {
-        __ b(codegen_->GetLabelOf(if_instr->IfTrueSuccessor()));
+      if (always_true_target != nullptr) {
+        __ b(always_true_target);
       }
       return;
     } else {
@@ -913,10 +926,10 @@
   } else {
     if (!cond->IsCondition() || cond->AsCondition()->NeedsMaterialization()) {
       // Condition has been materialized, compare the output to 0
-      DCHECK(if_instr->GetLocations()->InAt(0).IsRegister());
-      __ cmp(if_instr->GetLocations()->InAt(0).AsRegister<Register>(),
+      DCHECK(instruction->GetLocations()->InAt(0).IsRegister());
+      __ cmp(instruction->GetLocations()->InAt(0).AsRegister<Register>(),
              ShifterOperand(0));
-      __ b(codegen_->GetLabelOf(if_instr->IfTrueSuccessor()), NE);
+      __ b(true_target, NE);
     } else {
       // Condition has not been materialized, use its inputs as the
       // comparison and its condition as the branch condition.
@@ -938,16 +951,55 @@
           __ cmp(left, ShifterOperand(temp));
         }
       }
-      __ b(codegen_->GetLabelOf(if_instr->IfTrueSuccessor()),
-           ARMCondition(cond->AsCondition()->GetCondition()));
+      __ b(true_target, ARMCondition(cond->AsCondition()->GetCondition()));
     }
   }
-  if (!codegen_->GoesToNextBlock(if_instr->GetBlock(),
-                                 if_instr->IfFalseSuccessor())) {
-    __ b(codegen_->GetLabelOf(if_instr->IfFalseSuccessor()));
+  if (false_target != nullptr) {
+    __ b(false_target);
   }
 }
 
+void LocationsBuilderARM::VisitIf(HIf* if_instr) {
+  LocationSummary* locations =
+      new (GetGraph()->GetArena()) LocationSummary(if_instr, LocationSummary::kNoCall);
+  HInstruction* cond = if_instr->InputAt(0);
+  if (!cond->IsCondition() || cond->AsCondition()->NeedsMaterialization()) {
+    locations->SetInAt(0, Location::RequiresRegister());
+  }
+}
+
+void InstructionCodeGeneratorARM::VisitIf(HIf* if_instr) {
+  Label* true_target = codegen_->GetLabelOf(if_instr->IfTrueSuccessor());
+  Label* false_target = codegen_->GetLabelOf(if_instr->IfFalseSuccessor());
+  Label* always_true_target = true_target;
+  if (codegen_->GoesToNextBlock(if_instr->GetBlock(),
+                                if_instr->IfTrueSuccessor())) {
+    always_true_target = nullptr;
+  }
+  if (codegen_->GoesToNextBlock(if_instr->GetBlock(),
+                                if_instr->IfFalseSuccessor())) {
+    false_target = nullptr;
+  }
+  GenerateTestAndBranch(if_instr, true_target, false_target, always_true_target);
+}
+
+void LocationsBuilderARM::VisitDeoptimize(HDeoptimize* deoptimize) {
+  LocationSummary* locations = new (GetGraph()->GetArena())
+      LocationSummary(deoptimize, LocationSummary::kCallOnSlowPath);
+  HInstruction* cond = deoptimize->InputAt(0);
+  DCHECK(cond->IsCondition());
+  if (cond->AsCondition()->NeedsMaterialization()) {
+    locations->SetInAt(0, Location::RequiresRegister());
+  }
+}
+
+void InstructionCodeGeneratorARM::VisitDeoptimize(HDeoptimize* deoptimize) {
+  SlowPathCodeARM* slow_path = new (GetGraph()->GetArena())
+      DeoptimizationSlowPathARM(deoptimize);
+  codegen_->AddSlowPath(slow_path);
+  Label* slow_path_entry = slow_path->GetEntryLabel();
+  GenerateTestAndBranch(deoptimize, slow_path_entry, nullptr, slow_path_entry);
+}
 
 void LocationsBuilderARM::VisitCondition(HCondition* comp) {
   LocationSummary* locations =
diff --git a/compiler/optimizing/code_generator_arm.h b/compiler/optimizing/code_generator_arm.h
index bcdea7a..06f425e 100644
--- a/compiler/optimizing/code_generator_arm.h
+++ b/compiler/optimizing/code_generator_arm.h
@@ -188,6 +188,10 @@
   void HandleFieldGet(HInstruction* instruction, const FieldInfo& field_info);
   void GenerateImplicitNullCheck(HNullCheck* instruction);
   void GenerateExplicitNullCheck(HNullCheck* instruction);
+  void GenerateTestAndBranch(HInstruction* instruction,
+                             Label* true_target,
+                             Label* false_target,
+                             Label* always_true_target);
 
   ArmAssembler* const assembler_;
   CodeGeneratorARM* const codegen_;
diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index 03d3445..ee04b3a 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -352,6 +352,26 @@
   DISALLOW_COPY_AND_ASSIGN(TypeCheckSlowPathARM64);
 };
 
+class DeoptimizationSlowPathARM64 : public SlowPathCodeARM64 {
+ public:
+  explicit DeoptimizationSlowPathARM64(HInstruction* instruction)
+    : instruction_(instruction) {}
+
+  void EmitNativeCode(CodeGenerator* codegen) OVERRIDE {
+    __ Bind(GetEntryLabel());
+    SaveLiveRegisters(codegen, instruction_->GetLocations());
+    DCHECK(instruction_->IsDeoptimize());
+    HDeoptimize* deoptimize = instruction_->AsDeoptimize();
+    uint32_t dex_pc = deoptimize->GetDexPc();
+    CodeGeneratorARM64* arm64_codegen = down_cast<CodeGeneratorARM64*>(codegen);
+    arm64_codegen->InvokeRuntime(QUICK_ENTRY_POINT(pDeoptimize), instruction_, dex_pc, this);
+  }
+
+ private:
+  HInstruction* const instruction_;
+  DISALLOW_COPY_AND_ASSIGN(DeoptimizationSlowPathARM64);
+};
+
 #undef __
 
 Location InvokeDexCallingConventionVisitor::GetNextLocation(Primitive::Type type) {
@@ -1615,25 +1635,18 @@
   }
 }
 
-void LocationsBuilderARM64::VisitIf(HIf* if_instr) {
-  LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(if_instr);
-  HInstruction* cond = if_instr->InputAt(0);
-  if (!cond->IsCondition() || cond->AsCondition()->NeedsMaterialization()) {
-    locations->SetInAt(0, Location::RequiresRegister());
-  }
-}
-
-void InstructionCodeGeneratorARM64::VisitIf(HIf* if_instr) {
-  HInstruction* cond = if_instr->InputAt(0);
+void InstructionCodeGeneratorARM64::GenerateTestAndBranch(HInstruction* instruction,
+                                                          vixl::Label* true_target,
+                                                          vixl::Label* false_target,
+                                                          vixl::Label* always_true_target) {
+  HInstruction* cond = instruction->InputAt(0);
   HCondition* condition = cond->AsCondition();
-  vixl::Label* true_target = codegen_->GetLabelOf(if_instr->IfTrueSuccessor());
-  vixl::Label* false_target = codegen_->GetLabelOf(if_instr->IfFalseSuccessor());
 
   if (cond->IsIntConstant()) {
     int32_t cond_value = cond->AsIntConstant()->GetValue();
     if (cond_value == 1) {
-      if (!codegen_->GoesToNextBlock(if_instr->GetBlock(), if_instr->IfTrueSuccessor())) {
-        __ B(true_target);
+      if (always_true_target != nullptr) {
+        __ B(always_true_target);
       }
       return;
     } else {
@@ -1641,9 +1654,9 @@
     }
   } else if (!cond->IsCondition() || condition->NeedsMaterialization()) {
     // The condition instruction has been materialized, compare the output to 0.
-    Location cond_val = if_instr->GetLocations()->InAt(0);
+    Location cond_val = instruction->GetLocations()->InAt(0);
     DCHECK(cond_val.IsRegister());
-    __ Cbnz(InputRegisterAt(if_instr, 0), true_target);
+    __ Cbnz(InputRegisterAt(instruction, 0), true_target);
   } else {
     // The condition instruction has not been materialized, use its inputs as
     // the comparison and its condition as the branch condition.
@@ -1661,11 +1674,52 @@
       __ B(arm64_cond, true_target);
     }
   }
-  if (!codegen_->GoesToNextBlock(if_instr->GetBlock(), if_instr->IfFalseSuccessor())) {
+  if (false_target != nullptr) {
     __ B(false_target);
   }
 }
 
+void LocationsBuilderARM64::VisitIf(HIf* if_instr) {
+  LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(if_instr);
+  HInstruction* cond = if_instr->InputAt(0);
+  if (!cond->IsCondition() || cond->AsCondition()->NeedsMaterialization()) {
+    locations->SetInAt(0, Location::RequiresRegister());
+  }
+}
+
+void InstructionCodeGeneratorARM64::VisitIf(HIf* if_instr) {
+  vixl::Label* true_target = codegen_->GetLabelOf(if_instr->IfTrueSuccessor());
+  vixl::Label* false_target = codegen_->GetLabelOf(if_instr->IfFalseSuccessor());
+  vixl::Label* always_true_target = true_target;
+  if (codegen_->GoesToNextBlock(if_instr->GetBlock(),
+                                if_instr->IfTrueSuccessor())) {
+    always_true_target = nullptr;
+  }
+  if (codegen_->GoesToNextBlock(if_instr->GetBlock(),
+                                if_instr->IfFalseSuccessor())) {
+    false_target = nullptr;
+  }
+  GenerateTestAndBranch(if_instr, true_target, false_target, always_true_target);
+}
+
+void LocationsBuilderARM64::VisitDeoptimize(HDeoptimize* deoptimize) {
+  LocationSummary* locations = new (GetGraph()->GetArena())
+      LocationSummary(deoptimize, LocationSummary::kCallOnSlowPath);
+  HInstruction* cond = deoptimize->InputAt(0);
+  DCHECK(cond->IsCondition());
+  if (cond->AsCondition()->NeedsMaterialization()) {
+    locations->SetInAt(0, Location::RequiresRegister());
+  }
+}
+
+void InstructionCodeGeneratorARM64::VisitDeoptimize(HDeoptimize* deoptimize) {
+  SlowPathCodeARM64* slow_path = new (GetGraph()->GetArena())
+      DeoptimizationSlowPathARM64(deoptimize);
+  codegen_->AddSlowPath(slow_path);
+  vixl::Label* slow_path_entry = slow_path->GetEntryLabel();
+  GenerateTestAndBranch(deoptimize, slow_path_entry, nullptr, slow_path_entry);
+}
+
 void LocationsBuilderARM64::VisitInstanceFieldGet(HInstanceFieldGet* instruction) {
   LocationSummary* locations =
       new (GetGraph()->GetArena()) LocationSummary(instruction, LocationSummary::kNoCall);
diff --git a/compiler/optimizing/code_generator_arm64.h b/compiler/optimizing/code_generator_arm64.h
index f555de5..7edb129 100644
--- a/compiler/optimizing/code_generator_arm64.h
+++ b/compiler/optimizing/code_generator_arm64.h
@@ -165,6 +165,10 @@
   void HandleShift(HBinaryOperation* instr);
   void GenerateImplicitNullCheck(HNullCheck* instruction);
   void GenerateExplicitNullCheck(HNullCheck* instruction);
+  void GenerateTestAndBranch(HInstruction* instruction,
+                             vixl::Label* true_target,
+                             vixl::Label* false_target,
+                             vixl::Label* always_true_target);
 
   Arm64Assembler* const assembler_;
   CodeGeneratorARM64* const codegen_;
diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index 0d5fe49..c9831af 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -294,6 +294,27 @@
   DISALLOW_COPY_AND_ASSIGN(TypeCheckSlowPathX86);
 };
 
+class DeoptimizationSlowPathX86 : public SlowPathCodeX86 {
+ public:
+  explicit DeoptimizationSlowPathX86(HInstruction* instruction)
+    : instruction_(instruction) {}
+
+  void EmitNativeCode(CodeGenerator* codegen) OVERRIDE {
+    __ Bind(GetEntryLabel());
+    SaveLiveRegisters(codegen, instruction_->GetLocations());
+    __ fs()->call(Address::Absolute(QUICK_ENTRYPOINT_OFFSET(kX86WordSize, pDeoptimize)));
+    // No need to restore live registers.
+    DCHECK(instruction_->IsDeoptimize());
+    HDeoptimize* deoptimize = instruction_->AsDeoptimize();
+    uint32_t dex_pc = deoptimize->GetDexPc();
+    codegen->RecordPcInfo(instruction_, dex_pc, this);
+  }
+
+ private:
+  HInstruction* const instruction_;
+  DISALLOW_COPY_AND_ASSIGN(DeoptimizationSlowPathX86);
+};
+
 #undef __
 #define __ reinterpret_cast<X86Assembler*>(GetAssembler())->
 
@@ -784,24 +805,17 @@
   UNUSED(exit);
 }
 
-void LocationsBuilderX86::VisitIf(HIf* if_instr) {
-  LocationSummary* locations =
-      new (GetGraph()->GetArena()) LocationSummary(if_instr, LocationSummary::kNoCall);
-  HInstruction* cond = if_instr->InputAt(0);
-  if (!cond->IsCondition() || cond->AsCondition()->NeedsMaterialization()) {
-    locations->SetInAt(0, Location::Any());
-  }
-}
-
-void InstructionCodeGeneratorX86::VisitIf(HIf* if_instr) {
-  HInstruction* cond = if_instr->InputAt(0);
+void InstructionCodeGeneratorX86::GenerateTestAndBranch(HInstruction* instruction,
+                                                        Label* true_target,
+                                                        Label* false_target,
+                                                        Label* always_true_target) {
+  HInstruction* cond = instruction->InputAt(0);
   if (cond->IsIntConstant()) {
     // Constant condition, statically compared against 1.
     int32_t cond_value = cond->AsIntConstant()->GetValue();
     if (cond_value == 1) {
-      if (!codegen_->GoesToNextBlock(if_instr->GetBlock(),
-                                     if_instr->IfTrueSuccessor())) {
-        __ jmp(codegen_->GetLabelOf(if_instr->IfTrueSuccessor()));
+      if (always_true_target != nullptr) {
+        __ jmp(always_true_target);
       }
       return;
     } else {
@@ -814,20 +828,19 @@
     // evaluated just before the if, we don't need to evaluate it
     // again.
     bool eflags_set = cond->IsCondition()
-        && cond->AsCondition()->IsBeforeWhenDisregardMoves(if_instr);
+        && cond->AsCondition()->IsBeforeWhenDisregardMoves(instruction);
     if (materialized) {
       if (!eflags_set) {
         // Materialized condition, compare against 0.
-        Location lhs = if_instr->GetLocations()->InAt(0);
+        Location lhs = instruction->GetLocations()->InAt(0);
         if (lhs.IsRegister()) {
           __ testl(lhs.AsRegister<Register>(), lhs.AsRegister<Register>());
         } else {
           __ cmpl(Address(ESP, lhs.GetStackIndex()), Immediate(0));
         }
-        __ j(kNotEqual,  codegen_->GetLabelOf(if_instr->IfTrueSuccessor()));
+        __ j(kNotEqual, true_target);
       } else {
-        __ j(X86Condition(cond->AsCondition()->GetCondition()),
-             codegen_->GetLabelOf(if_instr->IfTrueSuccessor()));
+        __ j(X86Condition(cond->AsCondition()->GetCondition()), true_target);
       }
     } else {
       Location lhs = cond->GetLocations()->InAt(0);
@@ -846,16 +859,56 @@
       } else {
         __ cmpl(lhs.AsRegister<Register>(), Address(ESP, rhs.GetStackIndex()));
       }
-      __ j(X86Condition(cond->AsCondition()->GetCondition()),
-           codegen_->GetLabelOf(if_instr->IfTrueSuccessor()));
+      __ j(X86Condition(cond->AsCondition()->GetCondition()), true_target);
     }
   }
-  if (!codegen_->GoesToNextBlock(if_instr->GetBlock(),
-                                 if_instr->IfFalseSuccessor())) {
-    __ jmp(codegen_->GetLabelOf(if_instr->IfFalseSuccessor()));
+  if (false_target != nullptr) {
+    __ jmp(false_target);
   }
 }
 
+void LocationsBuilderX86::VisitIf(HIf* if_instr) {
+  LocationSummary* locations =
+      new (GetGraph()->GetArena()) LocationSummary(if_instr, LocationSummary::kNoCall);
+  HInstruction* cond = if_instr->InputAt(0);
+  if (!cond->IsCondition() || cond->AsCondition()->NeedsMaterialization()) {
+    locations->SetInAt(0, Location::Any());
+  }
+}
+
+void InstructionCodeGeneratorX86::VisitIf(HIf* if_instr) {
+  Label* true_target = codegen_->GetLabelOf(if_instr->IfTrueSuccessor());
+  Label* false_target = codegen_->GetLabelOf(if_instr->IfFalseSuccessor());
+  Label* always_true_target = true_target;
+  if (codegen_->GoesToNextBlock(if_instr->GetBlock(),
+                                if_instr->IfTrueSuccessor())) {
+    always_true_target = nullptr;
+  }
+  if (codegen_->GoesToNextBlock(if_instr->GetBlock(),
+                                if_instr->IfFalseSuccessor())) {
+    false_target = nullptr;
+  }
+  GenerateTestAndBranch(if_instr, true_target, false_target, always_true_target);
+}
+
+void LocationsBuilderX86::VisitDeoptimize(HDeoptimize* deoptimize) {
+  LocationSummary* locations = new (GetGraph()->GetArena())
+      LocationSummary(deoptimize, LocationSummary::kCallOnSlowPath);
+  HInstruction* cond = deoptimize->InputAt(0);
+  DCHECK(cond->IsCondition());
+  if (cond->AsCondition()->NeedsMaterialization()) {
+    locations->SetInAt(0, Location::Any());
+  }
+}
+
+void InstructionCodeGeneratorX86::VisitDeoptimize(HDeoptimize* deoptimize) {
+  SlowPathCodeX86* slow_path = new (GetGraph()->GetArena())
+      DeoptimizationSlowPathX86(deoptimize);
+  codegen_->AddSlowPath(slow_path);
+  Label* slow_path_entry = slow_path->GetEntryLabel();
+  GenerateTestAndBranch(deoptimize, slow_path_entry, nullptr, slow_path_entry);
+}
+
 void LocationsBuilderX86::VisitLocal(HLocal* local) {
   local->SetLocations(nullptr);
 }
diff --git a/compiler/optimizing/code_generator_x86.h b/compiler/optimizing/code_generator_x86.h
index 6a4d42d..2a26c86 100644
--- a/compiler/optimizing/code_generator_x86.h
+++ b/compiler/optimizing/code_generator_x86.h
@@ -176,6 +176,10 @@
 
   void GenerateImplicitNullCheck(HNullCheck* instruction);
   void GenerateExplicitNullCheck(HNullCheck* instruction);
+  void GenerateTestAndBranch(HInstruction* instruction,
+                             Label* true_target,
+                             Label* false_target,
+                             Label* always_true_target);
 
   X86Assembler* const assembler_;
   CodeGeneratorX86* const codegen_;
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index ef60280..0c4c0b3 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -314,6 +314,27 @@
   DISALLOW_COPY_AND_ASSIGN(TypeCheckSlowPathX86_64);
 };
 
+class DeoptimizationSlowPathX86_64 : public SlowPathCodeX86_64 {
+ public:
+  explicit DeoptimizationSlowPathX86_64(HInstruction* instruction)
+      : instruction_(instruction) {}
+
+  void EmitNativeCode(CodeGenerator* codegen) OVERRIDE {
+    __ Bind(GetEntryLabel());
+    SaveLiveRegisters(codegen, instruction_->GetLocations());
+    __ gs()->call(
+        Address::Absolute(QUICK_ENTRYPOINT_OFFSET(kX86_64WordSize, pDeoptimize), true));
+    DCHECK(instruction_->IsDeoptimize());
+    HDeoptimize* deoptimize = instruction_->AsDeoptimize();
+    uint32_t dex_pc = deoptimize->GetDexPc();
+    codegen->RecordPcInfo(instruction_, dex_pc, this);
+  }
+
+ private:
+  HInstruction* const instruction_;
+  DISALLOW_COPY_AND_ASSIGN(DeoptimizationSlowPathX86_64);
+};
+
 #undef __
 #define __ reinterpret_cast<X86_64Assembler*>(GetAssembler())->
 
@@ -734,24 +755,17 @@
   UNUSED(exit);
 }
 
-void LocationsBuilderX86_64::VisitIf(HIf* if_instr) {
-  LocationSummary* locations =
-      new (GetGraph()->GetArena()) LocationSummary(if_instr, LocationSummary::kNoCall);
-  HInstruction* cond = if_instr->InputAt(0);
-  if (!cond->IsCondition() || cond->AsCondition()->NeedsMaterialization()) {
-    locations->SetInAt(0, Location::Any());
-  }
-}
-
-void InstructionCodeGeneratorX86_64::VisitIf(HIf* if_instr) {
-  HInstruction* cond = if_instr->InputAt(0);
+void InstructionCodeGeneratorX86_64::GenerateTestAndBranch(HInstruction* instruction,
+                                                           Label* true_target,
+                                                           Label* false_target,
+                                                           Label* always_true_target) {
+  HInstruction* cond = instruction->InputAt(0);
   if (cond->IsIntConstant()) {
     // Constant condition, statically compared against 1.
     int32_t cond_value = cond->AsIntConstant()->GetValue();
     if (cond_value == 1) {
-      if (!codegen_->GoesToNextBlock(if_instr->GetBlock(),
-                                     if_instr->IfTrueSuccessor())) {
-        __ jmp(codegen_->GetLabelOf(if_instr->IfTrueSuccessor()));
+      if (always_true_target != nullptr) {
+        __ jmp(always_true_target);
       }
       return;
     } else {
@@ -764,21 +778,20 @@
     // evaluated just before the if, we don't need to evaluate it
     // again.
     bool eflags_set = cond->IsCondition()
-        && cond->AsCondition()->IsBeforeWhenDisregardMoves(if_instr);
+        && cond->AsCondition()->IsBeforeWhenDisregardMoves(instruction);
     if (materialized) {
       if (!eflags_set) {
         // Materialized condition, compare against 0.
-        Location lhs = if_instr->GetLocations()->InAt(0);
+        Location lhs = instruction->GetLocations()->InAt(0);
         if (lhs.IsRegister()) {
           __ testl(lhs.AsRegister<CpuRegister>(), lhs.AsRegister<CpuRegister>());
         } else {
           __ cmpl(Address(CpuRegister(RSP), lhs.GetStackIndex()),
                   Immediate(0));
         }
-        __ j(kNotEqual, codegen_->GetLabelOf(if_instr->IfTrueSuccessor()));
+        __ j(kNotEqual, true_target);
       } else {
-        __ j(X86_64Condition(cond->AsCondition()->GetCondition()),
-             codegen_->GetLabelOf(if_instr->IfTrueSuccessor()));
+        __ j(X86_64Condition(cond->AsCondition()->GetCondition()), true_target);
       }
     } else {
       Location lhs = cond->GetLocations()->InAt(0);
@@ -796,16 +809,56 @@
         __ cmpl(lhs.AsRegister<CpuRegister>(),
                 Address(CpuRegister(RSP), rhs.GetStackIndex()));
       }
-      __ j(X86_64Condition(cond->AsCondition()->GetCondition()),
-           codegen_->GetLabelOf(if_instr->IfTrueSuccessor()));
+      __ j(X86_64Condition(cond->AsCondition()->GetCondition()), true_target);
     }
   }
-  if (!codegen_->GoesToNextBlock(if_instr->GetBlock(),
-                                 if_instr->IfFalseSuccessor())) {
-    __ jmp(codegen_->GetLabelOf(if_instr->IfFalseSuccessor()));
+  if (false_target != nullptr) {
+    __ jmp(false_target);
   }
 }
 
+void LocationsBuilderX86_64::VisitIf(HIf* if_instr) {
+  LocationSummary* locations =
+      new (GetGraph()->GetArena()) LocationSummary(if_instr, LocationSummary::kNoCall);
+  HInstruction* cond = if_instr->InputAt(0);
+  if (!cond->IsCondition() || cond->AsCondition()->NeedsMaterialization()) {
+    locations->SetInAt(0, Location::Any());
+  }
+}
+
+void InstructionCodeGeneratorX86_64::VisitIf(HIf* if_instr) {
+  Label* true_target = codegen_->GetLabelOf(if_instr->IfTrueSuccessor());
+  Label* false_target = codegen_->GetLabelOf(if_instr->IfFalseSuccessor());
+  Label* always_true_target = true_target;
+  if (codegen_->GoesToNextBlock(if_instr->GetBlock(),
+                                if_instr->IfTrueSuccessor())) {
+    always_true_target = nullptr;
+  }
+  if (codegen_->GoesToNextBlock(if_instr->GetBlock(),
+                                if_instr->IfFalseSuccessor())) {
+    false_target = nullptr;
+  }
+  GenerateTestAndBranch(if_instr, true_target, false_target, always_true_target);
+}
+
+void LocationsBuilderX86_64::VisitDeoptimize(HDeoptimize* deoptimize) {
+  LocationSummary* locations = new (GetGraph()->GetArena())
+      LocationSummary(deoptimize, LocationSummary::kCallOnSlowPath);
+  HInstruction* cond = deoptimize->InputAt(0);
+  DCHECK(cond->IsCondition());
+  if (cond->AsCondition()->NeedsMaterialization()) {
+    locations->SetInAt(0, Location::Any());
+  }
+}
+
+void InstructionCodeGeneratorX86_64::VisitDeoptimize(HDeoptimize* deoptimize) {
+  SlowPathCodeX86_64* slow_path = new (GetGraph()->GetArena())
+      DeoptimizationSlowPathX86_64(deoptimize);
+  codegen_->AddSlowPath(slow_path);
+  Label* slow_path_entry = slow_path->GetEntryLabel();
+  GenerateTestAndBranch(deoptimize, slow_path_entry, nullptr, slow_path_entry);
+}
+
 void LocationsBuilderX86_64::VisitLocal(HLocal* local) {
   local->SetLocations(nullptr);
 }
diff --git a/compiler/optimizing/code_generator_x86_64.h b/compiler/optimizing/code_generator_x86_64.h
index a380b6a..4b8f087 100644
--- a/compiler/optimizing/code_generator_x86_64.h
+++ b/compiler/optimizing/code_generator_x86_64.h
@@ -182,6 +182,10 @@
   void GenerateExplicitNullCheck(HNullCheck* instruction);
   void PushOntoFPStack(Location source, uint32_t temp_offset,
                        uint32_t stack_adjustment, bool is_float);
+  void GenerateTestAndBranch(HInstruction* instruction,
+                             Label* true_target,
+                             Label* false_target,
+                             Label* always_true_target);
 
   X86_64Assembler* const assembler_;
   CodeGeneratorX86_64* const codegen_;
diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index dca612e..d8a8554 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -752,8 +752,8 @@
   }
 }
 
-bool HCondition::IsBeforeWhenDisregardMoves(HIf* if_) const {
-  return this == if_->GetPreviousDisregardingMoves();
+bool HCondition::IsBeforeWhenDisregardMoves(HInstruction* instruction) const {
+  return this == instruction->GetPreviousDisregardingMoves();
 }
 
 bool HInstruction::Equals(HInstruction* other) const {
diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 21ed350..c73d8cc 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -682,6 +682,7 @@
   M(ClinitCheck, Instruction)                                           \
   M(Compare, BinaryOperation)                                           \
   M(Condition, BinaryOperation)                                         \
+  M(Deoptimize, Instruction)                                            \
   M(Div, BinaryOperation)                                               \
   M(DivZeroCheck, Instruction)                                          \
   M(DoubleConstant, Constant)                                           \
@@ -1544,12 +1545,31 @@
 
   DECLARE_INSTRUCTION(If);
 
-  virtual bool IsIfInstruction() const { return true; }
-
  private:
   DISALLOW_COPY_AND_ASSIGN(HIf);
 };
 
+// Deoptimize to interpreter, upon checking a condition.
+class HDeoptimize : public HTemplateInstruction<1> {
+ public:
+  HDeoptimize(HInstruction* cond, uint32_t dex_pc)
+      : HTemplateInstruction(SideEffects::None()),
+        dex_pc_(dex_pc) {
+    SetRawInputAt(0, cond);
+  }
+
+  bool NeedsEnvironment() const OVERRIDE { return true; }
+  bool CanThrow() const OVERRIDE { return true; }
+  uint32_t GetDexPc() const { return dex_pc_; }
+
+  DECLARE_INSTRUCTION(Deoptimize);
+
+ private:
+  uint32_t dex_pc_;
+
+  DISALLOW_COPY_AND_ASSIGN(HDeoptimize);
+};
+
 class HUnaryOperation : public HExpression<1> {
  public:
   HUnaryOperation(Primitive::Type result_type, HInstruction* input)
@@ -1667,8 +1687,8 @@
   void ClearNeedsMaterialization() { needs_materialization_ = false; }
 
   // For code generation purposes, returns whether this instruction is just before
-  // `if_`, and disregard moves in between.
-  bool IsBeforeWhenDisregardMoves(HIf* if_) const;
+  // `instruction`, and disregard moves in between.
+  bool IsBeforeWhenDisregardMoves(HInstruction* instruction) const;
 
   DECLARE_INSTRUCTION(Condition);
 
diff --git a/compiler/optimizing/prepare_for_register_allocation.cc b/compiler/optimizing/prepare_for_register_allocation.cc
index 0161984..f5d8d82 100644
--- a/compiler/optimizing/prepare_for_register_allocation.cc
+++ b/compiler/optimizing/prepare_for_register_allocation.cc
@@ -64,7 +64,7 @@
     needs_materialization = true;
   } else {
     HInstruction* user = condition->GetUses().GetFirst()->GetUser();
-    if (!user->IsIf()) {
+    if (!user->IsIf() && !user->IsDeoptimize()) {
       needs_materialization = true;
     } else {
       // TODO: if there is no intervening instructions with side-effect between this condition