Reland of [ignition/turbo] Perform liveness analysis on the bytecodes

src/compiler/bytecode-graph-builder.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/bytecode-graph-builder.h"
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/compilation-info.h"
 #include "src/compiler/compiler-source-position-table.h"
@@ skipping 17 matching lines @@
   // Specifies whether environment binding methods should attach frame state
   // inputs to nodes representing the value being bound. This is done because
   // the {OutputFrameStateCombine} is closely related to the binding method.
   enum FrameStateAttachmentMode { kAttachFrameState, kDontAttachFrameState };
 
   int parameter_count() const { return parameter_count_; }
   int register_count() const { return register_count_; }
 
   Node* LookupAccumulator() const;
   Node* LookupRegister(interpreter::Register the_register) const;
-  void MarkAllRegistersLive();
 
   void BindAccumulator(Node* node,
                        FrameStateAttachmentMode mode = kDontAttachFrameState);
   void BindRegister(interpreter::Register the_register, Node* node,
                     FrameStateAttachmentMode mode = kDontAttachFrameState);
   void BindRegistersToProjections(
       interpreter::Register first_reg, Node* node,
       FrameStateAttachmentMode mode = kDontAttachFrameState);
   void RecordAfterState(Node* node,
                         FrameStateAttachmentMode mode = kDontAttachFrameState);
 
   // Effect dependency tracked by this environment.
   Node* GetEffectDependency() { return effect_dependency_; }
   void UpdateEffectDependency(Node* dependency) {
     effect_dependency_ = dependency;
   }
 
   // Preserve a checkpoint of the environment for the IR graph. Any
   // further mutation of the environment will not affect checkpoints.
   Node* Checkpoint(BailoutId bytecode_offset, OutputFrameStateCombine combine,
-                   bool owner_has_exception);
+                   bool owner_has_exception, const BitVector* liveness);
 
   // Control dependency tracked by this environment.
   Node* GetControlDependency() const { return control_dependency_; }
   void UpdateControlDependency(Node* dependency) {
     control_dependency_ = dependency;
   }
 
   Node* Context() const { return context_; }
   void SetContext(Node* new_context) { context_ = new_context; }
 
   Environment* CopyForConditional();
   Environment* CopyForLoop();
   Environment* CopyForOsrEntry();
   void Merge(Environment* other);
   void PrepareForOsrEntry();
 
   void PrepareForLoopExit(Node* loop);
 
  private:
-  Environment(const Environment* copy, LivenessAnalyzerBlock* liveness_block);
+  explicit Environment(const Environment* copy);
   void PrepareForLoop();
 
-  bool StateValuesRequireUpdate(Node** state_values, int offset, int count);
-  void UpdateStateValues(Node** state_values, int offset, int count);
+  bool StateValuesRequireUpdate(Node** state_values, Node** values, int count);
+  void UpdateStateValues(Node** state_values, Node** values, int count);
+  void UpdateStateValuesWithCache(Node** state_values, Node** values,
+                                  int count);
 
   int RegisterToValuesIndex(interpreter::Register the_register) const;
 
-  bool IsLivenessBlockConsistent() const;
-
   Zone* zone() const { return builder_->local_zone(); }
   Graph* graph() const { return builder_->graph(); }
   CommonOperatorBuilder* common() const { return builder_->common(); }
   BytecodeGraphBuilder* builder() const { return builder_; }
-  LivenessAnalyzerBlock* liveness_block() const { return liveness_block_; }
   const NodeVector* values() const { return &values_; }
   NodeVector* values() { return &values_; }
   int register_base() const { return register_base_; }
   int accumulator_base() const { return accumulator_base_; }
 
   BytecodeGraphBuilder* builder_;
   int register_count_;
   int parameter_count_;
-  LivenessAnalyzerBlock* liveness_block_;
   Node* context_;
   Node* control_dependency_;
   Node* effect_dependency_;
   NodeVector values_;
   Node* parameters_state_values_;
   Node* registers_state_values_;
   Node* accumulator_state_values_;
   int register_base_;
   int accumulator_base_;
+
+  NodeVector tmp_values_;

[Jarin, 2016/11/24 12:47:17]

Nit: Could we give this a more descriptive name (checkpoint_values_buffer_ or
some such) or describe in a comment what this is about?

[Leszek Swirski, 2016/11/25 17:31:27]

Done.

 };
 
 
 // Issues:
 // - Scopes - intimately tied to AST. Need to eval what is needed.
 // - Need to resolve closure parameter treatment.
 BytecodeGraphBuilder::Environment::Environment(BytecodeGraphBuilder* builder,
                                                int register_count,
                                                int parameter_count,
                                                Node* control_dependency,
                                                Node* context)
     : builder_(builder),
       register_count_(register_count),
       parameter_count_(parameter_count),
-      liveness_block_(builder->is_liveness_analysis_enabled_
-                          ? builder_->liveness_analyzer()->NewBlock()
-                          : nullptr),
       context_(context),
       control_dependency_(control_dependency),
       effect_dependency_(control_dependency),
       values_(builder->local_zone()),
       parameters_state_values_(nullptr),
       registers_state_values_(nullptr),
-      accumulator_state_values_(nullptr) {
+      accumulator_state_values_(nullptr),
+      tmp_values_(builder->local_zone()) {
   // The layout of values_ is:
   //
   // [receiver] [parameters] [registers] [accumulator]
   //
   // parameter[0] is the receiver (this), parameters 1..N are the
   // parameters supplied to the method (arg0..argN-1). The accumulator
   // is stored separately.
 
   // Parameters including the receiver
   for (int i = 0; i < parameter_count; i++) {
     const char* debug_name = (i == 0) ? "%this" : nullptr;
     const Operator* op = common()->Parameter(i, debug_name);
     Node* parameter = builder->graph()->NewNode(op, graph()->start());
     values()->push_back(parameter);
   }
 
   // Registers
   register_base_ = static_cast<int>(values()->size());
   Node* undefined_constant = builder->jsgraph()->UndefinedConstant();
   values()->insert(values()->end(), register_count, undefined_constant);
 
   // Accumulator
   accumulator_base_ = static_cast<int>(values()->size());
   values()->push_back(undefined_constant);
+
+  tmp_values_.resize(register_count_);
 }
 
 BytecodeGraphBuilder::Environment::Environment(
-    const BytecodeGraphBuilder::Environment* other,
-    LivenessAnalyzerBlock* liveness_block)
+    const BytecodeGraphBuilder::Environment* other)
     : builder_(other->builder_),
       register_count_(other->register_count_),
       parameter_count_(other->parameter_count_),
-      liveness_block_(liveness_block),
       context_(other->context_),
       control_dependency_(other->control_dependency_),
       effect_dependency_(other->effect_dependency_),
       values_(other->zone()),
       parameters_state_values_(nullptr),
       registers_state_values_(nullptr),
       accumulator_state_values_(nullptr),
       register_base_(other->register_base_),
-      accumulator_base_(other->accumulator_base_) {
+      accumulator_base_(other->accumulator_base_),
+      tmp_values_(other->zone()) {
   values_ = other->values_;
+  tmp_values_.resize(register_count_);
 }
 
 
 int BytecodeGraphBuilder::Environment::RegisterToValuesIndex(
     interpreter::Register the_register) const {
   if (the_register.is_parameter()) {
     return the_register.ToParameterIndex(parameter_count());
   } else {
     return the_register.index() + register_base();
   }
 }
 
-bool BytecodeGraphBuilder::Environment::IsLivenessBlockConsistent() const {
-  return !builder_->IsLivenessAnalysisEnabled() ==
-         (liveness_block() == nullptr);
-}
-
 Node* BytecodeGraphBuilder::Environment::LookupAccumulator() const {
-  DCHECK(IsLivenessBlockConsistent());
-  if (liveness_block() != nullptr) {
-    liveness_block()->LookupAccumulator();
-  }
   return values()->at(accumulator_base_);
 }
 
 
 Node* BytecodeGraphBuilder::Environment::LookupRegister(
     interpreter::Register the_register) const {
   if (the_register.is_current_context()) {
     return Context();
   } else if (the_register.is_function_closure()) {
     return builder()->GetFunctionClosure();
   } else if (the_register.is_new_target()) {
     return builder()->GetNewTarget();
   } else {
     int values_index = RegisterToValuesIndex(the_register);
-    if (liveness_block() != nullptr && !the_register.is_parameter()) {
-      DCHECK(IsLivenessBlockConsistent());
-      liveness_block()->Lookup(the_register.index());
-    }
     return values()->at(values_index);
   }
 }
 
-void BytecodeGraphBuilder::Environment::MarkAllRegistersLive() {
-  DCHECK(IsLivenessBlockConsistent());
-  if (liveness_block() != nullptr) {
-    for (int i = 0; i < register_count(); ++i) {
-      liveness_block()->Lookup(i);
-    }
-  }
-}
-
 void BytecodeGraphBuilder::Environment::BindAccumulator(
     Node* node, FrameStateAttachmentMode mode) {
   if (mode == FrameStateAttachmentMode::kAttachFrameState) {
     builder()->PrepareFrameState(node, OutputFrameStateCombine::PokeAt(0));
   }
-  DCHECK(IsLivenessBlockConsistent());
-  if (liveness_block() != nullptr) {
-    liveness_block()->BindAccumulator();
-  }
   values()->at(accumulator_base_) = node;
 }
 
 void BytecodeGraphBuilder::Environment::BindRegister(
     interpreter::Register the_register, Node* node,
     FrameStateAttachmentMode mode) {
   int values_index = RegisterToValuesIndex(the_register);
   if (mode == FrameStateAttachmentMode::kAttachFrameState) {
     builder()->PrepareFrameState(node, OutputFrameStateCombine::PokeAt(
                                            accumulator_base_ - values_index));
   }
   values()->at(values_index) = node;
-  if (liveness_block() != nullptr && !the_register.is_parameter()) {
-    DCHECK(IsLivenessBlockConsistent());
-    liveness_block()->Bind(the_register.index());
-  }
 }
 
 void BytecodeGraphBuilder::Environment::BindRegistersToProjections(
     interpreter::Register first_reg, Node* node,
     FrameStateAttachmentMode mode) {
   int values_index = RegisterToValuesIndex(first_reg);
   if (mode == FrameStateAttachmentMode::kAttachFrameState) {
     builder()->PrepareFrameState(node, OutputFrameStateCombine::PokeAt(
                                            accumulator_base_ - values_index));
   }
   for (int i = 0; i < node->op()->ValueOutputCount(); i++) {
     values()->at(values_index + i) =
         builder()->NewNode(common()->Projection(i), node);
   }
 }
 
 void BytecodeGraphBuilder::Environment::RecordAfterState(
     Node* node, FrameStateAttachmentMode mode) {
   if (mode == FrameStateAttachmentMode::kAttachFrameState) {
     builder()->PrepareFrameState(node, OutputFrameStateCombine::Ignore());
   }
 }
 
 
 BytecodeGraphBuilder::Environment*
 BytecodeGraphBuilder::Environment::CopyForLoop() {
   PrepareForLoop();
-  if (liveness_block() != nullptr) {
-    // Finish the current block before copying.
-    liveness_block_ = builder_->liveness_analyzer()->NewBlock(liveness_block());
-  }
-  return new (zone()) Environment(this, liveness_block());
+  return new (zone()) Environment(this);
 }
 
 BytecodeGraphBuilder::Environment*
 BytecodeGraphBuilder::Environment::CopyForOsrEntry() {
-  return new (zone())
-      Environment(this, builder_->liveness_analyzer()->NewBlock());
+  return new (zone()) Environment(this);
 }
 
 BytecodeGraphBuilder::Environment*
 BytecodeGraphBuilder::Environment::CopyForConditional() {
-  LivenessAnalyzerBlock* copy_liveness_block = nullptr;
-  if (liveness_block() != nullptr) {
-    copy_liveness_block =
-        builder_->liveness_analyzer()->NewBlock(liveness_block());
-    liveness_block_ = builder_->liveness_analyzer()->NewBlock(liveness_block());
-  }
-  return new (zone()) Environment(this, copy_liveness_block);
+  return new (zone()) Environment(this);
 }
 
 
 void BytecodeGraphBuilder::Environment::Merge(
     BytecodeGraphBuilder::Environment* other) {
-  if (builder_->is_liveness_analysis_enabled_) {
-    if (GetControlDependency()->opcode() != IrOpcode::kLoop) {
-      liveness_block_ =
-          builder()->liveness_analyzer()->NewBlock(liveness_block());
-    }
-    liveness_block()->AddPredecessor(other->liveness_block());
-  }
-
   // Create a merge of the control dependencies of both environments and update
   // the current environment's control dependency accordingly.
   Node* control = builder()->MergeControl(GetControlDependency(),
                                           other->GetControlDependency());
   UpdateControlDependency(control);
 
   // Create a merge of the effect dependencies of both environments and update
   // the current environment's effect dependency accordingly.
   Node* effect = builder()->MergeEffect(GetEffectDependency(),
                                         other->GetEffectDependency(), control);
@@ skipping 47 matching lines @@
   int size = static_cast<int>(values()->size());
   for (int i = 0; i < size; i++) {
     int idx = i;  // Indexing scheme follows {StandardFrame}, adapt accordingly.
     if (i >= register_base()) idx += InterpreterFrameConstants::kExtraSlotCount;
     if (i >= accumulator_base()) idx = Linkage::kOsrAccumulatorRegisterIndex;
     values()->at(i) = graph()->NewNode(common()->OsrValue(idx), entry);
   }
 
   BailoutId loop_id(builder_->bytecode_iterator().current_offset());
   Node* frame_state =
-      Checkpoint(loop_id, OutputFrameStateCombine::Ignore(), false);
+      Checkpoint(loop_id, OutputFrameStateCombine::Ignore(), false, nullptr);
   Node* checkpoint =
       graph()->NewNode(common()->Checkpoint(), frame_state, entry, entry);
   UpdateEffectDependency(checkpoint);
 
   // Create the OSR guard nodes.
   const Operator* guard_op = common()->OsrGuard(OsrGuardType::kUninitialized);
   Node* effect = checkpoint;
   for (int i = 0; i < size; i++) {
     values()->at(i) = effect =
         graph()->NewNode(guard_op, values()->at(i), effect, entry);
   }
   Node* context = effect = graph()->NewNode(guard_op, Context(), effect, entry);
   SetContext(context);
   UpdateEffectDependency(effect);
 }
 
 bool BytecodeGraphBuilder::Environment::StateValuesRequireUpdate(
-    Node** state_values, int offset, int count) {
+    Node** state_values, Node** values, int count) {
   if (*state_values == nullptr) {
     return true;
   }
   DCHECK_EQ((*state_values)->InputCount(), count);
-  DCHECK_LE(static_cast<size_t>(offset + count), values()->size());
-  Node** env_values = (count == 0) ? nullptr : &values()->at(offset);
   for (int i = 0; i < count; i++) {
-    if ((*state_values)->InputAt(i) != env_values[i]) {
+    if ((*state_values)->InputAt(i) != values[i]) {
       return true;
     }
   }
   return false;
 }
 
 void BytecodeGraphBuilder::Environment::PrepareForLoopExit(Node* loop) {
   DCHECK_EQ(loop->opcode(), IrOpcode::kLoop);
 
   Node* control = GetControlDependency();
@@ skipping 13 matching lines @@
 
   // Rename the environmnent values.
   for (size_t i = 0; i < values_.size(); i++) {
     Node* rename =
         graph()->NewNode(common()->LoopExitValue(), values_[i], loop_exit);
     values_[i] = rename;
   }
 }
 
 void BytecodeGraphBuilder::Environment::UpdateStateValues(Node** state_values,
-                                                          int offset,
+                                                          Node** values,
                                                           int count) {
-  if (StateValuesRequireUpdate(state_values, offset, count)) {
+  if (StateValuesRequireUpdate(state_values, values, count)) {
     const Operator* op = common()->StateValues(count);
-    (*state_values) = graph()->NewNode(op, count, &values()->at(offset));
+    (*state_values) = graph()->NewNode(op, count, values);
   }
 }
 
+void BytecodeGraphBuilder::Environment::UpdateStateValuesWithCache(
+    Node** state_values, Node** values, int count) {
+  *state_values = builder_->state_values_cache_.GetNodeForValues(
+      values, static_cast<size_t>(count));
+}
+
 Node* BytecodeGraphBuilder::Environment::Checkpoint(
     BailoutId bailout_id, OutputFrameStateCombine combine,
-    bool owner_has_exception) {
-  UpdateStateValues(&parameters_state_values_, 0, parameter_count());
-  UpdateStateValues(&registers_state_values_, register_base(),
-                    register_count());
-  UpdateStateValues(&accumulator_state_values_, accumulator_base(), 1);
+    bool owner_has_exception, const BitVector* liveness) {
+  UpdateStateValues(&parameters_state_values_, &values()->at(0),
+                    parameter_count());
+
+  if (liveness) {
+    Node* optimized_out = builder()->jsgraph()->OptimizedOutConstant();
+
+    for (int i = 0; i < register_count(); ++i) {
+      tmp_values_[i] = liveness->Contains(i) ? values()->at(register_base() + i)
+                                             : optimized_out;
+    }
+
+    Node* accumulator_value = liveness->Contains(register_count())
+                                  ? values()->at(accumulator_base())
+                                  : optimized_out;
+
+    UpdateStateValuesWithCache(&registers_state_values_, tmp_values_.data(),
+                               register_count());
+
+    UpdateStateValues(&accumulator_state_values_, &accumulator_value, 1);
+  } else {
+    UpdateStateValuesWithCache(&registers_state_values_,
+                               &values()->at(register_base()),
+                               register_count());
+    UpdateStateValues(&accumulator_state_values_,
+                      &values()->at(accumulator_base()), 1);
+  }
+
+  // PrintF("liveness: ");
+  // for (int i = 0; i < liveness->length(); ++i) {
+  //   if (liveness && !liveness->Contains(i)) {
+  //     PrintF(".");
+  //   } else {
+  //     PrintF("L");
+  //   }
+  // }
+  // PrintF("\n");
+
+  // PrintF("stv live: ");
+  // for (const auto& node : StateValuesAccess(registers_state_values_)) {
+  //   if (node.node == builder()->jsgraph()->OptimizedOutConstant()) {
+  //     PrintF(".");
+  //   } else {
+  //     PrintF("L");
+  //   }
+  // }
+  // for (const auto& node : StateValuesAccess(accumulator_state_values_)) {
+  //   if (node.node == builder()->jsgraph()->OptimizedOutConstant()) {
+  //     PrintF(".");
+  //   } else {
+  //     PrintF("L");
+  //   }
+  // }
+  // PrintF("\n");
 
   const Operator* op = common()->FrameState(
       bailout_id, combine, builder()->frame_state_function_info());
   Node* result = graph()->NewNode(
       op, parameters_state_values_, registers_state_values_,
       accumulator_state_values_, Context(), builder()->GetFunctionClosure(),
       builder()->graph()->start());
 
-  if (liveness_block() != nullptr) {
-    // If the owning node has an exception, register the checkpoint to the
-    // predecessor so that the checkpoint is used for both the normal and the
-    // exceptional paths. Yes, this is a terrible hack and we might want
-    // to use an explicit frame state for the exceptional path.
-    if (owner_has_exception) {
-      liveness_block()->GetPredecessor()->Checkpoint(result);
-    } else {
-      liveness_block()->Checkpoint(result);
-    }
-  }
-
   return result;
 }
 
 BytecodeGraphBuilder::BytecodeGraphBuilder(
     Zone* local_zone, CompilationInfo* info, JSGraph* jsgraph,
     float invocation_frequency, SourcePositionTable* source_positions,
     int inlining_id)
     : local_zone_(local_zone),
       jsgraph_(jsgraph),
       invocation_frequency_(invocation_frequency),
       bytecode_array_(handle(info->shared_info()->bytecode_array())),
       exception_handler_table_(
           handle(HandlerTable::cast(bytecode_array()->handler_table()))),
       feedback_vector_(handle(info->closure()->feedback_vector())),
       frame_state_function_info_(common()->CreateFrameStateFunctionInfo(
           FrameStateType::kInterpretedFunction,
           bytecode_array()->parameter_count(),
           bytecode_array()->register_count(), info->shared_info())),
       osr_ast_id_(info->osr_ast_id()),
       merge_environments_(local_zone),
       exception_handlers_(local_zone),
       current_exception_handler_(0),
       input_buffer_size_(0),
       input_buffer_(nullptr),
       exit_controls_(local_zone),
       is_liveness_analysis_enabled_(FLAG_analyze_environment_liveness &&
                                     info->is_deoptimization_enabled()),
       state_values_cache_(jsgraph),
-      liveness_analyzer_(
-          static_cast<size_t>(bytecode_array()->register_count()), true,
-          local_zone),
       source_positions_(source_positions),
       start_position_(info->shared_info()->start_position(), inlining_id) {}
 
 Node* BytecodeGraphBuilder::GetNewTarget() {
   if (!new_target_.is_set()) {
     int params = bytecode_array()->parameter_count();
     int index = Linkage::GetJSCallNewTargetParamIndex(params);
     const Operator* op = common()->Parameter(index, "%new.target");
     Node* node = NewNode(op, graph()->start());
     new_target_.set(node);
@@ skipping 57 matching lines @@
 
   VisitBytecodes(stack_check);
 
   // Finish the basic structure of the graph.
   DCHECK_NE(0u, exit_controls_.size());
   int const input_count = static_cast<int>(exit_controls_.size());
   Node** const inputs = &exit_controls_.front();
   Node* end = graph()->NewNode(common()->End(input_count), input_count, inputs);
   graph()->SetEnd(end);
 
-  ClearNonLiveSlotsInFrameStates();
-
   return true;
 }
 
 void BytecodeGraphBuilder::PrepareEagerCheckpoint() {
   if (environment()->GetEffectDependency()->opcode() != IrOpcode::kCheckpoint) {
     // Create an explicit checkpoint node for before the operation. This only
     // needs to happen if we aren't effect-dominated by a {Checkpoint} already.
     Node* node = NewNode(common()->Checkpoint());
     DCHECK_EQ(1, OperatorProperties::GetFrameStateInputCount(node->op()));
     DCHECK_EQ(IrOpcode::kDead,
               NodeProperties::GetFrameStateInput(node)->opcode());
     BailoutId bailout_id(bytecode_iterator().current_offset());
+
+    const BitVector* liveness_before = bytecode_analysis()->GetInLivenessFor(
+        bytecode_iterator().current_offset());
+
     Node* frame_state_before = environment()->Checkpoint(
-        bailout_id, OutputFrameStateCombine::Ignore(), false);
+        bailout_id, OutputFrameStateCombine::Ignore(), false, liveness_before);
     NodeProperties::ReplaceFrameStateInput(node, frame_state_before);
   }
 }
 
 void BytecodeGraphBuilder::PrepareFrameState(Node* node,
                                              OutputFrameStateCombine combine) {
   if (OperatorProperties::HasFrameStateInput(node->op())) {
     // Add the frame state for after the operation. The node in question has
     // already been created and had a {Dead} frame state input up until now.
     DCHECK_EQ(1, OperatorProperties::GetFrameStateInputCount(node->op()));
     DCHECK_EQ(IrOpcode::kDead,
               NodeProperties::GetFrameStateInput(node)->opcode());
     BailoutId bailout_id(bytecode_iterator().current_offset());
     bool has_exception = NodeProperties::IsExceptionalCall(node);
-    Node* frame_state_after =
-        environment()->Checkpoint(bailout_id, combine, has_exception);
+
+    const BitVector* liveness_after = bytecode_analysis()->GetOutLivenessFor(
+        bytecode_iterator().current_offset());
+
+    Node* frame_state_after = environment()->Checkpoint(
+        bailout_id, combine, has_exception, liveness_after);
     NodeProperties::ReplaceFrameStateInput(node, frame_state_after);
   }
 }
 
-void BytecodeGraphBuilder::ClearNonLiveSlotsInFrameStates() {
-  if (!IsLivenessAnalysisEnabled()) {
-    return;
-  }
-  NonLiveFrameStateSlotReplacer replacer(
-      &state_values_cache_, jsgraph()->OptimizedOutConstant(),
-      liveness_analyzer()->local_count(), true, local_zone());
-  liveness_analyzer()->Run(&replacer);
-  if (FLAG_trace_environment_liveness) {
-    OFStream os(stdout);
-    liveness_analyzer()->Print(os);
-  }
-}
-
 void BytecodeGraphBuilder::VisitBytecodes(bool stack_check) {
   BytecodeAnalysis bytecode_analysis(bytecode_array(), local_zone());
   bytecode_analysis.Analyze();
   set_bytecode_analysis(&bytecode_analysis);
 
   interpreter::BytecodeArrayIterator iterator(bytecode_array());
   set_bytecode_iterator(&iterator);
   SourcePositionTableIterator source_position_iterator(
       bytecode_array()->source_position_table());
 
+  if (FLAG_trace_environment_liveness) {
+    OFStream of(stdout);
+
+    interpreter::BytecodeArrayIterator trace_iterator(bytecode_array());
+
+    for (; !trace_iterator.done(); trace_iterator.Advance()) {
+      const BitVector* in_liveness =
+          bytecode_analysis.GetInLivenessFor(trace_iterator.current_offset());
+      for (int i = 0; i < in_liveness->length(); ++i) {
+        of << (in_liveness->Contains(i) ? "L" : ".");
+      }
+      of << " -> ";
+
+      const BitVector* out_liveness =
+          bytecode_analysis.GetOutLivenessFor(trace_iterator.current_offset());
+      for (int i = 0; i < out_liveness->length(); ++i) {
+        of << (out_liveness->Contains(i) ? "L" : ".");
+      }
+      of << " | " << trace_iterator.current_offset() << ": ";
+      trace_iterator.Output(of) << std::endl;
+    }
+  }
+
   BuildOSRNormalEntryPoint();
+  OFStream of(stdout);
+
   for (; !iterator.done(); iterator.Advance()) {
     int current_offset = iterator.current_offset();
     UpdateCurrentSourcePosition(&source_position_iterator, current_offset);
     EnterAndExitExceptionHandlers(current_offset);
     SwitchToMergeEnvironment(current_offset);
     if (environment() != nullptr) {
       BuildLoopHeaderEnvironment(current_offset);
       BuildOSRLoopEntryPoint(current_offset);
 
       // Skip the first stack check if stack_check is false
@@ skipping 1100 matching lines @@
   Node* control =
       NewNode(common()->Return(), pop_node, environment()->LookupAccumulator());
   MergeControlToLeaveFunction(control);
 }
 
 void BytecodeGraphBuilder::VisitDebugger() {
   PrepareEagerCheckpoint();
   Node* call =
       NewNode(javascript()->CallRuntime(Runtime::kHandleDebuggerStatement));
   environment()->BindAccumulator(call, Environment::kAttachFrameState);
-  environment()->MarkAllRegistersLive();
 }
 
 // We cannot create a graph from the debugger copy of the bytecode array.
 #define DEBUG_BREAK(Name, ...) \
   void BytecodeGraphBuilder::Visit##Name() { UNREACHABLE(); }
 DEBUG_BREAK_BYTECODE_LIST(DEBUG_BREAK);
 #undef DEBUG_BREAK
 
 void BytecodeGraphBuilder::BuildForInPrepare() {
   PrepareEagerCheckpoint();
@@ skipping 445 matching lines @@
         it->source_position().ScriptOffset(), start_position_.InliningId()));
     it->Advance();
   } else {
     DCHECK_GT(it->code_offset(), offset);
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8