[turbofan] Initial support for escape analysis.

src/compiler/escape-analysis.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/escape-analysis.h"
+
+#include "src/base/flags.h"
+#include "src/bootstrapper.h"
+#include "src/compilation-dependencies.h"
+#include "src/compiler/common-operator.h"
+#include "src/compiler/graph-reducer.h"
+#include "src/compiler/js-operator.h"
+#include "src/compiler/node.h"
+#include "src/compiler/node-matchers.h"
+#include "src/compiler/node-properties.h"
+#include "src/compiler/simplified-operator.h"
+#include "src/objects-inl.h"
+#include "src/type-cache.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+bool VirtualObject::UpdateFrom(const VirtualObject& other) {
+  bool changed = status_ != other.status_;
+  status_ = other.status_;
+  changed = replacement_ != other.replacement_ || changed;
+  replacement_ = other.replacement_;
+  if (fields_.size() != other.fields_.size()) {
+    fields_ = other.fields_;
+    return true;
+  }
+  for (size_t i = 0; i < fields_.size(); ++i) {
+    if (fields_[i] != other.fields_[i]) {
+      changed = true;
+      fields_[i] = other.fields_[i];
+    }
+  }
+  return changed;
+}
+
+
+VirtualState::VirtualState(Zone* zone, size_t size)
+    : info_(zone), last_changed_(nullptr) {
+  info_.resize(size);
+}
+
+
+VirtualState::VirtualState(const VirtualState& state)
+    : info_(state.info_.get_allocator().zone()),
+      last_changed_(state.last_changed_) {
+  info_.resize(state.info_.size());
+  for (size_t i = 0; i < state.info_.size(); ++i) {
+    if (state.info_[i] && state.info_[i]->id() == i) {
+      info_[i] = new (state.info_.get_allocator().zone())
+          VirtualObject(*state.info_[i]);
+    }
+  }
+  for (size_t i = 0; i < state.info_.size(); ++i) {
+    if (state.info_[i] && state.info_[i]->id() != i) {
+      info_[i] = info_[state.info_[i]->id()];
+    }
+  }
+}
+
+
+VirtualObject* VirtualState::GetVirtualObject(size_t id) { return info_[id]; }
+
+
+VirtualObject* VirtualState::GetVirtualObject(Node* node) {
+  return GetVirtualObject(node->id());
+}
+
+
+VirtualObject* VirtualState::GetOrCreateTrackedVirtualObject(NodeId id,
+                                                             Zone* zone) {
+  if (VirtualObject* obj = GetVirtualObject(id)) {
+    return obj;
+  }
+  VirtualObject* obj = new (zone) VirtualObject(id, zone, 0);
+  SetVirtualObject(id, obj);
+  return obj;
+}
+
+
+void VirtualState::SetVirtualObject(NodeId id, VirtualObject* obj) {
+  info_[id] = obj;
+}
+
+
+bool VirtualState::UpdateFrom(NodeId id, VirtualObject* fromObj, Zone* zone) {
+  VirtualObject* obj = GetVirtualObject(id);
+  if (!obj) {
+    obj = new (zone) VirtualObject(*fromObj);
+    SetVirtualObject(id, obj);
+    if (FLAG_trace_turbo_escape) {
+      PrintF("  Taking field for #%d from %p\n", id,
+             static_cast<void*>(fromObj));
+    }
+    return true;
+  }
+
+  if (obj->UpdateFrom(*fromObj)) {
+    if (FLAG_trace_turbo_escape) {
+      PrintF("  Updating field for #%d from %p\n", id,
+             static_cast<void*>(fromObj));
+    }
+    return true;
+  }
+
+  return false;
+}
+
+
+bool VirtualState::UpdateFrom(VirtualState* from, Zone* zone) {
+  DCHECK_EQ(size(), from->size());
+  bool changed = false;
+  for (NodeId id = 0; id < size(); ++id) {
+    VirtualObject* ls = GetVirtualObject(id);
+    VirtualObject* rs = from->GetVirtualObject(id);
+
+    if (rs == nullptr) {
+      continue;
+    }
+
+    if (ls == nullptr) {
+      ls = new (zone) VirtualObject(*rs);
+      SetVirtualObject(id, ls);
+      changed = true;
+      continue;
+    }
+
+    if (FLAG_trace_turbo_escape) {
+      PrintF("  Updating fields of #%d\n", id);
+    }
+
+    changed = ls->UpdateFrom(*rs) || changed;
+  }
+  return false;
+}
+
+
+bool VirtualState::MergeFrom(VirtualState* left, VirtualState* right,
+                             Zone* zone, Graph* graph,
+                             CommonOperatorBuilder* common, Node* control) {
+  bool changed = false;
+  for (NodeId id = 0; id < std::min(left->size(), right->size()); ++id) {
+    VirtualObject* ls = left->GetVirtualObject(id);
+    VirtualObject* rs = right->GetVirtualObject(id);
+
+    if (ls != nullptr && rs != nullptr) {
+      if (FLAG_trace_turbo_escape) {
+        PrintF("  Merging fields of #%d\n", id);
+      }
+      VirtualObject* mergeObject = GetOrCreateTrackedVirtualObject(id, zone);
+      size_t fields = std::max(ls->fields(), rs->fields());
+      changed = mergeObject->ResizeFields(fields) || changed;
+      for (size_t i = 0; i < fields; ++i) {
+        if (ls->GetField(i) == rs->GetField(i)) {
+          changed = mergeObject->SetField(i, ls->GetField(i)) || changed;
+          if (FLAG_trace_turbo_escape && ls->GetField(i)) {
+            PrintF("    Field %zu agree on rep #%d\n", i,
+                   ls->GetField(i)->id());
+          }
+        } else if (ls->GetField(i) != nullptr && rs->GetField(i) != nullptr) {
+          Node* phi = graph->NewNode(common->Phi(kMachAnyTagged, 2),
+                                     ls->GetField(i), rs->GetField(i), control);
+          if (mergeObject->SetField(i, phi)) {
+            if (FLAG_trace_turbo_escape) {
+              PrintF("    Creating Phi #%d as merge of #%d and #%d\n",
+                     phi->id(), ls->GetField(i)->id(), rs->GetField(i)->id());
+            }
+            changed = true;
+          }
+        } else {
+          changed = mergeObject->SetField(i, nullptr) || changed;
+        }
+      }
+    }
+  }
+  return changed;
+}
+
+
+Node* VirtualState::ResolveReplacement(Node* node) {
+  if (VirtualObject* obj = GetVirtualObject(node)) {
+    if (Node* rep = obj->GetReplacement()) {
+      return rep;
+    }
+  }
+  return node;
+}
+
+
+bool VirtualState::UpdateReplacement(Node* node, Node* rep, Zone* zone) {
+  if (!GetVirtualObject(node)) {
+    SetVirtualObject(node->id(), new (zone) VirtualObject(node->id(), zone));
+  }
+  if (GetVirtualObject(node)->SetReplacement(rep)) {
+    LastChangedAt(node);
+    if (FLAG_trace_turbo_escape) {
+      PrintF("Representation of #%d is #%d (%s)\n", node->id(), rep->id(),
+             rep->op()->mnemonic());
+    }
+    return true;
+  }
+  return false;
+}
+
+
+// ------------------------------EscapeStatusAnalysis---------------------------
+
+
+EscapeStatusAnalysis::EscapeStatusAnalysis(
+    EscapeObjectAnalysis* object_analysis, Graph* graph, Zone* zone)
+    : object_analysis_(object_analysis),
+      graph_(graph),
+      zone_(zone),
+      info_(zone),
+      queue_(zone) {}
+
+
+EscapeStatusAnalysis::~EscapeStatusAnalysis() {}
+
+
+bool EscapeStatusAnalysis::HasEntry(Node* node) {
+  return info_[node->id()] != kUnknown;
+}
+
+
+bool EscapeStatusAnalysis::IsVirtual(Node* node) {
+  if (node->id() >= info_.size()) {
+    return false;
+  }
+  return info_[node->id()] == kVirtual;
+}
+
+
+bool EscapeStatusAnalysis::IsEscaped(Node* node) {
+  return info_[node->id()] == kEscaped;
+}
+
+
+bool EscapeStatusAnalysis::SetEscaped(Node* node) {
+  bool changed = info_[node->id()] != kEscaped;
+  info_[node->id()] = kEscaped;
+  return changed;
+}
+
+
+void EscapeStatusAnalysis::Run() {
+  info_.resize(graph()->NodeCount());
+  ZoneVector<bool> visited(zone());
+  visited.resize(graph()->NodeCount());
+  queue_.push_back(graph()->end());
+  while (!queue_.empty()) {
+    Node* node = queue_.front();
+    queue_.pop_front();
+    Process(node);
+    if (!visited[node->id()]) {
+      RevisitInputs(node);
+    }
+    visited[node->id()] = true;
+  }
+  if (FLAG_trace_turbo_escape) {
+    DebugPrint();
+  }
+}
+
+
+void EscapeStatusAnalysis::RevisitInputs(Node* node) {
+  for (Edge edge : node->input_edges()) {
+    Node* input = edge.to();
+    queue_.push_back(input);
+  }
+}
+
+
+void EscapeStatusAnalysis::RevisitUses(Node* node) {
+  for (Edge edge : node->use_edges()) {
+    Node* use = edge.from();
+    queue_.push_back(use);
+  }
+}
+
+
+void EscapeStatusAnalysis::Process(Node* node) {
+  switch (node->opcode()) {
+    case IrOpcode::kAllocate:
+      ProcessAllocate(node);
+      break;
+    case IrOpcode::kFinishRegion:
+      ProcessFinishRegion(node);
+      break;
+    case IrOpcode::kStoreField:
+      ProcessStoreField(node);
+      break;
+    case IrOpcode::kLoadField: {
+      if (Node* rep = object_analysis_->GetReplacement(node, node->id())) {
+        if (rep->opcode() == IrOpcode::kAllocate ||
+            rep->opcode() == IrOpcode::kFinishRegion) {
+          if (CheckUsesForEscape(node, rep)) {
+            RevisitInputs(rep);
+            RevisitUses(rep);
+          }
+        }
+      }
+      break;
+    }
+    case IrOpcode::kPhi:
+      if (!HasEntry(node)) {
+        info_[node->id()] = kVirtual;
+      }
+      CheckUsesForEscape(node);
+    default:
+      break;
+  }
+}
+
+
+void EscapeStatusAnalysis::ProcessStoreField(Node* node) {
+  DCHECK_EQ(node->opcode(), IrOpcode::kStoreField);
+  Node* to = NodeProperties::GetValueInput(node, 0);
+  Node* val = NodeProperties::GetValueInput(node, 1);
+  if (IsEscaped(to) && SetEscaped(val)) {
+    RevisitUses(val);
+    if (FLAG_trace_turbo_escape) {
+      PrintF("Setting #%d (%s) to escaped because of store to field of #%d\n",
+             val->id(), val->op()->mnemonic(), to->id());
+    }
+  }
+}
+
+
+void EscapeStatusAnalysis::ProcessAllocate(Node* node) {
+  DCHECK_EQ(node->opcode(), IrOpcode::kAllocate);
+  if (!HasEntry(node)) {
+    info_[node->id()] = kVirtual;
+    if (FLAG_trace_turbo_escape) {
+      PrintF("Created status entry for node #%d (%s)\n", node->id(),
+             node->op()->mnemonic());
+    }
+    NumberMatcher size(node->InputAt(0));
+    if (!size.HasValue() && SetEscaped(node)) {
+      RevisitUses(node);
+      if (FLAG_trace_turbo_escape) {
+        PrintF("Setting #%d to escaped because of non-const alloc\n",
+               node->id());
+      }
+      // This node is known to escape, uses do not have to be checked.
+      return;
+    }
+  }
+  if (CheckUsesForEscape(node)) {
+    RevisitUses(node);
+  }
+}
+
+
+bool EscapeStatusAnalysis::CheckUsesForEscape(Node* uses, Node* rep) {
+  for (Edge edge : uses->use_edges()) {
+    Node* use = edge.from();
+    if (!NodeProperties::IsValueEdge(edge)) continue;
+    switch (use->opcode()) {
+      case IrOpcode::kStoreField:
+      case IrOpcode::kLoadField:
+      case IrOpcode::kFrameState:
+      case IrOpcode::kStateValues:
+      case IrOpcode::kReferenceEqual:
+      case IrOpcode::kFinishRegion:
+      case IrOpcode::kPhi:
+        if (HasEntry(use) && IsEscaped(use) && SetEscaped(rep)) {
+          if (FLAG_trace_turbo_escape) {
+            PrintF(
+                "Setting #%d (%s) to escaped because of use by escaping node "
+                "#%d (%s)\n",
+                rep->id(), rep->op()->mnemonic(), use->id(),
+                use->op()->mnemonic());
+          }
+          return true;
+        }
+        break;
+      default:
+        if (SetEscaped(rep)) {
+          if (FLAG_trace_turbo_escape) {
+            PrintF("Setting #%d (%s) to escaped because of use by #%d (%s)\n",
+                   rep->id(), rep->op()->mnemonic(), use->id(),
+                   use->op()->mnemonic());
+          }
+          return true;
+        }
+        if (use->op()->EffectInputCount() == 0 &&
+            uses->op()->EffectInputCount() > 0 &&
+            uses->opcode() != IrOpcode::kLoadField) {
+          if (FLAG_trace_turbo_escape) {
+            PrintF("Encountered unaccounted use by #%d (%s)\n", use->id(),
+                   use->op()->mnemonic());
+          }
+          UNREACHABLE();
+        }
+    }
+  }
+  return false;
+}
+
+
+void EscapeStatusAnalysis::ProcessFinishRegion(Node* node) {
+  DCHECK_EQ(node->opcode(), IrOpcode::kFinishRegion);
+  if (!HasEntry(node)) {
+    info_[node->id()] = kVirtual;
+    RevisitUses(node);
+  }
+  if (CheckUsesForEscape(node)) {
+    RevisitInputs(node);
+  }
+}
+
+
+void EscapeStatusAnalysis::DebugPrint() {
+  for (NodeId id = 0; id < info_.size(); id++) {
+    if (info_[id] != kUnknown) {
+      PrintF("Node #%d is %s\n", id,
+             info_[id] == kEscaped ? "escaping" : "virtual");
+    }
+  }
+}
+
+
+// -----------------------------EscapeObjectAnalysis---------------------------
+
+
+EscapeObjectAnalysis::EscapeObjectAnalysis(Graph* graph,
+                                           CommonOperatorBuilder* common,
+                                           Zone* zone)
+    : graph_(graph), common_(common), zone_(zone), virtual_states_(zone) {}
+
+
+EscapeObjectAnalysis::~EscapeObjectAnalysis() {}
+
+
+void EscapeObjectAnalysis::Run() {
+  virtual_states_.resize(graph()->NodeCount());
+  ZoneVector<Node*> queue(zone());
+  queue.push_back(graph()->start());
+  while (!queue.empty()) {
+    Node* node = queue.back();
+    queue.pop_back();
+    if (Process(node)) {
+      for (Edge edge : node->use_edges()) {
+        if (NodeProperties::IsEffectEdge(edge)) {
+          Node* use = edge.from();
+          if (use->opcode() != IrOpcode::kLoadField ||
+              !IsDanglingEffectNode(use)) {
+            queue.push_back(use);
+          }
+        }
+      }
+      // First process loads: dangling loads are a problem otherwise.
+      for (Edge edge : node->use_edges()) {
+        if (NodeProperties::IsEffectEdge(edge)) {
+          Node* use = edge.from();
+          if (use->opcode() == IrOpcode::kLoadField &&
+              IsDanglingEffectNode(use)) {
+            queue.push_back(use);
+          }
+        }
+      }
+    }
+  }
+  if (FLAG_trace_turbo_escape) {
+    DebugPrint();
+  }
+}
+
+
+bool EscapeObjectAnalysis::IsDanglingEffectNode(Node* node) {
+  if (node->op()->EffectInputCount() == 0) return false;
+  if (node->op()->EffectOutputCount() == 0) return false;
+  for (Edge edge : node->use_edges()) {
+    if (NodeProperties::IsEffectEdge(edge)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+
+bool EscapeObjectAnalysis::Process(Node* node) {
+  switch (node->opcode()) {
+    case IrOpcode::kAllocate:
+      ProcessAllocation(node);
+      break;
+    case IrOpcode::kBeginRegion:
+      ForwardVirtualState(node);
+      break;
+    case IrOpcode::kFinishRegion:
+      ProcessFinishRegion(node);
+      break;
+    case IrOpcode::kStoreField:
+      ProcessStoreField(node);
+      break;
+    case IrOpcode::kLoadField:
+      ProcessLoadField(node);
+      break;
+    case IrOpcode::kStart:
+      ProcessStart(node);
+      break;
+    case IrOpcode::kEffectPhi:
+      return ProcessEffectPhi(node);
+      break;
+    default:
+      if (node->op()->EffectInputCount() > 0) {
+        ForwardVirtualState(node);
+      }
+      break;
+  }
+  return true;
+}
+
+
+bool EscapeObjectAnalysis::IsEffectBranchPoint(Node* node) {
+  int count = 0;
+  for (Edge edge : node->use_edges()) {
+    Node* use = edge.from();
+    if (NodeProperties::IsEffectEdge(edge) &&
+        use->opcode() != IrOpcode::kLoadField) {
+      if (++count > 1) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+
+void EscapeObjectAnalysis::ForwardVirtualState(Node* node) {
+  DCHECK_EQ(node->op()->EffectInputCount(), 1);
+  if (node->opcode() != IrOpcode::kLoadField && IsDanglingEffectNode(node)) {
+    PrintF("Dangeling effect node: #%d (%s)\n", node->id(),
+           node->op()->mnemonic());
+    DCHECK(false);
+  }
+  Node* effect = NodeProperties::GetEffectInput(node);
+  // Break the cycle for effect phis.
+  if (effect->opcode() == IrOpcode::kEffectPhi) {
+    if (virtual_states_[effect->id()] == nullptr) {
+      virtual_states_[effect->id()] =
+          new (zone()) VirtualState(zone(), graph()->NodeCount());
+    }
+  }
+  DCHECK_NOT_NULL(virtual_states_[effect->id()]);
+  if (IsEffectBranchPoint(effect)) {
+    if (virtual_states_[node->id()]) return;
+    virtual_states_[node->id()] =
+        new (zone()) VirtualState(*virtual_states_[effect->id()]);
+    if (FLAG_trace_turbo_escape) {
+      PrintF("Copying object state %p from #%d (%s) to #%d (%s)\n",
+             static_cast<void*>(virtual_states_[effect->id()]), effect->id(),
+             effect->op()->mnemonic(), node->id(), node->op()->mnemonic());
+    }
+  } else {
+    virtual_states_[node->id()] = virtual_states_[effect->id()];
+    if (FLAG_trace_turbo_escape) {
+      PrintF("Forwarding object state %p from #%d (%s) to #%d (%s)\n",
+             static_cast<void*>(virtual_states_[effect->id()]), effect->id(),
+             effect->op()->mnemonic(), node->id(), node->op()->mnemonic());
+    }
+  }
+}
+
+
+void EscapeObjectAnalysis::ProcessStart(Node* node) {
+  DCHECK_EQ(node->opcode(), IrOpcode::kStart);
+  virtual_states_[node->id()] =
+      new (zone()) VirtualState(zone(), graph()->NodeCount());
+}
+
+
+bool EscapeObjectAnalysis::ProcessEffectPhi(Node* node) {
+  DCHECK_EQ(node->opcode(), IrOpcode::kEffectPhi);
+  // For now only support binary phis.
+  DCHECK_EQ(node->op()->EffectInputCount(), 2);
+  Node* left = NodeProperties::GetEffectInput(node, 0);
+  Node* right = NodeProperties::GetEffectInput(node, 1);
+  bool changed = false;
+
+  VirtualState* mergeState = virtual_states_[node->id()];
+  if (!mergeState) {
+    mergeState = new (zone()) VirtualState(zone(), graph()->NodeCount());
+    virtual_states_[node->id()] = mergeState;
+    changed = true;
+    if (FLAG_trace_turbo_escape) {
+      PrintF("Phi #%d got new states map %p.\n", node->id(),
+             static_cast<void*>(mergeState));
+    }
+  } else if (mergeState->GetLastChanged() != node) {
+    changed = true;
+  }
+
+  VirtualState* l = virtual_states_[left->id()];
+  VirtualState* r = virtual_states_[right->id()];
+
+  if (l == nullptr && r == nullptr) {
+    return changed;
+  }
+
+  if (FLAG_trace_turbo_escape) {
+    PrintF("At Phi #%d, merging states %p (from #%d) and %p (from #%d)\n",
+           node->id(), static_cast<void*>(l), left->id(), static_cast<void*>(r),
+           right->id());
+  }
+
+  if (r && l == nullptr) {
+    changed = mergeState->UpdateFrom(r, zone()) || changed;
+  } else if (l && r == nullptr) {
+    changed = mergeState->UpdateFrom(l, zone()) || changed;
+  } else {
+    changed = mergeState->MergeFrom(l, r, zone(), graph(), common(),
+                                    NodeProperties::GetControlInput(node)) ||
+              changed;
+  }
+  if (FLAG_trace_turbo_escape) {
+    PrintF("Merge %s the node.\n", changed ? "changed" : "did not change");
+  }
+  if (changed) {
+    mergeState->LastChangedAt(node);
+  }
+  return changed;
+}
+
+
+void EscapeObjectAnalysis::ProcessAllocation(Node* node) {
+  DCHECK_EQ(node->opcode(), IrOpcode::kAllocate);
+  ForwardVirtualState(node);
+
+  // Check if we have already processed this node.
+  if (virtual_states_[node->id()]->GetVirtualObject(node)) return;
+
+  NumberMatcher size(node->InputAt(0));
+  if (size.HasValue()) {
+    virtual_states_[node->id()]->SetVirtualObject(
+        node->id(), new (zone()) VirtualObject(node->id(), zone(),
+                                               size.Value() / kPointerSize));
+  } else {
+    virtual_states_[node->id()]->SetVirtualObject(
+        node->id(), new (zone()) VirtualObject(node->id(), zone()));
+  }
+  virtual_states_[node->id()]->LastChangedAt(node);
+}
+
+
+void EscapeObjectAnalysis::ProcessFinishRegion(Node* node) {
+  DCHECK_EQ(node->opcode(), IrOpcode::kFinishRegion);
+  ForwardVirtualState(node);
+  Node* allocation = NodeProperties::GetValueInput(node, 0);
+  if (allocation->opcode() == IrOpcode::kAllocate) {
+    VirtualState* states = virtual_states_[node->id()];
+    DCHECK_NOT_NULL(states->GetVirtualObject(allocation));
+    if (!states->GetVirtualObject(node->id())) {
+      states->SetVirtualObject(node->id(),
+                               states->GetVirtualObject(allocation));
+      if (FLAG_trace_turbo_escape) {
+        PrintF("Linked finish region node #%d to node #%d\n", node->id(),
+               allocation->id());
+      }
+      states->LastChangedAt(node);
+    }
+  }
+}
+
+
+Node* EscapeObjectAnalysis::GetReplacement(Node* at, NodeId id) {
+  VirtualState* states = virtual_states_[at->id()];
+  if (VirtualObject* obj = states->GetVirtualObject(id)) {
+    return obj->GetReplacement();
+  }
+  return nullptr;
+}
+
+
+int EscapeObjectAnalysis::OffsetFromAccess(Node* node) {
+  DCHECK(OpParameter<FieldAccess>(node).offset % kPointerSize == 0);
+  return OpParameter<FieldAccess>(node).offset / kPointerSize;
+}
+
+
+void EscapeObjectAnalysis::ProcessLoadField(Node* node) {
+  DCHECK_EQ(node->opcode(), IrOpcode::kLoadField);
+  ForwardVirtualState(node);
+  Node* from = NodeProperties::GetValueInput(node, 0);
+  int offset = OffsetFromAccess(node);
+  VirtualState* states = virtual_states_[node->id()];
+  if (VirtualObject* state = states->GetVirtualObject(from)) {
+    if (!state->IsTracked()) return;
+    Node* value = state->GetField(offset);
+    if (value) {
+      // Record that the load has this alias.
+      states->UpdateReplacement(node, value, zone());
+    } else if (FLAG_trace_turbo_escape) {
+      PrintF("No field %d on record for #%d\n", offset, from->id());
+    }
+  } else {
+    if (from->opcode() == IrOpcode::kPhi) {
+      // Only binary phis are supported for now.
+      CHECK_EQ(from->op()->ValueInputCount(), 2);
+      if (FLAG_trace_turbo_escape) {
+        PrintF("Load #%d from phi #%d", node->id(), from->id());
+      }
+      Node* left = NodeProperties::GetValueInput(from, 0);
+      Node* right = NodeProperties::GetValueInput(from, 1);
+      VirtualObject* l = states->GetVirtualObject(left);
+      VirtualObject* r = states->GetVirtualObject(right);
+      if (l && r) {
+        Node* lv = l->GetField(offset);
+        Node* rv = r->GetField(offset);
+        if (lv && rv) {
+          if (!states->GetVirtualObject(node)) {
+            states->SetVirtualObject(
+                node->id(), new (zone()) VirtualObject(node->id(), zone()));
+          }
+          Node* rep = states->GetVirtualObject(node)->GetReplacement();
+          if (!rep || rep->opcode() != IrOpcode::kPhi ||
+              NodeProperties::GetValueInput(rep, 0) != lv ||
+              NodeProperties::GetValueInput(rep, 1) != rv) {
+            Node* phi =
+                graph()->NewNode(common()->Phi(kMachAnyTagged, 2), lv, rv,
+                                 NodeProperties::GetControlInput(from));
+            states->GetVirtualObject(node)->SetReplacement(phi);
+            states->LastChangedAt(node);
+            if (FLAG_trace_turbo_escape) {
+              PrintF(" got phi of #%d is #%d created.\n", lv->id(), rv->id());
+            }
+          } else if (FLAG_trace_turbo_escape) {
+            PrintF(" has already the right phi representation.\n");
+          }
+        } else if (FLAG_trace_turbo_escape) {
+          PrintF(" has incomplete field info: %p %p\n", static_cast<void*>(lv),
+                 static_cast<void*>(rv));
+        }
+      } else if (FLAG_trace_turbo_escape) {
+        PrintF(" has incomplete virtual object info: %p %p\n",
+               static_cast<void*>(l), static_cast<void*>(r));
+      }
+    }
+  }
+}
+
+
+void EscapeObjectAnalysis::ProcessStoreField(Node* node) {
+  DCHECK_EQ(node->opcode(), IrOpcode::kStoreField);
+  ForwardVirtualState(node);
+  Node* to = NodeProperties::GetValueInput(node, 0);
+  Node* val = NodeProperties::GetValueInput(node, 1);
+  int offset = OffsetFromAccess(node);
+  VirtualState* states = virtual_states_[node->id()];
+  if (VirtualObject* obj = states->GetVirtualObject(to)) {
+    if (!obj->IsTracked()) return;
+    if (obj->SetField(offset, states->ResolveReplacement(val))) {
+      states->LastChangedAt(node);
+    }
+  }
+}
+
+
+void EscapeObjectAnalysis::DebugPrint() {
+  ZoneVector<VirtualState*> object_states(zone());
+  for (NodeId id = 0; id < virtual_states_.size(); id++) {
+    if (VirtualState* states = virtual_states_[id]) {
+      if (std::find(object_states.begin(), object_states.end(), states) ==
+          object_states.end()) {
+        object_states.push_back(states);
+      }
+    }
+  }
+  for (size_t n = 0; n < object_states.size(); n++) {
+    PrintF("Dumping object state %p\n", static_cast<void*>(object_states[n]));
+    for (size_t id = 0; id < object_states[n]->size(); id++) {
+      if (VirtualObject* obj = object_states[n]->GetVirtualObject(id)) {
+        if (obj->id() == id) {
+          PrintF("  Object #%zu with %zu fields", id, obj->fields());
+          if (Node* rep = obj->GetReplacement()) {
+            PrintF(", rep = #%d (%s)", rep->id(), rep->op()->mnemonic());
+          }
+          PrintF("\n");
+          for (size_t i = 0; i < obj->fields(); ++i) {
+            if (Node* f = obj->GetField(i)) {
+              PrintF("    Field %zu = #%d (%s)\n", i, f->id(),
+                     f->op()->mnemonic());
+            }
+          }
+        } else {
+          PrintF("  Object #%zu links to object #%d\n", id, obj->id());
+        }
+      }
+    }
+  }
+}
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8