[turbofan] escape analysis supports arguments object and rest elements

src/compiler/instruction.h

Index: src/compiler/instruction.h
diff --git a/src/compiler/instruction.h b/src/compiler/instruction.h
index f207c7622e90cc8d6144cdab4b3c69ff0f9ee510..114198cfd87394e4f8de8e8d2148e3dec61abb48 100644
--- a/src/compiler/instruction.h
+++ b/src/compiler/instruction.h
@@ -1122,7 +1122,7 @@ std::ostream& operator<<(std::ostream& os, const Constant& constant);
 class FrameStateDescriptor;
 
 enum class StateValueKind : uint8_t {
-  kArguments,
+  kArgumentsElements,
   kPlain,
   kOptimizedOut,
   kNested,
@@ -1132,45 +1132,62 @@ enum class StateValueKind : uint8_t {
 class StateValueDescriptor {
  public:
   StateValueDescriptor()
-      : kind_(StateValueKind::kPlain),
-        type_(MachineType::AnyTagged()),
-        id_(0) {}
+      : kind_(StateValueKind::kPlain), type_(MachineType::AnyTagged()) {}
 
-  static StateValueDescriptor Arguments() {
-    return StateValueDescriptor(StateValueKind::kArguments,
-                                MachineType::AnyTagged(), 0);
+  static StateValueDescriptor ArgumentsElements(bool is_rest) {
+    StateValueDescriptor descr(StateValueKind::kArgumentsElements,
+                               MachineType::AnyTagged());
+    descr.is_rest_ = is_rest;
+    return descr;
   }
   static StateValueDescriptor Plain(MachineType type) {
-    return StateValueDescriptor(StateValueKind::kPlain, type, 0);
+    return StateValueDescriptor(StateValueKind::kPlain, type);
   }
   static StateValueDescriptor OptimizedOut() {
     return StateValueDescriptor(StateValueKind::kOptimizedOut,
-                                MachineType::AnyTagged(), 0);
+                                MachineType::AnyTagged());
   }
   static StateValueDescriptor Recursive(size_t id) {
-    return StateValueDescriptor(StateValueKind::kNested,
-                                MachineType::AnyTagged(), id);
+    StateValueDescriptor descr(StateValueKind::kNested,
+                               MachineType::AnyTagged());
+    descr.id_ = id;
+    return descr;
   }
   static StateValueDescriptor Duplicate(size_t id) {
-    return StateValueDescriptor(StateValueKind::kDuplicate,
-                                MachineType::AnyTagged(), id);
+    StateValueDescriptor descr(StateValueKind::kDuplicate,
+                               MachineType::AnyTagged());
+    descr.id_ = id;
+    return descr;
   }
 
-  bool IsArguments() const { return kind_ == StateValueKind::kArguments; }
+  bool IsArgumentsElements() const {
+    return kind_ == StateValueKind::kArgumentsElements;
+  }
   bool IsPlain() const { return kind_ == StateValueKind::kPlain; }
   bool IsOptimizedOut() const { return kind_ == StateValueKind::kOptimizedOut; }
   bool IsNested() const { return kind_ == StateValueKind::kNested; }
   bool IsDuplicate() const { return kind_ == StateValueKind::kDuplicate; }
   MachineType type() const { return type_; }
-  size_t id() const { return id_; }
+  size_t id() const {
+    DCHECK(kind_ == StateValueKind::kDuplicate ||
+           kind_ == StateValueKind::kNested);
+    return id_;
+  }
+  int is_rest() const {
+    DCHECK(kind_ == StateValueKind::kArgumentsElements);
+    return is_rest_;
+  }
 
  private:
-  StateValueDescriptor(StateValueKind kind, MachineType type, size_t id)
-      : kind_(kind), type_(type), id_(id) {}
+  StateValueDescriptor(StateValueKind kind, MachineType type)
+      : kind_(kind), type_(type) {}
 
   StateValueKind kind_;
   MachineType type_;
-  size_t id_;
+  union {
+    size_t id_;
+    bool is_rest_;
+  };
 };
 
 class StateValueList {
@@ -1229,7 +1246,9 @@ class StateValueList {
     nested_.push_back(nested);
     return nested;
   }
-  void PushArguments() { fields_.push_back(StateValueDescriptor::Arguments()); }
+  void PushArgumentsElements(int skip) {

[Jarin, 2017/02/27 13:24:34]

How about 

int skip ==> bool is_rest

?

+    fields_.push_back(StateValueDescriptor::ArgumentsElements(skip));
+  }
   void PushDuplicate(size_t id) {
     fields_.push_back(StateValueDescriptor::Duplicate(id));
   }