Deoptimize context value in Turbofan (and Crankshaft).

src/compiler/graph-builder.h

 // Copyright 2013 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.
 
 #ifndef V8_COMPILER_GRAPH_BUILDER_H_
 #define V8_COMPILER_GRAPH_BUILDER_H_
 
 #include "src/v8.h"
 
 #include "src/allocation.h"
@@ skipping 83 matching lines @@
   Node* NewIfTrue() { return NewNode(common()->IfTrue()); }
   Node* NewIfFalse() { return NewNode(common()->IfFalse()); }
   Node* NewMerge() { return NewNode(common()->Merge(1)); }
   Node* NewLoop() { return NewNode(common()->Loop(1)); }
   Node* NewBranch(Node* condition) {
     return NewNode(common()->Branch(), condition);
   }
 
  protected:
   class Environment;
+  friend class Environment;
   friend class ControlBuilder;
 
   // The following method creates a new node having the specified operator and
   // ensures effect and control dependencies are wired up. The dependencies
   // tracked by the environment might be mutated.
   virtual Node* MakeNode(Operator* op, int value_input_count,
                          Node** value_inputs);
 
   Environment* environment() const { return environment_; }
   void set_environment(Environment* env) { environment_ = env; }
@@ skipping 81 matching lines @@
     env->MarkAsUnreachable();
     return env;
   }
 
   // Copies this environment at a loop header control-flow point.
   Environment* CopyForLoop() {
     PrepareForLoop();
     return builder()->CopyEnvironment(this);
   }
 
+  Node* GetContext() { return builder_->current_context(); }
+
  protected:
   // TODO(mstarzinger): Use phase-local zone instead!
   Zone* zone() const { return graph()->zone(); }
   Graph* graph() const { return builder_->graph(); }
   StructuredGraphBuilder* builder() const { return builder_; }
   CommonOperatorBuilder* common() { return builder_->common(); }
   NodeVector* values() { return &values_; }
 
   // Prepare environment to be used as loop header.
   void PrepareForLoop();
 
  private:
   StructuredGraphBuilder* builder_;
   Node* control_dependency_;
   Node* effect_dependency_;
   NodeVector values_;
 };
 }
 }
 }  // namespace v8::internal::compiler
 
 #endif  // V8_COMPILER_GRAPH_BUILDER_H__