Implement loop variable assignment analysis.

src/compiler/ast-graph-builder.h

 // Copyright 2014 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_AST_GRAPH_BUILDER_H_
 #define V8_COMPILER_AST_GRAPH_BUILDER_H_
 
 #include "src/v8.h"
 
 #include "src/ast.h"
 #include "src/compiler/graph-builder.h"
 #include "src/compiler/js-graph.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 class ControlBuilder;
+class Graph;
+class LoopAssignmentAnalysis;
 class LoopBuilder;
-class Graph;
 
 // The AstGraphBuilder produces a high-level IR graph, based on an
 // underlying AST. The produced graph can either be compiled into a
 // stand-alone function or be wired into another graph for the purposes
 // of function inlining.
 class AstGraphBuilder : public StructuredGraphBuilder, public AstVisitor {
  public:
   AstGraphBuilder(Zone* local_zone, CompilationInfo* info, JSGraph* jsgraph);
 
   // Creates a graph by visiting the entire AST.
@@ skipping 97 matching lines @@
   // Stack of breakable statements entered by the visitor.
   BreakableScope* breakable_;
 
   // Stack of context objects pushed onto the chain by the visitor.
   ContextScope* execution_context_;
 
   // Nodes representing values in the activation record.
   SetOncePointer<Node> function_closure_;
   SetOncePointer<Node> function_context_;
 
+  LoopAssignmentAnalysis* loop_assignment_analysis_;
+
   CompilationInfo* info() const { return info_; }
   inline StrictMode strict_mode() const;
   JSGraph* jsgraph() { return jsgraph_; }
   JSOperatorBuilder* javascript() { return jsgraph_->javascript(); }
   ZoneList<Handle<Object> >* globals() { return &globals_; }
 
   // Current scope during visitation.
   inline Scope* current_scope() const;
 
   // Named and keyed loads require a VectorSlotPair for successful lowering.
@@ skipping 33 matching lines @@
   // Dispatched from VisitForInStatement.
   void VisitForInAssignment(Expression* expr, Node* value);
 
   // Builds deoptimization for a given node.
   void PrepareFrameState(
       Node* node, BailoutId ast_id,
       OutputFrameStateCombine combine = OutputFrameStateCombine::Ignore());
 
   OutputFrameStateCombine StateCombineFromAstContext();
 
+  BitVector* GetVariablesAssignedInLoop(IterationStatement* stmt);
+
   DEFINE_AST_VISITOR_SUBCLASS_MEMBERS();
   DISALLOW_COPY_AND_ASSIGN(AstGraphBuilder);
 };
 
 
 // The abstract execution environment for generated code consists of
 // parameter variables, local variables and the operand stack. The
 // environment will perform proper SSA-renaming of all tracked nodes
 // at split and merge points in the control flow. Internally all the
 // values are stored in one list using the following layout:
@@ skipping 231 matching lines @@
 };
 
 Scope* AstGraphBuilder::current_scope() const {
   return execution_context_->scope();
 }
 }
 }
 }  // namespace v8::internal::compiler
 
 #endif  // V8_COMPILER_AST_GRAPH_BUILDER_H_