Fix OSR for nested loops.

src/full-codegen.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 74 matching lines @@
       : masm_(masm),
         info_(info),
         scope_(info->scope()),
         nesting_stack_(NULL),
         loop_depth_(0),
         globals_(NULL),
         context_(NULL),
         bailout_entries_(info->HasDeoptimizationSupport()
                          ? info->function()->ast_node_count() : 0,
                          info->zone()),
-        stack_checks_(2, info->zone()),  // There's always at least one.
+        back_edges_(2, info->zone()),
         type_feedback_cells_(info->HasDeoptimizationSupport()
                              ? info->function()->ast_node_count() : 0,
                              info->zone()),
         ic_total_count_(0),
         zone_(info->zone()) {
     Initialize();
   }
 
   void Initialize();
 
@@ skipping 22 matching lines @@
 #elif V8_TARGET_ARCH_X64
   static const int kBackEdgeDistanceUnit = 162;
 #elif V8_TARGET_ARCH_ARM
   static const int kBackEdgeDistanceUnit = 142;
 #elif V8_TARGET_ARCH_MIPS
   static const int kBackEdgeDistanceUnit = 142;
 #else
 #error Unsupported target architecture.
 #endif
 
+  static const int kBackEdgeEntrySize = 2 * kIntSize + kOneByteSize;
 
  private:
   class Breakable;
   class Iteration;
 
   class TestContext;
 
   class NestedStatement BASE_EMBEDDED {
    public:
     explicit NestedStatement(FullCodeGenerator* codegen) : codegen_(codegen) {
@@ skipping 304 matching lines @@
   // neither a with nor a catch context.
   void EmitDebugCheckDeclarationContext(Variable* variable);
 
   // This is meant to be called at loop back edges, |back_edge_target| is
   // the jump target of the back edge and is used to approximate the amount
   // of code inside the loop.
   void EmitBackEdgeBookkeeping(IterationStatement* stmt,
                                Label* back_edge_target);
   // Record the OSR AST id corresponding to a back edge in the code.
   void RecordBackEdge(BailoutId osr_ast_id);
-  // Emit a table of stack check ids and pcs into the code stream.  Return
-  // the offset of the start of the table.
-  unsigned EmitStackCheckTable();
+  // Emit a table of back edge ids, pcs and loop depths into the code stream.
+  // Return the offset of the start of the table.
+  unsigned EmitBackEdgeTable();
 
   void EmitProfilingCounterDecrement(int delta);
   void EmitProfilingCounterReset();
 
   // Platform-specific return sequence
   void EmitReturnSequence();
 
   // Platform-specific code sequences for calls
   void EmitCallWithStub(Call* expr, CallFunctionFlags flags);
   void EmitCallWithIC(Call* expr, Handle<Object> name, RelocInfo::Mode mode);
@@ skipping 142 matching lines @@
   void PopulateTypeFeedbackInfo(Handle<Code> code);
   void PopulateTypeFeedbackCells(Handle<Code> code);
 
   Handle<FixedArray> handler_table() { return handler_table_; }
 
   struct BailoutEntry {
     BailoutId id;
     unsigned pc_and_state;
   };
 
+  struct BackEdgeEntry {
+    BailoutId id;
+    unsigned pc;
+    uint8_t loop_depth;
+  };
+
   struct TypeFeedbackCellEntry {
     TypeFeedbackId ast_id;
     Handle<JSGlobalPropertyCell> cell;
   };
 
 
   class ExpressionContext BASE_EMBEDDED {
    public:
     explicit ExpressionContext(FullCodeGenerator* codegen)
         : masm_(codegen->masm()), old_(codegen->context()), codegen_(codegen) {
@@ skipping 174 matching lines @@
   Scope* scope_;
   Label return_label_;
   NestedStatement* nesting_stack_;
   int loop_depth_;
   ZoneList<Handle<Object> >* globals_;
   Handle<FixedArray> modules_;
   int module_index_;
   const ExpressionContext* context_;
   ZoneList<BailoutEntry> bailout_entries_;
   GrowableBitVector prepared_bailout_ids_;
-  // TODO(svenpanne) Rename this to something like back_edges_ and rename
-  // related functions accordingly.
-  ZoneList<BailoutEntry> stack_checks_;
+  ZoneList<BackEdgeEntry> back_edges_;
   ZoneList<TypeFeedbackCellEntry> type_feedback_cells_;
   int ic_total_count_;
   Handle<FixedArray> handler_table_;
   Handle<JSGlobalPropertyCell> profiling_counter_;
   bool generate_debug_code_;
   Zone* zone_;
 
   friend class NestedStatement;
 
   DEFINE_AST_VISITOR_SUBCLASS_MEMBERS();
@@ skipping 19 matching lines @@
   }
 
  private:
   Zone* zone_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FULL_CODEGEN_H_