Fix OSR for nested loops.

src/full-codegen.h

Index: src/full-codegen.h
diff --git a/src/full-codegen.h b/src/full-codegen.h
index c4f3fcc722b3252ce6970c87abb02b3a8a4423f7..96855bd5eb1b70ff37a7f37fae48db93f98330d8 100644
--- a/src/full-codegen.h
+++ b/src/full-codegen.h
@@ -92,7 +92,7 @@ class FullCodeGenerator: public AstVisitor {
         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()),  // There's always at least one.

[Jakob Kummerow, 2013/04/09 17:23:25]

nit: the comment is outdated, just remove it. (There's only a back edge if
there's a loop.)

[Yang, 2013/04/10 08:08:30]

Done.

         type_feedback_cells_(info->HasDeoptimizationSupport()
                              ? info->function()->ast_node_count() : 0,
                              info->zone()),
@@ -461,7 +461,7 @@ class FullCodeGenerator: public AstVisitor {
   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();
+  unsigned EmitBackEdgeTable();
 
   void EmitProfilingCounterDecrement(int delta);
   void EmitProfilingCounterReset();
@@ -624,6 +624,12 @@ class FullCodeGenerator: public AstVisitor {
     unsigned pc_and_state;
   };
 
+  struct BackEdgeEntry {
+    BailoutId id;
+    unsigned pc;
+    uint8_t loop_depth;
+  };
+
   struct TypeFeedbackCellEntry {
     TypeFeedbackId ast_id;
     Handle<JSGlobalPropertyCell> cell;
@@ -820,7 +826,7 @@ class FullCodeGenerator: public AstVisitor {
   GrowableBitVector prepared_bailout_ids_;
   // TODO(svenpanne) Rename this to something like back_edges_ and rename

[Jakob Kummerow, 2013/04/09 17:23:25]

You can remove this TODO, since it describes exactly what this CL is doing.

[Yang, 2013/04/10 08:08:30]

Done.

   // related functions accordingly.
-  ZoneList<BailoutEntry> stack_checks_;
+  ZoneList<BackEdgeEntry> back_edges_;
   ZoneList<TypeFeedbackCellEntry> type_feedback_cells_;
   int ic_total_count_;
   Handle<FixedArray> handler_table_;