Support OSR in for-in loops.

src/hydrogen.cc

 // 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 3040 matching lines @@
   HBasicBlock* osr_entry = graph()->CreateBasicBlock();
   HValue* true_value = graph()->GetConstantTrue();
   HBranch* test = new(zone()) HBranch(true_value, non_osr_entry, osr_entry);
   current_block()->Finish(test);
 
   HBasicBlock* loop_predecessor = graph()->CreateBasicBlock();
   non_osr_entry->Goto(loop_predecessor);
 
   set_current_block(osr_entry);
   int osr_entry_id = statement->OsrEntryId();
-  // We want the correct environment at the OsrEntry instruction.  Build
-  // it explicitly.  The expression stack should be empty.
-  ASSERT(environment()->ExpressionStackIsEmpty());
-  for (int i = 0; i < environment()->length(); ++i) {
+  int first_expression_index = environment()->first_expression_index();
+  int length = environment()->length();
+  for (int i = 0; i < first_expression_index; ++i) {
     HUnknownOSRValue* osr_value = new(zone()) HUnknownOSRValue;
     AddInstruction(osr_value);
     environment()->Bind(i, osr_value);
   }
 
+  if (first_expression_index != length) {
+    environment()->Drop(length - first_expression_index);
+    for (int i = first_expression_index; i < length; ++i) {
+      HUnknownOSRValue* osr_value = new(zone()) HUnknownOSRValue;
+      AddInstruction(osr_value);
+      environment()->Push(osr_value);
+    }
+  }
+
+
   AddSimulate(osr_entry_id);
   AddInstruction(new(zone()) HOsrEntry(osr_entry_id));
   HContext* context = new(zone()) HContext;
   AddInstruction(context);
   environment()->BindContext(context);
   current_block()->Goto(loop_predecessor);
   loop_predecessor->SetJoinId(statement->EntryId());
   set_current_block(loop_predecessor);
 }
 
@@ skipping 187 matching lines @@
   Push(start_index);
 
   HInstruction* index_cache = AddInstruction(
       new(zone()) HForInCacheArray(
           enumerable,
           map,
           DescriptorArray::kEnumCacheBridgeIndicesCacheIndex));
   HForInCacheArray::cast(array)->set_index_cache(
       HForInCacheArray::cast(index_cache));
 
+  PreProcessOsrEntry(stmt);
   HBasicBlock* loop_entry = CreateLoopHeaderBlock();
   current_block()->Goto(loop_entry);
   set_current_block(loop_entry);
 
-  HValue* index = Top();
+  HValue* index = environment()->ExpressionStackAt(0);
+  HValue* limit = environment()->ExpressionStackAt(1);
 
   // Check that we still have more keys.
   HCompareIDAndBranch* compare_index =
-      new(zone()) HCompareIDAndBranch(index, array_length, Token::LT);
+      new(zone()) HCompareIDAndBranch(index, limit, Token::LT);
   compare_index->SetInputRepresentation(Representation::Integer32());
 
   HBasicBlock* loop_body = graph()->CreateBasicBlock();
   HBasicBlock* loop_successor = graph()->CreateBasicBlock();
 
   compare_index->SetSuccessorAt(0, loop_body);
   compare_index->SetSuccessorAt(1, loop_successor);
   current_block()->Finish(compare_index);
 
   set_current_block(loop_successor);
   Drop(5);
 
   set_current_block(loop_body);
 
   HValue* key = AddInstruction(
       new(zone()) HLoadKeyedFastElement(
-          array, index, HLoadKeyedFastElement::OMIT_HOLE_CHECK));
+          environment()->ExpressionStackAt(2),  // Enum cache.
+          environment()->ExpressionStackAt(0),  // Iteration index.
+          HLoadKeyedFastElement::OMIT_HOLE_CHECK));
 
   // Check if the expected map still matches that of the enumerable.
   // If not just deoptimize.
-  AddInstruction(new(zone()) HCheckMapValue(enumerable, map));
+  AddInstruction(new(zone()) HCheckMapValue(
+      environment()->ExpressionStackAt(4),
+      environment()->ExpressionStackAt(3)));
 
   Bind(each_var, key);
 
   BreakAndContinueInfo break_info(stmt, 5);
   CHECK_BAILOUT(VisitLoopBody(stmt, loop_entry, &break_info));
 
   HBasicBlock* body_exit =
       JoinContinue(stmt, current_block(), break_info.continue_block());
 
   if (body_exit != NULL) {
@@ skipping 4116 matching lines @@
   values_[index] = value;
 }
 
 
 bool HEnvironment::HasExpressionAt(int index) const {
   return index >= parameter_count_ + specials_count_ + local_count_;
 }
 
 
 bool HEnvironment::ExpressionStackIsEmpty() const {
-  int first_expression = parameter_count() + specials_count() + local_count();
-  ASSERT(length() >= first_expression);
-  return length() == first_expression;
+  ASSERT(length() >= first_expression_index());
+  return length() == first_expression_index();
 }
 
 
 void HEnvironment::SetExpressionStackAt(int index_from_top, HValue* value) {
   int count = index_from_top + 1;
   int index = values_.length() - count;
   ASSERT(HasExpressionAt(index));
   // The push count must include at least the element in question or else
   // the new value will not be included in this environment's history.
   if (push_count_ < count) {
@@ skipping 426 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal