Fix a bug in deoptimization environments.

src/hydrogen.cc

 // Copyright 2010 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 110 matching lines @@
 
 HSimulate* HBasicBlock::CreateSimulate(int id) {
   ASSERT(HasEnvironment());
   HEnvironment* environment = last_environment();
   ASSERT(id == AstNode::kNoNumber ||
          environment->closure()->shared()->VerifyBailoutId(id));
 
   int push_count = environment->push_count();
   int pop_count = environment->pop_count();
 
-  int length = environment->values()->length();
+  int length = environment->length();
   HSimulate* instr = new HSimulate(id, pop_count, length);
   for (int i = push_count - 1; i >= 0; --i) {
     instr->AddPushedValue(environment->ExpressionStackAt(i));
   }
   for (int i = 0; i < environment->assigned_variables()->length(); ++i) {
     int index = environment->assigned_variables()->at(i);
     instr->AddAssignedValue(index, environment->Lookup(index));
   }
   environment->ClearHistory();
   return instr;
@@ skipping 73 matching lines @@
 
 
 void HBasicBlock::RegisterPredecessor(HBasicBlock* pred) {
   if (!predecessors_.is_empty()) {
     // Only loop header blocks can have a predecessor added after
     // instructions have been added to the block (they have phis for all
     // values in the environment, these phis may be eliminated later).
     ASSERT(IsLoopHeader() || first_ == NULL);
     HEnvironment* incoming_env = pred->last_environment();
     if (IsLoopHeader()) {
-      ASSERT(phis()->length() == incoming_env->values()->length());
+      ASSERT(phis()->length() == incoming_env->length());
       for (int i = 0; i < phis_.length(); ++i) {
         phis_[i]->AddInput(incoming_env->values()->at(i));
       }
     } else {
       last_environment()->AddIncomingEdge(this, pred->last_environment());
     }
   } else if (!HasEnvironment() && !IsFinished()) {
     ASSERT(!IsLoopHeader());
     SetInitialEnvironment(pred->last_environment()->Copy());
   }
@@ skipping 1739 matching lines @@
   }
 }
 
 
 // Implementation of utility classes to represent an expression's context in
 // the AST.
 AstContext::AstContext(HGraphBuilder* owner, Expression::Context kind)
     : owner_(owner), kind_(kind), outer_(owner->ast_context()) {
   owner->set_ast_context(this);  // Push.
 #ifdef DEBUG
-  original_count_ = owner->environment()->total_count();
+  original_length_ = owner->environment()->length();
 #endif
 }
 
 
 AstContext::~AstContext() {
   owner_->set_ast_context(outer_);  // Pop.
 }
 
 
 EffectContext::~EffectContext() {
   ASSERT(owner()->HasStackOverflow() ||
          !owner()->subgraph()->HasExit() ||
-         owner()->environment()->total_count() == original_count_);
+         owner()->environment()->length() == original_length_);
 }
 
 
 ValueContext::~ValueContext() {
   ASSERT(owner()->HasStackOverflow() ||
          !owner()->subgraph()->HasExit() ||
-         owner()->environment()->total_count() == original_count_ + 1);
+         owner()->environment()->length() == original_length_ + 1);
 }
 
 
 void EffectContext::ReturnValue(HValue* value) {
   // The value is simply ignored.
 }
 
 
 void ValueContext::ReturnValue(HValue* value) {
   // The value is tracked in the bailout environment, and communicated
@@ skipping 320 matching lines @@
 
   // Set the initial values of parameters including "this".  "This" has
   // parameter index 0.
   int count = scope->num_parameters() + 1;
   for (int i = 0; i < count; ++i) {
     HInstruction* parameter = AddInstruction(new HParameter(i));
     environment()->Bind(i, parameter);
   }
 
   // Set the initial values of stack-allocated locals.
-  for (int i = count; i < environment()->values()->length(); ++i) {
+  for (int i = count; i < environment()->length(); ++i) {
     environment()->Bind(i, undefined_constant);
   }
 
   // Handle the arguments and arguments shadow variables specially (they do
   // not have declarations).
   if (scope->arguments() != NULL) {
     HArgumentsObject* object = new HArgumentsObject;
     AddInstruction(object);
     graph()->SetArgumentsObject(object);
     environment()->Bind(scope->arguments(), object);
@@ skipping 338 matching lines @@
   HValue* true_value = graph()->GetConstantTrue();
   HBranch* branch = new HBranch(non_osr_entry, osr_entry, true_value);
   exit_block()->Finish(branch);
 
   HBasicBlock* loop_predecessor = graph()->CreateBasicBlock();
   non_osr_entry->Goto(loop_predecessor);
 
   int osr_entry_id = statement->OsrEntryId();
   // We want the correct environment at the OsrEntry instruction.  Build
   // it explicitly.  The expression stack should be empty.
-  int count = osr_entry->last_environment()->total_count();
+  int count = osr_entry->last_environment()->length();
   ASSERT(count == (osr_entry->last_environment()->parameter_count() +
                    osr_entry->last_environment()->local_count()));
   for (int i = 0; i < count; ++i) {
     HUnknownOSRValue* unknown = new HUnknownOSRValue;
     osr_entry->AddInstruction(unknown);
     osr_entry->last_environment()->Bind(i, unknown);
   }
 
   osr_entry->AddSimulate(osr_entry_id);
   osr_entry->AddInstruction(new HOsrEntry(osr_entry_id));
@@ skipping 2556 matching lines @@
   parameter_count_ = parameter_count;
   local_count_ = local_count;
 
   // Avoid reallocating the temporaries' backing store on the first Push.
   int total = parameter_count + local_count + stack_height;
   values_.Initialize(total + 4);
   for (int i = 0; i < total; ++i) values_.Add(NULL);
 }
 
 
+void HEnvironment::Initialize(const HEnvironment* other) {
+  closure_ = other->closure();
+  values_.AddAll(other->values_);
+  assigned_variables_.AddAll(other->assigned_variables_);
+  parameter_count_ = other->parameter_count_;
+  local_count_ = other->local_count_;
+  if (other->outer_ != NULL) outer_ = other->outer_->Copy();  // Deep copy.
+  pop_count_ = other->pop_count_;
+  push_count_ = other->push_count_;
+  ast_id_ = other->ast_id_;
+}
+
+
 void HEnvironment::AddIncomingEdge(HBasicBlock* block, HEnvironment* other) {
   ASSERT(!block->IsLoopHeader());
   ASSERT(values_.length() == other->values_.length());
 
   int length = values_.length();
   for (int i = 0; i < length; ++i) {
     HValue* value = values_[i];
     if (value != NULL && value->IsPhi() && value->block() == block) {
       // There is already a phi for the i'th value.
       HPhi* phi = HPhi::cast(value);
@@ skipping 10 matching lines @@
         phi->AddInput(old_value);
       }
       phi->AddInput(other->values_[i]);
       this->values_[i] = phi;
       block->AddPhi(phi);
     }
   }
 }
 
 
-void HEnvironment::Initialize(const HEnvironment* other) {
-  closure_ = other->closure();
-  values_.AddAll(other->values_);
-  assigned_variables_.AddAll(other->assigned_variables_);
-  parameter_count_ = other->parameter_count_;
-  local_count_ = other->local_count_;
-  if (other->outer_ != NULL) outer_ = other->outer_->Copy();  // Deep copy.
-  pop_count_ = other->pop_count_;
-  push_count_ = other->push_count_;
-  ast_id_ = other->ast_id_;
+void HEnvironment::Bind(int index, HValue* value) {
+  ASSERT(value != NULL);
+  if (!assigned_variables_.Contains(index)) {
+    assigned_variables_.Add(index);
+  }
+  values_[index] = value;
 }
 
 
-int HEnvironment::IndexFor(Variable* variable) const {
-  Slot* slot = variable->AsSlot();
-  ASSERT(slot != NULL && slot->IsStackAllocated());
-  if (slot->type() == Slot::PARAMETER) {
-    return slot->index() + 1;
-  } else {
-    return parameter_count_ + slot->index();
+bool HEnvironment::HasExpressionAt(int index) const {
+  return index >= parameter_count_ + local_count_;
+}
+
+
+bool HEnvironment::ExpressionStackIsEmpty() const {
+  int first_expression = parameter_count() + local_count();
+  ASSERT(length() >= first_expression);
+  return length() == first_expression;
+}
+
+
+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) {
+    // This is the same effect as popping then re-pushing 'count' elements.
+    pop_count_ += (count - push_count_);
+    push_count_ = count;
+  }
+  values_[index] = value;
+}
+
+
+void HEnvironment::Drop(int count) {
+  for (int i = 0; i < count; ++i) {
+    Pop();
   }
 }
 
 
 HEnvironment* HEnvironment::Copy() const {
   return new HEnvironment(this);
 }
 
 
 HEnvironment* HEnvironment::CopyWithoutHistory() const {
@@ skipping 44 matching lines @@
   for (int i = 0; i < local_count; ++i) {
     inner->SetValueAt(local_base + i, undefined);
   }
 
   inner->set_ast_id(function->id());
   return inner;
 }
 
 
 void HEnvironment::PrintTo(StringStream* stream) {
-  for (int i = 0; i < total_count(); i++) {
+  for (int i = 0; i < length(); i++) {
     if (i == 0) stream->Add("parameters\n");
     if (i == parameter_count()) stream->Add("locals\n");
     if (i == parameter_count() + local_count()) stream->Add("expressions");
     HValue* val = values_.at(i);
     stream->Add("%d: ", i);
     if (val != NULL) {
       val->PrintNameTo(stream);
     } else {
       stream->Add("NULL");
     }
@@ skipping 287 matching lines @@
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify();
   if (chunk_ != NULL) chunk_->Verify();
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal