[Interpreter] Fix a register allocation bug and add a DCHECK.

src/interpreter/bytecode-array-builder.cc

 // Copyright 2015 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.
 
 #include "src/interpreter/bytecode-array-builder.h"
 
 namespace v8 {
 namespace internal {
 namespace interpreter {
 
@@ skipping 1043 matching lines @@
 }
 
 
 Register TemporaryRegisterScope::NewRegister() {
   int allocated = builder_->BorrowTemporaryRegister();
   allocated_.push_back(allocated);
   return Register(allocated);
 }
 
 
+bool TemporaryRegisterScope::AllocatedRegister(Register reg) const {

[oth, 2015/10/27 12:30:23]

Suggest renaming to RegisterIsAllocated() to match other register property
methods.

[rmcilroy, 2015/10/27 13:13:24]

Renamed to RegisterIsAllocatedInThisScope() to be super clear what it does :).

+  for (auto i = allocated_.begin(); i != allocated_.end(); i++) {
+    if (*i == reg.index()) return true;
+  }
+  return false;
+}
+
+
 void TemporaryRegisterScope::PrepareForConsecutiveAllocations(size_t count) {
   if (static_cast<int>(count) > next_consecutive_count_) {
     next_consecutive_register_ =
         builder_->PrepareForConsecutiveTemporaryRegisters(count);
     next_consecutive_count_ = static_cast<int>(count);
   }
 }
 
 
 Register TemporaryRegisterScope::NextConsecutiveRegister() {
   DCHECK_GE(next_consecutive_register_, 0);
   DCHECK_GT(next_consecutive_count_, 0);
   builder_->BorrowConsecutiveTemporaryRegister(next_consecutive_register_);
   allocated_.push_back(next_consecutive_register_);
   next_consecutive_count_--;
   return Register(next_consecutive_register_++);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8