Fix off-by-one bug in TurboFan register allocator.

src/compiler/register-allocator.cc

 // Copyright 2014 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/compiler/register-allocator.h"
 
 #include "src/compiler/linkage.h"
 #include "src/hydrogen.h"
 #include "src/string-stream.h"
 
@@ skipping 1310 matching lines @@
     // Now live is live_in for this block except not including values live
     // out on backward successor edges.
     live_in_sets_[block_id] = live;
 
     if (block->IsLoopHeader()) {
       // Add a live range stretching from the first loop instruction to the last
       // for each value live on entry to the header.
       BitVector::Iterator iterator(live);
       LifetimePosition start = LifetimePosition::FromInstructionIndex(
           block->first_instruction_index());
-      int end_index = code()
-                          ->InstructionBlockAt(block->loop_end())
-                          ->last_instruction_index();
       LifetimePosition end =
-          LifetimePosition::FromInstructionIndex(end_index).NextInstruction();
+          LifetimePosition::FromInstructionIndex(
+              code()->LastLoopInstructionIndex(block)).NextInstruction();
       while (!iterator.Done()) {
         int operand_index = iterator.Current();
         LiveRange* range = LiveRangeFor(operand_index);
         range->EnsureInterval(start, end, zone());
         iterator.Advance();
       }
 
       // Insert all values into the live in sets of all blocks in the loop.
       for (int i = block->rpo_number().ToInt() + 1;
            i < block->loop_end().ToInt(); ++i) {
@@ skipping 878 matching lines @@
                     allocator_zone_start_allocation_size_;
     isolate()->GetTStatistics()->SaveTiming(name(), base::TimeDelta(), size);
   }
 #ifdef DEBUG
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 }
 }
 }  // namespace v8::internal::compiler