[Turbofan] Allow compiler to elide complex aliasing code.

src/compiler/register-allocator.h

 // 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.
 
 #ifndef V8_REGISTER_ALLOCATOR_H_
 #define V8_REGISTER_ALLOCATOR_H_
 
 #include "src/compiler/instruction.h"
 #include "src/ostreams.h"
 #include "src/register-configuration.h"
@@ skipping 946 matching lines @@
 
  protected:
   RegisterAllocationData* data() const { return data_; }
   InstructionSequence* code() const { return data()->code(); }
   RegisterKind mode() const { return mode_; }
   int num_registers() const { return num_registers_; }
   int num_allocatable_registers() const { return num_allocatable_registers_; }
   const int* allocatable_register_codes() const {
     return allocatable_register_codes_;
   }
-  // Returns true if registers do not combine to form larger registers, i.e.
-  // no complex aliasing detection is required. This is always true for the
-  // general register pass, and true for the FP register pass except for arm
-  // and mips archs.
-  bool no_combining() const { return no_combining_; }
 
   // TODO(mtrofin): explain why splitting in gap START is always OK.
   LifetimePosition GetSplitPositionForInstruction(const LiveRange* range,
                                                   int instruction_index);
 
   Zone* allocation_zone() const { return data()->allocation_zone(); }
 
   // Find the optimal split for ranges defined by a memory operand, e.g.
   // constants or function parameters passed on the stack.
   void SplitAndSpillRangesDefinedByMemoryOperand(bool operands_only);
@@ skipping 199 matching lines @@
   RegisterAllocationData* const data_;
 
   DISALLOW_COPY_AND_ASSIGN(LiveRangeConnector);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REGISTER_ALLOCATOR_H_