[Turbofan] Reduce register allocation work when we can.

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/base/compiler-specific.h"
 #include "src/compiler/instruction.h"
 #include "src/globals.h"
@@ skipping 964 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 iff. we must check float register aliasing.
+  bool check_fp_aliasing() const { return check_fp_aliasing_; }
 
   // 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();
@@ skipping 30 matching lines @@
 
   const ZoneVector<TopLevelLiveRange*>& GetFixedRegisters() const;
   const char* RegisterName(int allocation_index) const;
 
  private:
   RegisterAllocationData* const data_;
   const RegisterKind mode_;
   const int num_registers_;
   int num_allocatable_registers_;
   const int* allocatable_register_codes_;
+  bool check_fp_aliasing_;
 
  private:
   bool no_combining_;
 
   DISALLOW_COPY_AND_ASSIGN(RegisterAllocator);
 };
 
 
 class LinearScanAllocator final : public RegisterAllocator {
  public:
@@ skipping 158 matching lines @@
   RegisterAllocationData* const data_;
 
   DISALLOW_COPY_AND_ASSIGN(LiveRangeConnector);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REGISTER_ALLOCATOR_H_