[turbofan] optimize hot loop in ResolveControlFlow

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/zone-containers.h"
 
@@ skipping 168 matching lines @@
 class LiveRange FINAL : public ZoneObject {
  public:
   static const int kInvalidAssignment = 0x7fffffff;
 
   LiveRange(int id, Zone* zone);
 
   UseInterval* first_interval() const { return first_interval_; }
   UsePosition* first_pos() const { return first_pos_; }
   LiveRange* parent() const { return parent_; }
   LiveRange* TopLevel() { return (parent_ == NULL) ? this : parent_; }
+  const LiveRange* TopLevel() const {
+    return (parent_ == NULL) ? this : parent_;
+  }
   LiveRange* next() const { return next_; }
   bool IsChild() const { return parent() != NULL; }
   int id() const { return id_; }
   bool IsFixed() const { return id_ < 0; }
   bool IsEmpty() const { return first_interval() == NULL; }
-  InstructionOperand* CreateAssignedOperand(Zone* zone);
+  InstructionOperand* CreateAssignedOperand(Zone* zone) const;
   int assigned_register() const { return assigned_register_; }
   int spill_start_index() const { return spill_start_index_; }
   void set_assigned_register(int reg, Zone* zone);
   void MakeSpilled(Zone* zone);
   bool is_phi() const { return is_phi_; }
   void set_is_phi(bool is_phi) { is_phi_ = is_phi; }
   bool is_non_loop_phi() const { return is_non_loop_phi_; }
   void set_is_non_loop_phi(bool is_non_loop_phi) {
     is_non_loop_phi_ = is_non_loop_phi;
   }
@@ skipping 135 matching lines @@
   BitVector* assigned_double_registers() { return assigned_double_registers_; }
 
   const ZoneList<LiveRange*>& live_ranges() const { return live_ranges_; }
   const ZoneVector<LiveRange*>& fixed_live_ranges() const {
     return fixed_live_ranges_;
   }
   const ZoneVector<LiveRange*>& fixed_double_live_ranges() const {
     return fixed_double_live_ranges_;
   }
   InstructionSequence* code() const { return code_; }
+  // This zone is for datastructures only needed during register allocation.
+  Zone* zone() const { return zone_; }

[Jarin, 2014/11/04 10:42:09]

Since you already touching this, could you possibly rename to local_zone()?

[dcarney, 2014/11/05 09:02:02]

Done.

 
  private:
   int GetVirtualRegister() {
     int vreg = code()->NextVirtualRegister();
     if (vreg >= UnallocatedOperand::kMaxVirtualRegisters) {
       allocation_ok_ = false;
       // Maintain the invariant that we return something below the maximum.
       return 0;
     }
     return vreg;
   }
 
   // Checks whether the value of a given virtual register is a reference.
   // TODO(titzer): rename this to IsReference.
   bool HasTaggedValue(int virtual_register) const;
 
   // Returns the register kind required by the given virtual register.
   RegisterKind RequiredRegisterKind(int virtual_register) const;
 
-  // This zone is for datastructures only needed during register allocation.
-  Zone* zone() const { return zone_; }
-
   // This zone is for InstructionOperands and moves that live beyond register
   // allocation.
   Zone* code_zone() const { return code()->zone(); }
 
 #ifdef DEBUG
   void Verify() const;
 #endif
 
   void MeetRegisterConstraints();
   void ResolvePhis();
@@ skipping 86 matching lines @@
 
   // If we are trying to spill a range inside the loop try to
   // hoist spill position out to the point just before the loop.
   LifetimePosition FindOptimalSpillingPos(LiveRange* range,
                                           LifetimePosition pos);
 
   void Spill(LiveRange* range);
   bool IsBlockBoundary(LifetimePosition pos);
 
   // Helper methods for resolving control flow.
-  void ResolveControlFlow(LiveRange* range, const InstructionBlock* block,
-                          const InstructionBlock* pred);
+  void ResolveControlFlow(const InstructionBlock* block,
+                          const LiveRange* cur_cover,
+                          const InstructionBlock* pred,
+                          const LiveRange* pred_cover);
 
   void SetLiveRangeAssignedRegister(LiveRange* range, int reg);
 
   // Return parallel move that should be used to connect ranges split at the
   // given position.
   ParallelMove* GetConnectingParallelMove(LifetimePosition pos);
 
   // Return the block which contains give lifetime position.
   const InstructionBlock* GetInstructionBlock(LifetimePosition pos);
 
@@ skipping 50 matching lines @@
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(RegisterAllocator);
 };
 
 }
 }
 }  // namespace v8::internal::compiler
 
 #endif  // V8_REGISTER_ALLOCATOR_H_