[turbofan] reuse spill slots for phis

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 448 matching lines @@
   void AddToUnhandledSorted(LiveRange* range);
   void AddToUnhandledUnsorted(LiveRange* range);
   void SortUnhandled();
   bool UnhandledIsSorted();
   void ActiveToHandled(LiveRange* range);
   void ActiveToInactive(LiveRange* range);
   void InactiveToHandled(LiveRange* range);
   void InactiveToActive(LiveRange* range);
 
   // Helper methods for allocating registers.
+  bool TryReuseSpillForPhi(LiveRange* range);
   bool TryAllocateFreeReg(LiveRange* range);
   void AllocateBlockedReg(LiveRange* range);
   SpillRange* AssignSpillRangeToLiveRange(LiveRange* range);
   void FreeSpillSlot(LiveRange* range);
   InstructionOperand* TryReuseSpillSlot(LiveRange* range);
 
   // Live range splitting helpers.
 
   // Split the given range at the given position.
   // If range starts at or after the given position then the
@@ skipping 60 matching lines @@
   GapInstruction* GetLastGap(const InstructionBlock* block);
 
   const char* RegisterName(int allocation_index);
 
   Instruction* InstructionAt(int index) { return code()->InstructionAt(index); }
 
   Frame* frame() const { return frame_; }
   const char* debug_name() const { return debug_name_; }
   const RegisterConfiguration* config() const { return config_; }
 
+  struct PhiMapValue {
+    PhiMapValue(PhiInstruction* phi, const InstructionBlock* block)
+        : phi(phi), block(block) {}
+    PhiInstruction* const phi;
+    const InstructionBlock* const block;
+  };
+  typedef std::map<int, PhiMapValue, std::less<int>,
+                   zone_allocator<std::pair<int, PhiMapValue>>> PhiMap;
+
   Zone* const local_zone_;
   Frame* const frame_;
   InstructionSequence* const code_;
   const char* const debug_name_;
 
   const RegisterConfiguration* config_;
 
+  PhiMap phi_map_;
+
   // During liveness analysis keep a mapping from block id to live_in sets
   // for blocks already analyzed.
   ZoneVector<BitVector*> live_in_sets_;
 
   // Liveness analysis results.
   ZoneVector<LiveRange*> live_ranges_;
 
   // Lists of live ranges
   ZoneVector<LiveRange*> fixed_live_ranges_;
   ZoneVector<LiveRange*> fixed_double_live_ranges_;
@@ skipping 17 matching lines @@
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(RegisterAllocator);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REGISTER_ALLOCATOR_H_