When spilling live range with not register uses inside the loop try to move spilling out of the loo…

src/lithium-allocator.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 293 matching lines @@
   // Returns use position for which register is required in this live
   // range and which follows both start and last processed use position
   // Modifies internal state of live range!
   UsePosition* NextRegisterPosition(LifetimePosition start);
 
   // Returns use position for which register is beneficial in this live
   // range and which follows both start and last processed use position
   // Modifies internal state of live range!
   UsePosition* NextUsePositionRegisterIsBeneficial(LifetimePosition start);
 
+  // Returns use position for which register is beneficial in this live
+  // range and which precedes start.
+  UsePosition* PreviousUsePositionRegisterIsBeneficial(LifetimePosition start);
+
   // Can this live range be spilled at this position.
   bool CanBeSpilled(LifetimePosition pos);
 
   // Split this live range at the given position which must follow the start of
   // the range.
   // All uses following the given position will be moved from this
   // live range to the result live range.
   void SplitAt(LifetimePosition position, LiveRange* result, Zone* zone);
 
   bool IsDouble() const { return is_double_; }
@@ skipping 232 matching lines @@
   // Spill the given life range after position pos.
   void SpillAfter(LiveRange* range, LifetimePosition pos);
 
   // Spill the given life range after position start and up to position end.
   void SpillBetween(LiveRange* range,
                     LifetimePosition start,
                     LifetimePosition end);
 
   void SplitAndSpillIntersecting(LiveRange* range);
 
+  // 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,
                           HBasicBlock* block,
                           HBasicBlock* pred);
 
   // Return parallel move that should be used to connect ranges split at the
   // given position.
@@ skipping 56 matching lines @@
   // Indicates success or failure during register allocation.
   bool allocation_ok_;
 
   DISALLOW_COPY_AND_ASSIGN(LAllocator);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_LITHIUM_ALLOCATOR_H_