[turbofan] Split before loops.

src/compiler/greedy-allocator.h

 // Copyright 2015 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_GREEDY_ALLOCATOR_H_
 #define V8_GREEDY_ALLOCATOR_H_
 
 #include "src/compiler/coalesced-live-ranges.h"
 #include "src/compiler/register-allocator.h"
 #include "src/zone-containers.h"
@@ skipping 114 matching lines @@
   // This is the extension point for splitting heuristics.
   void SplitOrSpillBlockedRange(LiveRange* range);
 
   // Find a good position where to fill, after a range was spilled after a call.
   LifetimePosition FindSplitPositionAfterCall(const LiveRange* range,
                                               int call_index);
   // Split a range around all calls it passes over. Returns true if any changes
   // were made, or false if no calls were found.
   bool TrySplitAroundCalls(LiveRange* range);
 
+  // Find a split position at the outmost loop.
+  LifetimePosition FindSplitPositionBeforeLoops(LiveRange* range);
+
   // Finds the first call instruction in the path of this range. Splits before
   // and requeues that segment (if any), spills the section over the call, and
   // returns the section after the call. The return is:
   // - same range, if no call was found
   // - nullptr, if the range finished at the call and there's no "after the
   //   call" portion.
   // - the portion after the call.
   LiveRange* GetRemainderAfterSplittingAroundFirstCall(LiveRange* range);
 
   // Necessary heuristic: spill when all else failed.
   void SpillRangeAsLastResort(LiveRange* range);
 
   void AssignRangeToRegister(int reg_id, LiveRange* range);
 
   Zone* local_zone_;
   ZoneVector<CoalescedLiveRanges*> allocations_;
   AllocationScheduler scheduler_;
   DISALLOW_COPY_AND_ASSIGN(GreedyAllocator);
 };
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_GREEDY_ALLOCATOR_H_