check if we can split (linear scan)

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/ostreams.h"
 #include "src/register-configuration.h"
@@ skipping 28 matching lines @@
   // the gap with the given index.
   static LifetimePosition GapFromInstructionIndex(int index) {
     return LifetimePosition(index * kStep);
   }
   // Return the lifetime position that corresponds to the beginning of
   // the instruction with the given index.
   static LifetimePosition InstructionFromInstructionIndex(int index) {
     return LifetimePosition(index * kStep + kHalfStep);
   }
 
+  static bool ExistsGapPositionBetween(LifetimePosition pos1,
+                                       LifetimePosition pos2) {
+    if (pos1 > pos2) std::swap(pos1, pos2);
+    LifetimePosition next(pos1.value_ + 1);
+    if (next.IsGapPosition()) return next < pos2;
+    return next.NextFullStart() < pos2;
+  }
+
   // Returns a numeric representation of this lifetime position.
   int value() const { return value_; }
 
   // Returns the index of the instruction to which this lifetime position
   // corresponds.
   int ToInstructionIndex() const {
     DCHECK(IsValid());
     return value_ / kStep;
   }
 
@@ skipping 1130 matching lines @@
   RegisterAllocationData* const data_;
 
   DISALLOW_COPY_AND_ASSIGN(LiveRangeConnector);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REGISTER_ALLOCATOR_H_