Heuristically predict interference on the back edge and use it to minimize number of register reshu…

runtime/vm/locations.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_LOCATIONS_H_
 #define VM_LOCATIONS_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/bitfield.h"
@@ skipping 259 matching lines @@
 
   const char* Name() const;
   void PrintTo(BufferFormatter* f) const;
   void Print() const;
 
   // Compare two locations.
   bool Equals(Location other) const {
     return value_ == other.value_;
   }
 
+  // If current location is constant might return something that
+  // is not equal to any Kind.
+  Kind kind() const {
+    return KindField::decode(value_);
+  }
+
  private:
   explicit Location(uword value) : value_(value) { }
 
   Location(Kind kind, uword payload)
       : value_(KindField::encode(kind) | PayloadField::encode(payload)) { }
 
   uword payload() const {
     return PayloadField::decode(value_);
   }
 
-  // If current location is constant might return something that
-  // is not equal to any Kind.
-  Kind kind() const {
-    return KindField::decode(value_);
-  }
-
   typedef BitField<Kind, 0, kBitsForKind> KindField;
   typedef BitField<uword, kBitsForKind, kBitsForPayload> PayloadField;
 
   // Layout for kUnallocated locations payload.
   typedef BitField<Policy, 0, 3> PolicyField;
 
   // Layout for register locations payload. The representation bit is only used
   // for XmmRegister and unused for Register.
   static const intptr_t kBitsForRepresentation = 1;
   static const intptr_t kBitsForRegister =
@@ skipping 163 matching lines @@
   BitmapBuilder* stack_bitmap_;
 
   const ContainsCall contains_call_;
   RegisterSet live_registers_;
 };
 
 
 }  // namespace dart
 
 #endif  // VM_LOCATIONS_H_