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

runtime/vm/locations.h

Index: runtime/vm/locations.h
diff --git a/runtime/vm/locations.h b/runtime/vm/locations.h
index 4522b1aba725967d89ab3c732c4990c6c7441332..0c2bc097b9212d1ffceddd5228490139274ed677 100644
--- a/runtime/vm/locations.h
+++ b/runtime/vm/locations.h
@@ -277,6 +277,12 @@ class Location : public ValueObject {
     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) { }
 
@@ -287,12 +293,6 @@ class Location : public ValueObject {
     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;