Rematerialize constants instead of spilling them.

runtime/vm/flow_graph_allocator.h

Index: runtime/vm/flow_graph_allocator.h
diff --git a/runtime/vm/flow_graph_allocator.h b/runtime/vm/flow_graph_allocator.h
index f8b62f30681d287feb2c32ee92070d0dcb73579c..ab788297597d6f1a9a621a2b9e6c01e33ba1c396 100644
--- a/runtime/vm/flow_graph_allocator.h
+++ b/runtime/vm/flow_graph_allocator.h
@@ -126,6 +126,8 @@ class FlowGraphAllocator : public ValueObject {
                             BlockEntryInstr* source_block,
                             BlockEntryInstr* target_block);
 
+  // Returns true if the target location is the spill slot for the given range.
+  bool TargetLocationIsSpillSlot(LiveRange* range, Location target);
 
   // Update location slot corresponding to the use with location allocated for
   // the use's live range.