--- old/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.lir.amd64/src/org/graalvm/compiler/lir/amd64/AMD64ZapRegistersOp.java	2017-03-20 17:39:35.000000000 -0700
+++ new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.lir.amd64/src/org/graalvm/compiler/lir/amd64/AMD64ZapRegistersOp.java	2017-03-20 17:39:35.000000000 -0700
@@ -24,14 +24,13 @@
 
 import static org.graalvm.compiler.lir.amd64.AMD64SaveRegistersOp.prune;
 
-import java.util.Set;
-
 import org.graalvm.compiler.asm.amd64.AMD64MacroAssembler;
 import org.graalvm.compiler.lir.LIRInstructionClass;
 import org.graalvm.compiler.lir.Opcode;
 import org.graalvm.compiler.lir.StandardOp.SaveRegistersOp;
 import org.graalvm.compiler.lir.asm.CompilationResultBuilder;
 import org.graalvm.compiler.lir.framemap.FrameMap;
+import org.graalvm.util.EconomicSet;
 
 import jdk.vm.ci.code.Register;
 import jdk.vm.ci.code.RegisterSaveLayout;
@@ -76,7 +75,7 @@
     }
 
     @Override
-    public int remove(Set<Register> doNotSave) {
+    public int remove(EconomicSet<Register> doNotSave) {
         return prune(doNotSave, zappedRegisters);
     }