--- old/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.core/src/org/graalvm/compiler/core/target/Backend.java	2017-03-20 17:37:49.000000000 -0700
+++ new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.core/src/org/graalvm/compiler/core/target/Backend.java	2017-03-20 17:37:49.000000000 -0700
@@ -22,8 +22,6 @@
  */
 package org.graalvm.compiler.core.target;
 
-import java.util.Set;
-
 import org.graalvm.compiler.asm.Assembler;
 import org.graalvm.compiler.code.CompilationResult;
 import org.graalvm.compiler.core.common.CompilationIdentifier;
@@ -45,6 +43,7 @@
 import org.graalvm.compiler.phases.tiers.SuitesProvider;
 import org.graalvm.compiler.phases.tiers.TargetProvider;
 import org.graalvm.compiler.phases.util.Providers;
+import org.graalvm.util.EconomicSet;
 
 import jdk.vm.ci.code.BailoutException;
 import jdk.vm.ci.code.CodeCacheProvider;
@@ -113,7 +112,13 @@
      */
     public abstract FrameMapBuilder newFrameMapBuilder(RegisterConfig registerConfig);
 
-    public abstract RegisterAllocationConfig newRegisterAllocationConfig(RegisterConfig registerConfig);
+    /**
+     * Creates a new configuration for register allocation.
+     *
+     * @param allocationRestrictedTo if not {@code null}, register allocation will be restricted to
+     *            registers whose names appear in this array
+     */
+    public abstract RegisterAllocationConfig newRegisterAllocationConfig(RegisterConfig registerConfig, String[] allocationRestrictedTo);
 
     public abstract FrameMap newFrameMap(RegisterConfig registerConfig);
 
@@ -220,7 +225,7 @@
      * is needed for architectures where input/output registers are renamed during a call (e.g.
      * register windows on SPARC). Registers which are not visible by the caller are removed.
      */
-    public abstract Set<Register> translateToCallerRegisters(Set<Register> calleeRegisters);
+    public abstract EconomicSet<Register> translateToCallerRegisters(EconomicSet<Register> calleeRegisters);
 
     /**
      * Gets the compilation id for a given {@link ResolvedJavaMethod}. Returns