--- a/graal/com.oracle.graal.compiler.common/src/com/oracle/graal/compiler/common/cfg/AbstractControlFlowGraph.java	Fri Feb 27 20:17:59 2015 +0100
+++ b/graal/com.oracle.graal.compiler.common/src/com/oracle/graal/compiler/common/cfg/AbstractControlFlowGraph.java	Fri Feb 27 15:34:43 2015 -0800
@@ -24,8 +24,6 @@
 
 import java.util.*;
 
-import com.oracle.graal.compiler.common.*;
-
 public interface AbstractControlFlowGraph<T extends AbstractBlockBase<T>> {
 
     int BLOCK_ID_INITIAL = -1;
@@ -73,26 +71,22 @@
      * True if block {@code a} is dominated by block {@code b}.
      */
     static boolean isDominatedBy(AbstractBlockBase<?> a, AbstractBlockBase<?> b) {
-        assert a != null;
-        AbstractBlockBase<?> dominator = a;
-        int i = 0;
-        while (dominator != null) {
-            if (i++ == Integer.MAX_VALUE) { // For safety
-                throw GraalInternalError.shouldNotReachHere();
-            }
-            if (dominator == b) {
-                return true;
-            }
-            dominator = dominator.getDominator();
+        assert a != null && b != null;
+        if (a == b) {
+            return true;
         }
-        return false;
+        if (a.getDominatorDepth() < b.getDominatorDepth()) {
+            return false;
+        }
+
+        return b == (AbstractBlockBase<?>) a.getDominator(a.getDominatorDepth() - b.getDominatorDepth());
     }
 
     /**
      * True if block {@code a} dominates block {@code b}.
      */
     static boolean dominates(AbstractBlockBase<?> a, AbstractBlockBase<?> b) {
-        assert a != null;
+        assert a != null && b != null;
         return isDominatedBy(b, a);
     }