--- a/graal/com.oracle.graal.replacements/src/com/oracle/graal/replacements/nodes/BranchProbabilityNode.java	Thu Apr 25 17:42:55 2013 +0200
+++ b/graal/com.oracle.graal.replacements/src/com/oracle/graal/replacements/nodes/BranchProbabilityNode.java	Thu Apr 25 18:11:30 2013 +0200
@@ -22,6 +22,7 @@
  */
 package com.oracle.graal.replacements.nodes;
 
+import com.oracle.graal.graph.*;
 import com.oracle.graal.nodes.*;
 import com.oracle.graal.nodes.spi.*;
 import com.oracle.graal.nodes.type.*;
@@ -32,7 +33,7 @@
  * the if node's taken probability. Then the branch probability node will be removed. This node is
  * intended primarily for snippets, so that they can define their fast and slow paths.
  */
-public class BranchProbabilityNode extends FixedWithNextNode implements Simplifiable {
+public class BranchProbabilityNode extends FixedWithNextNode implements Simplifiable, Lowerable {
 
     public static final double LIKELY_PROBABILITY = 0.6;
     public static final double NOT_LIKELY_PROBABILITY = 1 - LIKELY_PROBABILITY;
@@ -46,38 +47,52 @@
     public static final double NOT_DEOPT_PATH_PROBABILITY = 0.999;
     public static final double DEOPT_PATH_PROBABILITY = 1 - NOT_DEOPT_PATH_PROBABILITY;
 
-    private final double probability;
+    @Input private ValueNode probability;
 
-    public BranchProbabilityNode(double probability) {
+    public BranchProbabilityNode(ValueNode probability) {
         super(StampFactory.forVoid());
-        assert probability >= 0 && probability <= 1;
         this.probability = probability;
     }
 
     @Override
     public void simplify(SimplifierTool tool) {
-        FixedNode current = this;
-        while (!(current instanceof BeginNode)) {
-            current = (FixedNode) current.predecessor();
+        if (probability.isConstant()) {
+            double probabilityValue = probability.asConstant().asDouble();
+            if (probabilityValue < 0.0) {
+                throw new GraalInternalError("A negative probability of " + probabilityValue + " is not allowed!");
+            } else if (probabilityValue > 1.0) {
+                throw new GraalInternalError("A probability of more than 1.0 (" + probabilityValue + ") is not allowed!");
+            }
+            FixedNode current = this;
+            while (!(current instanceof BeginNode)) {
+                current = (FixedNode) current.predecessor();
+            }
+            BeginNode begin = (BeginNode) current;
+            if (!(begin.predecessor() instanceof IfNode)) {
+                throw new GraalInternalError("Injected branch probability cannot follow a merge, only if nodes");
+            }
+            IfNode ifNode = (IfNode) begin.predecessor();
+            if (ifNode.trueSuccessor() == begin) {
+                ifNode.setTrueSuccessorProbability(probabilityValue);
+            } else {
+                ifNode.setTrueSuccessorProbability(1 - probabilityValue);
+            }
+
+            FixedNode next = next();
+            setNext(null);
+            ((FixedWithNextNode) predecessor()).setNext(next);
+            GraphUtil.killCFG(this);
         }
-        BeginNode begin = (BeginNode) current;
-        assert begin.predecessor() instanceof IfNode : "explicit branch probability cannot follow a merge, only if nodes";
-        IfNode ifNode = (IfNode) begin.predecessor();
-        if (ifNode.trueSuccessor() == begin) {
-            ifNode.setTrueSuccessorProbability(probability);
-        } else {
-            ifNode.setTrueSuccessorProbability(1 - probability);
-        }
-
-        FixedNode next = next();
-        setNext(null);
-        ((FixedWithNextNode) predecessor()).setNext(next);
-        GraphUtil.killCFG(this);
     }
 
     @SuppressWarnings("unused")
     @NodeIntrinsic
-    public static void probability(@ConstantNodeParameter double probability) {
+    public static void probability(double probability) {
+    }
+
+    @Override
+    public void lower(LoweringTool tool, LoweringType loweringType) {
+        throw new GraalInternalError("Branch probability could not be injected, because the probability value did not reduce to a constant value.");
     }
 
 }