--- a/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/Debug.java	Tue Sep 10 14:32:55 2013 +0200
+++ b/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/Debug.java	Tue Sep 10 15:40:28 2013 +0200
@@ -330,7 +330,7 @@
 
     public static DebugMetric metric(String name) {
         if (ENABLED) {
-            return new MetricImpl(name);
+            return new MetricImpl(name, true);
         } else {
             return VOID_METRIC;
         }
@@ -405,11 +405,19 @@
 
         public void add(long value) {
         }
+
+        public void setConditional(boolean flag) {
+            throw new InternalError("Cannot make void metric conditional");
+        }
+
+        public boolean isConditional() {
+            return false;
+        }
     };
 
     public static DebugTimer timer(String name) {
         if (ENABLED) {
-            return new TimerImpl(name);
+            return new TimerImpl(name, true);
         } else {
             return VOID_TIMER;
         }
@@ -420,5 +428,13 @@
         public TimerCloseable start() {
             return TimerImpl.VOID_CLOSEABLE;
         }
+
+        public void setConditional(boolean flag) {
+            throw new InternalError("Cannot make void timer conditional");
+        }
+
+        public boolean isConditional() {
+            return false;
+        }
     };
 }

--- a/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/DebugMetric.java	Tue Sep 10 14:32:55 2013 +0200
+++ b/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/DebugMetric.java	Tue Sep 10 15:40:28 2013 +0200
@@ -22,9 +22,32 @@
  */
 package com.oracle.graal.debug;
 
+/**
+ * A counter for some value of interest.
+ */
 public interface DebugMetric {
 
+    /**
+     * Adds 1 to this counter if metering is {@link Debug#isMeterEnabled() enabled} or this is an
+     * {@linkplain #isConditional() unconditional} metric.
+     */
     void increment();
 
+    /**
+     * Adds {@code value} to this counter if metering is {@link Debug#isMeterEnabled() enabled} or
+     * this is an {@linkplain #isConditional() unconditional} metric.
+     */
     void add(long value);
+
+    /**
+     * Sets a flag determining if this counter is only enabled if metering is
+     * {@link Debug#isMeterEnabled() enabled}.
+     */
+    void setConditional(boolean flag);
+
+    /**
+     * Determines if this counter is only enabled if metering is {@link Debug#isMeterEnabled()
+     * enabled}.
+     */
+    boolean isConditional();
 }

--- a/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/DebugTimer.java	Tue Sep 10 14:32:55 2013 +0200
+++ b/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/DebugTimer.java	Tue Sep 10 15:40:28 2013 +0200
@@ -24,7 +24,36 @@
 
 import com.oracle.graal.debug.internal.*;
 
+/**
+ * A timer for some activity of interest. A timer should be deployed using the try-with-resources
+ * pattern:
+ * 
+ * <pre>
+ * try (TimerCloseable a = timer.start()) {
+ *     // the code to time
+ * }
+ * </pre>
+ */
 public interface DebugTimer {
 
+    /**
+     * Starts this timer if timing is {@linkplain Debug#isTimeEnabled() enabled} or this is an
+     * {@linkplain #isConditional() unconditional} timer.
+     * 
+     * @return an object that must be closed once the activity has completed to add the elapsed time
+     *         since this call to the total for this timer
+     */
     TimerCloseable start();
+
+    /**
+     * Sets a flag determining if this timer is only enabled if metering is
+     * {@link Debug#isMeterEnabled() enabled}.
+     */
+    void setConditional(boolean flag);
+
+    /**
+     * Determines if this timer is only enabled if metering is {@link Debug#isMeterEnabled()
+     * enabled}.
+     */
+    boolean isConditional();
 }

--- a/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/internal/MetricImpl.java	Tue Sep 10 14:32:55 2013 +0200
+++ b/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/internal/MetricImpl.java	Tue Sep 10 15:40:28 2013 +0200
@@ -26,8 +26,11 @@
 
 public final class MetricImpl extends DebugValue implements DebugMetric {
 
-    public MetricImpl(String name) {
+    private boolean conditional;
+
+    public MetricImpl(String name, boolean conditional) {
         super(name);
+        this.conditional = conditional;
     }
 
     public void increment() {
@@ -35,7 +38,7 @@
     }
 
     public void add(long value) {
-        if (Debug.isMeterEnabled()) {
+        if (!conditional || Debug.isMeterEnabled()) {
             super.addToCurrentValue(value);
         }
     }
@@ -44,4 +47,12 @@
     public String toString(long value) {
         return Long.toString(value);
     }
+
+    public void setConditional(boolean flag) {
+        conditional = flag;
+    }
+
+    public boolean isConditional() {
+        return conditional;
+    }
 }

--- a/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/internal/TimerCloseable.java	Tue Sep 10 14:32:55 2013 +0200
+++ b/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/internal/TimerCloseable.java	Tue Sep 10 15:40:28 2013 +0200
@@ -22,6 +22,12 @@
  */
 package com.oracle.graal.debug.internal;
 
+import com.oracle.graal.debug.*;
+
+/**
+ * An object returned by {@link DebugTimer#start()} that when closed, stops the associated timer and
+ * adds the elapsed time since {@code start()} to the total for the timer.
+ */
 public interface TimerCloseable extends AutoCloseable {
 
     void close();

--- a/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/internal/TimerImpl.java	Tue Sep 10 14:32:55 2013 +0200
+++ b/graal/com.oracle.graal.debug/src/com/oracle/graal/debug/internal/TimerImpl.java	Tue Sep 10 15:40:28 2013 +0200
@@ -38,9 +38,19 @@
     };
 
     private ThreadLocal<Long> valueToSubstract = new ThreadLocal<>();
+    private boolean conditional;
 
-    public TimerImpl(String name) {
+    public TimerImpl(String name, boolean conditional) {
         super(name);
+        this.conditional = conditional;
+    }
+
+    public void setConditional(boolean flag) {
+        conditional = flag;
+    }
+
+    public boolean isConditional() {
+        return conditional;
     }
 
     @Override