# HG changeset patch
# User Christos Kotselidis <christos.kotselidis@oracle.com>
# Date 1371820306 -7200
# Node ID d18fbe96ba76fb9e8b136615fc9f6a5174c12e05
# Parent  0fe1b0886dbf69a021490546132b215ab3a7693d
Attach G1 Pre barrier to load field of referent field

diff -r 0fe1b0886dbf -r d18fbe96ba76 graal/com.oracle.graal.hotspot/src/com/oracle/graal/hotspot/meta/HotSpotRuntime.java
--- a/graal/com.oracle.graal.hotspot/src/com/oracle/graal/hotspot/meta/HotSpotRuntime.java	Fri Jun 21 15:03:26 2013 +0200
+++ b/graal/com.oracle.graal.hotspot/src/com/oracle/graal/hotspot/meta/HotSpotRuntime.java	Fri Jun 21 15:11:46 2013 +0200
@@ -534,7 +534,8 @@
             HotSpotResolvedJavaField field = (HotSpotResolvedJavaField) loadField.field();
             ValueNode object = loadField.isStatic() ? ConstantNode.forObject(field.getDeclaringClass().mirror(), this, graph) : loadField.object();
             assert loadField.kind() != Kind.Illegal;
-            ReadNode memoryRead = graph.add(new ReadNode(object, createFieldLocation(graph, field), loadField.stamp(), WriteBarrierType.NONE, (loadField.kind() == Kind.Object)));
+            WriteBarrierType barrierType = getFieldLoadBarrierType(field);
+            ReadNode memoryRead = graph.add(new ReadNode(object, createFieldLocation(graph, field), loadField.stamp(), barrierType, (loadField.kind() == Kind.Object)));
             tool.createNullCheckGuard(memoryRead, object);
 
             graph.replaceFixedWithFixed(loadField, memoryRead);
@@ -828,6 +829,14 @@
         return hub;
     }
 
+    private static WriteBarrierType getFieldLoadBarrierType(HotSpotResolvedJavaField loadField) {
+        WriteBarrierType barrierType = WriteBarrierType.NONE;
+        if (config().useG1GC && loadField.getKind() == Kind.Object && loadField.getDeclaringClass().mirror() == java.lang.ref.Reference.class && loadField.getName().equals("referent")) {
+            barrierType = WriteBarrierType.PRECISE;
+        }
+        return barrierType;
+    }
+
     private static WriteBarrierType getFieldStoreBarrierType(StoreFieldNode storeField) {
         WriteBarrierType barrierType = WriteBarrierType.NONE;
         if (storeField.field().getKind() == Kind.Object && !storeField.value().objectStamp().alwaysNull()) {