# HG changeset patch
# User Tom Rodriguez <tom.rodriguez@oracle.com>
# Date 1439248963 25200
# Node ID b20e743478d3da2d335bfeb1e7edfe394a442e7a
# Parent  c96f260ac76d90a48d2ab96dffd7934ebf662466
Unguarded floating read should adopt Pi guard if possible

diff -r c96f260ac76d -r b20e743478d3 graal/com.oracle.graal.nodes/src/com/oracle/graal/nodes/memory/FloatingReadNode.java
--- a/graal/com.oracle.graal.nodes/src/com/oracle/graal/nodes/memory/FloatingReadNode.java	Mon Aug 10 16:22:28 2015 -0700
+++ b/graal/com.oracle.graal.nodes/src/com/oracle/graal/nodes/memory/FloatingReadNode.java	Mon Aug 10 16:22:43 2015 -0700
@@ -75,9 +75,17 @@
     public Node canonical(CanonicalizerTool tool) {
         if (getAddress() instanceof OffsetAddressNode) {
             OffsetAddressNode objAddress = (OffsetAddressNode) getAddress();
-            if (objAddress.getBase() instanceof PiNode && ((PiNode) objAddress.getBase()).getGuard() == getGuard()) {
-                OffsetAddressNode newAddress = new OffsetAddressNode(((PiNode) objAddress.getBase()).getOriginalNode(), objAddress.getOffset());
-                return new FloatingReadNode(newAddress, getLocationIdentity(), getLastLocationAccess(), stamp(), getGuard(), getBarrierType());
+            if (objAddress.getBase() instanceof PiNode) {
+                PiNode piBase = (PiNode) objAddress.getBase();
+                /*
+                 * If the Pi and the read have the same guard or the read is unguarded, use the
+                 * guard of the Pi along with the original value. This encourages a canonical form
+                 * guarded reads.
+                 */
+                if (piBase.getGuard() == getGuard() || getGuard() == null) {
+                    OffsetAddressNode newAddress = new OffsetAddressNode(piBase.getOriginalNode(), objAddress.getOffset());
+                    return new FloatingReadNode(newAddress, getLocationIdentity(), getLastLocationAccess(), stamp(), getGuard() == null ? piBase.getGuard() : getGuard(), getBarrierType());
+                }
             }
         }
         return ReadNode.canonicalizeRead(this, getAddress(), getLocationIdentity(), tool);