# HG changeset patch
# User Bernhard Urban <bernhard.urban@jku.at>
# Date 1377790102 -7200
# Node ID 2da44804f720bdaffd84a1eed47131e8ce680c79
# Parent  ac2bddbe3b5176abf13fb04ed8298788f00a6adc
LoweringPhase: move detection of first lastFixedNode out of the loop, add comment

diff -r ac2bddbe3b51 -r 2da44804f720 graal/com.oracle.graal.phases.common/src/com/oracle/graal/phases/common/LoweringPhase.java
--- a/graal/com.oracle.graal.phases.common/src/com/oracle/graal/phases/common/LoweringPhase.java	Thu Aug 29 17:28:21 2013 +0200
+++ b/graal/com.oracle.graal.phases.common/src/com/oracle/graal/phases/common/LoweringPhase.java	Thu Aug 29 17:28:22 2013 +0200
@@ -128,7 +128,7 @@
         }
 
         private void setLastFixedNode(FixedWithNextNode n) {
-            assert n == null || n.isAlive() : n;
+            assert n.isAlive() : n;
             lastFixedNode = n;
         }
     }
@@ -220,7 +220,7 @@
 
             // Lower the instructions of this block.
             List<ScheduledNode> nodes = schedule.nodesFor(b);
-            loweringTool.setLastFixedNode(null);
+            loweringTool.setLastFixedNode(b.getBeginNode());
             for (Node node : nodes) {
 
                 if (node.isDeleted()) {
@@ -228,23 +228,11 @@
                     continue;
                 }
 
-                if (loweringTool.lastFixedNode() == null) {
-                    AbstractBeginNode beginNode = b.getBeginNode();
-                    if (node == beginNode) {
-                        loweringTool.setLastFixedNode(beginNode);
-                    } else {
-                        assert !(node instanceof Lowerable) : "SchedulingError: Lowerable " + node + " should not float before begin node " + beginNode;
-                        assert node instanceof FloatingNode : "skipped node must be a FloatingNode: " + node;
-                        continue;
-                    }
-                }
-
                 // Cache the next node to be able to reconstruct the previous of the next node
                 // after lowering.
                 FixedNode nextNode = null;
                 if (node instanceof FixedWithNextNode) {
-                    FixedWithNextNode fixed = (FixedWithNextNode) node;
-                    nextNode = fixed.next();
+                    nextNode = ((FixedWithNextNode) node).next();
                 } else {
                     nextNode = loweringTool.lastFixedNode().next();
                 }
@@ -255,6 +243,8 @@
                 }
 
                 if (!nextNode.isAlive()) {
+                    // can happen when the rest of the block is killed by lowering (e.g. by a
+                    // unconditional deopt)
                     break;
                 } else {
                     Node nextLastFixed = nextNode.predecessor();