--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.graal.snippets/src/com/oracle/graal/replacements/SnippetFrameStateCleanupPhase.java	Wed Mar 20 22:23:14 2013 +0100
@@ -0,0 +1,119 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.graal.replacements;
+
+import java.util.*;
+
+import com.oracle.graal.nodes.*;
+import com.oracle.graal.nodes.util.*;
+import com.oracle.graal.phases.*;
+import com.oracle.graal.phases.graph.*;
+import com.oracle.graal.phases.graph.ReentrantNodeIterator.LoopInfo;
+import com.oracle.graal.phases.graph.ReentrantNodeIterator.NodeIteratorClosure;
+
+/**
+ * Removes frame states from {@linkplain StateSplit#hasSideEffect() non-side-effecting} nodes in a
+ * snippet.
+ * 
+ * The frame states of side-effecting nodes are replaced with
+ * {@linkplain FrameState#INVALID_FRAMESTATE_BCI invalid} frame states. Loops that contain invalid
+ * frame states are also assigned an invalid frame state.
+ * 
+ * The invalid frame states ensure that no deoptimization to a snippet frame state will happen.
+ */
+public class SnippetFrameStateCleanupPhase extends Phase {
+
+    @Override
+    protected void run(StructuredGraph graph) {
+        ReentrantNodeIterator.apply(new SnippetFrameStateCleanupClosure(), graph.start(), new CleanupState(false), null);
+    }
+
+    private static class CleanupState {
+
+        public boolean containsFrameState;
+
+        public CleanupState(boolean containsFrameState) {
+            this.containsFrameState = containsFrameState;
+        }
+    }
+
+    /**
+     * A proper (loop-aware) iteration over the graph is used to detect loops that contain invalid
+     * frame states, so that they can be marked with an invalid frame state.
+     */
+    private static class SnippetFrameStateCleanupClosure extends NodeIteratorClosure<CleanupState> {
+
+        @Override
+        protected void processNode(FixedNode node, CleanupState currentState) {
+            if (node instanceof StateSplit) {
+                StateSplit stateSplit = (StateSplit) node;
+                FrameState frameState = stateSplit.stateAfter();
+                if (frameState != null) {
+                    if (stateSplit.hasSideEffect()) {
+                        currentState.containsFrameState = true;
+                        stateSplit.setStateAfter(node.graph().add(new FrameState(FrameState.INVALID_FRAMESTATE_BCI)));
+                    } else {
+                        stateSplit.setStateAfter(null);
+                    }
+                    if (frameState.usages().isEmpty()) {
+                        GraphUtil.killWithUnusedFloatingInputs(frameState);
+                    }
+                }
+            }
+        }
+
+        @Override
+        protected CleanupState merge(MergeNode merge, List<CleanupState> states) {
+            for (CleanupState state : states) {
+                if (state.containsFrameState) {
+                    return new CleanupState(true);
+                }
+            }
+            return new CleanupState(false);
+        }
+
+        @Override
+        protected CleanupState afterSplit(BeginNode node, CleanupState oldState) {
+            return new CleanupState(oldState.containsFrameState);
+        }
+
+        @Override
+        protected Map<LoopExitNode, CleanupState> processLoop(LoopBeginNode loop, CleanupState initialState) {
+            LoopInfo<CleanupState> info = ReentrantNodeIterator.processLoop(this, loop, new CleanupState(false));
+            boolean containsFrameState = false;
+            for (CleanupState state : info.endStates.values()) {
+                containsFrameState |= state.containsFrameState;
+            }
+            if (containsFrameState) {
+                loop.setStateAfter(loop.graph().add(new FrameState(FrameState.INVALID_FRAMESTATE_BCI)));
+            }
+            if (containsFrameState || initialState.containsFrameState) {
+                for (CleanupState state : info.exitStates.values()) {
+                    state.containsFrameState = true;
+                }
+            }
+            return info.exitStates;
+        }
+
+    }
+}