Mercurial > hg > graal-compiler
view graal/com.oracle.graal.phases.common/src/com/oracle/graal/phases/common/DeadCodeEliminationPhase.java @ 8602:db2b8fbbf8fc
Merge.
author | Roland Schatz <roland.schatz@oracle.com> |
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date | Tue, 02 Apr 2013 12:57:58 +0200 |
parents | 5e3d1a68664e |
children | 71ebe4030676 |
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/* * 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.phases.common; import com.oracle.graal.debug.*; import com.oracle.graal.graph.*; import com.oracle.graal.nodes.*; import com.oracle.graal.phases.*; public class DeadCodeEliminationPhase extends Phase { // Metrics private static final DebugMetric metricNodesRemoved = Debug.metric("NodesRemoved"); private NodeFlood flood; @Override protected void run(StructuredGraph graph) { this.flood = graph.createNodeFlood(); flood.add(graph.start()); iterateSuccessors(); disconnectCFGNodes(graph); iterateInputs(graph); deleteNodes(graph); // remove chained Merges for (MergeNode merge : graph.getNodes(MergeNode.class)) { if (merge.forwardEndCount() == 1 && !(merge instanceof LoopBeginNode)) { graph.reduceTrivialMerge(merge); } } } private void iterateSuccessors() { for (Node current : flood) { if (current instanceof EndNode) { EndNode end = (EndNode) current; flood.add(end.merge()); } else { for (Node successor : current.successors()) { flood.add(successor); } } } } private void disconnectCFGNodes(StructuredGraph graph) { for (EndNode node : graph.getNodes(EndNode.class)) { if (!flood.isMarked(node)) { MergeNode merge = node.merge(); if (merge != null && flood.isMarked(merge)) { // We are a dead end node leading to a live merge. merge.removeEnd(node); } } } for (LoopBeginNode loop : graph.getNodes(LoopBeginNode.class)) { if (flood.isMarked(loop)) { boolean reachable = false; for (LoopEndNode end : loop.loopEnds()) { if (flood.isMarked(end)) { reachable = true; break; } } if (!reachable) { Debug.log("Removing loop with unreachable end: %s", loop); for (LoopEndNode end : loop.loopEnds().snapshot()) { loop.removeEnd(end); } graph.reduceDegenerateLoopBegin(loop); } } } } private void deleteNodes(StructuredGraph graph) { for (Node node : graph.getNodes()) { if (!flood.isMarked(node)) { node.clearInputs(); node.clearSuccessors(); } } for (Node node : graph.getNodes()) { if (!flood.isMarked(node)) { metricNodesRemoved.increment(); node.safeDelete(); } } } private void iterateInputs(StructuredGraph graph) { for (Node node : graph.getNodes()) { if (node instanceof LocalNode) { flood.add(node); } if (flood.isMarked(node)) { for (Node input : node.inputs()) { flood.add(input); } } } for (Node current : flood) { for (Node input : current.inputs()) { flood.add(input); } } } }