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view graal/GraalCompiler/src/com/sun/c1x/graph/CriticalEdgeFinder.java @ 2706:5a784215351a
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author | Thomas Wuerthinger <thomas@wuerthinger.net> |
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date | Wed, 18 May 2011 17:35:14 +0200 |
parents | 6ab73784566a |
children | 27512ea6bbcb |
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/* * Copyright (c) 2009, 2010, 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.sun.c1x.graph; import java.util.*; import com.sun.c1x.*; import com.sun.c1x.debug.*; import com.sun.c1x.ir.*; /** * This class finds and splits "critical" edges in the control flow graph. * An edge between two blocks {@code A} and {@code B} is "critical" if {@code A} * has more than one successor and {@code B} has more than one predecessor. Such * edges are split by adding a block between the two blocks. */ public class CriticalEdgeFinder implements BlockClosure { private final IR ir; /** * The graph edges represented as a map from source to target nodes. * Using a linked hash map makes compilation tracing more deterministic and thus eases debugging. */ private Map<BlockBegin, Set<BlockBegin>> edges = C1XOptions.DetailedAsserts ? new LinkedHashMap<BlockBegin, Set<BlockBegin>>() : new HashMap<BlockBegin, Set<BlockBegin>>(); public CriticalEdgeFinder(IR ir) { this.ir = ir; } public void apply(BlockBegin block) { if (block.numberOfSux() >= 2) { for (BlockBegin succ : block.end().blockSuccessors()) { if (succ.numberOfPreds() >= 2) { // TODO: (tw) probably we don't have to make it a critical edge if succ only contains the _same_ predecessor multiple times. recordCriticalEdge(block, succ); } } } } private void recordCriticalEdge(BlockBegin block, BlockBegin succ) { if (!edges.containsKey(block)) { edges.put(block, new HashSet<BlockBegin>()); } edges.get(block).add(succ); } public void splitCriticalEdges() { for (Map.Entry<BlockBegin, Set<BlockBegin>> entry : edges.entrySet()) { BlockBegin from = entry.getKey(); for (BlockBegin to : entry.getValue()) { BlockBegin split = ir.splitEdge(from, to); if (C1XOptions.PrintHIR) { TTY.println("Split edge between block %d and block %d, creating new block %d", from.blockID, to.blockID, split.blockID); } } } } }