Mercurial > hg > graal-jvmci-8
diff graal/Compiler/src/com/sun/c1x/graph/CriticalEdgeFinder.java @ 2507:9ec15d6914ca
Pull over of compiler from maxine repository.
author | Thomas Wuerthinger <thomas@wuerthinger.net> |
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date | Wed, 27 Apr 2011 11:43:22 +0200 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/graal/Compiler/src/com/sun/c1x/graph/CriticalEdgeFinder.java Wed Apr 27 11:43:22 2011 +0200 @@ -0,0 +1,84 @@ +/* + * 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. + * + * @author Thomas Wuerthinger + */ +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().successors()) { + 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 (BlockBegin from : edges.keySet()) { + for (BlockBegin to : edges.get(from)) { + 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); + } + } + } + } +}