001 /*
002 * This file is part of the Jikes RVM project (http://jikesrvm.org).
003 *
004 * This file is licensed to You under the Eclipse Public License (EPL);
005 * You may not use this file except in compliance with the License. You
006 * may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/eclipse-1.0.php
009 *
010 * See the COPYRIGHT.txt file distributed with this work for information
011 * regarding copyright ownership.
012 */
013 package org.jikesrvm.compilers.opt.controlflow;
014
015 import java.lang.reflect.Constructor;
016
017 import org.jikesrvm.compilers.opt.OperationNotImplementedException;
018 import org.jikesrvm.compilers.opt.OptOptions;
019 import org.jikesrvm.compilers.opt.driver.CompilerPhase;
020 import org.jikesrvm.compilers.opt.driver.OptimizingCompiler;
021 import org.jikesrvm.compilers.opt.ir.IR;
022
023 /**
024 * Driver routine for dominator computation. This phase invokes
025 * the Lengauer-Tarjan dominator calculation.
026 */
027 public final class DominatorsPhase extends CompilerPhase {
028
029 /**
030 * Should we unfactor the CFG?
031 */
032 private final boolean unfactor;
033
034 /**
035 * @param unfactor Should we unfactor the CFG before computing
036 * dominators?
037 */
038 public DominatorsPhase(boolean unfactor) {
039 super(new Object[]{unfactor});
040 this.unfactor = unfactor;
041 }
042
043 /**
044 * Constructor for this compiler phase
045 */
046 private static final Constructor<CompilerPhase> constructor =
047 getCompilerPhaseConstructor(DominatorsPhase.class, new Class[]{Boolean.TYPE});
048
049 /**
050 * Get a constructor object for this compiler phase
051 * @return compiler phase constructor
052 */
053 @Override
054 public Constructor<CompilerPhase> getClassConstructor() {
055 return constructor;
056 }
057
058 /**
059 * Should this phase be performed? This is a member of a composite
060 * phase, so always return true. The parent composite phase will
061 * dictate.
062 * @param options controlling compiler options
063 * @return {@code true}
064 */
065 @Override
066 public boolean shouldPerform(OptOptions options) {
067 return true;
068 }
069
070 /**
071 * Return a string representation of this phase
072 * @return "Dominators + LpStrTree"
073 */
074 @Override
075 public String getName() {
076 return "Dominators + LpStrTree";
077 }
078
079 /**
080 * Should the IR be printed before and/or after this phase?
081 * @param options controlling compiler options
082 * @param before query control
083 * @return {@code false}
084 */
085 @Override
086 public boolean printingEnabled(OptOptions options, boolean before) {
087 return false;
088 }
089
090 /**
091 * Main driver for the dominator calculation.
092 */
093 @Override
094 public void perform(IR ir) {
095 try {
096 // reset flags in case an exception is thrown inside "perform"
097 // and it doesn't return normally
098 ir.HIRInfo.dominatorsAreComputed = false;
099
100 // compute (forward) dominators,
101 // leaves info in scratch object of basic blocks
102 LTDominators.perform(ir, true, unfactor);
103
104 // create the dominator tree, relies on dominator info being
105 // in scratch object of basic blocks
106 DominatorTree.perform(ir, true);
107
108 // create the loop structured tree (LST)
109 LSTGraph.perform(ir);
110
111 // computation completed, so set flag
112 ir.HIRInfo.dominatorsAreComputed = true;
113 } catch (OperationNotImplementedException e) {
114 OptimizingCompiler.report(e.getMessage());
115 }
116 }
117 }