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.ssa;
014
015 import java.lang.reflect.Constructor;
016
017 import org.jikesrvm.compilers.opt.DefUse;
018 import org.jikesrvm.compilers.opt.ExpressionFolding;
019 import org.jikesrvm.compilers.opt.OptOptions;
020 import org.jikesrvm.compilers.opt.Simple;
021 import org.jikesrvm.compilers.opt.controlflow.DominanceFrontier;
022 import org.jikesrvm.compilers.opt.controlflow.DominatorsPhase;
023 import org.jikesrvm.compilers.opt.driver.CompilerPhase;
024 import org.jikesrvm.compilers.opt.driver.OptimizationPlanAtomicElement;
025 import org.jikesrvm.compilers.opt.driver.OptimizationPlanCompositeElement;
026 import org.jikesrvm.compilers.opt.driver.OptimizationPlanElement;
027 import org.jikesrvm.compilers.opt.ir.IR;
028
029 /**
030 * This phase puts the IR in SSA form and performs a set of simple
031 * optimizations to clean up.
032 */
033 public final class SSATuneUp extends OptimizationPlanCompositeElement {
034
035 /**
036 * Build this phase as a composite of others.
037 */
038 public SSATuneUp() {
039 super("SSA Tune Up", new OptimizationPlanElement[]{
040 // 1. Set up IR state to control SSA translation as needed
041 new OptimizationPlanAtomicElement(new TuneUpPreparation()),
042 // 2. Get the desired SSA form
043 new OptimizationPlanAtomicElement(new EnterSSA()),
044 // 3. Perform simple optimizations
045 new OptimizationPlanAtomicElement(new Simple(1, true, true, false, false)),
046 // 4. Perform expression simplification
047 new OptimizationPlanAtomicElement(new FoldingDriver())});
048 }
049
050 @Override
051 public boolean shouldPerform(OptOptions options) {
052 return options.SSA;
053 }
054
055 /**
056 * This class drives expression folding.
057 */
058 private static class FoldingDriver extends CompilerPhase {
059
060 /**
061 * Return this instance of this phase. This phase contains no
062 * per-compilation instance fields.
063 * @param ir not used
064 * @return this
065 */
066 @Override
067 public CompilerPhase newExecution(IR ir) {
068 return this;
069 }
070
071 @Override
072 public final boolean shouldPerform(OptOptions options) {
073 return options.SSA && options.SSA_EXPRESSION_FOLDING;
074 }
075
076 @Override
077 public final String getName() {
078 return "SSA Expression Folding";
079 }
080
081 /**
082 * Execute expression folding.
083 */
084 @Override
085 public final void perform(IR ir) {
086 DefUse.computeDU(ir);
087 ExpressionFolding.perform(ir);
088 }
089 }
090
091 /**
092 * This class sets up the IR state prior to entering SSA.
093 */
094 public static class TuneUpPreparation extends CompilerPhase {
095
096 /**
097 * Compiler phases necessary to re-build dominators and dominance
098 * frontier
099 */
100 private final CompilerPhase dominators, frontier;
101
102 public TuneUpPreparation() {
103 dominators = new DominatorsPhase(true);
104 frontier = new DominanceFrontier();
105 }
106
107 /**
108 * Constructor for this compiler phase
109 */
110 private static final Constructor<CompilerPhase> constructor =
111 getCompilerPhaseConstructor(TuneUpPreparation.class);
112
113 /**
114 * Get a constructor object for this compiler phase
115 * @return compiler phase constructor
116 */
117 @Override
118 public Constructor<CompilerPhase> getClassConstructor() {
119 return constructor;
120 }
121
122 @Override
123 public final boolean shouldPerform(OptOptions options) {
124 return options.SSA;
125 }
126
127 @Override
128 public final String getName() {
129 return "SSA Tune UpPreparation";
130 }
131
132 /**
133 * register in the IR the SSA properties we need for simple scalar
134 * optimizations
135 */
136 @Override
137 public final void perform(IR ir) {
138 ir.desiredSSAOptions = new SSAOptions();
139 ir.desiredSSAOptions.setScalarsOnly(true);
140 ir.desiredSSAOptions.setBackwards(false);
141 ir.desiredSSAOptions.setInsertUsePhis(false);
142 if (!ir.HIRInfo.dominatorsAreComputed) {
143 dominators.perform(ir);
144 frontier.perform(ir);
145 }
146 }
147 }
148 }