| /* |
| * Copyright 2013 Google Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except |
| * in compliance with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software distributed under the License |
| * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express |
| * or implied. See the License for the specific language governing permissions and limitations under |
| * the License. |
| */ |
| package com.google.gwt.dev.jjs.impl.codesplitter; |
| |
| import com.google.gwt.core.ext.TreeLogger; |
| import com.google.gwt.dev.jjs.ast.JRunAsync; |
| import com.google.gwt.dev.jjs.impl.ControlFlowAnalyzer; |
| |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.List; |
| |
| /** |
| * This strategy implements the fragment merge by similarity strategy. |
| * |
| * <p> |
| * The fragment merge by similarity computes the set of live atoms starting for the splitpoints in |
| * the fragment. This is a rough under-approximation as it does not consider atoms that would be |
| * reachable by the splitpoints in this fragment if a different fragment is loaded first. |
| * </p> |
| * |
| * <p> |
| * A similarity graph is constructed (represented by a similarity matrix) from the results of the |
| * control flow analysis, and fragments linked by the highest weights are merged. |
| * </p> |
| * |
| * <p> |
| * Finally, fragments that might result very small are also merged into some related fragment. |
| * </p> |
| * |
| * <p> |
| * The control flow analysis that is computed by this strategy is not used to determine exclusivity. |
| * </p> |
| */ |
| class MergeBySimilarityFragmentPartitionStrategy implements FragmentPartitionStrategy { |
| private final int minSize; |
| private final int targetNumberOfFragments; |
| |
| public MergeBySimilarityFragmentPartitionStrategy(int targetNumberOfFragments, int minSize) { |
| this.targetNumberOfFragments = targetNumberOfFragments; |
| this.minSize = minSize; |
| } |
| |
| @Override |
| public Collection<Fragment> partitionIntoFragments(TreeLogger logger, |
| ControlFlowAnalyzer initialSequenceCfa, Collection<Collection<JRunAsync>> |
| groupedNonInitialRunAsyncs) { |
| Collection<Collection<JRunAsync>> fragmentRunAsyncLists = |
| mergeRunAsyncs(logger, initialSequenceCfa, groupedNonInitialRunAsyncs); |
| |
| List<Fragment> fragments = new ArrayList<Fragment>(); |
| for (Collection<JRunAsync> fragmentRunAsyncs : fragmentRunAsyncLists) { |
| Fragment fragment = new Fragment(Fragment.Type.EXCLUSIVE); |
| fragment.addRunAsyncs(fragmentRunAsyncs); |
| fragments.add(fragment); |
| } |
| return fragments; |
| } |
| |
| private Collection<Collection<JRunAsync>> mergeRunAsyncs(TreeLogger logger, |
| ControlFlowAnalyzer initialSequenceCfa, Collection<Collection<JRunAsync>> groupedRunAsyncs) { |
| LiveAtomsByRunAsyncSets liveAtomsByRunAsyncSets = new LiveAtomsByRunAsyncSets(logger); |
| |
| // Compute the under-approximate liveset map. |
| liveAtomsByRunAsyncSets.recordLiveSubsetsAndEstimateTheirSizes(initialSequenceCfa, |
| groupedRunAsyncs); |
| |
| // Merge by similarity. |
| int mergeCount = liveAtomsByRunAsyncSets.getRunAsyncCount() - targetNumberOfFragments; |
| Collection<Collection<JRunAsync>> fragmentRunAsyncLists = |
| liveAtomsByRunAsyncSets.mergeSimilarPairs(mergeCount); |
| |
| // Merge by size if specified |
| if (minSize > 0) { |
| liveAtomsByRunAsyncSets.mergeSmallFragments(fragmentRunAsyncLists, minSize); |
| } |
| |
| return fragmentRunAsyncLists; |
| } |
| } |