[SYSTEMML-1990] New cleanup rewrite for removal of empty basic blocks This new rewrite removes empty basic blocks, i.e., last-level blocks without hops, which can originate from the original program or a sequence of rewrites.
Project: http://git-wip-us.apache.org/repos/asf/systemml/repo Commit: http://git-wip-us.apache.org/repos/asf/systemml/commit/d90073d8 Tree: http://git-wip-us.apache.org/repos/asf/systemml/tree/d90073d8 Diff: http://git-wip-us.apache.org/repos/asf/systemml/diff/d90073d8 Branch: refs/heads/master Commit: d90073d804322f6b601b0f06d03979dae6322c25 Parents: 78586a1 Author: Matthias Boehm <mboe...@gmail.com> Authored: Wed Nov 29 22:30:30 2017 -0800 Committer: Matthias Boehm <mboe...@gmail.com> Committed: Wed Nov 29 22:30:54 2017 -0800 ---------------------------------------------------------------------- .../sysml/hops/rewrite/ProgramRewriter.java | 3 +- .../rewrite/RewriteRemoveEmptyBasicBlocks.java | 58 ++++++++++++++++++++ 2 files changed, 60 insertions(+), 1 deletion(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/systemml/blob/d90073d8/src/main/java/org/apache/sysml/hops/rewrite/ProgramRewriter.java ---------------------------------------------------------------------- diff --git a/src/main/java/org/apache/sysml/hops/rewrite/ProgramRewriter.java b/src/main/java/org/apache/sysml/hops/rewrite/ProgramRewriter.java index ee8d27c..a73ea6d 100644 --- a/src/main/java/org/apache/sysml/hops/rewrite/ProgramRewriter.java +++ b/src/main/java/org/apache/sysml/hops/rewrite/ProgramRewriter.java @@ -105,7 +105,7 @@ public class ProgramRewriter if( OptimizerUtils.ALLOW_BRANCH_REMOVAL ) { _sbRuleSet.add( new RewriteRemoveUnnecessaryBranches() ); //dependency: constant folding _sbRuleSet.add( new RewriteMergeBlockSequence() ); //dependency: remove branches - } + } _sbRuleSet.add( new RewriteCompressedReblock() ); if( OptimizerUtils.ALLOW_SPLIT_HOP_DAGS ) _sbRuleSet.add( new RewriteSplitDagUnknownCSVRead() ); //dependency: reblock, merge blocks @@ -137,6 +137,7 @@ public class ProgramRewriter _dagRuleSet.add( new RewriteRemoveUnnecessaryCasts() ); if( OptimizerUtils.ALLOW_COMMON_SUBEXPRESSION_ELIMINATION ) _dagRuleSet.add( new RewriteCommonSubexpressionElimination(true) ); + _sbRuleSet.add( new RewriteRemoveEmptyBasicBlocks() ); } /** http://git-wip-us.apache.org/repos/asf/systemml/blob/d90073d8/src/main/java/org/apache/sysml/hops/rewrite/RewriteRemoveEmptyBasicBlocks.java ---------------------------------------------------------------------- diff --git a/src/main/java/org/apache/sysml/hops/rewrite/RewriteRemoveEmptyBasicBlocks.java b/src/main/java/org/apache/sysml/hops/rewrite/RewriteRemoveEmptyBasicBlocks.java new file mode 100644 index 0000000..5010618 --- /dev/null +++ b/src/main/java/org/apache/sysml/hops/rewrite/RewriteRemoveEmptyBasicBlocks.java @@ -0,0 +1,58 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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 org.apache.sysml.hops.rewrite; + +import java.util.ArrayList; +import java.util.List; + +import org.apache.sysml.hops.HopsException; +import org.apache.sysml.parser.StatementBlock; + +/** + * Rule: Simplify program structure by removing empty last-level blocks, + * which may originate from the original program or due to a sequence of + * rewrites (e.g., checkpoint injection and subsequent IPA). + */ +public class RewriteRemoveEmptyBasicBlocks extends StatementBlockRewriteRule +{ + @Override + public List<StatementBlock> rewriteStatementBlock(StatementBlock sb, ProgramRewriteStatus state) + throws HopsException + { + ArrayList<StatementBlock> ret = new ArrayList<>(); + + //prune last level blocks with empty hops + if( HopRewriteUtils.isLastLevelStatementBlock(sb) + && (sb.getHops() == null || sb.getHops().isEmpty()) ) { + if( LOG.isDebugEnabled() ) + LOG.debug("Applied removeEmptyBasicBlocks (lines "+sb.getBeginLine()+"-"+sb.getEndLine()+")."); + } + else //keep original sb + ret.add( sb ); + + return ret; + } + + @Override + public List<StatementBlock> rewriteStatementBlocks(List<StatementBlock> sbs, ProgramRewriteStatus sate) + throws HopsException { + return sbs; + } +}
