[SYSTEMDS-3798] Fix rewrite loop vectorization and code coverage

The existing single loop vectorization rewrite only checked for
correct results not if the rewrite was indeed applied. This issue has
been found while improving the code coverage of rewrites. When the
handling of predicates (with special transient write) was changed in
the past, these rewrites were not properly updated. This patch fixes
all rewrites and also add tests for all cases.

Furthermore, this patch also removes two other unused hop rewrites.

Author: mboehm7

src/main/java/org/apache/sysds/hops/rewrite/ProgramRewriter.java

@@ -75,7 +75,6 @@ public ProgramRewriter(boolean staticRewrites, boolean dynamicRewrites)
 		if( staticRewrites )
 		{
 			//add static HOP DAG rewrite rules
-			_dagRuleSet.add(     new RewriteTransientWriteParentHandling()       );
 			_dagRuleSet.add(     new RewriteRemoveReadAfterWrite()               ); //dependency: before blocksize
 			_dagRuleSet.add(     new RewriteBlockSizeAndReblock()                );
 			if( OptimizerUtils.ALLOW_ALGEBRAIC_SIMPLIFICATION )

src/main/java/org/apache/sysds/hops/rewrite/RewriteForLoopVectorization.java

@@ -21,23 +21,23 @@
 
 import java.util.HashMap;
 
+import org.junit.Assert;
 import org.junit.Test;
 import org.apache.sysds.hops.OptimizerUtils;
 import org.apache.sysds.runtime.matrix.data.MatrixValue.CellIndex;
 import org.apache.sysds.test.AutomatedTestBase;
 import org.apache.sysds.test.TestConfiguration;
 import org.apache.sysds.test.TestUtils;
+import org.apache.sysds.utils.Statistics;
 
-/**
- * Regression test for loop vectorization rewrite
- * for(i in 1:n) s = s + as.scalar(A[i,1]) -> s = s + sum(A[1:n,1])
- * 
- */
 public class RewriteLoopVectorization extends AutomatedTestBase 
 {
 	private static final String TEST_NAME1 = "RewriteLoopVectorizationSum"; //amendable
 	private static final String TEST_NAME2 = "RewriteLoopVectorizationSum2"; //not amendable
-
+	private static final String TEST_NAME3 = "RewriteLoopVectorizationBinary"; //amendable
+	private static final String TEST_NAME4 = "RewriteLoopVectorizationUnary"; //amendable
+	private static final String TEST_NAME5 = "RewriteLoopVectorizationIndexedCopy"; //amendable
+	
 	private static final String TEST_DIR = "functions/rewrite/";
 	private static final String TEST_CLASS_DIR = TEST_DIR + RewriteLoopVectorization.class.getSimpleName() + "/";
 
@@ -46,6 +46,9 @@ public void setUp() {
 		TestUtils.clearAssertionInformation();
 		addTestConfiguration( TEST_NAME1, new TestConfiguration(TEST_CLASS_DIR, TEST_NAME1, new String[] { "R" }) );
 		addTestConfiguration( TEST_NAME2, new TestConfiguration(TEST_CLASS_DIR, TEST_NAME2, new String[] { "R" }) );
+		addTestConfiguration( TEST_NAME3, new TestConfiguration(TEST_CLASS_DIR, TEST_NAME3, new String[] { "R" }) );
+		addTestConfiguration( TEST_NAME4, new TestConfiguration(TEST_CLASS_DIR, TEST_NAME4, new String[] { "R" }) );
+		addTestConfiguration( TEST_NAME5, new TestConfiguration(TEST_CLASS_DIR, TEST_NAME5, new String[] { "R" }) );
 	}
 
 	@Test
@@ -68,14 +71,39 @@ public void testLoopVectorizationSum2Rewrite() {
 		testRewriteLoopVectorizationSum( TEST_NAME2, true );
 	}
 
-	/**
-	 * 
-	 * @param testname
-	 * @param rewrites
-	 */
+	@Test
+	public void testLoopVectorizationBinaryNoRewrite() {
+		testRewriteLoopVectorizationSum( TEST_NAME3, false );
+	}
+	
+	@Test
+	public void testLoopVectorizationBinaryRewrite() {
+		testRewriteLoopVectorizationSum( TEST_NAME3, true );
+	}
+	
+	@Test
+	public void testLoopVectorizationUnaryNoRewrite() {
+		testRewriteLoopVectorizationSum( TEST_NAME4, false );
+	}
+	
+	@Test
+	public void testLoopVectorizationUnaryRewrite() {
+		testRewriteLoopVectorizationSum( TEST_NAME4, true );
+	}
+	
+	@Test
+	public void testLoopVectorizationIndexedCopyNoRewrite() {
+		testRewriteLoopVectorizationSum( TEST_NAME5, false );
+	}
+	
+	@Test
+	public void testLoopVectorizationIndexedCopyRewrite() {
+		testRewriteLoopVectorizationSum( TEST_NAME5, true );
+	}
+	
 	private void testRewriteLoopVectorizationSum( String testname, boolean rewrites )
 	{	
-		boolean oldFlag = OptimizerUtils.ALLOW_ALGEBRAIC_SIMPLIFICATION;
+		boolean oldFlag = OptimizerUtils.ALLOW_AUTO_VECTORIZATION;
 
 		try
 		{
@@ -84,12 +112,12 @@ private void testRewriteLoopVectorizationSum( String testname, boolean rewrites
 
 			String HOME = SCRIPT_DIR + TEST_DIR;
 			fullDMLScriptName = HOME + testname + ".dml";
-			programArgs = new String[]{ "-stats","-args", output("Scalar") };
+			programArgs = new String[]{ "-stats", "-args", output("Scalar") };
 
 			fullRScriptName = HOME + testname + ".R";
-			rCmd = getRCmd(inputDir(), expectedDir());			
+			rCmd = getRCmd(inputDir(), expectedDir());
 
-			OptimizerUtils.ALLOW_ALGEBRAIC_SIMPLIFICATION = rewrites;
+			OptimizerUtils.ALLOW_AUTO_VECTORIZATION = rewrites;
 
 			runTest(true, false, null, -1); 
 			runRScript(true); 
@@ -98,9 +126,11 @@ private void testRewriteLoopVectorizationSum( String testname, boolean rewrites
 			HashMap<CellIndex, Double> dmlfile = readDMLScalarFromOutputDir("Scalar");
 			HashMap<CellIndex, Double> rfile  = readRScalarFromExpectedDir("Scalar");
 			TestUtils.compareScalars(dmlfile.toString(), rfile.toString());
+			if( !testname.equals(TEST_NAME2) && rewrites )
+				Assert.assertTrue(Statistics.getCPHeavyHitterCount("rightIndex") <= 2);
 		}
 		finally {
-			OptimizerUtils.ALLOW_ALGEBRAIC_SIMPLIFICATION = oldFlag;
-		}	
-	}	
-}
+			OptimizerUtils.ALLOW_AUTO_VECTORIZATION = oldFlag;
+		}
+	}
+}

src/main/java/org/apache/sysds/hops/rewrite/RewriteRemoveDanglingParentReferences.java

@@ -0,0 +1,34 @@
+# 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.
+#
+#-------------------------------------------------------------
+
+args<-commandArgs(TRUE)
+
+A = matrix(7.0, 10, 10)
+B = matrix(3.0, 10, 10)
+n = nrow(A)
+s = 0.0
+
+X = A
+for(i in 2:(n-1)) {
+  X[i,2] = A[i,1] + B[i,3]
+}
+s = sum(X)
+
+write(s, paste(args[2], "Scalar",sep=""))
+

src/main/java/org/apache/sysds/hops/rewrite/RewriteTransientWriteParentHandling.java

@@ -0,0 +1,33 @@
+#-------------------------------------------------------------
+#
+# 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.
+#
+#-------------------------------------------------------------
+
+A = matrix(7.0, 10, 10)
+B = matrix(3.0, 10, 10)
+n = nrow(A)
+s = 0.0
+
+X = A
+for(i in 2:n-1) {
+  X[i,2] = A[i,1] + B[i,3]
+}
+s = sum(X)
+
+write(s, $1)