Examples with IndexingOp org.apache.sysml.hops.IndexingOp used on opensource projects

Example 31 with IndexingOp

use of org.apache.sysml.hops.IndexingOp in project incubator-systemml by apache.

the class RewriteAlgebraicSimplificationStatic method simplifySlicedMatrixMult.

private static Hop simplifySlicedMatrixMult(Hop parent, Hop hi, int pos) {
    // e.g., (X%*%Y)[1,1] -> X[1,] %*% Y[,1]
    if (hi instanceof IndexingOp && ((IndexingOp) hi).isRowLowerEqualsUpper() && ((IndexingOp) hi).isColLowerEqualsUpper() && // rix is single mm consumer
    hi.getInput().get(0).getParent().size() == 1 && HopRewriteUtils.isMatrixMultiply(hi.getInput().get(0))) {
        Hop mm = hi.getInput().get(0);
        Hop X = mm.getInput().get(0);
        Hop Y = mm.getInput().get(1);
        // rl==ru
        Hop rowExpr = hi.getInput().get(1);
        // cl==cu
        Hop colExpr = hi.getInput().get(3);
        HopRewriteUtils.removeAllChildReferences(mm);
        // create new indexing operations
        IndexingOp ix1 = new IndexingOp("tmp1", DataType.MATRIX, ValueType.DOUBLE, X, rowExpr, rowExpr, new LiteralOp(1), HopRewriteUtils.createValueHop(X, false), true, false);
        ix1.setOutputBlocksizes(X.getRowsInBlock(), X.getColsInBlock());
        ix1.refreshSizeInformation();
        IndexingOp ix2 = new IndexingOp("tmp2", DataType.MATRIX, ValueType.DOUBLE, Y, new LiteralOp(1), HopRewriteUtils.createValueHop(Y, true), colExpr, colExpr, false, true);
        ix2.setOutputBlocksizes(Y.getRowsInBlock(), Y.getColsInBlock());
        ix2.refreshSizeInformation();
        // rewire matrix mult over ix1 and ix2
        HopRewriteUtils.addChildReference(mm, ix1, 0);
        HopRewriteUtils.addChildReference(mm, ix2, 1);
        mm.refreshSizeInformation();
        hi = mm;
        LOG.debug("Applied simplifySlicedMatrixMult");
    }
    return hi;
}

Example 32 with IndexingOp

use of org.apache.sysml.hops.IndexingOp in project systemml by apache.

the class DMLTranslator method processIndexingExpression.

private Hop processIndexingExpression(IndexedIdentifier source, DataIdentifier target, HashMap<String, Hop> hops) {
    // process Hops for indexes (for source)
    Hop rowLowerHops = null, rowUpperHops = null, colLowerHops = null, colUpperHops = null;
    if (source.getRowLowerBound() != null)
        rowLowerHops = processExpression(source.getRowLowerBound(), null, hops);
    else
        rowLowerHops = new LiteralOp(1);
    if (source.getRowUpperBound() != null)
        rowUpperHops = processExpression(source.getRowUpperBound(), null, hops);
    else {
        if (source.getOrigDim1() != -1)
            rowUpperHops = new LiteralOp(source.getOrigDim1());
        else {
            rowUpperHops = new UnaryOp(source.getName(), DataType.SCALAR, ValueType.INT, Hop.OpOp1.NROW, hops.get(source.getName()));
            rowUpperHops.setParseInfo(source);
        }
    }
    if (source.getColLowerBound() != null)
        colLowerHops = processExpression(source.getColLowerBound(), null, hops);
    else
        colLowerHops = new LiteralOp(1);
    if (source.getColUpperBound() != null)
        colUpperHops = processExpression(source.getColUpperBound(), null, hops);
    else {
        if (source.getOrigDim2() != -1)
            colUpperHops = new LiteralOp(source.getOrigDim2());
        else
            colUpperHops = new UnaryOp(source.getName(), DataType.SCALAR, ValueType.INT, Hop.OpOp1.NCOL, hops.get(source.getName()));
    }
    if (target == null) {
        target = createTarget(source);
    }
    // unknown nnz after range indexing (applies to indexing op but also
    // data dependent operations)
    target.setNnz(-1);
    Hop indexOp = new IndexingOp(target.getName(), target.getDataType(), target.getValueType(), hops.get(source.getName()), rowLowerHops, rowUpperHops, colLowerHops, colUpperHops, source.getRowLowerEqualsUpper(), source.getColLowerEqualsUpper());
    indexOp.setParseInfo(target);
    setIdentifierParams(indexOp, target);
    return indexOp;
}

Example 33 with IndexingOp

use of org.apache.sysml.hops.IndexingOp in project systemml by apache.

the class TemplateCell method rConstructCplan.

protected void rConstructCplan(Hop hop, CPlanMemoTable memo, HashMap<Long, CNode> tmp, HashSet<Hop> inHops, boolean compileLiterals) {
    // memoization for common subexpression elimination and to avoid redundant work
    if (tmp.containsKey(hop.getHopID()))
        return;
    MemoTableEntry me = memo.getBest(hop.getHopID(), TemplateType.CELL);
    // recursively process required childs
    if (me != null && me.type.isIn(TemplateType.ROW, TemplateType.OUTER)) {
        CNodeData cdata = TemplateUtils.createCNodeData(hop, compileLiterals);
        tmp.put(hop.getHopID(), cdata);
        inHops.add(hop);
        return;
    }
    for (int i = 0; i < hop.getInput().size(); i++) {
        Hop c = hop.getInput().get(i);
        if (me != null && me.isPlanRef(i) && !(c instanceof DataOp) && (me.type != TemplateType.MAGG || memo.contains(c.getHopID(), TemplateType.CELL)))
            rConstructCplan(c, memo, tmp, inHops, compileLiterals);
        else if (me != null && (me.type == TemplateType.MAGG || me.type == TemplateType.CELL) && HopRewriteUtils.isMatrixMultiply(hop) && // skip transpose
        i == 0)
            rConstructCplan(c.getInput().get(0), memo, tmp, inHops, compileLiterals);
        else {
            CNodeData cdata = TemplateUtils.createCNodeData(c, compileLiterals);
            tmp.put(c.getHopID(), cdata);
            inHops.add(c);
        }
    }
    // construct cnode for current hop
    CNode out = null;
    if (hop instanceof UnaryOp) {
        CNode cdata1 = tmp.get(hop.getInput().get(0).getHopID());
        cdata1 = TemplateUtils.wrapLookupIfNecessary(cdata1, hop.getInput().get(0));
        String primitiveOpName = ((UnaryOp) hop).getOp().name();
        out = new CNodeUnary(cdata1, UnaryType.valueOf(primitiveOpName));
    } else if (hop instanceof BinaryOp) {
        BinaryOp bop = (BinaryOp) hop;
        CNode cdata1 = tmp.get(hop.getInput().get(0).getHopID());
        CNode cdata2 = tmp.get(hop.getInput().get(1).getHopID());
        String primitiveOpName = bop.getOp().name();
        // add lookups if required
        cdata1 = TemplateUtils.wrapLookupIfNecessary(cdata1, hop.getInput().get(0));
        cdata2 = TemplateUtils.wrapLookupIfNecessary(cdata2, hop.getInput().get(1));
        // construct binary cnode
        out = new CNodeBinary(cdata1, cdata2, BinType.valueOf(primitiveOpName));
    } else if (hop instanceof TernaryOp) {
        TernaryOp top = (TernaryOp) hop;
        CNode cdata1 = tmp.get(hop.getInput().get(0).getHopID());
        CNode cdata2 = tmp.get(hop.getInput().get(1).getHopID());
        CNode cdata3 = tmp.get(hop.getInput().get(2).getHopID());
        // add lookups if required
        cdata1 = TemplateUtils.wrapLookupIfNecessary(cdata1, hop.getInput().get(0));
        cdata2 = TemplateUtils.wrapLookupIfNecessary(cdata2, hop.getInput().get(1));
        cdata3 = TemplateUtils.wrapLookupIfNecessary(cdata3, hop.getInput().get(2));
        // construct ternary cnode, primitive operation derived from OpOp3
        out = new CNodeTernary(cdata1, cdata2, cdata3, TernaryType.valueOf(top.getOp().name()));
    } else if (hop instanceof ParameterizedBuiltinOp) {
        CNode cdata1 = tmp.get(((ParameterizedBuiltinOp) hop).getTargetHop().getHopID());
        cdata1 = TemplateUtils.wrapLookupIfNecessary(cdata1, hop.getInput().get(0));
        CNode cdata2 = tmp.get(((ParameterizedBuiltinOp) hop).getParameterHop("pattern").getHopID());
        CNode cdata3 = tmp.get(((ParameterizedBuiltinOp) hop).getParameterHop("replacement").getHopID());
        TernaryType ttype = (cdata2.isLiteral() && cdata2.getVarname().equals("Double.NaN")) ? TernaryType.REPLACE_NAN : TernaryType.REPLACE;
        out = new CNodeTernary(cdata1, cdata2, cdata3, ttype);
    } else if (hop instanceof IndexingOp) {
        CNode cdata1 = tmp.get(hop.getInput().get(0).getHopID());
        out = new CNodeTernary(cdata1, TemplateUtils.createCNodeData(new LiteralOp(hop.getInput().get(0).getDim2()), true), TemplateUtils.createCNodeData(hop.getInput().get(4), true), TernaryType.LOOKUP_RC1);
    } else if (HopRewriteUtils.isTransposeOperation(hop)) {
        out = TemplateUtils.skipTranspose(tmp.get(hop.getHopID()), hop, tmp, compileLiterals);
        // correct indexing types of existing lookups
        if (!HopRewriteUtils.containsOp(hop.getParent(), AggBinaryOp.class))
            TemplateUtils.rFlipVectorLookups(out);
        // maintain input hops
        if (out instanceof CNodeData && !inHops.contains(hop.getInput().get(0)))
            inHops.add(hop.getInput().get(0));
    } else if (hop instanceof AggUnaryOp) {
        // aggregation handled in template implementation (note: we do not compile
        // ^2 of SUM_SQ into the operator to simplify the detection of single operators)
        out = tmp.get(hop.getInput().get(0).getHopID());
    } else if (hop instanceof AggBinaryOp) {
        // (1) t(X)%*%X -> sum(X^2) and t(X) %*% Y -> sum(X*Y)
        if (HopRewriteUtils.isTransposeOfItself(hop.getInput().get(0), hop.getInput().get(1))) {
            CNode cdata1 = tmp.get(hop.getInput().get(1).getHopID());
            if (TemplateUtils.isColVector(cdata1))
                cdata1 = new CNodeUnary(cdata1, UnaryType.LOOKUP_R);
            out = new CNodeUnary(cdata1, UnaryType.POW2);
        } else {
            CNode cdata1 = TemplateUtils.skipTranspose(tmp.get(hop.getInput().get(0).getHopID()), hop.getInput().get(0), tmp, compileLiterals);
            if (cdata1 instanceof CNodeData && !inHops.contains(hop.getInput().get(0).getInput().get(0)))
                inHops.add(hop.getInput().get(0).getInput().get(0));
            if (TemplateUtils.isColVector(cdata1))
                cdata1 = new CNodeUnary(cdata1, UnaryType.LOOKUP_R);
            CNode cdata2 = tmp.get(hop.getInput().get(1).getHopID());
            if (TemplateUtils.isColVector(cdata2))
                cdata2 = new CNodeUnary(cdata2, UnaryType.LOOKUP_R);
            out = new CNodeBinary(cdata1, cdata2, BinType.MULT);
        }
    }
    tmp.put(hop.getHopID(), out);
}

Example 34 with IndexingOp

use of org.apache.sysml.hops.IndexingOp in project systemml by apache.

the class TemplateRow method rConstructCplan.

private void rConstructCplan(Hop hop, CPlanMemoTable memo, HashMap<Long, CNode> tmp, HashSet<Hop> inHops, HashMap<String, Hop> inHops2, boolean compileLiterals) {
    // memoization for common subexpression elimination and to avoid redundant work
    if (tmp.containsKey(hop.getHopID()))
        return;
    // recursively process required childs
    MemoTableEntry me = memo.getBest(hop.getHopID(), TemplateType.ROW, TemplateType.CELL);
    for (int i = 0; i < hop.getInput().size(); i++) {
        Hop c = hop.getInput().get(i);
        if (me != null && me.isPlanRef(i))
            rConstructCplan(c, memo, tmp, inHops, inHops2, compileLiterals);
        else {
            CNodeData cdata = TemplateUtils.createCNodeData(c, compileLiterals);
            tmp.put(c.getHopID(), cdata);
            inHops.add(c);
        }
    }
    // construct cnode for current hop
    CNode out = null;
    if (hop instanceof AggUnaryOp) {
        CNode cdata1 = tmp.get(hop.getInput().get(0).getHopID());
        if (((AggUnaryOp) hop).getDirection() == Direction.Row && HopRewriteUtils.isAggUnaryOp(hop, SUPPORTED_ROW_AGG)) {
            if (hop.getInput().get(0).getDim2() == 1)
                out = (cdata1.getDataType() == DataType.SCALAR) ? cdata1 : new CNodeUnary(cdata1, UnaryType.LOOKUP_R);
            else {
                String opcode = "ROW_" + ((AggUnaryOp) hop).getOp().name().toUpperCase() + "S";
                out = new CNodeUnary(cdata1, UnaryType.valueOf(opcode));
                if (cdata1 instanceof CNodeData && !inHops2.containsKey("X"))
                    inHops2.put("X", hop.getInput().get(0));
            }
        } else if (((AggUnaryOp) hop).getDirection() == Direction.Col && ((AggUnaryOp) hop).getOp() == AggOp.SUM) {
            // vector add without temporary copy
            if (cdata1 instanceof CNodeBinary && ((CNodeBinary) cdata1).getType().isVectorScalarPrimitive())
                out = new CNodeBinary(cdata1.getInput().get(0), cdata1.getInput().get(1), ((CNodeBinary) cdata1).getType().getVectorAddPrimitive());
            else
                out = cdata1;
        } else if (((AggUnaryOp) hop).getDirection() == Direction.RowCol && ((AggUnaryOp) hop).getOp() == AggOp.SUM) {
            out = (cdata1.getDataType().isMatrix()) ? new CNodeUnary(cdata1, UnaryType.ROW_SUMS) : cdata1;
        }
    } else if (hop instanceof AggBinaryOp) {
        CNode cdata1 = tmp.get(hop.getInput().get(0).getHopID());
        CNode cdata2 = tmp.get(hop.getInput().get(1).getHopID());
        if (HopRewriteUtils.isTransposeOperation(hop.getInput().get(0))) {
            // correct input under transpose
            cdata1 = TemplateUtils.skipTranspose(cdata1, hop.getInput().get(0), tmp, compileLiterals);
            inHops.remove(hop.getInput().get(0));
            if (cdata1 instanceof CNodeData)
                inHops.add(hop.getInput().get(0).getInput().get(0));
            // note: vectorMultAdd applicable to vector-scalar, and vector-vector
            if (hop.getInput().get(1).getDim2() == 1)
                out = new CNodeBinary(cdata1, cdata2, BinType.VECT_MULT_ADD);
            else {
                out = new CNodeBinary(cdata1, cdata2, BinType.VECT_OUTERMULT_ADD);
                if (!inHops2.containsKey("B1")) {
                    // incl modification of X for consistency
                    if (cdata1 instanceof CNodeData)
                        inHops2.put("X", hop.getInput().get(0).getInput().get(0));
                    inHops2.put("B1", hop.getInput().get(1));
                }
            }
            if (!inHops2.containsKey("X"))
                inHops2.put("X", hop.getInput().get(0).getInput().get(0));
        } else {
            if (hop.getInput().get(0).getDim2() == 1 && hop.getInput().get(1).getDim2() == 1)
                out = new CNodeBinary((cdata1.getDataType() == DataType.SCALAR) ? cdata1 : new CNodeUnary(cdata1, UnaryType.LOOKUP0), (cdata2.getDataType() == DataType.SCALAR) ? cdata2 : new CNodeUnary(cdata2, UnaryType.LOOKUP0), BinType.MULT);
            else if (hop.getInput().get(1).getDim2() == 1) {
                out = new CNodeBinary(cdata1, cdata2, BinType.DOT_PRODUCT);
                inHops2.put("X", hop.getInput().get(0));
            } else {
                out = new CNodeBinary(cdata1, cdata2, BinType.VECT_MATRIXMULT);
                inHops2.put("X", hop.getInput().get(0));
                inHops2.put("B1", hop.getInput().get(1));
            }
        }
    } else if (HopRewriteUtils.isTransposeOperation(hop)) {
        out = TemplateUtils.skipTranspose(tmp.get(hop.getHopID()), hop, tmp, compileLiterals);
        if (out instanceof CNodeData && !inHops.contains(hop.getInput().get(0)))
            inHops.add(hop.getInput().get(0));
    } else if (hop instanceof UnaryOp) {
        CNode cdata1 = tmp.get(hop.getInput().get(0).getHopID());
        // if one input is a matrix then we need to do vector by scalar operations
        if (hop.getInput().get(0).getDim1() >= 1 && hop.getInput().get(0).getDim2() > 1 || (!hop.dimsKnown() && cdata1.getDataType() == DataType.MATRIX)) {
            if (HopRewriteUtils.isUnary(hop, SUPPORTED_VECT_UNARY)) {
                String opname = "VECT_" + ((UnaryOp) hop).getOp().name();
                out = new CNodeUnary(cdata1, UnaryType.valueOf(opname));
                if (cdata1 instanceof CNodeData && !inHops2.containsKey("X"))
                    inHops2.put("X", hop.getInput().get(0));
            } else
                throw new RuntimeException("Unsupported unary matrix " + "operation: " + ((UnaryOp) hop).getOp().name());
        } else // general scalar case
        {
            cdata1 = TemplateUtils.wrapLookupIfNecessary(cdata1, hop.getInput().get(0));
            String primitiveOpName = ((UnaryOp) hop).getOp().toString();
            out = new CNodeUnary(cdata1, UnaryType.valueOf(primitiveOpName));
        }
    } else if (HopRewriteUtils.isBinary(hop, OpOp2.CBIND)) {
        // special case for cbind with zeros
        CNode cdata1 = tmp.get(hop.getInput().get(0).getHopID());
        CNode cdata2 = null;
        if (HopRewriteUtils.isDataGenOpWithConstantValue(hop.getInput().get(1))) {
            cdata2 = TemplateUtils.createCNodeData(HopRewriteUtils.getDataGenOpConstantValue(hop.getInput().get(1)), true);
            // rm 0-matrix
            inHops.remove(hop.getInput().get(1));
        } else {
            cdata2 = tmp.get(hop.getInput().get(1).getHopID());
            cdata2 = TemplateUtils.wrapLookupIfNecessary(cdata2, hop.getInput().get(1));
        }
        out = new CNodeBinary(cdata1, cdata2, BinType.VECT_CBIND);
        if (cdata1 instanceof CNodeData && !inHops2.containsKey("X"))
            inHops2.put("X", hop.getInput().get(0));
    } else if (hop instanceof BinaryOp) {
        CNode cdata1 = tmp.get(hop.getInput().get(0).getHopID());
        CNode cdata2 = tmp.get(hop.getInput().get(1).getHopID());
        // if one input is a matrix then we need to do vector by scalar operations
        if ((hop.getInput().get(0).getDim1() >= 1 && hop.getInput().get(0).getDim2() > 1) || (hop.getInput().get(1).getDim1() >= 1 && hop.getInput().get(1).getDim2() > 1) || (!(hop.dimsKnown() && hop.getInput().get(0).dimsKnown() && hop.getInput().get(1).dimsKnown()) && // not a known vector output
        (hop.getDim2() != 1) && (cdata1.getDataType().isMatrix() || cdata2.getDataType().isMatrix()))) {
            if (HopRewriteUtils.isBinary(hop, SUPPORTED_VECT_BINARY)) {
                if (TemplateUtils.isMatrix(cdata1) && (TemplateUtils.isMatrix(cdata2) || TemplateUtils.isRowVector(cdata2))) {
                    String opname = "VECT_" + ((BinaryOp) hop).getOp().name();
                    out = new CNodeBinary(cdata1, cdata2, BinType.valueOf(opname));
                } else {
                    String opname = "VECT_" + ((BinaryOp) hop).getOp().name() + "_SCALAR";
                    if (TemplateUtils.isColVector(cdata1))
                        cdata1 = new CNodeUnary(cdata1, UnaryType.LOOKUP_R);
                    if (TemplateUtils.isColVector(cdata2))
                        cdata2 = new CNodeUnary(cdata2, UnaryType.LOOKUP_R);
                    out = new CNodeBinary(cdata1, cdata2, BinType.valueOf(opname));
                }
                if (cdata1 instanceof CNodeData && !inHops2.containsKey("X") && !(cdata1.getDataType() == DataType.SCALAR)) {
                    inHops2.put("X", hop.getInput().get(0));
                }
            } else
                throw new RuntimeException("Unsupported binary matrix " + "operation: " + ((BinaryOp) hop).getOp().name());
        } else // one input is a vector/scalar other is a scalar
        {
            String primitiveOpName = ((BinaryOp) hop).getOp().toString();
            if (TemplateUtils.isColVector(cdata1))
                cdata1 = new CNodeUnary(cdata1, UnaryType.LOOKUP_R);
            if (// vector or vector can be inferred from lhs
            TemplateUtils.isColVector(cdata2) || (TemplateUtils.isColVector(hop.getInput().get(0)) && cdata2 instanceof CNodeData && hop.getInput().get(1).getDataType().isMatrix()))
                cdata2 = new CNodeUnary(cdata2, UnaryType.LOOKUP_R);
            out = new CNodeBinary(cdata1, cdata2, BinType.valueOf(primitiveOpName));
        }
    } else if (hop instanceof TernaryOp) {
        TernaryOp top = (TernaryOp) hop;
        CNode cdata1 = tmp.get(hop.getInput().get(0).getHopID());
        CNode cdata2 = tmp.get(hop.getInput().get(1).getHopID());
        CNode cdata3 = tmp.get(hop.getInput().get(2).getHopID());
        // add lookups if required
        cdata1 = TemplateUtils.wrapLookupIfNecessary(cdata1, hop.getInput().get(0));
        cdata3 = TemplateUtils.wrapLookupIfNecessary(cdata3, hop.getInput().get(2));
        // construct ternary cnode, primitive operation derived from OpOp3
        out = new CNodeTernary(cdata1, cdata2, cdata3, TernaryType.valueOf(top.getOp().toString()));
    } else if (HopRewriteUtils.isNary(hop, OpOpN.CBIND)) {
        CNode[] inputs = new CNode[hop.getInput().size()];
        for (int i = 0; i < hop.getInput().size(); i++) {
            Hop c = hop.getInput().get(i);
            CNode cdata = tmp.get(c.getHopID());
            if (TemplateUtils.isColVector(cdata) || TemplateUtils.isRowVector(cdata))
                cdata = TemplateUtils.wrapLookupIfNecessary(cdata, c);
            inputs[i] = cdata;
            if (i == 0 && cdata instanceof CNodeData && !inHops2.containsKey("X"))
                inHops2.put("X", c);
        }
        out = new CNodeNary(inputs, NaryType.VECT_CBIND);
    } else if (hop instanceof ParameterizedBuiltinOp) {
        CNode cdata1 = tmp.get(((ParameterizedBuiltinOp) hop).getTargetHop().getHopID());
        cdata1 = TemplateUtils.wrapLookupIfNecessary(cdata1, hop.getInput().get(0));
        CNode cdata2 = tmp.get(((ParameterizedBuiltinOp) hop).getParameterHop("pattern").getHopID());
        CNode cdata3 = tmp.get(((ParameterizedBuiltinOp) hop).getParameterHop("replacement").getHopID());
        TernaryType ttype = (cdata2.isLiteral() && cdata2.getVarname().equals("Double.NaN")) ? TernaryType.REPLACE_NAN : TernaryType.REPLACE;
        out = new CNodeTernary(cdata1, cdata2, cdata3, ttype);
    } else if (hop instanceof IndexingOp) {
        CNode cdata1 = tmp.get(hop.getInput().get(0).getHopID());
        out = new CNodeTernary(cdata1, TemplateUtils.createCNodeData(new LiteralOp(hop.getInput().get(0).getDim2()), true), TemplateUtils.createCNodeData(hop.getInput().get(4), true), (hop.getDim2() != 1) ? TernaryType.LOOKUP_RVECT1 : TernaryType.LOOKUP_RC1);
    }
    if (out == null) {
        throw new RuntimeException(hop.getHopID() + " " + hop.getOpString());
    }
    if (out.getDataType().isMatrix()) {
        out.setNumRows(hop.getDim1());
        out.setNumCols(hop.getDim2());
    }
    tmp.put(hop.getHopID(), out);
}

Example 35 with IndexingOp

use of org.apache.sysml.hops.IndexingOp in project systemml by apache.

the class RewriteAlgebraicSimplificationDynamic method removeEmptyRightIndexing.

private static Hop removeEmptyRightIndexing(Hop parent, Hop hi, int pos) {
    if (// indexing op
    hi instanceof IndexingOp && hi.getDataType() == DataType.MATRIX) {
        Hop input = hi.getInput().get(0);
        if (// nnz input known and empty
        input.getNnz() == 0 && // output dims known
        HopRewriteUtils.isDimsKnown(hi)) {
            // remove unnecessary right indexing
            Hop hnew = HopRewriteUtils.createDataGenOpByVal(new LiteralOp(hi.getDim1()), new LiteralOp(hi.getDim2()), 0);
            HopRewriteUtils.replaceChildReference(parent, hi, hnew, pos);
            HopRewriteUtils.cleanupUnreferenced(hi, input);
            hi = hnew;
            LOG.debug("Applied removeEmptyRightIndexing");
        }
    }
    return hi;
}