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[SYSTEMDS-3547] Permute Function #2426

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[SYSTEMDS-3547] Permute Function #2426

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BeceHQ Jan 17, 2026
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BeceHQ Jan 30, 2026
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338 changes: 338 additions & 0 deletions src/main/java/org/apache/sysds/runtime/matrix/data/LibMatrixReorg.java
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Original file line number Diff line number Diff line change
Expand Up @@ -4515,4 +4515,342 @@ private static int eulerTotient(int[] primes, int[] exponents, int[] iExponents,
}
return count;
}







private static long[] getStridesForPermutation(int[] dims) {
long[] strides = new long[dims.length];
long stride = 1;
for( int i = dims.length - 1; i >= 0; i-- ) {
strides[i] = stride;
stride *= dims[i];
}
return strides;
}

public static MatrixBlock permute(MatrixBlock in, int[] inDims, int[] perm) {
return permute(in, inDims, perm, 1);
}

public static MatrixBlock permute(MatrixBlock in, int[] inDims, int[] perm, int k) {
int rank = inDims.length;

boolean isIdentity = true;
for( int i = 0; i < rank; i++ ) {
if( perm[i] != i ) {
isIdentity = false;
break;
}
}

if( isIdentity ) {
return new MatrixBlock(in);
}

int[] outDims = new int[rank];
for( int i = 0; i < rank; i++ ) {
outDims[i] = inDims[perm[i]];
}

long length = 1;
for( int d : outDims ) {
length *= d;
}

MatrixBlock out = new MatrixBlock(1, (int)length, false);
out.allocateDenseBlock();

DenseBlock inDB = in.getDenseBlock();
DenseBlock outDB = out.getDenseBlock();

long[] inStrides = getStridesForPermutation(inDims);
long[] outStrides = getStridesForPermutation(outDims);

long[] permutedStrides = new long[rank];
for( int i = 0; i < rank; i++ ) {
permutedStrides[i] = outStrides[perm[i]];
}

boolean useParallel = (k > 1 || k == -1) && length >= PAR_NUMCELL_THRESHOLD;
int numThreads = k == -1 ? Runtime.getRuntime().availableProcessors() : k;

if( inDB.numBlocks() == 1 && outDB.numBlocks() == 1 ) {
double[] inData = inDB.valuesAt(0);
double[] outData = outDB.valuesAt(0);

if( useParallel && rank > 0 ) {
permuteSingleBlockParallel(inData, outData, inDims, inStrides,
permutedStrides, numThreads, length);
} else {
permuteSingleBlock(inData, outData, inDims, inStrides,
permutedStrides, 0, 0, 0);
}
} else {
if( useParallel && rank > 0 ) {
permuteMultiBlockParallel(inDB, outDB, inDims, inStrides,
permutedStrides, numThreads, length);
} else {
permuteMultiBlock(inDB, outDB, inDims, inStrides,
permutedStrides, 0, 0L, 0L);
}
}
return out;
}

private static void permuteSingleBlock(
double[] inData, double[] outData,
int[] inDims, long[] inStrides, long[] permutedStrides,
int dim, int inOffset, int outOffset) {

if( dim == inDims.length - 1 ) {
int len = inDims[dim];
int outStride = (int) permutedStrides[dim];

if( outStride == 1 ) {
System.arraycopy(inData, inOffset, outData, outOffset, len);
} else {
transposeRow(inData, outData, inOffset, outOffset, outStride, len);
}
return;
}

int dimSize = inDims[dim];
long inStep = inStrides[dim];
long outStep = permutedStrides[dim];

final int BLOCK_SIZE = 128;
for( int bi = 0; bi < dimSize; bi += BLOCK_SIZE ) {
int bimin = Math.min(bi + BLOCK_SIZE, dimSize);
for( int i = bi; i < bimin; i++ ) {
permuteSingleBlock(
inData, outData, inDims, inStrides, permutedStrides,
dim + 1,
inOffset + (int)(i * inStep),
outOffset + (int)(i * outStep)
);
}
}
}

private static void permuteSingleBlockParallel(
double[] inData, double[] outData,
int[] inDims, long[] inStrides, long[] permutedStrides,
int k, long totalElements) {

final long elementsPerThread = Math.max(1024, (totalElements + k - 1) / k);
final int actualThreads = (int) Math.min(k, (totalElements + elementsPerThread - 1) / elementsPerThread);

final ExecutorService pool = CommonThreadPool.get(actualThreads);
try {
final ArrayList<PermuteSingleBlockTask> tasks = new ArrayList<>();

for( int t = 0; t < actualThreads; t++ ) {
final long start = t * elementsPerThread;
final long end = Math.min(start + elementsPerThread, totalElements);

if( start >= totalElements ) {
break;
}

tasks.add(new PermuteSingleBlockTask(inData, outData, inDims,
inStrides, permutedStrides, start, end));
}

for( Future<Object> task : pool.invokeAll(tasks) ) {
task.get();
}
} catch (Exception ex) {
throw new DMLRuntimeException(ex);
} finally {
pool.shutdown();
}
}

private static void permuteMultiBlock(
DenseBlock inDB, DenseBlock outDB,
int[] inDims, long[] inStrides, long[] permutedStrides,
int dim, long inOffset, long outOffset) {

if( dim == inDims.length - 1 ) {
int len = inDims[dim];
long outStride = permutedStrides[dim];

int inBlockSize = inDB.blockSize();
int outBlockSize = outDB.blockSize();

for( int i = 0; i < len; i++ ) {
long currentInAbs = inOffset + i * inStrides[dim];
long currentOutAbs = outOffset + i * outStride;

int inBlockIdx = (int) (currentInAbs / inBlockSize);
int inRelIdx = (int) (currentInAbs % inBlockSize);

int outBlockIdx = (int) (currentOutAbs / outBlockSize);
int outRelIdx = (int) (currentOutAbs % outBlockSize);

double[] inArr = inDB.valuesAt(inBlockIdx);
double[] outArr = outDB.valuesAt(outBlockIdx);

if( inArr != null && outArr != null &&
inRelIdx < inArr.length && outRelIdx < outArr.length ) {
outArr[outRelIdx] = inArr[inRelIdx];
}
}
return;
}

int dimSize = inDims[dim];
long inStep = inStrides[dim];
long outStep = permutedStrides[dim];

final int BLOCK_SIZE = 128;
for( int bi = 0; bi < dimSize; bi += BLOCK_SIZE ) {
int bimin = Math.min(bi + BLOCK_SIZE, dimSize);
for( int i = bi; i < bimin; i++ ) {
permuteMultiBlock(
inDB, outDB, inDims, inStrides, permutedStrides,
dim + 1,
inOffset + i * inStep,
outOffset + i * outStep
);
}
}
}

private static void permuteMultiBlockParallel(
DenseBlock inDB, DenseBlock outDB,
int[] inDims, long[] inStrides, long[] permutedStrides,
int k, long totalElements) {

final long elementsPerThread = Math.max(1024, (totalElements + k - 1) / k);
final int actualThreads = (int) Math.min(k, (totalElements + elementsPerThread - 1) / elementsPerThread);

final ExecutorService pool = CommonThreadPool.get(actualThreads);
try {
final ArrayList<PermuteMultiBlockTask> tasks = new ArrayList<>();

for( int t = 0; t < actualThreads; t++ ) {
final long start = t * elementsPerThread;
final long end = Math.min(start + elementsPerThread, totalElements);

if( start >= totalElements ) {
break;
}

tasks.add(new PermuteMultiBlockTask(inDB, outDB, inDims,
inStrides, permutedStrides, start, end));
}

for( Future<Object> task : pool.invokeAll(tasks) ) {
task.get();
}

} catch (Exception ex) {
throw new DMLRuntimeException(ex);
} finally {
pool.shutdown();
}
}

private static class PermuteSingleBlockTask implements Callable<Object> {
private final double[] inData;
private final double[] outData;
private final int[] inDims;
private final long[] inStrides;
private final long[] permutedStrides;
private final long start;
private final long end;

protected PermuteSingleBlockTask(double[] inData, double[] outData,
int[] inDims, long[] inStrides, long[] permutedStrides,
long start, long end) {
this.inData = inData;
this.outData = outData;
this.inDims = inDims;
this.inStrides = inStrides;
this.permutedStrides = permutedStrides;
this.start = start;
this.end = end;
}

@Override
public Object call() {
for( long idx = start; idx < end; idx++ ) {
long inIdx = 0;
long outIdx = 0;
long remaining = idx;

for( int d = 0; d < inDims.length; d++ ) {
long coord = remaining / inStrides[d];
remaining = remaining % inStrides[d];
inIdx += coord * inStrides[d];
outIdx += coord * permutedStrides[d];
}

outData[(int)outIdx] = inData[(int)inIdx];
}
return null;
}
}

private static class PermuteMultiBlockTask implements Callable<Object> {
private final DenseBlock inDB;
private final DenseBlock outDB;
private final int[] inDims;
private final long[] inStrides;
private final long[] permutedStrides;
private final long start;
private final long end;

protected PermuteMultiBlockTask(DenseBlock inDB, DenseBlock outDB,
int[] inDims, long[] inStrides, long[] permutedStrides,
long start, long end) {
this.inDB = inDB;
this.outDB = outDB;
this.inDims = inDims;
this.inStrides = inStrides;
this.permutedStrides = permutedStrides;
this.start = start;
this.end = end;
}

@Override
public Object call() {
int inBlockSize = inDB.blockSize();
int outBlockSize = outDB.blockSize();

for( long idx = start; idx < end; idx++ ) {
long inIdx = 0;
long outIdx = 0;
long remaining = idx;

for( int d = 0; d < inDims.length; d++ ) {
long coord = remaining / inStrides[d];
remaining = remaining % inStrides[d];
inIdx += coord * inStrides[d];
outIdx += coord * permutedStrides[d];
}

int inBlockIdx = (int) (inIdx / inBlockSize);
int inRelIdx = (int) (inIdx % inBlockSize);

int outBlockIdx = (int) (outIdx / outBlockSize);
int outRelIdx = (int) (outIdx % outBlockSize);

double[] inArr = inDB.valuesAt(inBlockIdx);
double[] outArr = outDB.valuesAt(outBlockIdx);

if( inArr != null && outArr != null &&
inRelIdx < inArr.length && outRelIdx < outArr.length ) {
outArr[outRelIdx] = inArr[inRelIdx];
}
}
return null;
}
}
}

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