Wrong results using Integer Matmul Kernels after Matrix resizing

[resting-dove]

The results of Matrix multiplications for integer value types are wrong in case that the Matrix has been resized before.

N = 3;
EWs = seq(1, N + 1, 1);
A = diagMatrix(EWs);
A = A[:N, :N];
B = A;
v = fill(1, N, 1);
print(A);

print(A@B);

print(A@t(B));

print(A@v);

DenseMatrix(3x3, int64_t)
1 0 0
0 2 0
0 0 3
DenseMatrix(3x3, int64_t)
1 0 0
0 0 0
0 0 0
DenseMatrix(3x3, int64_t)
1 0 0
0 4 0
0 0 0
DenseMatrix(3x1, int64_t)
1
2
0

Likely Explanation

Integer MatMul kernels are generated using the Eigen library. To use the library the Daphne Matrices are transformed into Eigen Matrices, assuming that the row offset in memory is the row length. When Daphne Matrices are resized they are not necessarily moved in memory, so the row offset does not equal the row length.