Methods of implementing a standard convolution on a graphics processing unit. The methods include: receiving, at the graphics processing unit, an input tensor in a dense format; identifying, at the graphics processing unit, active positions of the input tensor; performing, at the graphics processing unit, an indexed unfold operation on the input tensor based on the identified active positions of the input tensor to generate an input matrix comprising elements of the input tensor in each non-zero window of the input tensor; and performing, at the graphics processing unit, a matrix multiplication between a weight matrix and the input matrix to generate an output matrix that comprises elements of an output tensor of the standard convolution based on the non-zero windows of the input tensor.