A compiler device comprising - an input interface arranged to receive a computer program representation, - a processor circuit configured to - obtain a data flow graph representation from the computer program representation, at least part of the nodes in the data flow graph being marked as encoded or as non-encoded, wherein an encoded node represents an operation on encoded data and wherein a non-encoded node represents an operation on non-encoded data, - amend the data flow graph by - identifying a sub-graph in the data flow graph having one or more output nodes marked as encoded and one or more output nodes marked as non-encoded, - replacing the sub-graph by an encoded first sub-graph (210.1), and a non-encoded second sub-graph (210.2), wherein the first sub-graph has only encoded output nodes, and the second sub-graph has only non-encoded output nodes, the first sub-graph and the second subgraph being obtained as further sub-graphs of the sub-graph, and - inserting one or more nodes representing an encoding operation before the first sub-graph, so that the first sub-graph operates only on encoded data, and/or inserting one or more nodes representing a decoding operation before the second sub-graph, so that the second sub-graph operates only on non-encoded data, and - obtain a compilation of the computer program representation from at least said amended data flow graph. - an input interface arranged to receive a computer program representation, - a processor circuit configured to - obtain a data flow graph representation from the computer program representation, at least part of the nodes in the data flow graph being marked as encoded or as non-encoded, wherein an encoded node represents an operation on encoded data and wherein a non-encoded node represents an operation on non-encoded data, - amend the data flow graph by - identifying a sub-graph in the data flow graph having one or more output nodes marked as encoded and one or more output nodes marked as non-encoded, - replacing the sub-graph by an encoded first sub-graph (210.1), and a non-encoded second sub-graph (210.2), wherein the first sub-graph has only encoded output nodes, and the second sub-graph has only non-encoded output nodes, the first sub-graph and the second subgraph being obtained as further sub-graphs of the sub-graph, and - inserting one or more nodes representing an encoding operation before the first sub-graph, so that the first sub-graph operates only on encoded data, and/or inserting one or more nodes representing a decoding operation before the second sub-graph, so that the second sub-graph operates only on non-encoded data, and - obtain a compilation of the computer program representation from at least said amended data flow graph. - obtain a data flow graph representation from the computer program representation, at least part of the nodes in the data flow graph being marked as encoded or as non-encoded, wherein an encoded node represents an operation on encoded data and wherein a non-encoded node represents an operation on non-encoded data, - amend the data flow graph by - identifying a sub-graph in the data flow graph having one or more output nodes marked as encoded and one or more output nodes marked as non-encoded, - replacing the sub-graph by an encoded first sub-graph (210.1), and a non-encoded second sub-graph (210.2), wherein the first sub-graph has only encoded output nodes, and the second sub-graph has only non-encoded output nodes, the first sub-graph and the second subgraph being obtained as further sub-graphs of the sub-graph, and - inserting one or more nodes representing an encoding operation before the first sub-graph, so that the first sub-graph operates only on encoded data, and/or inserting one or more nodes representing a decoding operation before the second sub-graph, so that the second sub-graph operates only on non-encoded data, and - identifying a sub-graph in the data flow graph having one or more output nodes marked as encoded and one or more output nodes marked as non-encoded, - replacing the sub-graph by an encoded first sub-graph (210.1), and a non-encoded second sub-graph (210.2), wherein the first sub-graph has only encoded output nodes, and the second sub-graph has only non-encoded output nodes, the first sub-graph and the second subgraph being obtained as further sub-graphs of the sub-graph, and - inserting one or more nodes representing an encoding operation before the first sub-graph, so that the first sub-graph operates only on encoded data, and/or inserting one or more nodes representing a decoding operation before the second sub-graph, so that the second sub-graph operates only on non-encoded data, and - obtain a compilation of the computer program representation from at least said amended data flow graph.