The official FSF gcc doesn't have a target port to ARC's MXP architecture.
This port would be of rather limited use without an ARCompact port (See PR39303). It is doubtful that the mxp port will ever be properly finished. Moreover, due to the lack of overall design and instability of the instruction set, and a programming model that is different in a number of aspects from every other GCC target, and in even more aspects different from the majority of GCC targets, this is a high-maintenance port. Adding this port to the trunk without a maintainer who is able and willing to competently maintain this port on an on-going basis would only serve to impede GCC development. The port is available in branches/arc-20081210-branch.
target/39346, other/39347 and other/39348 are no longer relevant to other/39363, because the Successor of ARC International (UK) Ltd, Synopsys, does not offer an mxp option in its DesignWare ARC Processor Cores lineup.