The vendor-defined XTHeadMemPair (no comparable standard extension exists
at the time of writing) extension adds two-GPR load/store pair instructions.
It is supported by the C9xx cores (e.g., found in the wild in the
Allwinner D1) by Alibaba T-Head.
The current (as of this commit) public documentation for this
extension is available at:
Support for these instructions has already landed in GNU Binutils:
Depends on D143847