Configurable context save and restore

A method, comprising.

• receiving, while executing a first subroutine, a call instruction that includes a first opcode and a first set of bits, wherein the call instruction identifies a first target address, wherein the first target address stores a first instruction of a set of instructions for performing a second subroutine;
• determining a first set of context registers mapped to the first set of bits;
• storing content of the first set of context registers in first memory allocated for context storage for the first subroutine;
• and
• executing the first instruction stored in the first target address.

A processor coupled to a memory and configured to, when executing instructions stored in the memory, perform operations comprising.

• receiving, while executing a second subroutine, a return instruction that includes a first opcode and a first set of bits, wherein the return instruction identifies a first target address, wherein the first target address stores a first instruction of a set of instructions for performing a first subroutine;
• determining a set of context registers mapped to the first set of bits;
• restoring content of the set of context registers from memory allocated for context storage for the first subroutine;
• and
• executing the instruction stored in the first target address.