The may be operation means that it has an initial behavior which can be redefined
by later extensions to perform some other action.

The May-Be-Operations includes two extension: zimop and zcmop. Zimop has 40
instructions, whose initial behavior is writing zero to the destination register.
Zcmop, which requires the Zca extension, has 8 instructions whose initial
behavior is reading the source register.

The more details on this specifcation is here:
https://github.com/riscv/riscv-isa-manual/blob/main/src/zimop.adoc

LIU Zhiwei (4):
  target/riscv: Add zimop extension
  disas/riscv: Support zimop disassemble
  target/riscv: Add zcmop extension
  disas/riscv: Support zcmop disassemble

 disas/riscv.c                               | 123 ++++++++++++++++++++
 target/riscv/cpu.c                          |   4 +
 target/riscv/cpu_cfg.h                      |   2 +
 target/riscv/insn16.decode                  |   1 +
 target/riscv/insn32.decode                  |  11 ++
 target/riscv/insn_trans/trans_rvzcmop.c.inc |  29 +++++
 target/riscv/insn_trans/trans_rvzimop.c.inc |  37 ++++++
 target/riscv/tcg/tcg-cpu.c                  |   5 +
 target/riscv/translate.c                    |   2 +
 9 files changed, 214 insertions(+)
 create mode 100644 target/riscv/insn_trans/trans_rvzcmop.c.inc
 create mode 100644 target/riscv/insn_trans/trans_rvzimop.c.inc

-- 
2.25.1