Rounding mode rtz & rod are supported by vfcvt statically,
while other rounding modes such as rdn & rup are supported dynamically and controlled by FRM register, which also affects scalar floating-point operations.
This patch adds an additional operand to carry round-mode information in vfcvt pseudos.
Lowering and instruction selection can specify the needed round mode imm. value and let the backend deal with the round mode change at MachineInstr level at later stage.
Could you add a comment explaining what this flag means?
What I understand is that for "vfcvt" instructions we annotate the rounding mode. It'll be commonly dynamic except for cases when we want to explicitly round up or down.