We have several nodes which provide floating point <-> integer representation conversions. Some of this nodes use fmv instructions, other use store or load instructions to convert value.
On the RISC-V we prefer way using fmv instruction, because it faster, but now nodes, which use stack, selected.
This happens because reg_reg and stack_reg operations matches similar nodes and the matcher does not take into account the cost of transferring a value from the stack back to the register.
For example, we can have a look on IGV dumps for the simple code, which makes conversion like doubleToRawLongBits function. During matching MpveD2L machine independent node turn into MoveD2L_reg_stack node, and only after matching compiler adds BoundSpillCopy node to transfer converted value into the register.