solana_rbpf::ebpf
pub const ST_DW_IMM: u8 = BPF_ST | BPF_MEM | BPF_DW; // 0_x7au8
BPF opcode: stdw [dst + off], imm /// (dst + offset) as u64 = imm.
stdw [dst + off], imm
(dst + offset) as u64 = imm