solana_rbpf::ebpf
pub const ST_B_IMM: u8 = BPF_ST | BPF_MEM | BPF_B; // 114u8
BPF opcode: stb [dst + off], imm /// (dst + offset) as u8 = imm.
stb [dst + off], imm
(dst + offset) as u8 = imm