emit_atomic_r
void emit_atomic_r(struct jit_context *ctx, u8 dst, u8 src, s16 off, u8 code);
emit_atomic_r(ctx, lo(dst), lo(src), off, imm);
emit_atomic_r(ctx, tmp, src, off, imm);
emit_atomic_r(ctx, dst, MIPS_R_T4, off, imm);