Function emit_native_handler

src/codec.cpp:2500–3087

    }

    static void emit_native_handler(X64Emitter& e, const VMConfig& vm, bool is_jmp) {
        const auto& r = vm.dispatcher_regs();
        {
            // deferred data-island decrypt
            const auto& st_local = vm.state_layout();
            auto lbl_dec_done = e.new_label();

            // lea rax, [rip + data_island_init_flag]; cmp byte [rax], 0; jnz done
            auto flag_lea = e.lea_reg_rip(rx::rax, 0);
            e.add_fixup(
                flag_lea,
                static_cast<std::uint32_t>(FixupKind::DataIslandInitFlag),
                0,
                0
            );
            e.u8(0x80);
            e.emit_modrm_mem(
                7,
                rx::rax,
                rx::none,
                0,
                0
            );
            e.u8(0);
            e.jcc_label(cc::nz, lbl_dec_done);

            // save cipher_state + ip so the rest of the handler's fetch
            // invariant survives the loop.
            e.mov_mem_reg(
                r.state_ptr,
                static_cast<std::int32_t>(st_local.cipher_extra) + kPreDecryptCsOff,
                r.cipher_state,
                true
            );

            e.mov_mem_reg(
                r.state_ptr,
                static_cast<std::int32_t>(st_local.cipher_extra) + kPreDecryptIpOff,
                r.ip,
                true
            );

            // reset cipher_state to cipher_init and walk the island tom hanks
            e.mov_reg_imm64(rx::rax, vm.cipher_init_state());
            e.mov_reg_reg(r.cipher_state, rx::rax);
            auto src_slot = e.lea_reg_rip(r.ip, 0);
            e.add_fixup(
                src_slot,
                static_cast<std::uint32_t>(FixupKind::DataIsland),
                0,
                0
            );
            auto dst_slot = e.lea_reg_rip(r.scratch_b, 0);
            e.add_fixup(
                dst_slot,
                static_cast<std::uint32_t>(FixupKind::DataIsland),
                0,
                0