Function emit_cmp_test_handler

src/codec.cpp:1882–2051

    }

    static void emit_cmp_test_handler(X64Emitter& e, const VMConfig& vm, bool is_test) {
        const auto& r = vm.dispatcher_regs();

        // op0: tag + payload
        emit_fetch_byte_dec(e, vm, r.scratch_a);
        auto lbl_op0_imm = e.new_label(), lbl_op0_done = e.new_label();
        e.cmp_reg_imm32(r.scratch_a, 0);
        e.jcc_label(cc::nz, lbl_op0_imm);
        emit_fetch_byte_dec(e, vm, r.scratch_a); // slot
        emit_fetch_byte_dec(e, vm, r.scratch_b); // op0 width
        e.mov_reg_mem_sib(
            rx::rax,
            r.state_ptr,
            r.scratch_a,
            3,
            static_cast<std::int32_t>(vm.state_layout().regs_base),
            true
        );
        emit_extract_operand(
            e,
            vm,
            rx::rax,
            r.scratch_b
        );
        e.jmp_label(lbl_op0_done);
        e.bind(lbl_op0_imm);
        e.sub_reg_imm32(rx::rsp, 16);
        emit_fetch_uN_dec(
            e,
            vm,
            rx::rax,
            8
        );
        e.add_reg_imm32(rx::rsp, 16);

        // imm carries no per-operand width, gets masked by global width below.
        e.bind(lbl_op0_done);

        // op1
        emit_fetch_byte_dec(e, vm, r.scratch_a);
        auto lbl_imm = e.new_label(), lbl_mem = e.new_label(), lbl_done = e.new_label();
        e.cmp_reg_imm32(r.scratch_a, 1);
        e.jcc_label(cc::z, lbl_imm);
        e.cmp_reg_imm32(r.scratch_a, 2);
        e.jcc_label(cc::z, lbl_mem);
        emit_fetch_byte_dec(e, vm, r.scratch_a); // slot
        emit_fetch_byte_dec(e, vm, r.scratch_b); // op1 width
        e.mov_reg_mem_sib(
            rx::rcx,
            r.state_ptr,
            r.scratch_a,
            3,
            static_cast<std::int32_t>(vm.state_layout().regs_base),
            true
        );
        emit_extract_operand(
            e,
            vm,