Threads with function call generate incorrect hcode

[zhuanhao-wu]

File: https://github.com/intel/systemc-compiler/blob/main/designs/tests/cthread/test_cthread_read_defined_ref.cpp

    template<class T>
    void const_ref(const T& par) {
        auto i = par;
    }
    // Assign through reference
    template<class T>
    void ref_assign(T& par) {
        par = 0;
    }
    void fcall_ref_assign()
    {
        int i;
        sc_uint<2> k = 0;
        wait();

        while (1)
        {
            ref_assign(i);
            ref_assign(k);
            const_ref(i);
            const_ref(k ? 1 : 2);
//             sct_assert_defined(i);
//             sct_assert_defined(k);
//             sct_assert_register(i, false);
//             sct_assert_register(k, false);

            sc_uint<2> m;
            ref_assign(m);
            auto j = m / 2;
//             sct_assert_defined(m);
//             sct_assert_register(m, false);

            wait();
        }
    }

Currently the generated code looks as follows:

                hSwitchCase  NONAME [
                  hLiteral 1 NOLIST
                  hIfStmt  NONAME [
                    hLiteral 1 NOLIST
                  ]
                  hLiteral 1 NOLIST
                  hMethodCall A__const_ref_func_0 [
                    hCondop  NONAME [
                      hVarref k_fcall_ref_assign_thread_1 NOLIST
                      hLiteral 1 NOLIST
                      hLiteral 2 NOLIST
                    ]
                  ]
                  hMethodCall A__ref_assign_func_0 [
                    hVarref m_fcall_ref_assign_thread_2 NOLIST
                  ]
                  hVarAssign  NONAME [
                    hVarref j_fcall_ref_assign_thread_3 NOLIST
                    hBinop / [
                      hVarref m_fcall_ref_assign_thread_2 NOLIST
                      hLiteral 2 NOLIST
                    ]
                  ]
                  hBinop = [
                    hVarref _next_state_fcall_ref_assign# NOLIST
                    hLiteral 2 NOLIST
                  ]
                  hReturnStmt  NONAME NOLIST // the return statement is generated here, but we still have more statemetns
                  hLiteral 2 NOLIST
                  hMethodCall A__const_ref_func_0 [
                    hCondop  NONAME [
                      hVarref k_fcall_ref_assign_thread_1 NOLIST
                      hLiteral 1 NOLIST
                      hLiteral 2 NOLIST
                    ]
                  ]
                  hVarAssign  NONAME [  // here, we have a dangling assignment
                    hVarref m_fcall_ref_assign_thread_2 NOLIST
                  ]
                  hMethodCall A__ref_assign_func_1 [
                    hVarref m_fcall_ref_assign_thread_2 NOLIST
                  ]
                  hVarAssign  NONAME [
                    hVarref j_fcall_ref_assign_thread_3 NOLIST
                    hBinop / [
                      hVarref m_fcall_ref_assign_thread_2 NOLIST
                      hLiteral 2 NOLIST
                    ]
                  ]
                  hBinop = [
                    hVarref _next_state_fcall_ref_assign# NOLIST
                    hLiteral 2 NOLIST
                  ]
                  hReturnStmt  NONAME NOLIST
                ]

[zhuanhao-wu]

• Confirm SystemVerilog has support for inlining functions/pass-by-reference
• Check if the function is not pass-by-reference, the binary is still generating incorrect hcode

[zhuanhao-wu]

The code that is causing the issue is const_ref(k ? 1 : 2);.

1. Removing this line allows the tool to pass through
2. Changing const_ref to be not pass-by-reference does not help

    template<class T>
    void const_ref(T par) {
        auto i = par;
    }

[zhuanhao-wu]

SystemVerilog has support for pass-by-reference with the following form

    function automatic logic pipe(ref logic[31:0] ip);
        ip = ip + 1;
        return ip;
    endfunction