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Using Existing Variables from SUIF

The variable symbols in SUIF are represented by var_syms. A builder block can be created for a var_sym to use that variable in the builder system. See section Using Variables for more details. 

        var_sym * var = (variable in SUIF)
        block v(var);

Accessing a Field of a Structure

When accessing variables defining structures, each of the structure's elements can be accessed using the field() function by either specifying the name of the field or the field id. 
        type_node * tn = block::parse_type("struct { int a; int b }");
        block var(block::new_sym(tn, "var");
        block body(block(var.field("a") = block(0)),
                   block(var.field("b") = block(0)));
The builder code will create a structure variable and initialize the fields to zero.

Note: In the current builder implementation, accessing a structure field is limited to simple fields of structure variables. Composite operators such as accessing structures within structures or dereferencing a pointer to access a field in a structure are not implemented in the current version.

Pointer Operations

A value pointed to by a pointer can be accessed using the dref() function. The address of a variable can be taken using the addr() operator. The only operator that is not overloaded in block is the dereference operator * (see section Creating Expressions and Statements). 

        type_node * tn = (any type)
        type_node * ptn = block::parse_type("* %%", tn);
        block val(block::new_sym(tn, "val"));
        block ptr(block::new_sym(ptn, "prt_val"));
        block body(block(ptr = val.addr()),
                   block(ptr.dref() = block(0)));
The above code will create a variable of a given type and a pointer variable to that type. It will also assign the pointer to the data and initialize the data to zero using the pointer.

Array Accesses

Elements of an array can be accessed in the same way as in C. Another method to access array elements is by using the ARRAY() function. The first argument to the function is the block representing the array variable. The block structures representing the access functions are given as subsequent arguments. 
        var_sym * vs_i = (index variable from SUIF)
        type_node * tn = block::parse_type("int [100][100]");
        block A(tn, "A");
        block i(vs_i);
        block body(A[i][block(0)] = A[block(i+block(1))][block(0)]);

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