C file not instrumented for coverage, bad expr node kind

Question

I am using the legacy_code tool in MATLAB, to generate some S Functions, then I want the S Functions to be under analysis by the simulink coverage toolbox.

I am asking also here because maybe this is a C issue and not MATLAB related.

I am setting to true the flag to use the coverage toolbox when generating the S functions using the legacy_code tool.

def.Options.supportCoverage = true;

But I get the following error at compilation, I am using the MinGW 64 bits compiler for MATLAB in windows.

“lib_control.c", line 254: error: bad expr node kind (b:\matlab\polyspace\src\shared\cxx_front_end_kernel\edg\src\cp_gen_be.c, line 14084) Warning: File "lib_control.c" not instrumented for coverage because of previous error In codeinstrum.internal.LCInstrumenter/instrumentAllFiles In codeinstrum.internal.SFcnInstrumenter/instrument In slcovmexImpl In slcovmex (line 48) In legacycode.LCT/compile In legacycode.LCT.legacyCodeImpl In legacy_code (line 101) In generate_sfun (line 70)

In the C code I have the following kind of functions:

void controller( int n_var,
             double my_input,
             double my_output )
{
    double my_var[n_var];    
    for ( int i=0; i<n_var; i++ )
    {
        my_output = my_input + my_var[i];
    }
}

The compiler is complaining about this line:

double my_var[n_var];

Do I have to do something to declare variables like this, so they can be included in the coverage analysis?

Is this error from MATLAB or is it a C error for instrumentation of files?

If I compile without the coverage flag there is no problems and the S Functions is generated without warnings.

Answer 1

Seems your code won't work because of issues. First try to declare my_var like this

double *my_var = malloc(n_var * sizeof(double));
memset(my_var, 0, n_var * sizeof(double));

This is the correct way to allocate memory according to function parameter. And there is also an issue.

my_output = my_input + my_var[i];

So it is correct solution.

*my_output = *my_input + my_var[i];

You are going to change value of parameter which is stack register variable In C language, parameters are saved in to stack register so it will be freed after function ends. so it won't reflect any changes

To do this, you need to send pointer of variable as parameter

void controller( int n_var,
         double *my_input,
         double *my_output ) {
    *my_output = ....; // like this
}

and in caller side, you can do like this.

double a, b;
controller(10, &a, &b);

Hope this helps you