Codegen removes dead code while translating to C/C++

I tried using Matlab Code/codegen tool to translate following Matlab script to C (by wrapping it as a Matlab function named test).

$ matlab -nojvm -nosplash -batch "codegen -I . -config:lib -c test"

% line added by me
function test

 randn('seed',0);
 n  = 2;
 m = 2*n;
 A1 = [1 1; 1 -1; -1 1; -1 -1];
 A2 = [1 0; -1 0; 0 1; 0 -1];
 b1 = 2*ones(m,1);
 b2 = [5; -3; 4; -2];
 fprintf(1,'Hello world...');

end

But I see that the generated C code only contains printf statement.

I want codegen to translate dead (unused) Matlab code also. How can I achieve this? I did not see any codegen option to control this behavior.

void test(void)
{
  printf("Hello world...");
  fflush(stdout);
}

[Steven Lord]

I want codegen to translate dead (unused) Matlab code also.

Why? They have no impact on the result of this code, so why shouldn't MATLAB Coder get to optimize them away? What are you hoping to achieve by including them in your generated code?

[Niranjan]

I am trying to understand how different Matlab code elements gets translated into C. Is there a knob to control this behavior?

[Steven Lord]

You could modify the code so it returns those variables. That way they're not unused and so I believe couldn't be optimized away.

Answer 1

[Gojo]

Hey Niranjan,

I understand that you wish to control the optimizations being performed while generating the code. You can do so by following the below mentioned steps:

• Change the level of optimizations being performed while generating code. You can achieve this by modifying the settings in Model Configuration Pane and selecting the optimization level for your models by referring to the following documentation: https://www.mathworks.com/help/releases/R2024a/ecoder/ref/level.html
• The optimizations being performed are drastically reduced in the debugging mode. In order to generate the code using the MATLAB Coder with the debug option, Use the "coder.CodeConfig" object to modify the configuration parameters. For more information on changing the configuration parameters for the optimizations being performed, refer to the "BuildConfiguration" property from the following documentation: https://www.mathworks.com/help/releases/R2024a/coder/ref/coder.codeconfig.html

I hope this helps!

[Niranjan]

Hi Shubham,

Thanks for your inputs. I did try the option that you suggested, but it still does not preserve input Matlab code as it is. The command that I used is as follows:

matlab -batch "cfg = coder.config('lib','ecoder',false); cfg.BuildConfiguration='Debug'; codegen -I . -config cfg -c test