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Variables to initialize (-main-generator-writes-variables)

Specify global variables that you want the generated main to initialize

Description

This option affects a Code Prover analysis only.

This option is not available for code generated from MATLAB® code or Simulink® models.

Specify global variables that you want the generated main to initialize. Polyspace® considers these variables to have any value allowed by their type.

Set Option

User interface (desktop products only): In your project configuration, the option is on the Code Prover Verification node. See Dependencies for other options that you must also enable.

User interface (Polyspace Platform, desktop products only): In your project configuration, the option is on the Static Analysis tab on the Run Time Errors node.

Command line and options file: Use the option -main-generator-writes-variables. See Command-Line Information.

Why Use This Option

If you are verifying a module or library, Code Prover generates a main function if one does not exist. If a main exists, the analysis uses the existing main.

A Code Prover analysis of a module without a main function makes some default assumptions about global variable initialization. The analysis assumes that global variables that are not explicitly initialized can have the full range of values allowed by their data types upon each entry into an uncalled function. For instance, in the example below, which does not have a main function, the variable glob is assumed to have all possible int values both in foo and bar (despite the modification in foo). The assumption is a conservative one since the call context of foo and bar, including which function gets called earlier, is not known.

int glob;

int foo() {
   int locFoo = glob;
   glob++;
   return locFoo;
}

int bar() {
   int locBar = glob;
   return locBar;
}
To implement this assumption, the generation main initializes such global variables to full-range values before calling each otherwise uncalled function. Use this option to modify this default assumption and implement a different initialization strategy for global variables.

Settings

Default: public

uninit

The generated main only initializes global variables that you have not initialized during declaration.

none

The generated main does not initialize global variables.

Global variables are initialized according to the C/C+ standard. For instance, int or char variables are initialized to 0, float variables to 0.0, and so on.

public

The generated main initializes all global variables except those declared with keywords static and const.

all

The generated main initializes all global variables except those declared with keyword const.

custom

The generated main only initializes global variables that you specify. Click Add row to table icon. to add a field. Enter a global variable name.

Dependencies

You can use this option only if the following are true:

The option is disabled if you enable the option Ignore default initialization of global variables (-no-def-init-glob). Global variables are considered as uninitialized until you explicitly initialize them in the code.

Tips

This option only affects global variables that are defined in the project. If a global variable is declared as extern, the analysis considers that the variable can have any value allowed by its data type, irrespective of the value of this option.

Command-Line Information

Parameter: -main-generator-writes-variables
Value: uninit | none | public | all | custom=variable1[,variable2[,...]]
Default: public
Example (Code Prover): polyspace-code-prover -sources file_name -main-generator -main-generator-writes-variables all
Example (Code Prover Server): polyspace-code-prover-server -sources file_name -main-generator -main-generator-writes-variables all

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See Also

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