DIAG.UNEX.COMP : Unexercised Computation

Summary

Some of the code in a function is not exercised by the CodeSonar analysis; the most serious statement in the unexercised set is a computation (such as addition) on data.

Warnings of this and other Unexercised Code warning classes typically arise when the setting of configuration parameter SEARCH_BOUND is not high enough to permit all code to be exercised. Increase this setting to reduce or eliminate these warnings. Increase this setting to reduce these warnings, at the cost of increased analysis time. In most real programs, a search bound high enough to eliminate all Unexercised Code warnings will cause the analysis to take an impractically long time.

Note that these classes are concerned with code coverage rather than path coverage: in some cases it is entirely possible to cover all code in a procedure with a strict subset of the possible paths through that procedure.

For more information, see Unexercised Call: Note: Unexercised Code Warning Classes.

Properties

WARNING_FILTER += allow class="Unexercised Computation"

Example

For the sake of compact illustration, we lower the setting of SEARCH_BOUND by adding the following configuration file rule.

SEARCH_BOUND=3

With SEARCH_BOUND=3, CodeSonar will only explore three paths in procedure unex_comp(). However, there are four paths through the procedure: if only three paths are explored, one of the switch cases will not be exercised. The most serious statement type in each switch case is a computation, so an Unexercised Computation warning will be issued at one of those statements. We cannot predict exactly which one from source code alone: it will depend on various phenomena in the CodeSonar build and analysis.

int g(void);
        
void unex_comp(int j)
{
    int i = g();
    switch( j )
    {
    case __LINE__: j++; if (i) i=4; return; break;  /* 'Unexercised Computation' warning issued either here... */
    case __LINE__: j++; if (i) i=4; return; break;  /* ...or here... */
    case __LINE__: j++; if (i) i=4; return; break;  /* ...or here... */
    default: j++; if (i) i=4; return; break;        /* ...or here. */
    }
}

Relevant Configuration File Parameters

The following configuration file parameters affect checks for this warning class.

• REPORT_INTER_PARTIAL_UQ_WARNINGS
• REPORT_SIMILAR_WARNINGS
• SEARCH_BOUND
• TIME_LIMIT_INTRA_EXPLORE
• WARNING_FILTER