Polyspace computes the estimated static path count within a function, which represents the potential execution paths software can identify. The algorithm used by Polyspace is as follows:
- Rule (a): The path count for a sequence of non-control statements is 1.
- Rule (b): For an if statement, the path count is the sum of the paths in the then block and the else block.
- Rule (c): For loops (while, do-while, for), the path count is the paths in the loop body plus 1.
- Rule (d): For a switch statement, the path count is the sum of the paths for each case body.
- Rule (e): For consecutive control statements, the path count is the product of the path counts of the individual control statements. This applies to control structures such as if, while, do-while, for, and switch.
It's important to note that a for loop inherently has at least two paths. Consequently, according to Rule (e), two consecutive for loops will have a minimum path count of 4.
The paths computed by Polyspace reflect the definition of the estimated static path count. A high number of paths indicates that the routine contains numerous sequential control blocks, which are influenced by Rule (e). This rule also implies that the total number of paths in a routine increases rapidly with the number of loops or if statements.
For example, consider the below function:
void function(void) {
int i = 0, j = 0;
if (i == j);
if (i == j);
if (i == j);
if (i == j);
if (i == j);
if (i == j);
if (i == j);
if (i == j);
if (i == j);
for (i = 0; i < 10; i++) {
for (j = 0; j < 10; j++) {
if (i == 0) {
;
}
}
}
}
The Path metrics is 2048 for this simple function.
