[CAR] Improve Finding Missing Cases in Conditions

[ebehner]

We currently only consider missing-cases in condition-nodes with one branch is a switch-node. However, this can be extended to when a branch is a sequence node whose first or last child is a switch node.

For example, the function mpn_base_power_of_two_p in expr (coreutils) currently leads to the following output

unsigned int mpn_base_power_of_two_p(unsigned int b) {
    long var_0;
    if (b <= 1) {
        var_0 = 0L;
    }
    if ((b > 1) && (b <= 32)) {
        switch(b) {
        case 0x2:
            return 1L;
        case 0x4:
            return 2L;
        case 0x8:
            return 3L;
        case 0x10:
            return 4L;
        case 0x20:
            return 5L;
        default:
            return 0L;
        }
    }
    if (b > 32) {
        if (b == 128) { // <--- missing case, we currently do not find
            var_0 = 7L; 
        }
        else {
            switch(b) {
            case 64:
                var_0 = 6L;
                break;
            case 256:
                var_0 = 8L;
                break;
            default:
                var_0 = 0L;
            }
            if (b != 256) {
                return var_0;
            }
        }
    }
    return var_0;
}

A better output would be:

unsigned int mpn_base_power_of_two_p(unsigned int b) {
    long var_0;
    if (b <= 1) {
        var_0 = 0L;
    }
    if ((b > 1) && (b <= 32)) {
        switch(b) {
        case 0x2:
            return 1L;
        case 0x4:
            return 2L;
        case 0x8:
            return 3L;
        case 0x10:
            return 4L;
        case 0x20:
            return 5L;
        default:
            return 0L;
        }
    }
    if (b > 32) {
        switch(b) {
        case 64:
            var_0 = 6L;
            break;
        case 128:
            var_0 = 7L;
            break;
        case 256:
            var_0 = 8L;
            break;
        default:
            var_0 = 0L;
        }
        if ((b != 128) && (b != 256)) {
            return var_0;
        }
    }
    return var_0;
}

[steffenenders]

Looks good. Can be merged once the pipeline is succeeding again.