Excessive critical-edge splitting for phis with multiple constant args

[dubiousconst282]

This is more common in phis with constants and arguments, as they have no associated node in the interference graph and thus will always need critical edges to be split.

Repro:

static int SSA_MultiPreds1(int x, int y) {
    int r = 1;
    if (x > 0 && y < 100 && x * 3 < y) {
        r = 2;
    }
    return r;
}

Reg allocated CFG: