Consider

https://github.com/openjdk/jdk/blob/master/test/hotspot/jtreg/compiler/c2/irTests/MaxMinINodeIdealizationTests.java

Existing tests for the optimization check only one order of nodes, e.g.

    // Transform max(x + c0, max(y + c1, z)) to max(add(x, c2), z) if x == y, where c2 = MAX2(c0, c1).
    // c0,c1,c2 are constants. x,y,z can be any valid c2 nodes. In this example, x and y are
    // RShiftI nodes and z is a ConI.
    @Test
    @IR(counts = {IRNode.MAX_I, "1",
                  IRNode.ADD , "1",
                 })
    public int testMax1(int i) {
        return Math.max(((i >> 1) + 100), Math.max(((i >> 1) + 150), 200));
    }

If Max inputs are swapped, the optimization fails, e.g.

    @Test
    @IR(counts = {IRNode.MAX_I, "1",
                  IRNode.ADD , "1",
                 })
    public int testMax1i(int i) {
        return Math.max(((i >> 1) + 100), Math.max(200, ((i >> 1) + 150)));
    }

That happens because Ideal() looks for Add only as a first input but that is not guaranteed.

  // Get left input & constant
  Node* x = l;
  jint x_off = 0;
  if (x->Opcode() == Op_AddI...