add_dummy_inputs pass doesn't work with sliced signals

[jack-melchert]

For example, if i00.in0 is 16 bits, and I change this:
["self.in.0","i00.in0"]

to this:
["self.in.0","i00.in0.0:16"]

The add_dummy_inputs pass will wire a constant to every bit of i00.in0.

Failing input file:

{
  "top": "global.add1",
  "namespaces": {
    "global": {
      "modules": {
        "add1": {
          "type": ["Record",[
            ["in", ["Array",2,["Array",16,"BitIn"]]],
            ["out", ["Array",16,"Bit"]]
          ]],
          "instances": {
            "i00": {
              "genref": "coreir.add",
              "genargs": {"width":["Int", 16]}
            }
          },
          "connections": [
            ["self.in.0","i00.in0.0:16"],
            ["self.in.1","i00.in1"],
            ["i00.out","self.out"]
          ]
        }
      }
    }
  }
}

Command:

coreir -i failing_test.json -p add-dummy-inputs