newDirectedModule does not return a new version after a pass has been run

[leonardt]

This code

coreir/src/ir/module.cpp

Lines 54 to 59 in b167247

	DirectedModule* Module::newDirectedModule() {
	if (!directedModule) {
	directedModule = new DirectedModule(this);
	}
	return directedModule;
	}

always returns the first and only directed module that is created. This creates issues for code such as the following (pycoreir):

import coreir
def test_directed_upsample():
    c = coreir.Context()
    context = coreir.Context()
    context.load_library('commonlib')
    top_module = context.load_from_file('./tests/upsample.json')
    print(len(top_module.definition.instances))
    print(len(top_module.directed_module.connections))
    context.run_passes(['rungenerators', 'removebulkconnections',  'flattentypes', 'flatten'])
    top_def = top_module.definition
    print(len(top_def.instances))
    print(len(top_module.directed_module.connections))
    for con in top_module.directed_module.connections:
        print(1)
        src = con.source
        print(2)
        dst = con.sink
        print(3)
        size = con.size
        print(4)

upsample.json.txt

Notice that directed module is invoked before running passes, then invoked after (operating on a stale copy which causes a segfault).