[TKW] Bug: multiple issues with input/output determination

[GMNGeoffrey]

The current logic for inputs and outputs has a number of issues:

iree-turbine/iree/turbine/kernel/compiler/kernel_codegen.py

Lines 250 to 289 in e4550f3

	def determine_input_output_buffers(self, graph: fx.Graph):
	# Extract all placeholder nodes.
	placeholder_nodes = filter_fx_graph(graph, is_placeholder)
	def only_read_dependencies(node):
	return all([isinstance(get_custom(x), Read) for x in node.users.keys()])
	def only_write_dependencies(node):
	if len(node.users) == 0:
	return False
	return all([isinstance(get_custom(x), Write) for x in node.users.keys()])
	for node in placeholder_nodes:
	index = None
	for i, binding in enumerate(self.bindings):
	if binding.reference[1] == node:
	index = i
	break
	if index == None:
	continue
	# TODO: Match KernelBufferUsage to what bufferType that is expected on IREE.
	usage = KernelBufferUsage.INPUT
	if only_read_dependencies(node):
	usage = KernelBufferUsage.INPUT
	if only_write_dependencies(node):
	usage = KernelBufferUsage.OUTPUT
	# Create new Memory type with the correct usage
	memory_type = self.bindings[index].kernel_buffer_type
	self.bindings[index].kernel_buffer_type = Memory[
	(
	*memory_type.symbolic_shape,
	memory_type.address_space,
	memory_type.dtype,
	usage,
	)
	]
	return

(amongst other places)

1. If something has any dependency other than a write, it gets labeled an input, which then marks it as readonly and it comes out unmodified.
2. Writes inside of reductions are not considered for classifying an output.
3. Everything designated an output gets moved to the end of the signature, so when the compiled kernel is called the arguments are all scrambled.
4. Arguments that are unused somehow get stripped out during compilation and then when the compiled kernel is called the arguments are all scrambled.

So far, I've found that the easiest thing was to just mark everything as an output. Not sure what other implications that has besides passing up optimizations dependent on things being read-only. I think this also still doesn't fix problem 4.