Modifying RTL Files Using Pyslang Not Working

[zigzagtx2778]

Now that pyslang 9.0 is out with the new SyntaxRewriter, I'm trying to write a python script to modify files based on a command file that contains a list of modifications to be processed. I'll take a simple example, delete a module port.

I've found the module using by searching through the compilation.getRoot().topInstances, we'll call the result mod_obj. I then search through the Ports to find the port in question, using mod_obj.body.portList, we'll call this port_obj. Technically these can be lists as in the case of the ports, I could, for instance, perform a regex for a mass deletion of a memory bus.

Having the port_obj, which I believe is a PortSymbol, I then attempt to perform a routine similar to the pyslang/test/test_syntax_rewrite for the function test_rewriter_remove.

The equivalent to remove_int_var is located in a class where I set the remove_obj variable to the port_obj.syntax. I then call my remove function using the following:

        self.support.remove_obj     = port_obj[0].syntax
        self.support.remove_success = False
        new_tree = rewrite(self.tree, self.support.remove_module_port)
        if new_tree is not None:
            self.tree = new_tree

The remove_module_port is as follows:

    def remove_module_port(self, node: SyntaxNode, rewriter: SyntaxRewriter) -> None:
        if node.isEquivalentTo(self.remove_obj):
            self.logger.info("Found Matching Port to Remove: %s", node.name.valueText.strip())
            rewriter.remove(node)
            self.remove_success = True

If I look at len(self.tree.root.members[0].header.ports.ports) and compare to len(new_tree.root.members[0].header.ports.ports) they're the same count, but I can see the logged info message on the screen as well as the remove_success being set to True so I know that we found a match and the name matches the port I'm looking for.

What am I missing?

[zigzagtx2778]

Might be answering my own question a bit, but the port count went down when I modified the remove_module_port function to the following code. I did change out the remove variables to add is_ansi_port and name, so the name matching happens in the remove_module_port function. I'll need to work on a non-ansi case as well, but the count has gone down.

        if self.remove_is_ansi_port:
            if node.kind == SyntaxKind.ImplicitAnsiPort:
                if node.declarator.name.valueText == self.remove_name:
                    self.logger.info("Found Matching Port to Remove: %s", node.declarator.name.valueText.strip())
                    rewriter.remove(node)

I had noticed that when I was trying to str() that it was only printing "\n input wire" and such for the ports that were removed so that let me to I was just removing the name of the port, not the full port.

[MikePopoloski]

Not sure if your question is resolved then? It wasn't clear to me what you were asking in the first place.

[zigzagtx2778]

So I have a Python script that uses another vendor's parser/modification tool to modify RTL files. We prototype ASIC designs on FPGA platforms so some elements of the RTL files need to be modified before we can use them. We script up these changes in control files that tell the tool what RTL and IncDir's to include so that a file can be loaded, analyzed, modified, and written back out to a special folder.

That being said, I was starting off updating the script so that I could use pyslang to perform these modifications, hoping for a faster experience. I started off with a module top level port deletion. I had started by grabbing the module from comp.getRoot().topInstances (searching through the list and selecting the matching module name). I then tried parsing over the .body.portList to look for the port by name for removal. Once I had the port, an InstanceSymbol type in Python, I then use the pyslang.rewrite method to find that node and initiate a rewriter.remove on the node. That's where I failed at first, I was looking for a Symbol while it was parsing nodes.

I updated the method to grab the Node from the syntaxTree that matched the port I was trying to remove. Updated the function to match the Node and ran the rewriter.remove(node) to delete it. After the delete ports were completed, I looked at the port list length compared to the beginning length and found that it was less by the expected amount so I feel that I can remove things from the syntaxTree.

My problem is now in writing the final output back out. Either, I get the full untouched file, or even worse, I get the `define macros along with their decoded values next to each other.

Hope that makes better sense. I feel the original question is answered unless you see something wrong with the process flow in general. Now I need to figure out why the SyntaxPrinter isn't using the updated syntaxTree.

[MikePopoloski]

Did you figure this out? It's not obvious to me from your explanation what the problem is, so if you're still stuck you'll need to provide more complete example code to work with.

[zigzagtx2778]

For now, yes I'll consider the issue closed.