Add rule for writing GDS files #169

lpawelcz · 2023-06-16T12:35:57Z

Closes #20, closes #54.

This PR adds gds_write rule which allows writing GDS files. The rule have a set of inputs and dependencies which are:

Implemented RTL - the result of place_and_route target,
KLayout - delivered as Python module
Python script - for writing GDS files with KLayout module
KLayout technology file - XML file generated from KLayout GUI version, based on data from PDKs.
KLayout LEF file - technology LEF file of the PDK that includes all relevant information regarding metal layers, vias, and spacing requirements
Additional LEF files - List of hardened macro LEF view files.
Additional GDS files - List of platform GDS files
Fill config - JSON file with configuration for metal fill

Apart from the rules itself, PR:

adds KLayout python module into pip_requirements.txt
imports and modifies def2stream.py script from OpenROAD-flow-scripts
modifies place_and_route rule to also return SynthesisInfo provider which is convenient for accessing top module name for the GDS write script.
modifies StandardCellInfo provider to also store GDS files from PDKs
adds density_fill stage after detailed_routing

lpawelcz · 2023-06-26T07:37:39Z

Hi @QuantamHD and @proppy, please take a look at this PR

gds_write/build_defs.bzl

gds_write/def2stream.py

proppy · 2023-06-26T07:59:49Z

gds_write/def2stream.py

+parser.add_argument("-o", "--out",            required=True,  help="Path to output GDS file")
+parser.add_argument("-g", "--additional-gds", required=False, help="Paths to additional input GDS files", default="", nargs="*")
+parser.add_argument("-f", "--fill-config",    required=False, help="Path to JSON rule file for metal fill during chip finishing", default="")
+parser.add_argument("-s", "--seal",           required=False, help="Path to seal GDS/OAS file", default="")


what is seal for?

According to OpenROAD-flow-scripts those seal GDS files are used in GF12 platform. At first I wanted to keep this part in case it would be needed in the future but I will remove it so that the script will be cleaner.

gds_write/def2stream.py

proppy · 2023-06-26T08:04:27Z

gds_write/def2stream.py

+print("[INFO] Checking for missing cell from GDS/OAS...")
+missing_cell = False
+regex = None
+if 'GDS_ALLOW_EMPTY' in os.environ:


should we use a flag instead?

Replaced with --gds-allow-empty flag

gds_write/def2stream.py

proppy · 2023-06-26T08:06:55Z

gds_write/BUILD

+load("@rules_hdl_pip_deps//:requirements.bzl", "requirement")
+load("@rules_python//python:defs.bzl", "py_binary")
+
+py_binary(


should we have some py_test too?

Here we test the rule that uses this py_binary. If that is not enough I can add py_test but I think it would not be much different compared to the linked test. Please let me know what do you think.

I'll let @QuantamHD comment about the general approach taken by bazel_rules_hdl, but I'd think it'd be nice to have unittest for the python code as well.

proppy · 2023-06-26T08:07:11Z

place_and_route/build_defs.bzl

@@ -60,6 +60,7 @@ def _place_and_route_impl(ctx):

    return [
        DefaultInfo(files = depset(output_files)),
+        SynthesisInfo(top_module = ctx.attr.synthesized_rtl[SynthesisInfo].top_module),


curious why this is required? (it looks unrelated)

It would be helpful if place_and_route rule would return SynthesisInfo provider with the name of the top_module from the synthesized design. This name is required in GDS write script, see e.g. here

/cc @QuantamHD

Why not just return the ctx.attr.synthesized_rtl[SynthesisInfo] directly there's really no harm.

proppy · 2023-06-26T08:07:56Z

synthesis/tests/BUILD

+	klayout_lyt = "klayout.lyt",
+	klayout_lef = "klayout_tech.lef",
+	fill_config = "fill.json",
+	additional_lef = ["sky130_fd_sc_hd_merged.lef"],


can we get those thru dependencies?

I'm afraid that if we place all those files under single dependencies attribute we would have problems with distinguishing which file is which as they will be stored on a list and we would have to rely on file extensions.

see https://github.com/hdl/bazel_rules_hdl/tree/main/dependency_support/com_google_skywater_pdk

Oh, I see. I was able to use PDK dependencies to pass down LEF and GDS files through StandardCellInfo provider. From now on there is no need to specify input_lef and input_gds attributes. However I've left those attributes - they might be useful in some custom cases.

proppy

Sorry for the delay,

Looks very good! I made a first round of comments with nits and questions about the implementation.

QuantamHD · 2023-07-05T18:21:52Z

Sorry for the long poll in review time. I'm committed to get that down to 24 hours. I will be more responsive going forward.

Thank you for your contribution! You rock :)

Signed-off-by: Pawel Czarnecki <pczarnecki@antmicro.com>

Check for possible orphans cells in new layout is redundant because we create new layout and explicitly copy there only the tree of the top cell so it is impossible to have there cells without parents other than the top cell. Signed-off-by: Pawel Czarnecki <pczarnecki@antmicro.com>

Signed-off-by: Pawel Czarnecki <pczarnecki@antmicro.com>

QuantamHD · 2023-07-14T16:16:55Z

Thanks!

lpawelcz force-pushed the gds-write branch from f0fd211 to 78e0a75 Compare June 16, 2023 12:40

lpawelcz mentioned this pull request Jun 16, 2023

Add targets for writing GDS files google/xls#1031

Merged

lpawelcz requested review from proppy and QuantamHD June 16, 2023 13:46

lpawelcz marked this pull request as ready for review June 16, 2023 13:46