fix: remove PyYAML runtime dependency from Bazel flow scripts

.gitattributes

@@ -1,2 +1,3 @@
 # Make Github ignore the designs folder when determining repo language
 flow/designs/src/* linguist-vendored
+flow/scripts/variables.json linguist-generated=true

.github/workflows/github-actions-yaml-test.yml

@@ -15,22 +15,29 @@ jobs:
         fetch-depth: 1
         sparse-checkout: |
           flow/scripts/generate-variables-docs.py
+          flow/scripts/yaml_to_json.py
+          flow/scripts/variables.yaml
+          flow/scripts/variables.json
           docs/user/FlowVariables.md
           yamlfix.toml
+    - name: Install dependencies
+      run: |
+        python3 -m venv venv
+        venv/bin/pip install --quiet pyyaml yamlfix==1.19.1
     - name: Run generate-variables-docs.py
       run: |
-        python3 flow/scripts/generate-variables-docs.py
+        venv/bin/python3 flow/scripts/generate-variables-docs.py
     - name: Check if FlowVariables.md is up to date
       run: |
         git diff --exit-code docs/user/FlowVariables.md
-    - name: Install dependencies
+    - name: Check variables.json is up to date
       run: |
-        python3 -m venv venv
-        venv/bin/pip install --quiet yamlfix==1.17.0
+        venv/bin/python3 flow/scripts/yaml_to_json.py
+        git diff --exit-code flow/scripts/variables.json
     - name: Run yamlfix check
       run: |
         source venv/bin/activate
         yamlfix --version
         set -x
         yamlfix -c yamlfix.toml flow/scripts/variables.yaml
-        git diff flow/scripts/variables.yaml
+        git diff --exit-code flow/scripts/variables.yaml

docs/user/FlowVariables.md

@@ -305,7 +305,7 @@ configuration file.
 | <a name="SYNTH_OPERATIONS_ARGS"></a>SYNTH_OPERATIONS_ARGS| Extra arguments appended to the Yosys synth command operations list. When set, replaces the default Kogge-Stone adder extra-map.| |
 | <a name="SYNTH_OPT_HIER"></a>SYNTH_OPT_HIER| Optimize constants across hierarchical boundaries.| |
 | <a name="SYNTH_REPEATABLE_BUILD"></a>SYNTH_REPEATABLE_BUILD| License to prune anything that makes builds less repeatable, typically used with Bazel to ensure that builds are bit-for-bit identical so that caching works optimally. Removes debug information that encodes paths, timestamps, etc.| 0|
-| <a name="SYNTH_RETIME_MODULES"></a>SYNTH_RETIME_MODULES| *This is an experimental option and may cause adverse effects.* *No effort has been made to check if the retimed RTL is logically equivalent to the non-retimed RTL.* List of modules to apply automatic retiming to. These modules must not get dissolved and as such they should either be the top module or be included in SYNTH_KEEP_MODULES. The main use case is to quickly identify if performance can be improved by manually retiming the input RTL. Retiming will treat module ports like register endpoints/startpoints. The objective function of retiming isn't informed by SDC, even the clock period is ignored. As such, retiming will optimize for best delay at potentially high register number cost. Automatic retiming can produce suboptimal results as its timing model is crude and it doesn't find the optimal distribution of registers on long pipelines. See OR discussion #8080.| |
+| <a name="SYNTH_RETIME_MODULES"></a>SYNTH_RETIME_MODULES| *This is an experimental option and may cause adverse effects.* *No effort has been made to check if the retimed RTL is logically equivalent to the non-retimed RTL.* List of modules to apply automatic retiming to. These modules must not get dissolved and as such they should either be the top module or be included in SYNTH_KEEP_MODULES. The main use case is to quickly identify if performance can be improved by manually retiming the input RTL. Retiming will treat module ports like register endpoints/startpoints. The objective function of retiming isn't informed by SDC, even the clock period is ignored. As such, retiming will optimize for best delay at potentially high register number cost. Automatic retiming can produce suboptimal results as its timing model is crude and it doesn't find the optimal distribution of registers on long pipelines. See OR discussion  # 8080.| |
 | <a name="SYNTH_SLANG_ARGS"></a>SYNTH_SLANG_ARGS| Additional arguments passed to the slang frontend during synthesis.| |
 | <a name="SYNTH_WRAPPED_ADDERS"></a>SYNTH_WRAPPED_ADDERS| Specify the adder modules that can be used for synthesis, separated by commas. The default adder module is determined by the first element of this variable.| |
 | <a name="SYNTH_WRAPPED_MULTIPLIERS"></a>SYNTH_WRAPPED_MULTIPLIERS| Specify the multiplier modules that can be used for synthesis, separated by commas. The default multiplier module is determined by the first element of this variable.| |

flow/BUILD.bazel

@@ -7,6 +7,7 @@ exports_files(
 
 # files shared between scripts/synth.sh and scripts/flow.sh steps
 MAKEFILE_SHARED = [
+    "scripts/variables.json",
     "scripts/*.py",
     "scripts/*.sh",
     "scripts/*.yaml",

flow/scripts/defaults.py

@@ -1,13 +1,13 @@
 #!/usr/bin/env python3
 
+import json
 import os
-import yaml
 
 dir_path = os.path.dirname(os.path.realpath(__file__))
 
-yaml_path = os.path.join(dir_path, "variables.yaml")
-with open(yaml_path, "r") as file:
-    data = yaml.safe_load(file)
+json_path = os.path.join(dir_path, "variables.json")
+with open(json_path, "r") as file:
+    data = json.load(file)
 
 for key, value in data.items():
     if value.get("default", None) is None:

flow/scripts/non_stage_variables.py

@@ -5,15 +5,15 @@
 #
 # This script generates a list of variables known
 # not to be in the current stage.
+import json
 import os
 import sys
-import yaml
 
 dir_path = os.path.dirname(os.path.realpath(__file__))
 
-yaml_path = os.path.join(dir_path, "variables.yaml")
-with open(yaml_path, "r") as file:
-    data = yaml.safe_load(file)
+json_path = os.path.join(dir_path, "variables.json")
+with open(json_path, "r") as file:
+    data = json.load(file)
 
 for key, value in data.items():
     if "stages" not in value: