bazel: Yosys netlist canonicalization at home example

Signed-off-by: Øyvind Harboe <[email protected]>

Author: oharboe

flow/designs/asap7/swerv_wrapper/BUILD.bazel

@@ -73,6 +73,21 @@ filegroup(
     srcs = [":{}_netlist".format(name) for name in BLACKBOXES],
 )
 
+# Canonicalize the netlists to avoid rebuilds unecessarily.
+#
+# This is more a demonstration than a practical solution.
+#
+# Other things could be done here, like get a netlist from git lfs,
+# process the netlist in some other way, with Naja, etc.
+genrule(
+    name = "netlists_canonicalized",
+    srcs = [":netlists"],
+    outs = ["netlists_canonicalized.v"],
+    cmd = """
+        cat $(locations :netlists) | grep -v -E '\\(\\* src = "|Generated by Yosys' > $@
+    """,
+)
+
 [orfs_macro(
     name = top,
     lef = "lef/{}.lef".format(top),
@@ -100,7 +115,7 @@ orfs_flow(
     macros = FAKERAMS,
     sources = {
         "SDC_FILE": [":constraint.sdc"],
-        "SYNTH_NETLIST_FILES": [":netlists"],
+        "SYNTH_NETLIST_FILES": [":netlists_canonicalized"],
     },
     verilog_files = [],
 )