memories: a parameterized module as a macro

flow/scripts/memories/drop_parameters.tcl

@@ -0,0 +1,20 @@
+# AUTO_MEMORIES: the instances of a parameterized memory module (Sram
+# #(NUM_ENTRIES)) keep their parameters when the module becomes a black
+# box. The netlist then writes them out (`Sram #(.NUM_ENTRIES(32)) u0`),
+# and OpenROAD's Verilog reader stops on a parameterized instance of a
+# macro (STA-0171). The macro is the module at the widths detection
+# sized it: drop the parameters from its instances. Run after the
+# sources are read; `names` is the blackboxes.txt list.
+proc auto_memories_drop_parameters { names } {
+  foreach m $names {
+    set dump [tee -q -s result.string dump t:$m]
+    set params {}
+    foreach {- name} [regexp -all -inline -- {parameter \\(\S+)} $dump] {
+      lappend params $name
+    }
+    # once per name: dump lists it once per instance
+    foreach name [lsort -unique $params] {
+      setparam -unset $name t:$m
+    }
+  }
+}

flow/scripts/synth_preamble.tcl

@@ -49,6 +49,7 @@ proc read_checkpoint { file } {
 # canonicalization, one `<module> <area>` per line; see
 # docs/user/AutoMemories.md.
 source $::env(SCRIPTS_DIR)/memories/check_blackboxed.tcl
+source $::env(SCRIPTS_DIR)/memories/drop_parameters.tcl
 
 proc auto_memories_areas { } {
   if { ![env_var_equals AUTO_MEMORIES 1] } {
@@ -145,6 +146,7 @@ proc read_design_sources { } {
 
     yosys read_slang {*}$slang_args
     auto_memories_check_blackboxed [auto_memories_blackboxes]
+    auto_memories_drop_parameters [auto_memories_blackboxes]
 
     # Workaround for yosys-slang#119
     setattr -unset init

flow/test/test_auto_memories_parameters.py

@@ -0,0 +1,100 @@
+#!/usr/bin/env python3
+"""AUTO_MEMORIES drops the parameters from the instances of a
+parameterized memory module it blackboxes.
+
+A black box keeps its instances' parameters, and the netlist writes them
+out (`Sram #(.NUM_ENTRIES(32)) u0`), which OpenROAD's Verilog reader
+refuses for a macro. After auto_memories_drop_parameters the instance is
+written as a plain instance of the macro, its ports unchanged.
+
+Skipped when no yosys with read_slang is available: YOSYS_EXE or yosys on
+PATH, with the plugin from SLANG_PLUGIN_PATH when read_slang is not built
+in.
+"""
+
+import os
+import shutil
+import subprocess
+import tempfile
+import unittest
+
+DROP_TCL = os.path.join(
+    os.path.dirname(os.path.abspath(__file__)),
+    "..",
+    "scripts",
+    "memories",
+    "drop_parameters.tcl",
+)
+
+DESIGN = """\
+module Sram #(parameter NUM_ENTRIES = 64) (
+    input clk, input we, input [$clog2(NUM_ENTRIES)-1:0] addr,
+    input [15:0] d, output logic [15:0] q);
+  logic [15:0] mem [0:NUM_ENTRIES-1];
+  always_ff @(posedge clk) begin
+    if (we) mem[addr] <= d;
+    q <= mem[addr];
+  end
+endmodule
+module top (input clk, input we, input [4:0] addr, input [15:0] d,
+            output [15:0] q0, q1);
+  Sram #(.NUM_ENTRIES(32)) u0 (.clk, .we, .addr, .d, .q(q0));
+  Sram #(.NUM_ENTRIES(32)) u1 (.clk, .we, .addr, .d, .q(q1));
+endmodule
+"""
+
+
+def yosys_command():
+    yosys = os.environ.get("YOSYS_EXE") or shutil.which("yosys")
+    if not yosys:
+        return None
+    cmd = [yosys, "-q"]
+    plugin = os.environ.get("SLANG_PLUGIN_PATH")
+    if plugin:
+        cmd += ["-m", plugin]
+    probe = subprocess.run(cmd + ["-p", "help read_slang"], capture_output=True)
+    return cmd if probe.returncode == 0 else None
+
+
+class TestAutoMemoriesParameters(unittest.TestCase):
+    def netlist(self, drop):
+        cmd = yosys_command()
+        if cmd is None:
+            self.skipTest("no yosys with read_slang")
+        with tempfile.TemporaryDirectory() as tmp:
+            design = os.path.join(tmp, "top.sv")
+            with open(design, "w") as f:
+                f.write(DESIGN)
+            netlist = os.path.join(tmp, "out.v")
+            script = os.path.join(tmp, "drop.tcl")
+            with open(script, "w") as f:
+                f.write(
+                    "yosys -import\n"
+                    f"source {{{DROP_TCL}}}\n"
+                    "yosys read_slang --keep-hierarchy --top top"
+                    f" --blackboxed-module Sram {{{design}}}\n"
+                    + ("auto_memories_drop_parameters [list Sram]\n" if drop else "")
+                    + "hierarchy -top top\n"
+                    f"write_verilog -noattr {{{netlist}}}\n"
+                )
+            result = subprocess.run(
+                cmd + ["-c", script], capture_output=True, text=True
+            )
+            self.assertEqual(result.returncode, 0, result.stdout + result.stderr)
+            with open(netlist) as f:
+                return f.read()
+
+    def test_black_box_keeps_parameters(self):
+        # The problem: without the proc the instance is parameterized.
+        self.assertIn("Sram #(", self.netlist(drop=False))
+
+    def test_parameters_dropped(self):
+        netlist = self.netlist(drop=True)
+        self.assertNotIn("#(", netlist)
+        self.assertIn("Sram u0", netlist)
+        self.assertIn("Sram u1", netlist)
+        self.assertIn(".addr(addr)", netlist)
+
+
+if __name__ == "__main__":
+    unittest.main()