[MLIR] Make minor fixes and improvements

* Adds a tool to convert an MLIR file to Verilog with the same options
  we have in the top down flow. Useful for debugging (e.g. hand-modify
  .mlir file, recompile to Verilog).
* Always checks Verilog compilation for backend tests by default.
  Previously, this was turned off since (a) CI didn't always have
  `circt` available; (b) `circt-opt` wasn't standardized; and (c)
  running `circt-opt` was slow. Now all of these issues are addressed
  with v2.3.0.

magma/backend/mlir/mlir_to_verilog.py

@@ -1,5 +1,6 @@
 import dataclasses
 import io
+from typing import Optional
 
 import circt
 import circt.passmanager
@@ -10,6 +11,7 @@
 @dataclasses.dataclass
 class MlirToVerilogOpts:
     split_verilog: bool = False
+    split_verilog_directory: Optional[str] = None
 
 
 def mlir_to_verilog(
@@ -33,6 +35,7 @@ def mlir_to_verilog(
         )
         pm.run(module.operation)
     if opts.split_verilog:
-        circt.export_split_verilog(module, "")
+        directory = opts.split_verilog_directory or "."
+        circt.export_split_verilog(module, directory)
     else:
         circt.export_verilog(module, ostream)

tests/test_backend/test_mlir/golds/register_array_of_bit.v

@@ -1,4 +1,4 @@
-// Generated by CIRCT circtorg-0.0.0-2220-ge81df61a7
+// Generated by CIRCT firtool-1.48.0-34-g7018fb13b
 module register_array_of_bit(
   input  [3:0] I,
   input        CLK,

tests/test_backend/test_mlir/test_mlir_to_verilog.py

@@ -1,5 +1,8 @@
 import io
+import pathlib
 import pytest
+import tempfile
+import textwrap
 from typing import Optional
 
 import circt
@@ -43,7 +46,7 @@ def test_bad_input():
 
 @pytest.mark.parametrize("style", ("plain", "wrapInAtSquareBracket", "none"))
 def test_location_info_style(style):
-    ir = (
+    ir = textwrap.dedent(
         """
         module attributes {{circt.loweringOptions = "locationInfoStyle={style}"}} {{
           hw.module @M() -> () {{}}
@@ -57,16 +60,16 @@ def test_location_info_style(style):
     line = ostream.readline().rstrip()
     expected = "module M();"
     if style == "plain":
-        expected += "	// -:3:11"
+        expected += "	// -:3:3"
     elif style == "wrapInAtSquareBracket":
-        expected += "	// @[-:3:11]"
+        expected += "	// @[-:3:3]"
     assert line == expected
 
 
 @pytest.mark.parametrize("explicit_bitcast", (False, True))
 def test_explicit_bitcast(explicit_bitcast):
     explicit_bitcast_attr = ",explicitBitcast" if explicit_bitcast else ""
-    ir = (
+    ir = textwrap.dedent(
         """
         module attributes {{circt.loweringOptions = "locationInfoStyle=none{explicit_bitcast_attr}"}} {{
             hw.module @M(%a: i8, %b: i8) -> (y: i8) {{
@@ -98,7 +101,7 @@ def test_disallow_expression_inlining_in_ports(disallow_expression_inlining_in_p
         else ""
     )
 
-    ir = (
+    ir = textwrap.dedent(
         """
         module attributes {{circt.loweringOptions = "locationInfoStyle=none{disallow_expression_inlining_in_ports_attr}"}} {{
           hw.module.extern @Foo(%I: i1) -> (O: i1)
@@ -137,7 +140,7 @@ def test_omit_version_comment(omit_version_comment):
         else ""
     )
 
-    ir = (
+    ir = textwrap.dedent(
         """
         module attributes {{circt.loweringOptions = "locationInfoStyle=none{omit_version_comment_attr}"}} {{
           hw.module @M() -> () {{}}
@@ -156,22 +159,39 @@ def test_omit_version_comment(omit_version_comment):
         assert first.startswith("// Generated by")
 
 
-def test_split_verilog():
-    ir = (
+@pytest.mark.parametrize("specify_output_file", (False, True))
+def test_split_verilog(specify_output_file):
+    ir = textwrap.dedent(
         """
         module attributes {{circt.loweringOptions = "locationInfoStyle=none"}} {{
-          hw.module @M() -> () attributes {{output_file = {output_file}}} {{}}
+          hw.module @M() -> () {attribute_string} {{}}
         }}
         """
     )
-    output_file = "tests/test_backend/test_mlir/build/test_mlir_to_verilog_split_verilog.sv"
-    ir = ir.format(output_file=f"#hw.output_file<\"{output_file}\">")
-    _, ostream = _run_test(ir, split_verilog=True)
-    ostream.seek(0)
-    assert not ostream.readline()  # output expected to be empty
-
-    # Now read ostream from the expcted output file.
-    ostream = open(output_file)
-    ostream.readline()  # skip header
-    assert ostream.readline().rstrip() == "module M();"
-    assert ostream.readline().rstrip() == "endmodule"
+    with tempfile.TemporaryDirectory() as tempdir:
+        output_file = f"{tempdir}/outfile.sv"
+        if specify_output_file:
+            attribute_string = (
+                f"attributes "
+                f"{{output_file = #hw.output_file<\"{output_file}\">}}"
+            )
+        else:
+            attribute_string = ""
+        ir = ir.format(attribute_string=attribute_string)
+        opts = {"split_verilog": True}
+        if not specify_output_file:
+            opts["split_verilog_directory"] = tempdir
+        _, ostream = _run_test(ir, **opts)
+        ostream.seek(0)
+        # We expect the output to be empty due to split verilog.
+        assert not ostream.readline()
+
+        # Now read ostream from the expcted output file. If the output file is
+        # not specificed explicitly, then it goes into <split verilog
+        # directory>/<module name>.sv (in this case, <tempdir>/M.sv).
+        if not specify_output_file:
+            output_file = f"{tempdir}/M.sv"
+        with open(output_file, "r") as ostream:
+            ostream.readline()  # skip header
+            assert ostream.readline().rstrip() == "module M();"
+            assert ostream.readline().rstrip() == "endmodule"

tests/test_backend/test_mlir/test_utils.py

@@ -25,7 +25,7 @@
 
 config._register(
     test_mlir_check_verilog=EnvConfig(
-        "TEST_MLIR_CHECK_VERILOG", False, bool))
+        "TEST_MLIR_CHECK_VERILOG", True, bool))
 config._register(
     test_mlir_write_output_files=EnvConfig(
         "TEST_MLIR_WRITE_OUTPUT_FILES", False, bool))

tests/test_tools/test_mlir_to_verilog_main.py

@@ -0,0 +1,19 @@
+import pathlib
+import tempfile
+import textwrap
+
+from tools.mlir_to_verilog_main import main
+
+
+def test_basic():
+
+    with tempfile.TemporaryDirectory() as tempdir:
+        tempdir = pathlib.Path(tempdir)
+        infile = tempdir / "infile.mlir"
+        with open(infile, "w") as f:
+            f.write("module {}\n")
+        outfile = tempdir / "outfile.v"
+        main([str(infile), "--outfile", str(outfile)])
+        assert outfile.is_file()
+
+

tools/mlir_to_verilog_main.py

@@ -0,0 +1,74 @@
+import argparse
+import dataclasses
+import logging
+import os
+import sys
+from typing import Dict
+
+from magma.backend.mlir.mlir_to_verilog import mlir_to_verilog, MlirToVerilogOpts
+from magma.common import slice_opts
+
+
+logging.basicConfig(level=os.environ.get("LOGLEVEL", "WARNING").upper())
+
+
+def _field_to_argument_params(field: dataclasses.Field) -> Dict:
+    if field.default_factory is not dataclasses.MISSING:
+        raise TypeError(field)
+    params = {}
+    params["required"] = field.default is dataclasses.MISSING
+    if field.type is bool and not params["required"] and not field.default:
+        params["action"] = "store_true"
+        return params
+    if not params["required"]:
+        params["default"] = field.default
+    params["action"] = "store"
+    params["type"] = field.type
+    return params
+
+
+def _add_dataclass_arguments(parser: argparse.ArgumentParser, cls: type):
+    assert dataclasses.is_dataclass(cls)
+    for field in dataclasses.fields(cls):
+        params = _field_to_argument_params(field)
+        parser.add_argument(f"--{field.name}", **params)
+
+
+def main(prog_args = None) -> int:
+    parser = argparse.ArgumentParser(
+        "Compile a (MLIR) .mlir file to verilog (.v/.sv)"
+    )
+
+    parser.add_argument(
+        "infile",
+        metavar="<input filename>",
+        action="store",
+        type=str,
+        help="Input MLIR file",
+    )
+    parser.add_argument(
+        "--outfile",
+        metavar="<output filename>",
+        action="store",
+        type=argparse.FileType("w"),
+        required=False,
+        default=sys.stdout,
+    )
+    _add_dataclass_arguments(parser, MlirToVerilogOpts)
+
+    args = parser.parse_args(prog_args)
+    opts = slice_opts(vars(args), MlirToVerilogOpts)
+
+    logging.debug(f"Running with opts: {opts}")
+    if opts.split_verilog and args.outfile is not sys.stdout:
+        logging.warning(
+            f"outfile ({args.outfile.name}) ignored with split_verilog enabled"
+        )
+
+    with open(args.infile, "r") as f_in:
+        mlir_to_verilog(f_in, args.outfile, opts)
+
+
+if __name__ == "__main__":
+    exit(main())
+