refactor: refactor Yosys synthesis flow to support multiple recipes

- Introduced SYNTH_RECIPE variable to select between balanced, area, and speed synthesis recipes.
- Updated Makefile to handle new SYNTH_RECIPE variable and its validation.
- Modified synthesis scripts to utilize the selected recipe, ensuring outputs are directed to the appropriate directories.
- Enhanced documentation to reflect changes in synthesis flow and directory structure.
- Added tests to verify correct behavior of new synthesis recipes and their integration into the regression suite.
- Removed obsolete scripts and configurations related to previous synthesis methods.

tests/test_yosys_synth_recipes.py

@@ -0,0 +1,74 @@
+"""Tests for Yosys recipe selection and ABC period derivation."""
+
+from __future__ import annotations
+
+import subprocess
+import sys
+from pathlib import Path
+
+from scripts.yosys_period import period_ps
+
+
+ROOT = Path(__file__).resolve().parents[1]
+DOMAINS = ROOT / "rtl/mini/integration/clock_reset_domains.json"
+PERIOD_HELPER = ROOT / "scripts/yosys_period.py"
+YOSYS_SCRIPTS = ROOT / "physical/smoke/syn/yosys/script"
+
+
+def run_period(*args: str) -> subprocess.CompletedProcess[str]:
+    return subprocess.run(
+        [sys.executable, str(PERIOD_HELPER), *args],
+        text=True,
+        capture_output=True,
+    )
+
+
+def test_yosys_period_rounds_external_sta_period() -> None:
+    assert period_ps({"domains": [{"name": "external", "sta": {"period_ns": 13.888888889}}]}) == 13889
+
+    result = run_period("--domains", str(DOMAINS))
+    assert result.returncode == 0, result.stderr
+    assert result.stdout.strip() == "13889"
+
+
+def test_yosys_period_rejects_unknown_domain() -> None:
+    result = run_period("--domains", str(DOMAINS), "--domain", "missing")
+    assert result.returncode != 0
+    assert "domain missing is not declared" in result.stderr
+
+
+def test_yosys_recipe_scripts_and_public_slot_are_stable() -> None:
+    makefile = (ROOT / "Makefile").read_text(encoding="utf-8")
+    yosys_mk = (ROOT / "physical/smoke/syn/yosys/yosys.mk").read_text(encoding="utf-8")
+    synth_tcl = (YOSYS_SCRIPTS / "synth.tcl").read_text(encoding="utf-8")
+    opensta = (ROOT / "physical/smoke/sta/opensta/opensta.mk").read_text(encoding="utf-8")
+    iverilog = (ROOT / "rtl/mini/mk/iverilog.mk").read_text(encoding="utf-8")
+    vcs = (ROOT / "rtl/mini/mk/vcs.mk").read_text(encoding="utf-8")
+
+    assert "SYNTH_RECIPE ?= balanced" in makefile
+    assert "VALID_SYNTH_RECIPE  := balanced area speed" in makefile
+    assert "syn/yosys-$(SYNTH_RECIPE)" in makefile
+    assert "CONFIG_KEY_VARS" in makefile
+    assert "SYNTH_RECIPE" not in makefile.split("CONFIG_KEY_VARS", 1)[1].split("VARIANT_ID", 1)[0]
+    assert "--env SYNTH_RECIPE=$(SYNTH_RECIPE)" in yosys_mk
+    assert "--env YOSYS_TARGET_PERIOD_PS=$(YOSYS_TARGET_PERIOD_PS)" in yosys_mk
+    assert "abc_${synth_recipe}.script" in synth_tcl
+    assert "yosys abc {*}$tech_cells_args -D $period_ps -script $abc_script -constr $abc_constr" in synth_tcl
+    assert "S110" not in synth_tcl
+    assert "$(VARIANT_ROOT)/syn/yosys/out/retrosoc_asic_yosys.v" in opensta
+    assert "$(VARIANT_ROOT)/syn/yosys/out/retrosoc_asic_yosys.v" in iverilog
+    assert "$(VARIANT_ROOT)/syn/yosys/out/retrosoc_asic_yosys.v" in vcs
+    assert "SYN_BUILD_ROOT" not in opensta
+    assert "SYN_BUILD_ROOT" not in iverilog.split("NETLIST_PATH", 1)[1][:200]
+    assert (YOSYS_SCRIPTS / "abc_balanced.script").read_text(encoding="utf-8").count("&nf {D}") == 1
+    assert "&nf {D}" not in (YOSYS_SCRIPTS / "abc_area.script").read_text(encoding="utf-8")
+    assert (YOSYS_SCRIPTS / "abc_speed.script").read_text(encoding="utf-8").count("&nf {D}") == 6
+    leftover = {
+        "abc-opt.script",
+        "abc.constr",
+        "cell_dont_use.py",
+        "filter_output.awk",
+    }
+    assert leftover.isdisjoint({path.name for path in YOSYS_SCRIPTS.iterdir()})
+    assert not (ROOT / "physical/smoke/syn/dc").exists()
+    assert not (ROOT / "physical/smoke/syn/Makefile").exists()