Enable collecting coverage from VCS

Author: jan-malek

testbench/Makefile

@@ -11,6 +11,10 @@ BUILD_ARGS += -debug_access+all +memcbk -timescale=1ns/1ps
 SIM_ARGS += +dumpon
 EXTRA_ARGS += +vcs+vcdpluson +vpdfile+dump.vpd +warn=noLINX_KRNL
 
+ifneq ($(COVERAGE_TYPE),)
+	EXTRA_ARGS += -cm line+cond+fsm+tgl+branch
+endif
+
 .PHONY: all vcs-build vcs-sim clean
 all: vcs-sim
 

tools/nox_utils/src/nox_utils.py

@@ -101,11 +101,13 @@ def __init__(self, blockName: str, blockPath: str, testName: str, coverage: str
         defaultNameVCD = "dump.vcd"
         defaultNameCoverage = "coverage.dat"
         defaultTestNameLog = f"{testName}.log"
+        defaultNameVDB = f"sim_build-{testName}-{coverage}/simv.vdb"
 
         testNameVCD = f"{testName}.vcd"
         testNameXML = f"{testName}.xml"
-        testCoverageName = f"coverage_{testName}_{coverage}.dat"
+        testCoverageName = f"{testName}_{coverage}.dat"
         testNameLog = f"{testName}_{coverage}.log"
+        testNameVDB = f"{testName}.vdb"
 
         self.filenames = {
             "vcd_default": defaultNameVCD,
@@ -115,6 +117,8 @@ def __init__(self, blockName: str, blockPath: str, testName: str, coverage: str
             "log": testNameLog,
             "cov_default": defaultNameCoverage,
             "cov": testCoverageName,
+            "vdb_default": defaultNameVDB,
+            "vdb": testNameVDB,
         }
 
         def get_path(name):
@@ -128,19 +132,25 @@ def get_path(name):
             "log": get_path(testNameLog),
             "cov_default": get_path(defaultNameCoverage),
             "cov": get_path(testCoverageName),
+            "vdb_default": get_path(defaultNameVDB),
+            "vdb": get_path(testNameVDB),
         }
 
     def rename_default(self, dest: str):
         source = self.paths[f"{dest}_default"]
-        if not os.path.isfile(source):
+        if (not os.path.isfile(source)) and (not os.path.isdir(source)):
             print(f"Warning!  Can't find file to rename: {source}")
             return
         os.rename(source, self.paths[dest])
 
-    def rename_defaults(self, coverage: str | None):
+    def rename_defaults(self, coverage: str | None, simulator: str | None):
         if coverage:
-            self.rename_default("cov")
             self.rename_default("log")
+            if simulator is not None and "vcs" in simulator:
+                # VDB files are specific to VCS and will not be generated by other simulators
+                self.rename_default("vdb")
+            else:
+                self.rename_default("cov")
         self.rename_default("vcd")
 
 

verification/cocotb/common.mk

@@ -57,14 +57,28 @@ ifeq ($(SIM), vcs)
     COMPILE_ARGS += -debug_access+all +memcbk
     SIM_ARGS += +dumpon
     EXTRA_ARGS += +vcs+vcdpluson +vpdfile+dump.vpd
+
+    ifneq ($(COVERAGE_TYPE),)
+        EXTRA_ARGS += -cm line+cond+fsm+tgl+branch
+    endif
 endif
 
 COCOTB_HDL_TIMEUNIT         = 1ns
 COCOTB_HDL_TIMEPRECISION    = 10ps
 
 # Build directory
+comma := ,
 ifneq ($(COVERAGE_TYPE),)
-    SIM_BUILD := sim-build-$(COVERAGE_TYPE)
+    # Check if more than one test is provided
+    ifeq ($(findstring $(comma),$(MODULE)),$(comma))
+        # To collect accurate coverage results each tests needs to have a unique SIM_BUILD directory to store
+        # the results. If multiple tests were to use the same directory they would override each others coverage reports
+        # causing the reported values to be incorrect.
+        $(error Collecting coverage for multiple tests is not supported. Either unset 'COVERAGE_TYPE' to run tests without coverage reporting or use nox.)
+    else
+        # Construct a unique directory for each test and coverage type
+        SIM_BUILD := sim_build-$(MODULE)-$(COVERAGE_TYPE)
+    endif
 endif
 
 include $(shell cocotb-config --makefiles)/Makefile.sim

verification/cocotb/noxfile.py

@@ -15,11 +15,13 @@
 # Test configuration
 pip_requirements_path = "../../requirements.txt"
 
-# Coverage types to collect
-coverage_types = ["all", "branch", "toggle"] if os.getenv("TEST_COVERAGE_ENABLE") else None
-
 simulators = [os.getenv("SIMULATOR", "verilator")]
 
+# Coverage types to collect
+if os.getenv("TEST_COVERAGE_ENABLE", "0") == "1":
+    coverage_types = ["vcs"] if "vcs" in simulators else ["branch", "toggle"]
+else:
+    coverage_types = None
 
 def _verify(session, test_group, test_type, test_name, coverage=None, simulator=None):
     # session.install("-r", pip_requirements_path)
@@ -64,7 +66,7 @@ def _verify(session, test_group, test_type, test_name, coverage=None, simulator=
             stderr=test_log,
         )
     # Prevent coverage.dat and test log from being overwritten
-    test.rename_defaults(coverage)
+    test.rename_defaults(coverage, simulator)
 
     # Add check from results.xml to notify nox that test failed
     isTBFailure = isCocotbSimFailure(resultsFile=test.paths["xml"])