[LIT] Added an option to llvm-lit to emit the necessary test coverage data, divided per test case

This patch is the first part of https://llvm.org/OpenProjects.html#llvm_patch_coverage.

We have first define a new variable LLVM_TEST_COVERAGE which when set, pass --per-test-coverage option to
llvm-lit which will help in setting a unique value to LLVM_PROFILE_FILE for each RUN. So for example
coverage data for test case llvm/test/Analysis/AliasSet/memtransfer.ll will be emitted as
build/test/Analysis/AliasSet/memtransfer0.profraw

Reviewed By: hnrklssn

Differential Revision: https://reviews.llvm.org/D154280

Author: xgupta

llvm/CMakeLists.txt

@@ -676,6 +676,9 @@ set(LIT_ARGS_DEFAULT "-sv")
 if (MSVC_IDE OR XCODE)
   set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --no-progress-bar")
 endif()
+if(LLVM_INDIVIDUAL_TEST_COVERAGE)
+   set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --per-test-coverage")
+endif()
 set(LLVM_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "Default options for lit")
 
 # On Win32 hosts, provide an option to specify the path to the GnuWin32 tools.
@@ -797,24 +800,25 @@ if (MSVC_IDE)
   option(LLVM_ADD_NATIVE_VISUALIZERS_TO_SOLUTION "Configure project to use Visual Studio native visualizers" TRUE)
 endif()
 
-if (LLVM_BUILD_INSTRUMENTED OR LLVM_BUILD_INSTRUMENTED_COVERAGE OR
-    LLVM_ENABLE_IR_PGO)
-  if(NOT LLVM_PROFILE_MERGE_POOL_SIZE)
-    # A pool size of 1-2 is probably sufficient on a SSD. 3-4 should be fine
-    # for spining disks. Anything higher may only help on slower mediums.
-    set(LLVM_PROFILE_MERGE_POOL_SIZE "4")
-  endif()
-  if(NOT LLVM_PROFILE_FILE_PATTERN)
-    if(NOT LLVM_PROFILE_DATA_DIR)
-      file(TO_NATIVE_PATH "${LLVM_BINARY_DIR}/profiles" LLVM_PROFILE_DATA_DIR)
+if(NOT LLVM_INDIVIDUAL_TEST_COVERAGE)
+  if(LLVM_BUILD_INSTRUMENTED OR LLVM_BUILD_INSTRUMENTED_COVERAGE OR LLVM_ENABLE_IR_PGO)
+    if(NOT LLVM_PROFILE_MERGE_POOL_SIZE)
+      # A pool size of 1-2 is probably sufficient on an SSD. 3-4 should be fine
+      # for spinning disks. Anything higher may only help on slower mediums.
+      set(LLVM_PROFILE_MERGE_POOL_SIZE "4")
     endif()
-    file(TO_NATIVE_PATH "${LLVM_PROFILE_DATA_DIR}/%${LLVM_PROFILE_MERGE_POOL_SIZE}m.profraw" LLVM_PROFILE_FILE_PATTERN)
-  endif()
-  if(NOT LLVM_CSPROFILE_FILE_PATTERN)
-    if(NOT LLVM_CSPROFILE_DATA_DIR)
-      file(TO_NATIVE_PATH "${LLVM_BINARY_DIR}/csprofiles" LLVM_CSPROFILE_DATA_DIR)
+    if(NOT LLVM_PROFILE_FILE_PATTERN)
+      if(NOT LLVM_PROFILE_DATA_DIR)
+        file(TO_NATIVE_PATH "${LLVM_BINARY_DIR}/profiles" LLVM_PROFILE_DATA_DIR)
+      endif()
+      file(TO_NATIVE_PATH "${LLVM_PROFILE_DATA_DIR}/%${LLVM_PROFILE_MERGE_POOL_SIZE}m.profraw" LLVM_PROFILE_FILE_PATTERN)
+    endif()
+    if(NOT LLVM_CSPROFILE_FILE_PATTERN)
+      if(NOT LLVM_CSPROFILE_DATA_DIR)
+        file(TO_NATIVE_PATH "${LLVM_BINARY_DIR}/csprofiles" LLVM_CSPROFILE_DATA_DIR)
+      endif()
+      file(TO_NATIVE_PATH "${LLVM_CSPROFILE_DATA_DIR}/%${LLVM_PROFILE_MERGE_POOL_SIZE}m.profraw" LLVM_CSPROFILE_FILE_PATTERN)
     endif()
-    file(TO_NATIVE_PATH "${LLVM_CSPROFILE_DATA_DIR}/%${LLVM_PROFILE_MERGE_POOL_SIZE}m.profraw" LLVM_CSPROFILE_FILE_PATTERN)
   endif()
 endif()
 

llvm/cmake/modules/HandleLLVMOptions.cmake

@@ -1160,6 +1160,7 @@ if(LLVM_PROFDATA_FILE AND EXISTS ${LLVM_PROFDATA_FILE})
 endif()
 
 option(LLVM_BUILD_INSTRUMENTED_COVERAGE "Build LLVM and tools with Code Coverage instrumentation" Off)
+option(LLVM_INDIVIDUAL_TEST_COVERAGE "Emit individual coverage file for each test case." OFF)
 mark_as_advanced(LLVM_BUILD_INSTRUMENTED_COVERAGE)
 append_if(LLVM_BUILD_INSTRUMENTED_COVERAGE "-fprofile-instr-generate=\"${LLVM_PROFILE_FILE_PATTERN}\" -fcoverage-mapping"
   CMAKE_CXX_FLAGS

llvm/docs/CMake.rst

@@ -375,6 +375,12 @@ enabled sub-projects. Nearly all of these variable names begin with
   will limit code coverage summaries to just the listed directories. If unset,
   coverage reports will include all sources identified by the tooling.
 
+ **LLVM_INDIVIDUAL_TEST_COVERAGE**: BOOL
+  Enable individual test case coverage. When set to ON, code coverage data for
+  each test case will be generated and stored in a separate directory under the
+  config.test_exec_root path. This feature allows code coverage analysis of each
+  individual test case. Defaults to OFF.
+
 **LLVM_BUILD_LLVM_DYLIB**:BOOL
   If enabled, the target for building the libLLVM shared library is added.
   This library contains all of LLVM's components in a single shared library.

llvm/docs/CommandGuide/lit.rst

@@ -181,6 +181,12 @@ The timing data is stored in the `test_exec_root` in a file named
  Run the tests in a random order, not failing/slowest first. Deprecated,
  use :option:`--order` instead.
 
+.. option:: --per-test-coverage
+
+ Emit the necessary test coverage data, divided per test case (involves
+ setting a unique value to LLVM_PROFILE_FILE for each RUN). The coverage
+ data files will be emitted in the directory specified by `config.test_exec_root`.
+
 .. option:: --max-failures N
 
  Stop execution after the given number ``N`` of failures.

llvm/utils/lit/lit/LitConfig.py

@@ -37,6 +37,7 @@ def __init__(
         maxIndividualTestTime=0,
         parallelism_groups={},
         echo_all_commands=False,
+        per_test_coverage=False,
     ):
         # The name of the test runner.
         self.progname = progname
@@ -87,6 +88,7 @@ def __init__(
         self.maxIndividualTestTime = maxIndividualTestTime
         self.parallelism_groups = parallelism_groups
         self.echo_all_commands = echo_all_commands
+        self.per_test_coverage = per_test_coverage
 
     @property
     def maxIndividualTestTime(self):
@@ -128,6 +130,22 @@ def maxIndividualTestTime(self, value):
         elif self.maxIndividualTestTime < 0:
             self.fatal("The timeout per test must be >= 0 seconds")
 
+    @property
+    def per_test_coverage(self):
+        """
+        Interface for getting the per_test_coverage value
+        """
+        return self._per_test_coverage
+
+    @per_test_coverage.setter
+    def per_test_coverage(self, value):
+        """
+        Interface for setting the per_test_coverage value
+        """
+        if not isinstance(value, bool):
+            self.fatal("per_test_coverage must set to a value of type bool.")
+        self._per_test_coverage = value
+
     def load_config(self, config, path):
         """load_config(config, path) - Load a config object from an alternate
         path."""

llvm/utils/lit/lit/TestRunner.py

@@ -1067,10 +1067,25 @@ def executeScriptInternal(test, litConfig, tmpBase, commands, cwd):
 def executeScript(test, litConfig, tmpBase, commands, cwd):
     bashPath = litConfig.getBashPath()
     isWin32CMDEXE = litConfig.isWindows and not bashPath
+    coverage_index = 0  # Counter for coverage file index
     script = tmpBase + ".script"
     if isWin32CMDEXE:
         script += ".bat"
 
+    # Set unique LLVM_PROFILE_FILE for each run command
+    for j, ln in enumerate(commands):
+        match = re.match(kPdbgRegex, ln)
+        if match:
+            command = match.group(2)
+            commands[j] = match.expand(": '\\1'; \\2" if command else ": '\\1'")
+            if litConfig.per_test_coverage:
+                # Extract the test case name from the test object
+                test_case_name = test.path_in_suite[-1]
+                test_case_name = test_case_name.rsplit(".", 1)[0]  # Remove the file extension
+                llvm_profile_file = f"{test_case_name}{coverage_index}.profraw"
+                commands[j] = f"export LLVM_PROFILE_FILE={llvm_profile_file} && {commands[j]}"
+                coverage_index += 1
+
     # Write script file
     mode = "w"
     open_kwargs = {}

llvm/utils/lit/lit/cl_arguments.py

@@ -184,6 +184,12 @@ def parse_args():
         help="Do not fail the run if all tests are filtered out",
         action="store_true",
     )
+    execution_group.add_argument(
+        "--per-test-coverage",
+        dest="per_test_coverage",
+        action="store_true",
+        help="Enable individual test case coverage",
+    )
     execution_group.add_argument(
         "--ignore-fail",
         dest="ignoreFail",

llvm/utils/lit/lit/main.py

@@ -41,6 +41,7 @@ def main(builtin_params={}):
         params=params,
         config_prefix=opts.configPrefix,
         echo_all_commands=opts.echoAllCommands,
+        per_test_coverage=opts.per_test_coverage,
     )
 
     discovered_tests = lit.discovery.find_tests_for_inputs(

llvm/utils/lit/tests/Inputs/per-test-coverage-by-lit-cfg/lit.cfg

@@ -0,0 +1,8 @@
+import lit.formats
+import os
+
+config.name = "per-test-coverage-by-lit-cfg"
+config.suffixes = [".py"]
+config.test_format = lit.formats.ShTest(execute_external=True)
+lit_config.per_test_coverage = True
+config.substitutions.append(("%{python}", '"%s"' % (sys.executable)))

llvm/utils/lit/tests/Inputs/per-test-coverage-by-lit-cfg/per-test-coverage-by-lit-cfg.py

@@ -0,0 +1,11 @@
+# Check that the environment variable is set correctly
+# RUN: %{python} %s | FileCheck %s
+
+# Python script to read the environment variable
+# and print its value
+import os
+
+llvm_profile_file = os.environ.get('LLVM_PROFILE_FILE')
+print(llvm_profile_file)
+
+# CHECK: per-test-coverage-by-lit-cfg0.profraw

llvm/utils/lit/tests/Inputs/per-test-coverage/lit.cfg

@@ -0,0 +1,8 @@
+import lit.formats
+import os
+
+config.name = "per-test-coverage"
+config.suffixes = [".py"]
+config.test_format = lit.formats.ShTest(execute_external=True)
+config.substitutions.append(("%{python}", '"%s"' % (sys.executable)))
+

llvm/utils/lit/tests/Inputs/per-test-coverage/per-test-coverage.py

@@ -0,0 +1,11 @@
+# Check that the environment variable is set correctly
+# RUN: %{python} %s | FileCheck %s
+
+# Python script to read the environment variable
+# and print its value
+import os
+
+llvm_profile_file = os.environ.get('LLVM_PROFILE_FILE')
+print(llvm_profile_file)
+
+# CHECK: per-test-coverage0.profraw

llvm/utils/lit/tests/per-test-coverage-by-lit-cfg.py

@@ -0,0 +1,6 @@
+# Test if lit_config.per_test_coverage in lit.cfg sets individual test case coverage.
+
+# RUN: %{lit} -a -v %{inputs}/per-test-coverage-by-lit-cfg/per-test-coverage-by-lit-cfg.py \
+# RUN: | FileCheck -match-full-lines %s
+#
+# CHECK: PASS: per-test-coverage-by-lit-cfg :: per-test-coverage-by-lit-cfg.py ({{[^)]*}})

llvm/utils/lit/tests/per-test-coverage.py

@@ -0,0 +1,6 @@
+# Test LLVM_PROFILE_FILE is set when --per-test-coverage is passed to command line.
+
+# RUN: %{lit} -a -v --per-test-coverage %{inputs}/per-test-coverage/per-test-coverage.py \
+# RUN: | FileCheck -match-full-lines %s
+#
+# CHECK: PASS: per-test-coverage :: per-test-coverage.py ({{[^)]*}})