[libc++][lit] Allow overriding the executor for tests (#66545)

This is useful when trying to run multiple tests with different
arguments to the executor script. This is needed in my case since I
do not know the correct ssh connection arguments when building libc++.
The testing script I have spawns multiple QEMU instances that listen on
a given port on localhost and runs lit with the --num-shards/--run-shard
argument. In order to connect each shard to the right QEMU instances I
need to customize the arguments passed to ssh.py (--extra-ssh-args and
--extra-scp-args) but can't do this at configure time since the target
port is only known when running the tests but not when calling CMake.
This change allows me to pass `executor=ssh.py <args>` to lit once I
know
the right hostname/port for running the tests.

This also deprecates the `LIB{CXX,CXXABI,UNWIND}_EXECUTOR` CMake
variable
as the same can be achieved by adding `executor=...` to the
`LIB{CXX,CXXABI,UNWIND}_TEST_PARAMS` variable.

clang/cmake/caches/CrossWinToARMLinux.cmake

@@ -162,9 +162,9 @@ if(DEFINED REMOTE_TEST_HOST)
         "\\\"${Python3_EXECUTABLE}\\\" \\\"${LLVM_PROJECT_DIR}/llvm/utils/remote-exec.py\\\" --host=${REMOTE_TEST_USER}@${REMOTE_TEST_HOST}"
         CACHE STRING "")
 
-  set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBUNWIND_EXECUTOR                      "${DEFAULT_TEST_EXECUTOR}" CACHE STRING "")
-  set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXXABI_EXECUTOR                      "${DEFAULT_TEST_EXECUTOR}" CACHE STRING "")
-  set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_EXECUTOR                         "${DEFAULT_TEST_EXECUTOR}" CACHE STRING "")
+  set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBUNWIND_TEST_PARAMS "${RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_TEST_PARAMS} 'executor=${DEFAULT_TEST_EXECUTOR}'" CACHE STRING "")
+  set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXXABI_TEST_PARAMS "${RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_TEST_PARAMS} 'executor=${DEFAULT_TEST_EXECUTOR}'" CACHE STRING "")
+  set(RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_LIBCXX_TEST_PARAMS    "${RUNTIMES_${TOOLCHAIN_TARGET_TRIPLE}_TEST_PARAMS} 'executor=${DEFAULT_TEST_EXECUTOR}'" CACHE STRING "")
 endif()
 
 set(LLVM_INSTALL_TOOLCHAIN_ONLY ON CACHE BOOL "")

libcxx/docs/ReleaseNotes/18.rst

@@ -134,3 +134,8 @@ ABI Affecting Changes
 
 Build System Changes
 --------------------
+
+- The ``LIBCXX_EXECUTOR`` CMake variable has been deprecated. If you are relying on this, the new replacement is
+  passing ``-Dexecutor=...`` to ``llvm-lit``. Alternatively, this flag can be made persistent in the generated test
+  configuration file by passing ``-DLIBCXX_TEST_PARAMS=executor=...``. This also applies to the ``LIBUWIND_EXECTOR``
+  and ``LIBCXXABI_EXECUTOR`` CMake variables. LLVM 19 will completely remove support for the ``*_EXECUTOR`` variables.

libcxx/test/CMakeLists.txt

@@ -6,16 +6,18 @@ if (NOT LIBCXX_CXX_ABI_LIBRARY_PATH)
       "The path to libc++abi library.")
 endif()
 
-set(LIBCXX_EXECUTOR "\\\"${Python3_EXECUTABLE}\\\" ${CMAKE_CURRENT_LIST_DIR}/../utils/run.py" CACHE STRING
-    "Executor to use when running tests.")
-
 set(AUTO_GEN_COMMENT "## Autogenerated by libcxx configuration.\n# Do not edit!")
 set(SERIALIZED_LIT_PARAMS "# Lit parameters serialized here for llvm-lit to pick them up\n")
 
 macro(serialize_lit_param param value)
   string(APPEND SERIALIZED_LIT_PARAMS "config.${param} = ${value}\n")
 endmacro()
 
+if (LIBCXX_EXECUTOR)
+  message(DEPRECATION "LIBCXX_EXECUTOR is deprecated, please add executor=... to LIBCXX_TEST_PARAMS")
+  serialize_lit_param(executor "\"${LIBCXX_EXECUTOR}\"")
+endif()
+
 if (NOT LIBCXX_ENABLE_EXCEPTIONS)
   serialize_lit_param(enable_exceptions False)
 endif()

libcxx/test/configs/cmake-bridge.cfg.in

@@ -30,7 +30,6 @@ config.substitutions.append(('%{include}', '@LIBCXX_GENERATED_INCLUDE_DIR@'))
 config.substitutions.append(('%{target-include}', '@LIBCXX_GENERATED_INCLUDE_TARGET_DIR@'))
 config.substitutions.append(('%{lib}', '@LIBCXX_LIBRARY_DIR@'))
 config.substitutions.append(('%{module}', '@LIBCXX_GENERATED_MODULE_DIR@'))
-config.substitutions.append(('%{executor}', '@LIBCXX_EXECUTOR@'))
 config.substitutions.append(('%{test-tools}', '@LIBCXX_TEST_TOOLS_PATH@'))
 
 # The test needs to manually rebuild the module. The compiler flags used in the

libcxx/utils/libcxx/test/params.py

@@ -5,10 +5,13 @@
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #
 # ===----------------------------------------------------------------------===##
+import sys
+import re
+from pathlib import Path
 
 from libcxx.test.dsl import *
 from libcxx.test.features import _isMSVC
-import re
+
 
 _warningFlags = [
     "-Werror",
@@ -314,5 +317,12 @@ def getStdFlag(cfg, std):
             AddCompileFlag("-D_LIBCPP_REMOVE_TRANSITIVE_INCLUDES"),
         ],
     ),
+    Parameter(
+        name="executor",
+        type=str,
+        default=f"{sys.executable} {Path(__file__).resolve().parent.parent.parent / 'run.py'}",
+        help="Custom executor to use instead of the configured default.",
+        actions=lambda executor: [AddSubstitution("%{executor}", executor)],
+    )
 ]
 # fmt: on

libcxxabi/test/CMakeLists.txt

@@ -8,8 +8,6 @@ macro(pythonize_bool var)
 endmacro()
 
 pythonize_bool(LIBCXXABI_USE_LLVM_UNWINDER)
-set(LIBCXXABI_EXECUTOR "\\\"${Python3_EXECUTABLE}\\\" ${LIBCXXABI_LIBCXX_PATH}/utils/run.py" CACHE STRING
-    "Executor to use when running tests.")
 
 if (LIBCXXABI_ENABLE_SHARED)
   set(LIBCXXABI_TEST_DEPS cxxabi_shared)
@@ -29,6 +27,11 @@ macro(serialize_lit_param param value)
   string(APPEND SERIALIZED_LIT_PARAMS "config.${param} = ${value}\n")
 endmacro()
 
+if (LIBCXXABI_EXECUTOR)
+  message(DEPRECATION "LIBCXXABI_EXECUTOR is deprecated, please add executor=... to LIBCXXABI_TEST_PARAMS")
+  serialize_lit_param(executor "\"${LIBCXXABI_EXECUTOR}\"")
+endif()
+
 if (NOT LIBCXXABI_ENABLE_EXCEPTIONS)
   serialize_lit_param(enable_exceptions False)
 endif()

libcxxabi/test/configs/cmake-bridge.cfg.in

@@ -32,7 +32,6 @@ config.substitutions.append(('%{include}', '@LIBCXXABI_SOURCE_DIR@/include'))
 config.substitutions.append(('%{cxx-include}', '@LIBCXXABI_HEADER_DIR@/include/c++/v1'))
 config.substitutions.append(('%{cxx-target-include}', '@LIBCXXABI_HEADER_DIR@/include/%{triple}/c++/v1'))
 config.substitutions.append(('%{lib}', '@LIBCXXABI_LIBRARY_DIR@'))
-config.substitutions.append(('%{executor}', '@LIBCXXABI_EXECUTOR@'))
 
 if @LIBCXXABI_USE_LLVM_UNWINDER@:
     config.substitutions.append(('%{maybe-include-libunwind}', '-I "@LIBCXXABI_LIBUNWIND_INCLUDES_INTERNAL@"'))

libunwind/test/CMakeLists.txt

@@ -10,8 +10,6 @@ endmacro()
 pythonize_bool(LIBUNWIND_ENABLE_CET)
 pythonize_bool(LIBUNWIND_ENABLE_THREADS)
 pythonize_bool(LIBUNWIND_USES_ARM_EHABI)
-set(LIBUNWIND_EXECUTOR "\\\"${Python3_EXECUTABLE}\\\" ${LIBUNWIND_LIBCXX_PATH}/utils/run.py" CACHE STRING
-    "Executor to use when running tests.")
 
 set(AUTO_GEN_COMMENT "## Autogenerated by libunwind configuration.\n# Do not edit!")
 set(SERIALIZED_LIT_PARAMS "# Lit parameters serialized here for llvm-lit to pick them up\n")
@@ -20,6 +18,11 @@ macro(serialize_lit_param param value)
   string(APPEND SERIALIZED_LIT_PARAMS "config.${param} = ${value}\n")
 endmacro()
 
+if (LIBUNWIND_EXECUTOR)
+  message(DEPRECATION "LIBUNWIND_EXECUTOR is deprecated, please add executor=... to LIBUNWIND_TEST_PARAMS")
+  serialize_lit_param(executor "\"${LIBUNWIND_EXECUTOR}\"")
+endif()
+
 serialize_lit_param(enable_experimental False)
 
 if (LLVM_USE_SANITIZER)

libunwind/test/configs/cmake-bridge.cfg.in

@@ -31,6 +31,5 @@ if not @LIBUNWIND_ENABLE_THREADS@:
 # Add substitutions for bootstrapping the test suite configuration
 import shlex
 config.substitutions.append(('%{cxx}', shlex.quote('@CMAKE_CXX_COMPILER@')))
-config.substitutions.append(('%{executor}', '@LIBUNWIND_EXECUTOR@'))
 config.substitutions.append(('%{include}', '@LIBUNWIND_SOURCE_DIR@/include'))
 config.substitutions.append(('%{lib}', '@LIBUNWIND_LIBRARY_DIR@'))