Introduce LIBUNWIND_LIT_ARGS, LIBCXXABI_LIT_ARGS and LIBCXX_LIT_AGRS

[broadwaylamb]

Summary

Right now the LIT args that are used for running libunwind, libc++abi and libc++ tests are taken from the LLVM_LIT_ARGS variable. Furthermore, every test target in the LLVM project, be it LLVM, clang, lld or libc++, use that variable for running LIT.

This is suboptimal if we're building such projects simultaneously as one toolchain: for example, if we're leveraging the llvm/runtimes directory for building a toolchain in one go (like we do in builders llvm-clang-win-x-armv7l and llvm-clang-win-x-aarch64) we can't tell the clang LIT target to run 8 parallel jobs and the libc++ LIT target to run 64 parallel jobs.

This patch introduces three new CMake variables: LIBUNWIND_LIT_ARGS, LIBCXXABI_LIT_ARGS and LIBCXX_LIT_AGRS. If they are defined, we use them to configure LIT targets and don't look at LLVM_LIT_ARGS. If they are not defined, we fall back to LLVM_LIT_ARGS.

(I wonder if setting a global variable is a good solution, but I've looked at the llvm/cmake/modules/AddLLVM.cmake file, where the add_lit_target function is defined, and it doesn't seem easy to change the behavior to pass the string containing LIT args as an argument to the add_lit_target function. Mainly because some downstream projects (at least Swift) depend on that function.)

[ldionne]

I personally think we should move away from tying CMake and lit together by funneling lit arguments through it. Instead, it would be better to store special lit.cfg files in libcxx/ for use by bots. But we're not quite there yet, and this patch has the effect of decoupling libcxx/libcxxabi/libunwind from LLVM global variables, so I'm sort-of OK with it. I'd like to move towards a future where we don't need to process the CMake files in llvm/* to build the runtimes.

libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake

127

Why isn't that in libcxx/CMakeLists.txt?

[broadwaylamb]

libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake

127

We were setting LLVM_LIT_ARGS here, so I figured that LIBCXX_LIT_ARGS should also be set here.

[EricWF]

Why do we need separate options for each project?
I think that's the wrong direction.

[broadwaylamb]

@EricWF could you elaborate? What would be the right direction?

libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake

if (LLVM_INCLUDE_TESTS)
     # Required LIT Configuration ------------------------------------------------
     # Define the default arguments to use with 'lit', and an option for the user
     # to override.
     set(LLVM_DEFAULT_EXTERNAL_LIT "${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py")
     set(LIT_ARGS_DEFAULT "-sv --show-xfail --show-unsupported")
     if (MSVC OR XCODE)
       set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --no-progress-bar")
     endif()
-    set(LLVM_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "Default options for lit")
+    if (DEFINED LIBCXX_LIT_ARGS)
+      # libc++-specific LIT args always win over generic LIT args
+      set(LLVM_LIT_ARGS "${LIBCXX_LIT_ARGS}")
+    endif()
+    set(LIBCXX_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "libc++-specific options for lit")
+    set(LLVM_LIT_ARGS   "${LIBCXX_LIT_ARGS}"  CACHE STRING "Default options for lit")
   endif()
 
   # Required doc configuration
   if (LLVM_ENABLE_SPHINX)
     find_package(Sphinx REQUIRED)
   endif()
 
   if (LLVM_ON_UNIX AND NOT APPLE)
     set(LLVM_HAVE_LINK_VERSION_SCRIPT 1)
   else()
     set(LLVM_HAVE_LINK_VERSION_SCRIPT 0)
   endif()
 endmacro(configure_out_of_tree_llvm)
 
 configure_out_of_tree_llvm()

libcxxabi/cmake/Modules/HandleOutOfTreeLLVM.cmake

if (LLVM_INCLUDE_TESTS)
     # Required LIT Configuration ------------------------------------------------
     # Define the default arguments to use with 'lit', and an option for the user
     # to override.
     set(LLVM_DEFAULT_EXTERNAL_LIT "${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py")
     set(LIT_ARGS_DEFAULT "-sv --show-xfail --show-unsupported")
     if (MSVC OR XCODE)
       set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --no-progress-bar")
     endif()
-    set(LLVM_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "Default options for lit")
+    
+    if (DEFINED LIBCXXABI_LIT_ARGS)
+      # libc++abi-specific LIT args always win over generic LIT args
+      set(LLVM_LIT_ARGS "${LIBCXXABI_LIT_ARGS}")
+    endif()
+    set(LIBCXXABI_LIT_ARGS "${LIT_ARGS_DEFAULT}"   CACHE STRING "libc++abi-specific options for lit")
+    set(LLVM_LIT_ARGS      "${LIBCXXABI_LIT_ARGS}" CACHE STRING "Default options for lit")
   endif()
 
   # Required doc configuration
   if (LLVM_ENABLE_SPHINX)
     find_package(Sphinx REQUIRED)
   endif()
 
   if (LLVM_ON_UNIX AND NOT APPLE)
     set(LLVM_HAVE_LINK_VERSION_SCRIPT 1)
   else()
     set(LLVM_HAVE_LINK_VERSION_SCRIPT 0)
   endif()
 endmacro(configure_out_of_tree_llvm)
 
 configure_out_of_tree_llvm()

libunwind/CMakeLists.txt

if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBUNWIND_STANDALONE_BUILD)
 
   if (LLVM_LIT)
     # Define the default arguments to use with 'lit', and an option for the user
     # to override.
     set(LIT_ARGS_DEFAULT "-sv")
     if (MSVC OR XCODE)
       set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --no-progress-bar")
     endif()
-    set(LLVM_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "Default options for lit")
+
+    if (DEFINED LIBUNWIND_LIT_ARGS)
+      # libunwind-specific LIT args always win over generic LIT args
+      set(LLVM_LIT_ARGS "${LIBUNWIND_LIT_ARGS}")
+    endif()
+    set(LIBUNWIND_LIT_ARGS "${LIT_ARGS_DEFAULT}"   CACHE STRING "libunwind-specific options for lit")
+    set(LLVM_LIT_ARGS      "${LIBUNWIND_LIT_ARGS}" CACHE STRING "Default options for lit")
 
     # On Win32 hosts, provide an option to specify the path to the GnuWin32 tools.
     if (WIN32 AND NOT CYGWIN)
       set(LLVM_LIT_TOOLS_DIR "" CACHE PATH "Path to GnuWin32 tools")
     endif()
   else()
     set(LLVM_INCLUDE_TESTS OFF)
   endif()