[BOLT][CMAKE] Accept BOLT_CLANG_EXE and BOLT_LLD_EXE

[Amir]

Summary

Add CMake options to supply clang and lld binaries for use in check-bolt
instead of requiring the build of clang and lld projects.

Suggested by Mehdi Amini in https://lists.llvm.org/pipermail/llvm-dev/2021-December/154426.html

Test Plan:

cmake -G Ninja ~/local/llvm-project/llvm \
-DLLVM_TARGETS_TO_BUILD="X86"  \
-DCMAKE_BUILD_TYPE=Release \
-DLLVM_ENABLE_ASSERTIONS=ON \
-DLLVM_ENABLE_PROJECTS="bolt"  \
-DBOLT_CLANG_EXE=~/local/bin/clang \
-DBOLT_LLD_EXE=~/local/bin/lld

ninja check-bolt
...
llvm-lit: /home/aaupov/local/llvm-project/llvm/utils/lit/lit/llvm/config.py:436: note: using clang: /home/aaupov/local/bin/clang
llvm-lit: /home/aaupov/local/llvm-project/llvm/utils/lit/lit/llvm/config.py:436: note: using ld.lld: /home/aaupov/local/bin/ld.lld
llvm-lit: /home/aaupov/local/llvm-project/llvm/utils/lit/lit/llvm/config.py:436: note: using lld-link: /home/aaupov/local/bin/lld-link
llvm-lit: /home/aaupov/local/llvm-project/llvm/utils/lit/lit/llvm/config.py:436: note: using ld64.lld: /home/aaupov/local/bin/ld64.lld
llvm-lit: /home/aaupov/local/llvm-project/llvm/utils/lit/lit/llvm/config.py:436: note: using wasm-ld: /home/aaupov/local/bin/wasm-ld
...

Tested all configurations:

• LLVM_ENABLE_PROJECTS="bolt;clang;lld" + no BOLT_*_EXE
• LLVM_ENABLE_PROJECTS="bolt;clang" + BOLT_LLD_EXE
• LLVM_ENABLE_PROJECTS="bolt;lld" + BOLT_CLANG_EXE
• LLVM_ENABLE_PROJECTS="bolt" + BOLT_CLANG_EXE + BOLT_LLD_EXE
• LLVM_ENABLE_PROJECTS="bolt;clang;lld" + BOLT_CLANG_EXE + BOLT_LLD_EXE

[maksfb]

LGTM

[Amir]

@smeenai:

Hi Shoaib, can you please take a look at the CMake changes? I’m in no way a CMake expert and would love to hear the feedback about how idiomatic this code is.

[smeenai]

Looks mostly good, just had one question.

bolt/CMakeLists.txt

18–19

Not your diff, but CMake has if(IN_LIST) now, which you can use instead of the string(FIND), e.g.

if("clang" IN_LIST LLVM_ENABLE_PROJECTS)

bolt/test/CMakeLists.txt

17

Hmm, will these targets not clash with the clang and lld targets from those LLVM subprojects, if you have those enabled? Is the assumption that you would only use BOLT_CLANG_EXE and BOLT_LLD_EXE if you're not enabling those subprojects?

[Amir]

bolt/CMakeLists.txt

18–19

Thanks! Will fix in a separate diff.

bolt/test/CMakeLists.txt

17

Yes, that's the assumption. I thought about it a bit more and realized that if clang project is enabled, it will be picked up by logic in lit.cfg.py because BOLT_CLANG_EXE directory is used as an extra search path.

So the fix should be as follows:

1. Emit a warning in bolt/CMakeLists.txt if BOLT_CLANG_EXE is set and clang project is enabled about which one will be used (built-in clang).
2. Only add the clang target if BOLT_CLANG_EXE is set but clang project is not enabled to satisfy the dependency on clang in BOLT_TEST_DEPS.

[Amir]

Addressed the feedback from Shoaib

[Amir]

Updated warning message. BOLT_CLANG_EXE and BOLT_LLD_EXE take precedence over
project-built clang and lld (additional_tool_dirs is prepended to search paths).

bolt/CMakeLists.txt

 include(ExternalProject)
 
 set(BOLT_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 set(BOLT_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
 set(CMAKE_CXX_STANDARD 14)
 
 set(BOLT_ENABLE_RUNTIME OFF)
 if (CMAKE_HOST_SYSTEM_PROCESSOR MATCHES "x86_64")
   set(BOLT_ENABLE_RUNTIME ON)
 endif()
 
+set(BOLT_CLANG_EXE "" CACHE FILEPATH "Path to clang executable for the target \
+architecture for use in BOLT tests")
+set(BOLT_LLD_EXE "" CACHE FILEPATH "Path to lld executable for the target \
+architecture for use in BOLT tests")
+
 set(BOLT_INCLUDE_TESTS OFF)
 if (LLVM_INCLUDE_TESTS)
-  if ("clang" IN_LIST LLVM_ENABLE_PROJECTS)
-    if ("lld" IN_LIST LLVM_ENABLE_PROJECTS)
+  if ("clang" IN_LIST LLVM_ENABLE_PROJECTS OR BOLT_CLANG_EXE)
+    if ("clang" IN_LIST LLVM_ENABLE_PROJECTS AND BOLT_CLANG_EXE)
+      message(WARNING "BOLT_CLANG_EXE is set and clang project is enabled. \
+            BOLT_CLANG_EXE will be used for BOLT tests.")
+    endif()
+    if ("lld" IN_LIST LLVM_ENABLE_PROJECTS OR BOLT_LLD_EXE)
+      if ("lld" IN_LIST LLVM_ENABLE_PROJECTS AND BOLT_LLD_EXE)
+        message(WARNING "BOLT_LLD_EXE is set and lld project is enabled. \
+              BOLT_LLD_EXE will be used for BOLT tests.")
+      endif()
       set(BOLT_INCLUDE_TESTS ON)
     else()
-      message(WARNING "Not including BOLT tests since lld is disabled")
+      message(WARNING "Not including BOLT tests since lld is disabled. \
+            Enable lld in LLVM_ENABLE_PROJECTS or provide a path to lld binary \
+            in BOLT_LLD_EXE.")
     endif()
   else()
-    message(WARNING "Not including BOLT tests since clang is disabled")
+    message(WARNING "Not including BOLT tests since clang is disabled. \
+          Enable clang in LLVM_ENABLE_PROJECTS or provide a path to clang \
+          binary in BOLT_CLANG_EXE.")
   endif()
 endif()
 
 if (BOLT_ENABLE_RUNTIME)
   message(STATUS "Building BOLT runtime libraries for X86")
   ExternalProject_Add(bolt_rt
     SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/runtime"
     STAMP_DIR ${CMAKE_CURRENT_BINARY_DIR}/bolt_rt-stamps

bolt/test/CMakeLists.txt

 llvm_canonicalize_cmake_booleans(
   BOLT_ENABLE_RUNTIME
   )
 
 configure_lit_site_cfg(
   ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.py.in
   ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg.py
   MAIN_CONFIG
   ${CMAKE_CURRENT_SOURCE_DIR}/lit.cfg.py
   )
 
 set(BOLT_TEST_PARAMS
   bolt_site_config=${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg
   )
 
+if (BOLT_CLANG_EXE AND NOT "clang" IN_LIST LLVM_ENABLE_PROJECTS)
+  add_executable(clang IMPORTED GLOBAL)
+  set_property(TARGET clang PROPERTY IMPORTED_LOCATION "${BOLT_CLANG_EXE}")
+endif()
+
+if (BOLT_LLD_EXE AND NOT "lld" IN_LIST LLVM_ENABLE_PROJECTS)
+  add_executable(lld IMPORTED GLOBAL)
+  set_property(TARGET lld PROPERTY IMPORTED_LOCATION "${BOLT_LLD_EXE}")
+endif()
+
 list(APPEND BOLT_TEST_DEPS
   clang
   count
   FileCheck
   llc
   lld
   llvm-config
   llvm-bolt

bolt/test/lit.cfg.py

else:
     lit_config.warning('Setting a timeout per test not supported. ' + errormsg
                        + ' Some tests will be skipped.')
 
 if config.bolt_enable_runtime:
     config.available_features.add("bolt-runtime")
 
 llvm_config.use_default_substitutions()
 
-llvm_config.use_clang()
-llvm_config.use_lld()
+llvm_config.use_clang(additional_tool_dirs=[os.path.dirname(config.bolt_clang)])
+llvm_config.use_lld(additional_tool_dirs=[os.path.dirname(config.bolt_lld)])
 
 config.substitutions.append(('%cflags', '-no-pie'))
 config.substitutions.append(('%cxxflags', '-no-pie'))
 
 link_fdata_cmd = os.path.join(config.test_source_root, 'link_fdata.py')
 
 tool_dirs = [config.llvm_tools_dir,
              config.test_source_root]

bolt/test/lit.site.cfg.py.in

 config.host_triple = "@LLVM_HOST_TRIPLE@"
 config.target_triple = "@TARGET_TRIPLE@"
 config.llvm_use_sanitizer = "@LLVM_USE_SANITIZER@"
 config.enable_shared = @ENABLE_SHARED@
 config.enable_backtrace = @ENABLE_BACKTRACES@
 config.host_arch = "@HOST_ARCH@"
 config.enable_abi_breaking_checks = "@LLVM_ENABLE_ABI_BREAKING_CHECKS@"
 config.python_executable = "@PYTHON_EXECUTABLE@"
+config.bolt_clang = "@BOLT_CLANG_EXE@"
+config.bolt_lld = "@BOLT_LLD_EXE@"
 
 # Support substitution of the tools and libs dirs with user parameters. This is
 # used when we can't determine the tool dir at configuration time.
 try:
     config.llvm_tools_dir = config.llvm_tools_dir % lit_config.params
     config.llvm_shlib_dir = config.llvm_shlib_dir % lit_config.params
     config.llvm_libs_dir = config.llvm_libs_dir % lit_config.params
 except KeyError: