[WIP][Fuchsia] Set LLVM_TOOL_LLD_BUILD to allow some extra runtimes tests to run

[leonardchan]

Summary

LLVM_TOOL_LLD_BUILD is required for COMPILER_RT_HAS_LLD to be set which impacts tests in the following ways:

• This sets config.has_lld in various lit files. This allows hwasan tests to run for arm runtimes and sets the feature lld-available which is required for a couple of tests.
• Adds an "lld variant" of test suites for various sanitizers like msan that essentially run a suite of msan tests, but explicitly linked with lld.

[leonardchan]

Won't be landing this until I'm sure any new tests that will be running from this won't fail locally.

[leonardchan]

An alternative approach to this is update this bit of cmake in compiler-rt/CMakeLists.txt:

set(COMPILER_RT_LLD_PATH ${LLVM_MAIN_SRC_DIR}/tools/lld)
if(EXISTS ${COMPILER_RT_LLD_PATH}/ AND LLVM_TOOL_LLD_BUILD)
  set(COMPILER_RT_HAS_LLD TRUE)
else()
  set(COMPILER_RT_LLD_PATH ${LLVM_MAIN_SRC_DIR}/../lld)
  if(EXISTS ${COMPILER_RT_LLD_PATH}/ AND LLVM_TOOL_LLD_BUILD)
    set(COMPILER_RT_HAS_LLD TRUE)
  endif()
endif()

if(ANDROID)
  set(COMPILER_RT_HAS_LLD TRUE)
  set(COMPILER_RT_TEST_USE_LLD TRUE)
  append_list_if(COMPILER_RT_HAS_FUSE_LD_LLD_FLAG -fuse-ld=lld SANITIZER_COMMON_LINK_FLAGS)
  append_list_if(COMPILER_RT_HAS_LLD -fuse-ld=lld COMPILER_RT_UNITTEST_LINK_FLAGS)
endif()

to something like:

set(COMPILER_RT_LLD_PATH ${LLVM_MAIN_SRC_DIR}/../lld)
if(EXISTS ${COMPILER_RT_LLD_PATH})
  set(COMPILER_RT_HAS_LLD TRUE)
endif()

if(ANDROID)
  set(COMPILER_RT_HAS_LLD TRUE)
  set(COMPILER_RT_TEST_USE_LLD TRUE)
endif()
append_list_if(COMPILER_RT_HAS_FUSE_LD_LLD_FLAG -fuse-ld=lld SANITIZER_COMMON_LINK_FLAGS)
append_list_if(COMPILER_RT_HAS_LLD -fuse-ld=lld COMPILER_RT_UNITTEST_LINK_FLAGS)

I'm thinking LLVM_TOOL_LLD_BUILD might be a remnant of times before the monorepo since lld doesn't exist under llvm/tools anymore.

[leonardchan]

In D128567#3609635, @leonardchan wrote:

Won't be landing this until I'm sure any new tests that will be running from this won't fail locally.

Or given https://reviews.llvm.org/D126936 and this could just pass magically on our bots, maybe we could just land this at the cost of being able to reproduce failures locally.

[phosek]

In D128567#3609644, @leonardchan wrote:

I'm thinking LLVM_TOOL_LLD_BUILD might be a remnant of times before the monorepo since lld doesn't exist under llvm/tools anymore.

Yes, that's correct. The proposed cleanup is the solution I'd prefer. I recently did a similar cleanup for libc++ in D126905.

[aeubanks]

I've noticed that we're skipping compiler-rt tests with REQUIRED: lld-available because LLVM_TOOL_LLD_BUILD needs to be defined. any update on the proposed alternative?

[abrachet]

In D128567#3863178, @aeubanks wrote:

I've noticed that we're skipping compiler-rt tests with REQUIRED: lld-available because LLVM_TOOL_LLD_BUILD needs to be defined. any update on the proposed alternative?

I think the canonical way this is done throughout the code base is with

from lit.llvm import llvm_config

if llvm_config.use_lld(required=False):
    config.available_features.add('lld')

Though, what I think we don't do currently here or elsewhere is conditionally add test deps on lld if it is specified in LLVM_ENABLE_PROJECTS

[aeubanks]

In D128567#3863222, @abrachet wrote:

In D128567#3863178, @aeubanks wrote:

I've noticed that we're skipping compiler-rt tests with REQUIRED: lld-available because LLVM_TOOL_LLD_BUILD needs to be defined. any update on the proposed alternative?

I think the canonical way this is done throughout the code base is with

from lit.llvm import llvm_config

if llvm_config.use_lld(required=False):
    config.available_features.add('lld')

Though, what I think we don't do currently here or elsewhere is conditionally add test deps on lld if it is specified in LLVM_ENABLE_PROJECTS

I see things like

if(NOT APPLE AND COMPILER_RT_HAS_LLD AND "lld" IN_LIST LLVM_ENABLE_PROJECTS)
  list(APPEND ASAN_TEST_DEPS lld)
endif()

in multiple places like compiler-rt/test/asan/CMakeLists.txt

clang/cmake/caches/Fuchsia-stage2.cmake

if(LINUX_${target}_SYSROOT)
     set(RUNTIMES_${target}_SANITIZER_CXX_ABI "libc++" CACHE STRING "")
     set(RUNTIMES_${target}_SANITIZER_CXX_ABI_INTREE ON CACHE BOOL "")
     set(RUNTIMES_${target}_SANITIZER_TEST_CXX "libc++" CACHE STRING "")
     set(RUNTIMES_${target}_SANITIZER_TEST_CXX_INTREE ON CACHE BOOL "")
     set(RUNTIMES_${target}_COMPILER_RT_TEST_COMPILER_CFLAGS "--unwindlib=libunwind -static-libgcc" CACHE STRING "")
     set(RUNTIMES_${target}_SANITIZER_COMMON_TEST_TARGET_CFLAGS "--unwindlib=libunwind -static-libgcc" CACHE STRING "")
     set(RUNTIMES_${target}_TSAN_TEST_TARGET_CFLAGS "--unwindlib=libunwind -static-libgcc" CACHE STRING "")
     set(RUNTIMES_${target}_LLVM_TOOLS_DIR "${CMAKE_BINARY_DIR}/bin" CACHE BOOL "")
+    set(RUNTIMES_${target}_LLVM_TOOL_LLD_BUILD ON CACHE BOOL "")
     set(RUNTIMES_${target}_LLVM_ENABLE_RUNTIMES "compiler-rt;libcxx;libcxxabi;libunwind" CACHE STRING "")
 
     # Use .build-id link.
     list(APPEND RUNTIME_BUILD_ID_LINK "${target}")
   endif()
 endforeach()
 
 if(FUCHSIA_SDK)