Fix lld detection in standalone compiler-rt.

[eugenis]

Summary

Right now all hwasan tests on Android are silently disabled because they
require "has_lld" and standalone compiler-rt can not (and AFAIK was
never able to) set it.

[eugenis]

.

[eugenis]

Second attempt to re-enable hwasan testing. This time, do not add lld as a dependency of the test suites if it not a CMake target (i.e. if it is simply available through -fuse-ld=lld somehow).

[pcc]

LGTM

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)
   else()
-    set(COMPILER_RT_HAS_LLD FALSE)
+    set(COMPILER_RT_HAS_LLD ${COMPILER_RT_HAS_FUSE_LD_LLD_FLAG})
   endif()
 endif()
 pythonize_bool(COMPILER_RT_HAS_LLD)
 
 add_subdirectory(lib)
 
 if(COMPILER_RT_INCLUDE_TESTS)
   add_subdirectory(unittests)

compiler-rt/cmake/config-ix.cmake

if (ANDROID AND COMPILER_RT_HAS_LIBDL)
   # Android's libstdc++ has a dependency on libdl.
   list(APPEND CMAKE_REQUIRED_LIBRARIES dl)
 endif()
 check_library_exists(c++ __cxa_throw "" COMPILER_RT_HAS_LIBCXX)
 check_library_exists(stdc++ __cxa_throw "" COMPILER_RT_HAS_LIBSTDCXX)
 
 # Linker flags.
 check_linker_flag("-Wl,-z,text" COMPILER_RT_HAS_Z_TEXT)
+check_linker_flag("-fuse-ld=lld" COMPILER_RT_HAS_FUSE_LD_LLD_FLAG)
 
 if(ANDROID)
   check_linker_flag("-Wl,-z,global" COMPILER_RT_HAS_Z_GLOBAL)
   check_library_exists(log __android_log_write "" COMPILER_RT_HAS_LIBLOG)
 endif()
 
 # Architectures.
 

compiler-rt/test/hwasan/CMakeLists.txt

configure_lit_site_cfg(
     ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/lit.site.cfg.py)
   list(APPEND HWASAN_TESTSUITES ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME})
 endforeach()
 
 set(HWASAN_TEST_DEPS ${SANITIZER_COMMON_LIT_TEST_DEPS})
 if(NOT COMPILER_RT_STANDALONE_BUILD)
   list(APPEND HWASAN_TEST_DEPS hwasan)
   if(COMPILER_RT_HAS_LLD)
+    if (TARGET lld)
       list(APPEND HWASAN_TEST_DEPS lld)
     endif()
   endif()
+endif()
 
 add_lit_testsuite(check-hwasan "Running the HWAddressSanitizer tests"
   ${HWASAN_TESTSUITES}
   DEPENDS ${HWASAN_TEST_DEPS}
   )
 set_target_properties(check-hwasan PROPERTIES FOLDER "Compiler-RT Misc")

compiler-rt/test/msan/CMakeLists.txt

macro(add_msan_testsuite arch lld thinlto)
   string(TOUPPER ${arch} CONFIG_NAME)
 
   if (${thinlto})
     set(CONFIG_NAME "thinlto-${CONFIG_NAME}")
     list(APPEND MSAN_TEST_DEPS LTO)
   endif()
   if (${lld})
     set(CONFIG_NAME "lld-${CONFIG_NAME}")
+    if (TARGET lld)
       list(APPEND MSAN_TEST_DEPS lld)
     endif()
+  endif()
   set(MSAN_TEST_USE_THINLTO ${thinlto})
   set(MSAN_TEST_USE_LLD ${lld})
 
   configure_lit_site_cfg(
     ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.py.in
     ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME}/lit.site.cfg.py)
   list(APPEND MSAN_TESTSUITES ${CMAKE_CURRENT_BINARY_DIR}/${CONFIG_NAME})
 endmacro()

compiler-rt/test/ubsan/CMakeLists.txt

 set(UBSAN_LIT_TESTS_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 
 set(UBSAN_TESTSUITES)
 set(UBSAN_TEST_DEPS ${SANITIZER_COMMON_LIT_TEST_DEPS})
 
 macro(add_ubsan_testsuite test_mode sanitizer arch lld thinlto)
   set(UBSAN_LIT_TEST_MODE "${test_mode}")
   set(CONFIG_NAME ${UBSAN_LIT_TEST_MODE})
   if (${lld})
     set(CONFIG_NAME ${CONFIG_NAME}-lld)
+    if (TARGET lld)
       list(APPEND UBSAN_TEST_DEPS lld)
     endif()
+  endif()
   if (${thinlto})
     set(CONFIG_NAME ${CONFIG_NAME}-thinlto)
     list(APPEND UBSAN_TEST_DEPS LTO)
   endif()
   set(UBSAN_TEST_USE_LLD ${lld})
   set(UBSAN_TEST_USE_THINLTO ${thinlto})
   set(CONFIG_NAME ${CONFIG_NAME}-${arch})
   configure_lit_site_cfg(