[CMake] Fix pthread handling for out-of-tree builds

LLVM defines `PTHREAD_LIB` which is used by AddLLVM.cmake and various projects
to correctly link the threading library when needed. Unfortunately
`PTHREAD_LIB` is defined by LLVM's `config-ix.cmake` file which isn't installed
and therefore can't be used when configuring out-of-tree builds. This causes
such builds to fail since `pthread` isn't being correctly linked.

This patch attempts to fix that problem by renaming and exporting
`LLVM_PTHREAD_LIB` as part of`LLVMConfig.cmake`. I renamed `PTHREAD_LIB`
because It seemed likely to cause collisions with downstream users of
`LLVMConfig.cmake`.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294690 91177308-0d34-0410-b5e6-96231b3b80d8

cmake/config-ix.cmake

@@ -115,7 +115,7 @@ if(HAVE_LIBPTHREAD)
   set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
   set(THREADS_HAVE_PTHREAD_ARG Off)
   find_package(Threads REQUIRED)
-  set(PTHREAD_LIB ${CMAKE_THREAD_LIBS_INIT})
+  set(LLVM_PTHREAD_LIB ${CMAKE_THREAD_LIBS_INIT})
 endif()
 
 # Don't look for these libraries on Windows. Also don't look for them if we're

cmake/modules/AddLLVM.cmake

@@ -718,11 +718,11 @@ macro(add_llvm_executable name)
   if(NOT ARG_IGNORE_EXTERNALIZE_DEBUGINFO)
     llvm_externalize_debuginfo(${name})
   endif()
-  if (PTHREAD_LIB)
+  if (LLVM_PTHREAD_LIB)
     # libpthreads overrides some standard library symbols, so main
     # executable must be linked with it in order to provide consistent
     # API for all shared libaries loaded by this executable.
-    target_link_libraries(${name} ${PTHREAD_LIB})
+    target_link_libraries(${name} ${LLVM_PTHREAD_LIB})
   endif()
 endmacro(add_llvm_executable name)
 
@@ -1027,7 +1027,7 @@ function(add_unittest test_suite test_name)
   # libpthreads overrides some standard library symbols, so main
   # executable must be linked with it in order to provide consistent
   # API for all shared libaries loaded by this executable.
-  target_link_libraries(${test_name} gtest_main gtest ${PTHREAD_LIB})
+  target_link_libraries(${test_name} gtest_main gtest ${LLVM_PTHREAD_LIB})
 
   add_dependencies(${test_suite} ${test_name})
   get_target_property(test_suite_folder ${test_suite} FOLDER)

cmake/modules/LLVMConfig.cmake.in

@@ -45,6 +45,10 @@ set(LLVM_ENABLE_PIC @LLVM_ENABLE_PIC@)
 
 set(LLVM_BUILD_32_BITS @LLVM_BUILD_32_BITS@)
 
+if (NOT "@LLVM_PTHREAD_LIB@" STREQUAL "")
+  set(LLVM_PTHREAD_LIB "@LLVM_PTHREAD_LIB@")
+endif()
+
 set(LLVM_ENABLE_PLUGINS @LLVM_ENABLE_PLUGINS@)
 set(LLVM_EXPORT_SYMBOLS_FOR_PLUGINS @LLVM_EXPORT_SYMBOLS_FOR_PLUGINS@)
 set(LLVM_PLUGIN_EXT @LLVM_PLUGIN_EXT@)

examples/ParallelJIT/CMakeLists.txt

@@ -11,4 +11,4 @@ add_llvm_example(ParallelJIT
   ParallelJIT.cpp
   )
 
-target_link_libraries(ParallelJIT ${PTHREAD_LIB})
+target_link_libraries(ParallelJIT ${LLVM_PTHREAD_LIB})

lib/CodeGen/CMakeLists.txt

@@ -150,7 +150,7 @@ add_llvm_library(LLVMCodeGen
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/CodeGen
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/CodeGen/PBQP
 
-  LINK_LIBS ${PTHREAD_LIB}
+  LINK_LIBS ${LLVM_PTHREAD_LIB}
 
   DEPENDS
   intrinsics_gen

lib/ExecutionEngine/IntelJITEvents/CMakeLists.txt

@@ -4,7 +4,7 @@ if( HAVE_LIBDL )
     set(LLVM_INTEL_JIT_LIBS ${CMAKE_DL_LIBS})
 endif()
 
-set(LLVM_INTEL_JIT_LIBS ${PTHREAD_LIB} ${LLVM_INTEL_JIT_LIBS})
+set(LLVM_INTEL_JIT_LIBS ${LLVM_PTHREAD_LIB} ${LLVM_INTEL_JIT_LIBS})
 
 
 add_llvm_library(LLVMIntelJITEvents

lib/Fuzzer/CMakeLists.txt

@@ -34,12 +34,12 @@ if( LLVM_USE_SANITIZE_COVERAGE )
   add_library(LLVMFuzzerNoMain STATIC
     $<TARGET_OBJECTS:LLVMFuzzerNoMainObjects>
     )
-  target_link_libraries(LLVMFuzzerNoMain ${PTHREAD_LIB})
+  target_link_libraries(LLVMFuzzerNoMain ${LLVM_PTHREAD_LIB})
   add_library(LLVMFuzzer STATIC
     FuzzerMain.cpp
     $<TARGET_OBJECTS:LLVMFuzzerNoMainObjects>
     )
-  target_link_libraries(LLVMFuzzer ${PTHREAD_LIB})
+  target_link_libraries(LLVMFuzzer ${LLVM_PTHREAD_LIB})
 
   if( LLVM_INCLUDE_TESTS )
     add_subdirectory(test)

lib/Support/CMakeLists.txt

@@ -17,7 +17,7 @@ elseif( CMAKE_HOST_UNIX )
   if( LLVM_ENABLE_THREADS AND HAVE_LIBATOMIC )
     set(system_libs ${system_libs} atomic)
   endif()
-  set(system_libs ${system_libs} ${PTHREAD_LIB})
+  set(system_libs ${system_libs} ${LLVM_PTHREAD_LIB})
   if ( LLVM_ENABLE_ZLIB AND HAVE_LIBZ )
     set(system_libs ${system_libs} z)
   endif()

unittests/ExecutionEngine/Orc/CMakeLists.txt

@@ -21,4 +21,4 @@ add_llvm_unittest(OrcJITTests
   RPCUtilsTest.cpp
   )
 
-target_link_libraries(OrcJITTests ${PTHREAD_LIB})
+target_link_libraries(OrcJITTests ${LLVM_PTHREAD_LIB})

unittests/Support/CMakeLists.txt

@@ -64,4 +64,4 @@ add_llvm_unittest(SupportTests
   )
 
 # ManagedStatic.cpp uses <pthread>.
-target_link_libraries(SupportTests ${PTHREAD_LIB})
+target_link_libraries(SupportTests ${LLVM_PTHREAD_LIB})

utils/unittest/CMakeLists.txt

@@ -40,8 +40,8 @@ if (NOT LLVM_ENABLE_THREADS)
   add_definitions( -DGTEST_HAS_PTHREAD=0 )
 endif()
 
-find_library(PTHREAD_LIBRARY_PATH pthread)
-if (PTHREAD_LIBRARY_PATH)
+find_library(LLVM_PTHREAD_LIBRARY_PATH pthread)
+if (LLVM_PTHREAD_LIBRARY_PATH)
   list(APPEND LIBS pthread)
 endif()