Reenable OpenMP by reverting the following two commits. (#15315)

Summary:
Revert "Put back linker flag for OpenMP to prevent build break on ppc64le (#14569)"

This reverts commit a84e873bb156080ea76ab182171b1f3b4d5395f6.

Revert "Update OpenMP cmake setting for xcode 9 compiler(AppleClang 9.0) (#14473)"

This reverts commit 8901935ad42fe9bf093d1106ea43606008a4024d.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15315

Differential Revision: D13495852

Pulled By: ezyang

fbshipit-source-id: bcd3f60088b14831c53d3c171f10cd1ab6b35dee

.circleci/config.yml

@@ -117,7 +117,7 @@ pytorch_linux_test_defaults: &pytorch_linux_test_defaults
       <<: *setup_ci_environment
   - run:
       name: Test
-      no_output_timeout: "90m"
+      no_output_timeout: "1h"
       command: |
         set -e
         export COMMIT_DOCKER_IMAGE=${DOCKER_IMAGE}-${CIRCLE_SHA1}

.jenkins/pytorch/build-asan.sh

@@ -14,18 +14,8 @@ clang --version
 # symbolize=1: Gives us much better errors when things go wrong
 export ASAN_OPTIONS=detect_leaks=0:symbolize=1
 
-# FIXME: Remove the hardcoded "-pthread" option.
-# With asan build, the cmake thread CMAKE_HAVE_LIBC_CREATE[1] checking will
-# succeed because "pthread_create" is in libasan.so. However, libasan doesn't
-# have the full pthread implementation. Other advanced pthread functions doesn't
-# exist in libasan.so[2]. If we need some pthread advanced functions, we still
-# need to link the pthread library.
-# [1] https://github.com/Kitware/CMake/blob/8cabaaf054a16ea9c8332ce8e9291bd026b38c62/Modules/FindThreads.cmake#L135
-# [2] https://wiki.gentoo.org/wiki/AddressSanitizer/Problems
-#
 # TODO: Make the ASAN flags a more unified env var
 CC="clang" CXX="clang++" LDSHARED="clang --shared" \
-  CFLAGS="-fsanitize=address -fsanitize=undefined -fno-sanitize-recover=all -shared-libasan -pthread" \
+  CFLAGS="-fsanitize=address -fsanitize=undefined -fno-sanitize-recover=all -shared-libasan" \
-  CXX_FLAGS="-pthread" \
   NO_CUDA=1 USE_MKLDNN=0 \
   python setup.py install

caffe2/CMakeLists.txt

@@ -222,16 +222,8 @@ if(NOT BUILD_ATEN_ONLY)
   else()
     target_link_libraries(caffe2 PUBLIC protobuf::libprotobuf)
   endif()
-
-  #cmake only check for separate OpenMP library on AppleClang 7+
-  #https://github.com/Kitware/CMake/blob/42212f7539040139ecec092547b7d58ef12a4d72/Modules/FindOpenMP.cmake#L252
-  if (WITH_OPENMP AND CMAKE_CXX_COMPILER_ID MATCHES "AppleClang")
-    if (CMAKE_CXX_COMPILER_VERSION VERSION_EQUAL "7.0" OR
-        CMAKE_CXX_COMPILER_VERSION VERSION_GREATER "7.0")
-      target_link_libraries(caffe2 PRIVATE ${OpenMP_libomp_LIBRARY})
-    endif()
-  endif()
 endif()
+
 target_link_libraries(caffe2 PUBLIC c10)
 target_link_libraries(caffe2 PUBLIC ${Caffe2_PUBLIC_DEPENDENCY_LIBS})
 target_link_libraries(caffe2 PRIVATE ${Caffe2_DEPENDENCY_LIBS})

cmake/Dependencies.cmake

@@ -632,37 +632,12 @@ endif()
 
 # ---[ OpenMP
 if(USE_OPENMP)
-  set(WITH_OPENMP ON CACHE BOOL "OpenMP support if available?")
+  find_package(OpenMP)
-  if(APPLE AND CMAKE_COMPILER_IS_GNUCC)
-    exec_program(uname ARGS -v  OUTPUT_VARIABLE DARWIN_VERSION)
-    string(REGEX MATCH "[0-9]+" DARWIN_VERSION ${DARWIN_VERSION})
-    message(STATUS "MAC OS Darwin Version: ${DARWIN_VERSION}")
-    if(DARWIN_VERSION GREATER 9)
-      set(APPLE_OPENMP_SUCKS 1)
-    endif(DARWIN_VERSION GREATER 9)
-    execute_process(COMMAND ${CMAKE_C_COMPILER} -dumpversion
-      OUTPUT_VARIABLE GCC_VERSION)
-    if(APPLE_OPENMP_SUCKS AND GCC_VERSION VERSION_LESS 4.6.2)
-      message(STATUS "Warning: Disabling OpenMP (unstable with this version of GCC)")
-      message(STATUS " Install GCC >= 4.6.2 or change your OS to enable OpenMP")
-      add_compile_options(-Wno-unknown-pragmas)
-      set(WITH_OPENMP OFF CACHE BOOL "OpenMP support if available?" FORCE)
-    endif()
-  endif()
-
-  if(WITH_OPENMP AND NOT CHECKED_OPENMP)
-    find_package(OpenMP)
-    set(CHECKED_OPENMP ON CACHE BOOL "already checked for OpenMP")
-
-    # OPENMP_FOUND is not cached in FindOpenMP.cmake (all other variables are cached)
-    # see https://github.com/Kitware/CMake/blob/master/Modules/FindOpenMP.cmake
-    set(OPENMP_FOUND ${OPENMP_FOUND} CACHE BOOL "OpenMP Support found")
-  endif()
-
   if(OPENMP_FOUND)
     message(STATUS "Adding " ${OpenMP_CXX_FLAGS})
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${OpenMP_EXE_LINKER_FLAGS}")
   else()
     message(WARNING "Not compiling with OpenMP. Suppress this warning with -DUSE_OPENMP=OFF")
     caffe2_update_option(USE_OPENMP OFF)
@@ -1106,6 +1081,42 @@ if (NOT BUILD_ATEN_MOBILE)
     STRING(REPLACE "-DNDEBUG" "" CMAKE_CXX_FLAGS_DEBUG "" ${CMAKE_CXX_FLAGS_DEBUG})
     STRING(REPLACE "-DNDEBUG" "" CMAKE_CXX_FLAGS_RELEASE "" ${CMAKE_CXX_FLAGS_RELEASE})
   ENDIF()
+
+  # OpenMP support?
+  SET(WITH_OPENMP ON CACHE BOOL "OpenMP support if available?")
+  IF (APPLE AND CMAKE_COMPILER_IS_GNUCC)
+    EXEC_PROGRAM (uname ARGS -v  OUTPUT_VARIABLE DARWIN_VERSION)
+    STRING (REGEX MATCH "[0-9]+" DARWIN_VERSION ${DARWIN_VERSION})
+    MESSAGE (STATUS "MAC OS Darwin Version: ${DARWIN_VERSION}")
+    IF (DARWIN_VERSION GREATER 9)
+      SET(APPLE_OPENMP_SUCKS 1)
+    ENDIF (DARWIN_VERSION GREATER 9)
+    EXECUTE_PROCESS (COMMAND ${CMAKE_C_COMPILER} -dumpversion
+      OUTPUT_VARIABLE GCC_VERSION)
+    IF (APPLE_OPENMP_SUCKS AND GCC_VERSION VERSION_LESS 4.6.2)
+      MESSAGE(STATUS "Warning: Disabling OpenMP (unstable with this version of GCC)")
+      MESSAGE(STATUS " Install GCC >= 4.6.2 or change your OS to enable OpenMP")
+      add_compile_options(-Wno-unknown-pragmas)
+      SET(WITH_OPENMP OFF CACHE BOOL "OpenMP support if available?" FORCE)
+    ENDIF()
+  ENDIF()
+
+  IF (WITH_OPENMP AND NOT CHECKED_OPENMP)
+    FIND_PACKAGE(OpenMP)
+    SET(CHECKED_OPENMP ON CACHE BOOL "already checked for OpenMP")
+
+    # OPENMP_FOUND is not cached in FindOpenMP.cmake (all other variables are cached)
+    # see https://github.com/Kitware/CMake/blob/master/Modules/FindOpenMP.cmake
+    SET(OPENMP_FOUND ${OPENMP_FOUND} CACHE BOOL "OpenMP Support found")
+  ENDIF()
+
+  IF (OPENMP_FOUND)
+    MESSAGE(STATUS "Compiling with OpenMP support")
+    SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
+    SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
+  ENDIF()
+
+
   SET(CUDA_ATTACH_VS_BUILD_RULE_TO_CUDA_FILE OFF)
 
   FIND_PACKAGE(MAGMA)

modules/detectron/CMakeLists.txt

@@ -2,15 +2,6 @@ file(GLOB Detectron_CPU_SRCS ${CMAKE_CURRENT_SOURCE_DIR}/*.cc)
 file(GLOB Detectron_GPU_SRCS ${CMAKE_CURRENT_SOURCE_DIR}/*.cu)
 
 if (BUILD_CAFFE2_OPS)
-  #cmake only check for separate OpenMP library on AppleClang 7+
-  #https://github.com/Kitware/CMake/blob/42212f7539040139ecec092547b7d58ef12a4d72/Modules/FindOpenMP.cmake#L252
-  if (WITH_OPENMP AND CMAKE_CXX_COMPILER_ID MATCHES "AppleClang")
-    if (CMAKE_CXX_COMPILER_VERSION VERSION_EQUAL "7.0" OR
-        CMAKE_CXX_COMPILER_VERSION VERSION_GREATER "7.0")
-      Set(OpenMP_link ${OpenMP_libomp_LIBRARY})
-    endif()
-  endif()
-
   # Note(ilijar): Since Detectron ops currently have no
   # CPU implementation, we only build GPU ops for now.
   if (USE_CUDA)
@@ -19,11 +10,11 @@ if (BUILD_CAFFE2_OPS)
         ${Detectron_CPU_SRCS}
         ${Detectron_GPU_SRCS})
 
-    target_link_libraries(caffe2_detectron_ops_gpu caffe2_gpu ${OpenMP_link})
+    target_link_libraries(caffe2_detectron_ops_gpu caffe2_gpu)
     install(TARGETS caffe2_detectron_ops_gpu DESTINATION lib)
   elseif(NOT IOS_PLATFORM)
     add_library(caffe2_detectron_ops SHARED ${Detectron_CPU_SRCS})
-    target_link_libraries(caffe2_detectron_ops caffe2 ${OpenMP_link})
+    target_link_libraries(caffe2_detectron_ops caffe2)
     install(TARGETS caffe2_detectron_ops DESTINATION lib)
   endif()
 endif()

torch/CMakeLists.txt

@@ -3,7 +3,7 @@ if (CAFFE2_CMAKE_BUILDING_WITH_MAIN_REPO)
     return()
   endif()
 else()
-  cmake_minimum_required(VERSION 3.5 FATAL_ERROR)
+  cmake_minimum_required(VERSION 3.0 FATAL_ERROR)
   project(torch CXX C)
   find_package(Caffe2 REQUIRED)
   option(USE_CUDA "Use CUDA" ON)
@@ -331,16 +331,8 @@ if(OPENMP_FOUND)
   if (VERBOSE)
     message(STATUS "Compiling with OpenMP")
   endif()
-  target_compile_options(torch INTERFACE ${OpenMP_CXX_FLAGS})
+  target_compile_options(torch INTERFACE -fopenmp)
   target_link_libraries(torch -fopenmp)
-  #cmake only check for separate OpenMP library on AppleClang 7+
-  #https://github.com/Kitware/CMake/blob/42212f7539040139ecec092547b7d58ef12a4d72/Modules/FindOpenMP.cmake#L252
-  if (CMAKE_CXX_COMPILER_ID MATCHES "AppleClang")
-    if (CMAKE_CXX_COMPILER_VERSION VERSION_EQUAL "7.0" OR
-        CMAKE_CXX_COMPILER_VERSION VERSION_GREATER "7.0")
-      target_link_libraries(torch ${OpenMP_libomp_LIBRARY})
-    endif()
-  endif()
 endif()
 
 if (NOT NO_API)