Compatibility fixes for gcc-4.8.5 and CentOS-7.4 (#444)

(Squashing this commit but going to leave the full log here, unlike the way I usually do things)

* Incremental work on compatibility with system requirements

* Lower cmake version requirement so we can work with CentOS 7.4

* Disambiguate isnan call (CentOS's compiler doesn't like it)

* Make external_tbb conditional on NGRAPH_CPU_ENABLE

* Make MKLDNN inclusion conditional on NGRAPH_CPU_ENABLE

* Roll back desperation change to Ubuntu 14.04 binaries

* De-revert copyright date change (arrgh)

* Revert change of TBB's hard-coded compiler choice to gcc

* Cleanup of modified CMake stuff

* Add broken support for building LLVM from source

* Explain modification to json.hpp required compiler version

* Make TBB optional, and on by default. To disable, cmake -DNGRAPH_TBB_ENABLE=FALSE

* Add reasonable default for LLVM's CMAKE_ASM_COMPILER so users don't have to specify it

* Force TBB disabled if CMake is too old to build it (for CentOS)

* Build LLVM OpenMP as external project

* Tweak LLVM build options

* Minor comment edit in cmake scripts

* Workaround (fix?) for codegen crashes on CentOS

* Add some header paths for CentOS to resource_generator; temporary(?) tweak to ignore nonexistent paths

* Remove CMake compatibility figleaf since LLVM will require 3.1+ anyway

* Fix the TBB-enable flag to default to on

* Remove hard-coded choice of clang as tbb compiler

* ln -s -> ln -sf in command to create link for OpenMP source dir

* Make OpenMP build so it doesn't require symlink

* Allow use of prebuilt LLVM if requested at cmake time

* Some INSTALL instructions

* Allow NGRAPH_USE_PREBUILT_LLVM to be set in environment variable

* Tweak CI cmake options to use prebuilt LLVM

* Remove debug messages

* Rework defaulting behavior for LLVM_TARBALL_URL and LLVM_SHA1_HASH

* Remove warning message for unavailable header file directories

CMakeLists.txt

@@ -23,7 +23,7 @@ endif()
 
 project (ngraph)
 
-SET( GCC_MIN_VERSION 4.9)
+SET( GCC_MIN_VERSION 4.8)
 SET( CLANG_MIN_VERSION 3.8)
 
 if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
@@ -39,6 +39,10 @@ else()
     message(WARNING "You are using an unsupported compiler! Compilation has only been tested with Clang ( ${CLANG_MIN_VERSION} and up) and GCC ( ${GCC_MIN_VERSION} and up). ")
 endif()
 
+if($ENV{NGRAPH_USE_PREBUILT_LLVM})
+    set(NGRAPH_USE_PREBUILT_LLVM TRUE)
+endif()
+
 # These variables are undocumented but useful.
 set(CMAKE_DISABLE_SOURCE_CHANGES ON)
 set(CMAKE_DISABLE_IN_SOURCE_BUILD ON)
@@ -97,7 +101,11 @@ endif()
 
 # Set true if CPU backend is built by default
 if (NOT DEFINED NGRAPH_CPU_ENABLE)
-    SET(NGRAPH_CPU_ENABLE TRUE)
+    set(NGRAPH_CPU_ENABLE TRUE)
+endif()
+
+if (NOT DEFINED NGRAPH_TBB_ENABLE)
+    set(NGRAPH_TBB_ENABLE ${NGRAPH_CPU_ENABLE})
 endif()
 
 #-----------------------------------------------------------------------------------------------

INSTALL

+Currently two platforms are known to work:
+
+- Ubuntu 16.04
+- CentOS 7.4
+
+Ubuntu 16.04 Prerequisites
+==========================
+
+Compilers currently known to work are gcc-5.4.0, clang-3.9, and gcc-4.8.5.
+
+If you are using gcc-5.4.0 or clang-3.9, it is recommended to add the
+option `-DNGRAPH_USE_PREBUILT_LLVM=TRUE` to the `cmake` command. This causes
+the build system to fetch a pre-built tarball of LLVM+Clang from `llvm.org`,
+which substantially cuts down on build times.
+
+If you are using gcc-4.8, it may be necessary to add symlinksfrom `gcc` to
+`gcc-4.8`, and from `g++` to `g++-4.8`, in your PATH, even if you have
+specify CMAKE_C_COMPILER and CMAKE_CXX_COMPILER when building. (You should
+NOT supply the `-DNGRAPH_USE_PREBUILT_LLVM` flag in this case, because the
+prebuilt tarball supplied on llvm.org is not compatible with a gcc-4.8
+based build.)
+
+CentOS 7.4 Prerequisites
+========================
+
+CentOS supplies an older version of CMake that is not compatible with
+LLVM-5.0.1, which we build as an external dependency. There are two options:
+
+1. (requires root privileges) install the the `cmake3` package from EPEL, or
+2. (does not require root privileges) build CMake (3.1 or newer) from source,
+   and run it from its build directory.
+
+General Instructions
+====================
+
+These instructions assume that your system has been prepared in accordance
+with the above prerequisites.
+
+$ cd private-ngraph-cpp
+$ mkdir build
+$ cd build
+$ cmake .. \
+    -DCMAKE_C_COMPILER=<path to C compiler> \
+    -DCMAKE_CXX_COMPILER=<path to C++ compiler>
+$ make -j install

cmake/external_eigen.cmake

@@ -30,7 +30,7 @@ if (${CMAKE_VERSION} VERSION_LESS 3.2)
         GIT_REPOSITORY ${EIGEN_GIT_URL}
         GIT_TAG ${EIGEN_GIT_TAG}
         UPDATE_COMMAND ""
-        CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${EIGEN_INSTALL_DIR}
+        CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${EIGEN_INSTALL_DIR} -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER} -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
         )
 else()
     ExternalProject_Add(
@@ -38,7 +38,7 @@ else()
         GIT_REPOSITORY ${EIGEN_GIT_URL}
         GIT_TAG ${EIGEN_GIT_TAG}
         UPDATE_COMMAND ""
-        CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${EIGEN_INSTALL_DIR}
+        CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${EIGEN_INSTALL_DIR} -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER} -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
         BUILD_BYPRODUCTS "${EIGEN_INSTALL_DIR}/include/eigen3"
         )
 endif()

cmake/external_gtest.cmake

@@ -31,6 +31,7 @@ if (${CMAKE_VERSION} VERSION_LESS 3.2)
         # Disable install step
         INSTALL_COMMAND ""
         UPDATE_COMMAND ""
+        CMAKE_ARGS -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER} -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
         )
 else()
     ExternalProject_Add(
@@ -41,6 +42,7 @@ else()
         # Disable install step
         INSTALL_COMMAND ""
         UPDATE_COMMAND ""
+        CMAKE_ARGS -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER} -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
         BUILD_BYPRODUCTS "${CMAKE_CURRENT_BINARY_DIR}/gtest/src/gtest-build/googlemock/gtest/libgtest.a"
         )
 endif()

cmake/external_llvm.cmake

@@ -15,47 +15,69 @@ include(ExternalProject)
 
 if((NGRAPH_CPU_ENABLE OR NGRAPH_GPU_ENABLE) AND (NOT ${CMAKE_SYSTEM_NAME} MATCHES "Darwin") AND
                          (NOT ${CMAKE_SYSTEM_NAME} MATCHES "Windows"))
-    message(STATUS "Fetching LLVM from llvm.org")
-    set(LLVM_RELEASE_URL http://releases.llvm.org/5.0.0/clang+llvm-5.0.0-linux-x86_64-ubuntu16.04.tar.xz)
-    set(LLVM_SHA1_HASH 9cb81c92aa4d3f9707a9b8413c4d24b8dee90c59)
+    set(CMAKE_DISABLE_SOURCE_CHANGES ON)
+    set(CMAKE_DISABLE_IN_SOURCE_BUILD ON)
 
-    # Override default LLVM binaries
-    if(PREBUILT_LLVM)
-        if(NOT DEFINED PREBUILT_LLVM_HASH)
-            message(FATAL_ERROR "SHA1 hash of prebuilt llvm tarball not provided in PREBUILT_LLVM_HASH.")
-        endif()
-        set(LLVM_RELEASE_URL ${PREBUILT_LLVM})
-        set(LLVM_SHA1_HASH ${PREBUILT_LLVM_HASH})
-    endif()
+    set(RELEASE_TAG release_50)
+
+    set(EXTERNAL_INSTALL_LOCATION ${CMAKE_CURRENT_BINARY_DIR}/ext_llvm-prefix)
+
+    ExternalProject_Add(clang
+        GIT_REPOSITORY https://github.com/llvm-mirror/clang.git
+        GIT_TAG ${RELEASE_TAG}
+        CONFIGURE_COMMAND ""
+        BUILD_COMMAND ""
+        INSTALL_COMMAND ""
+        UPDATE_COMMAND ""
+    )
+
+    ExternalProject_Get_Property(clang SOURCE_DIR)
+    set(CLANG_SOURCE_DIR ${SOURCE_DIR})
+
+    ExternalProject_Add(openmp
+        GIT_REPOSITORY https://github.com/llvm-mirror/openmp.git
+        GIT_TAG ${RELEASE_TAG}
+        CONFIGURE_COMMAND ""
+        BUILD_COMMAND ""
+        INSTALL_COMMAND ""
+        UPDATE_COMMAND ""
+    )
 
-    # The 'BUILD_BYPRODUCTS' argument was introduced in CMake 3.2.
-    if(${CMAKE_VERSION} VERSION_LESS 3.2)
-        ExternalProject_Add(
-            ext_llvm
-            URL ${LLVM_RELEASE_URL}
-            URL_HASH SHA1=${LLVM_SHA1_HASH}
-            CONFIGURE_COMMAND ""
-            BUILD_COMMAND ""
-            INSTALL_COMMAND ""
-            UPDATE_COMMAND ""
-            )
+    ExternalProject_Get_Property(openmp SOURCE_DIR)
+    set(OPENMP_SOURCE_DIR ${SOURCE_DIR})
+
+    if(DEFINED CMAKE_ASM_COMPILER)
+        set(LLVM_CMAKE_ASM_COMPILER ${CMAKE_ASM_COMPILER})
     else()
-        ExternalProject_Add(
-            ext_llvm
-            URL ${LLVM_RELEASE_URL}
-            URL_HASH SHA1=${LLVM_SHA1_HASH}
-            CONFIGURE_COMMAND ""
-            BUILD_COMMAND ""
-            INSTALL_COMMAND ""
-            UPDATE_COMMAND ""
-            BUILD_BYPRODUCTS "${CMAKE_CURRENT_BINARY_DIR}/ext_llvm-prefix/src/ext_llvm/lib/libLLVMCore.a"
-            )
+        set(LLVM_CMAKE_ASM_COMPILER ${CMAKE_C_COMPILER})
     endif()
 
-    ExternalProject_Get_Property(ext_llvm source_dir)
-    set(LLVM_INCLUDE_DIR "${source_dir}/include" PARENT_SCOPE)
-    set(LLVM_INCLUDE_DIR "${source_dir}/include")  # used by other external projects in current scope
-    set(LLVM_LIB_DIR "${source_dir}/lib" PARENT_SCOPE)
+    ExternalProject_Add(ext_llvm
+        DEPENDS clang openmp
+        GIT_REPOSITORY https://github.com/llvm-mirror/llvm.git
+        GIT_TAG ${RELEASE_TAG}
+        CMAKE_ARGS -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
+                   -DCMAKE_ASM_COMPILER=${LLVM_CMAKE_ASM_COMPILER}
+                   -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
+                   -DCMAKE_INSTALL_PREFIX=${EXTERNAL_INSTALL_LOCATION}
+                   -DCMAKE_BUILD_TYPE=Release
+                   -DLLVM_ENABLE_ASSERTIONS=OFF
+                   -DLLVM_INCLUDE_TESTS=OFF
+                   -DLLVM_INCLUDE_EXAMPLES=OFF
+                   -DLLVM_BUILD_TOOLS=ON
+                   -DLLVM_TARGETS_TO_BUILD=X86
+                   -DLLVM_EXTERNAL_CLANG_SOURCE_DIR=${CLANG_SOURCE_DIR}
+                   -DLLVM_EXTERNAL_OPENMP_SOURCE_DIR=${OPENMP_SOURCE_DIR}
+        UPDATE_COMMAND ""
+    )
+
+    ExternalProject_Get_Property(ext_llvm SOURCE_DIR)
+    ExternalProject_Get_Property(ext_llvm BINARY_DIR)
+    ExternalProject_Get_Property(ext_llvm INSTALL_DIR)
+
+    set(LLVM_INCLUDE_DIR "${INSTALL_DIR}/include" PARENT_SCOPE)
+    set(LLVM_INCLUDE_DIR "${SOURCE_DIR}/include")  # used by other external projects in current scope
+    set(LLVM_LIB_DIR "${INSTALL_DIR}/lib" PARENT_SCOPE)
 
     set(LLVM_LINK_LIBS
         clangTooling
@@ -135,5 +157,4 @@ if((NGRAPH_CPU_ENABLE OR NGRAPH_GPU_ENABLE) AND (NOT ${CMAKE_SYSTEM_NAME} MATCHE
         z
         m
         PARENT_SCOPE)
-
 endif()

cmake/external_llvm_prebuilt.cmake

+# Copyright 2017 Nervana Systems Inc.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+include(ExternalProject)
+
+if((NGRAPH_CPU_ENABLE OR NGRAPH_GPU_ENABLE) AND (NOT ${CMAKE_SYSTEM_NAME} MATCHES "Darwin") AND
+                         (NOT ${CMAKE_SYSTEM_NAME} MATCHES "Windows"))
+    message(STATUS "Fetching LLVM from llvm.org")
+
+    # Override default LLVM binaries
+    if(NOT DEFINED LLVM_TARBALL_URL)
+        set(LLVM_TARBALL_URL http://releases.llvm.org/5.0.1/clang+llvm-5.0.1-x86_64-linux-gnu-ubuntu-16.04.tar.xz)
+    endif()
+
+    if(NOT DEFINED LLVM_SHA1_HASH)
+        set(LLVM_SHA1_HASH 2fddf9a90b182fa594786be6923e58f5ead71e9c)
+    endif()
+
+    # The 'BUILD_BYPRODUCTS' argument was introduced in CMake 3.2.
+    if(${CMAKE_VERSION} VERSION_LESS 3.2)
+        ExternalProject_Add(
+            ext_llvm
+            URL ${LLVM_TARBALL_URL}
+            URL_HASH SHA1=${LLVM_SHA1_HASH}
+            CONFIGURE_COMMAND ""
+            BUILD_COMMAND ""
+            INSTALL_COMMAND ""
+            UPDATE_COMMAND ""
+            )
+    else()
+        ExternalProject_Add(
+            ext_llvm
+            URL ${LLVM_TARBALL_URL}
+            URL_HASH SHA1=${LLVM_SHA1_HASH}
+            CONFIGURE_COMMAND ""
+            BUILD_COMMAND ""
+            INSTALL_COMMAND ""
+            UPDATE_COMMAND ""
+            BUILD_BYPRODUCTS "${CMAKE_CURRENT_BINARY_DIR}/ext_llvm-prefix/src/ext_llvm/lib/libLLVMCore.a"
+            )
+    endif()
+
+    ExternalProject_Get_Property(ext_llvm source_dir)
+    set(LLVM_INCLUDE_DIR "${source_dir}/include" PARENT_SCOPE)
+    set(LLVM_INCLUDE_DIR "${source_dir}/include")  # used by other external projects in current scope
+    set(LLVM_LIB_DIR "${source_dir}/lib" PARENT_SCOPE)
+
+    set(LLVM_LINK_LIBS
+        clangTooling
+        clangFrontendTool
+        clangFrontend
+        clangDriver
+        clangSerialization
+        clangCodeGen
+        clangParse
+        clangSema
+        clangStaticAnalyzerFrontend
+        clangStaticAnalyzerCheckers
+        clangStaticAnalyzerCore
+        clangAnalysis
+        clangARCMigrate
+        clangRewriteFrontend
+        clangEdit
+        clangAST
+        clangLex
+        clangBasic
+        LLVMLTO
+        LLVMPasses
+        LLVMObjCARCOpts
+        LLVMSymbolize
+        LLVMDebugInfoPDB
+        LLVMDebugInfoDWARF
+        LLVMMIRParser
+        LLVMCoverage
+        LLVMTableGen
+        LLVMDlltoolDriver
+        LLVMOrcJIT
+        LLVMObjectYAML
+        LLVMLibDriver
+        LLVMOption
+        LLVMX86Disassembler
+        LLVMX86AsmParser
+        LLVMX86CodeGen
+        LLVMGlobalISel
+        LLVMSelectionDAG
+        LLVMAsmPrinter
+        LLVMDebugInfoCodeView
+        LLVMDebugInfoMSF
+        LLVMX86Desc
+        LLVMMCDisassembler
+        LLVMX86Info
+        LLVMX86AsmPrinter
+        LLVMX86Utils
+        LLVMMCJIT
+        LLVMLineEditor
+        LLVMInterpreter
+        LLVMExecutionEngine
+        LLVMRuntimeDyld
+        LLVMCodeGen
+        LLVMTarget
+        LLVMCoroutines
+        LLVMipo
+        LLVMInstrumentation
+        LLVMVectorize
+        LLVMScalarOpts
+        LLVMLinker
+        LLVMIRReader
+        LLVMAsmParser
+        LLVMInstCombine
+        LLVMTransformUtils
+        LLVMBitWriter
+        LLVMAnalysis
+        LLVMProfileData
+        LLVMObject
+        LLVMMCParser
+        LLVMMC
+        LLVMBitReader
+        LLVMCore
+        LLVMBinaryFormat
+        LLVMSupport
+        LLVMDemangle
+        tinfo
+        z
+        m
+        PARENT_SCOPE)
+
+endif()

cmake/external_mkldnn.cmake

@@ -17,7 +17,7 @@ include(ExternalProject)
 # Fetch and install MKL-DNN
 #----------------------------------------------------------------------------------------------------------
 
-if(NOT ${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
+if(NGRAPH_CPU_ENABLE AND NOT ${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
 
     set(MKLDNN_GIT_REPO_URL https://github.com/intel/mkl-dnn)
     set(MKLDNN_GIT_TAG "3e1f8f5")

cmake/external_tbb.cmake

@@ -15,15 +15,17 @@
 # Fetch and configure TBB
 #----------------------------------------------------------------------------------------------------------
 
-set(TBB_GIT_REPO_URL https://github.com/01org/tbb)
-set(TBB_GIT_TAG "tbb_2018")
+if(NGRAPH_TBB_ENABLE)
+    set(TBB_GIT_REPO_URL https://github.com/01org/tbb)
+    set(TBB_GIT_TAG "tbb_2018")
 
-if(NOT ${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
-    configure_file(${CMAKE_SOURCE_DIR}/cmake/tbb_fetch.cmake.in ${CMAKE_CURRENT_BINARY_DIR}/tbb/CMakeLists.txt)
-    execute_process(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" .
-      WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/tbb")
-    execute_process(COMMAND "${CMAKE_COMMAND}" --build .
-      WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/tbb")
+    if(NOT ${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
+        configure_file(${CMAKE_SOURCE_DIR}/cmake/tbb_fetch.cmake.in ${CMAKE_CURRENT_BINARY_DIR}/tbb/CMakeLists.txt)
+        execute_process(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" .
+          WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/tbb")
+        execute_process(COMMAND "${CMAKE_COMMAND}" --build .
+          WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/tbb")
 
-    set(TBB_ROOT ${CMAKE_CURRENT_BINARY_DIR}/tbb/tbb-src PARENT_SCOPE)
+        set(TBB_ROOT ${CMAKE_CURRENT_BINARY_DIR}/tbb/tbb-src PARENT_SCOPE)
+    endif()
 endif()

contrib/docker/Makefile

@@ -29,8 +29,8 @@ DBUILD_DIR = ${DIR}/contrib/docker/.build-${DBUILD_VERSION}
 # For gcc builds, we do NOT regard warnings as errors
 # For clang builds, we DO make warnings into errors
 CMAKE_OPTIONS_COMMON=-DNGRAPH_BUILD_DOXYGEN_DOCS=ON -DNGRAPH_BUILD_SPHINX_DOCS=ON -DCMAKE_BUILD_TYPE=RelWithDebInfo
-CMAKE_OPTIONS_GCC=$CMAKE_OPTIONS_COMMON -DNGRAPH_INSTALL_PREFIX=${DOCKUSER_HOME}/ngraph-cpp-test/BUILD-GCC/ngraph_dist
-CMAKE_OPTIONS_CLANG=$CMAKE_OPTIONS_COMMON -DNGRAPH_INSTALL_PREFIX=${DOCKUSER_HOME}/ngraph-cpp-test/BUILD-CLANG/ngraph_dist -DCMAKE_CXX_COMPILER=clang++-3.9 -DCMAKE_C_COMPILER=clang-3.9 -DNGRAPH_WARNINGS_AS_ERRORS=ON
+CMAKE_OPTIONS_GCC=$CMAKE_OPTIONS_COMMON -DNGRAPH_INSTALL_PREFIX=${DOCKUSER_HOME}/ngraph-cpp-test/BUILD-GCC/ngraph_dist -DNGRAPH_USE_PREBUILT_LLVM=TRUE
+CMAKE_OPTIONS_CLANG=$CMAKE_OPTIONS_COMMON -DNGRAPH_INSTALL_PREFIX=${DOCKUSER_HOME}/ngraph-cpp-test/BUILD-CLANG/ngraph_dist -DCMAKE_CXX_COMPILER=clang++-3.9 -DCMAKE_C_COMPILER=clang-3.9 -DNGRAPH_WARNINGS_AS_ERRORS=ON -DNGRAPH_USE_PREBUILT_LLVM=TRUE
 
 CALLER_UID := $(shell id -u)
 CALLER_GID := $(shell id -g)

src/ngraph/CMakeLists.txt

@@ -137,14 +137,16 @@ if (NGRAPH_CPU_ENABLE AND LLVM_INCLUDE_DIR AND
     MKLDNN_INCLUDE_DIR)
     find_package(ZLIB REQUIRED)
 
-    include(${TBB_ROOT}/cmake/TBBBuild.cmake)
-    tbb_build(TBB_ROOT ${TBB_ROOT} MAKE_ARGS compiler=clang tbb_build_dir=${CMAKE_CURRENT_BINARY_DIR}/tbb_build
-              tbb_build_prefix=tbb CONFIG_DIR TBB_DIR)
-    find_package(TBB REQUIRED tbb)
-    if (NOT TBB_FOUND)
-        message(FATAL_ERROR "TBB is needed by the CPU backend and was not found")
-    else()
-        message(STATUS "Found TBB and imported target ${TBB_IMPORTED_TARGETS}")
+    if (NGRAPH_TBB_ENABLE)
+        include(${TBB_ROOT}/cmake/TBBBuild.cmake)
+        tbb_build(TBB_ROOT ${TBB_ROOT} MAKE_ARGS tbb_build_dir=${CMAKE_CURRENT_BINARY_DIR}/tbb_build
+                  tbb_build_prefix=tbb CONFIG_DIR TBB_DIR)
+        find_package(TBB REQUIRED tbb)
+        if (NOT TBB_FOUND)
+            message(FATAL_ERROR "TBB is needed by the CPU backend and was not found")
+        else()
+            message(STATUS "Found TBB and imported target ${TBB_IMPORTED_TARGETS}")
+            endif()
     endif()
 
     include_directories(SYSTEM ${LLVM_INCLUDE_DIR} ${MKLDNN_INCLUDE_DIR})
@@ -172,8 +174,14 @@ if (NGRAPH_CPU_ENABLE AND LLVM_INCLUDE_DIR AND
     # The built-in headers are in a version-specific directory
     # This must be kept in sync with the LLVM + Clang version in use
     set_source_files_properties(codegen/compiler.cpp PROPERTIES COMPILE_FLAGS "-fno-rtti")
-    set_source_files_properties(codegen/compiler.cpp PROPERTIES COMPILE_DEFINITIONS
-      "EIGEN_HEADERS_PATH=\"${EIGEN_INCLUDE_DIR}\";MKLDNN_HEADERS_PATH=\"${MKLDNN_INCLUDE_DIR}\";CLANG_BUILTIN_HEADERS_PATH=\"${LLVM_LIB_DIR}/clang/5.0.0/include\";TBB_HEADERS_PATH=\"${TBB_ROOT}/include\";NGRAPH_HEADERS_PATH=\"${NGRAPH_INCLUDE_PATH}\";INSTALLED_HEADERS_PATH=\"${CMAKE_INSTALL_PREFIX}/include\";")
+    if (NGRAPH_TBB_ENABLE)
+        set_source_files_properties(codegen/compiler.cpp PROPERTIES COMPILE_DEFINITIONS
+          "EIGEN_HEADERS_PATH=\"${EIGEN_INCLUDE_DIR}\";MKLDNN_HEADERS_PATH=\"${MKLDNN_INCLUDE_DIR}\";CLANG_BUILTIN_HEADERS_PATH=\"${LLVM_LIB_DIR}/clang/5.0.1/include\";TBB_HEADERS_PATH=\"${TBB_ROOT}/include\";NGRAPH_HEADERS_PATH=\"${NGRAPH_INCLUDE_PATH}\";INSTALLED_HEADERS_PATH=\"${CMAKE_INSTALL_PREFIX}/include\";NGRAPH_TBB_ENABLE;")
+        set_source_files_properties(runtime/cpu/cpu_external_function.cpp PROPERTIES COMPILE_DEFINITIONS "NGRAPH_TBB_ENABLE")
+    else()
+        set_source_files_properties(codegen/compiler.cpp PROPERTIES COMPILE_DEFINITIONS
+          "EIGEN_HEADERS_PATH=\"${EIGEN_INCLUDE_DIR}\";MKLDNN_HEADERS_PATH=\"${MKLDNN_INCLUDE_DIR}\";CLANG_BUILTIN_HEADERS_PATH=\"${LLVM_LIB_DIR}/clang/5.0.1/include\";NGRAPH_HEADERS_PATH=\"${NGRAPH_INCLUDE_PATH}\";INSTALLED_HEADERS_PATH=\"${CMAKE_INSTALL_PREFIX}/include\";")
+    endif()
     set(NGRAPH_CPU_DEBUGINFO_ENABLE 0 CACHE STRING "Enable debuginfo in the CPU backend")
     set_property(SOURCE codegen/compiler.cpp APPEND_STRING PROPERTY COMPILE_DEFINITIONS
       "NGCPU_DEBUGINFO=${NGRAPH_CPU_DEBUGINFO_ENABLE};")
@@ -292,7 +300,7 @@ if (NOT APPLE)
         DESTINATION "${NGRAPH_INSTALL_LIB}"
     )
 
-    if (NGRAPH_CPU_ENABLE)
+    if (NGRAPH_TBB_ENABLE)
         install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/tbb_build/tbb_release/
             DESTINATION ${NGRAPH_INSTALL_LIB}
             FILES_MATCHING PATTERN "libtbb.so.*"

src/ngraph/codegen/compiler.cpp

@@ -270,6 +270,9 @@ std::unique_ptr<codegen::Module>
                                      const string& source)
 {
     PreprocessorOptions& preprocessor_options = m_compiler->getInvocation().getPreprocessorOpts();
+
+    preprocessor_options.RetainRemappedFileBuffers = true;
+
     if (!m_precompiled_header_valid && m_precomiled_header_source.empty() == false)
     {
         generate_pch(m_precomiled_header_source);

src/ngraph/json.hpp

@@ -66,7 +66,12 @@ SOFTWARE.
         #error "unsupported Clang version - see https://github.com/nlohmann/json#supported-compilers"
     #endif
 #elif defined(__GNUC__) && !(defined(__ICC) || defined(__INTEL_COMPILER))
-    #if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) < 40900
+    // [Modified by Intel] The minimum GCC version below has been changed to
+    // gcc-4.8.5, from gcc-4.9.0. This library is not warranted to work with
+    // 4.8.5 due to certain compiler/runtime bugs, but testing seems to
+    // indicate that our usage of it is not actually triggering those bugs,
+    // since the relevant templates do not happen to be instantiated.
+    #if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) < 40805
         #error "unsupported GCC version - see https://github.com/nlohmann/json#supported-compilers"
     #endif
 #endif

src/ngraph/runtime/cpu/cpu_external_function.cpp

@@ -236,9 +236,14 @@ void runtime::cpu::CPU_ExternalFunction::compile()
         R"(// Generated by the NGraph CPU backend
 #include <cmath>
 
-#include <tbb/flow_graph.h>
+)";
+
+#ifdef NGRAPH_TBB_ENABLE
+    writer += "#include <tbb/flow_graph.h>\n\n";
+#endif
 
-#include <Eigen/Dense>
+    writer +=
+        R"(#include <Eigen/Dense>
 
 #include <mkldnn.hpp>
 #include "ngraph/runtime/aligned_buffer.hpp"

src/ngraph/runtime/interpreter/int_call_frame.cpp

@@ -313,7 +313,7 @@ void runtime::interpreter::INT_CallFrame::perform_nan_check(
             const float* data = reinterpret_cast<float*>(tv->get_data_ptr());
             for (size_t i = 0; i < tv->get_element_count(); i++)
             {
-                if (isnan(data[i]))
+                if (std::isnan(data[i]))
                 {
                     if (op)
                     {
@@ -332,7 +332,7 @@ void runtime::interpreter::INT_CallFrame::perform_nan_check(
             const double* data = reinterpret_cast<double*>(tv->get_data_ptr());
             for (size_t i = 0; i < tv->get_element_count(); i++)
             {
-                if (isnan(data[i]))
+                if (std::isnan(data[i]))
                 {
                     if (op)
                     {

src/resource/CMakeLists.txt

@@ -25,12 +25,21 @@ if (NGRAPH_CPU_ENABLE AND NOT APPLE)
     set(HEADER_PATHS
         "EIGEN_HEADERS_PATH=\"${EIGEN_INCLUDE_DIR}\""
         "MKLDNN_HEADERS_PATH=\"${MKLDNN_INCLUDE_DIR}\""
-        "CLANG_BUILTIN_HEADERS_PATH=\"${LLVM_LIB_DIR}/clang/5.0.0/include\""
-        "TBB_HEADERS_PATH=\"${TBB_ROOT}/include\""
+        "CLANG_BUILTIN_HEADERS_PATH=\"${LLVM_LIB_DIR}/clang/5.0.1/include\""
         "NGRAPH_HEADERS_PATH=\"${NGRAPH_INCLUDE_PATH}\""
     )
 
+    if(NGRAPH_TBB_ENABLE)
+        list(APPEND HEADER_PATHS "TBB_HEADERS_PATH=\"${TBB_ROOT}/include\"")
+    endif()
+
+    if(NGRAPH_TBB_ENABLE)
+        set(NGRAPH_TBB_OPTION "NGRAPH_TBB_ENABLE")
+    else()
+        set(NGRAPH_TBB_OPTION "")
+    endif()
+
     message("HEADER_PATHS ${HEADER_PATHS}")
 
-    set_source_files_properties(main.cpp PROPERTIES COMPILE_DEFINITIONS "${HEADER_PATHS}")
+    set_source_files_properties(main.cpp PROPERTIES COMPILE_DEFINITIONS "${HEADER_PATHS};${NGRAPH_TBB_OPTION}")
 endif()

src/resource/main.cpp

@@ -87,13 +87,17 @@ int main(int argc, char** argv)
     vector<ResourceInfo> include_paths;
     include_paths.push_back({CLANG_BUILTIN_HEADERS_PATH, {}, true});
     include_paths.push_back({"/usr/include/x86_64-linux-gnu", {"asm", "sys", "bits", "gnu"}});
+    include_paths.push_back({"/usr/include", {"asm", "sys", "bits", "gnu"}});
     include_paths.push_back({"/usr/include", {"linux", "asm-generic"}});
     include_paths.push_back({cpp0, {"bits"}});
+    include_paths.push_back({"/usr/include/c++/4.8.2/x86_64-redhat-linux", {"bits"}});
     include_paths.push_back({cpp1, {"bits", "ext", "debug", "backward"}});
     include_paths.push_back({EIGEN_HEADERS_PATH, {}, true});
     include_paths.push_back({MKLDNN_HEADERS_PATH, {}, true});
     include_paths.push_back({NGRAPH_HEADERS_PATH, {}, true});
+#ifdef NGRAPH_TBB_ENABLE
     include_paths.push_back({TBB_HEADERS_PATH, {}, true});
+#endif
 
     if (output_path.empty())
     {

src/resource/util.cpp

@@ -130,6 +130,8 @@ void iterate_files_worker(const string& path,
 {
     DIR* dir;
     struct dirent* ent;
+
+    // If we cannot open the directory, we silently ignore it.
     if ((dir = opendir(path.c_str())) != nullptr)
     {
         while ((ent = readdir(dir)) != nullptr)
@@ -160,10 +162,6 @@ void iterate_files_worker(const string& path,
         }
         closedir(dir);
     }
-    else
-    {
-        throw std::runtime_error("error enumerating file " + path);
-    }
 }
 
 void iterate_files(const string& path,

third-party/CMakeLists.txt

@@ -14,6 +14,10 @@
 include( ../cmake/external_gtest.cmake )
 include( ../cmake/external_eigen.cmake )
 include( ../cmake/external_mkldnn.cmake )
-include( ../cmake/external_llvm.cmake )
+if (NGRAPH_USE_PREBUILT_LLVM OR DEFINED LLVM_TARBALL_URL)
+    include( ../cmake/external_llvm_prebuilt.cmake )
+else()
+    include( ../cmake/external_llvm.cmake )
+endif()
 include( ../cmake/external_tbb.cmake )
 include( ../cmake/external_argon_transformer.cmake )