[build] Modify build script to support a cross-compiling toolchain

Also modified cmake/Modules/GetClangResourceDir.cmake to work around a missing
definition for PACKAGE_VERSION when cross-compiling OpenMP libraries.

Author: bryanpkc

build-llvm-project.sh

@@ -4,13 +4,14 @@
 TARGET="X86"
 BUILD_TYPE="Release"
 INSTALL_PREFIX="/usr/local"
+CROSS_TARGETS=""
 NPROC=1
 USE_CCACHE="0"
 DO_INSTALL="0"
 USE_SUDO="0"
 C_COMPILER_PATH="/usr/bin/gcc"
 CXX_COMPILER_PATH="/usr/bin/g++"
-LLVM_ENABLE_PROJECTS="clang;openmp"
+LLVM_EXTRA_PROJECTS=""
 EXTRA_CMAKE_OPTS=""
 VERBOSE=""
 
@@ -19,56 +20,50 @@ set -e # Exit script on first error.
 function print_usage {
     echo "Usage: ./build-llvm-project.sh [options]";
     echo "";
-    echo "Build and install classic-flang-llvm-project.";
+    echo "Build and install classic-flang-llvm-project (including clang, lld, and openmp).";
     echo "Run this script in a directory with project sources.";
     echo "Example:";
     echo "  $ git clone https://github.com/flang-compiler/classic-flang-llvm-project";
     echo "  $ cd classic-flang-llvm-project";
-    echo "  $ .github/workflows/build-llvm-project.sh -t X86 -p /install/prefix/ \\";
-    echo "  $ -a /usr/bin/gcc-10 -b /usr/bin/g++-10 -i -s";
+    echo "  $ ./build-llvm-project.sh -t X86 -p /opt/classic-flang/ -i -s";
     echo "";
     echo "Options:";
     echo "  -t  Target to build for (X86, AArch64, PowerPC). Default: X86";
     echo "  -d  Set the CMake build type. Default: Release";
     echo "  -p  Install prefix. Default: /usr/local";
+    echo "  -X  Cross-compile OpenMP for given list of target triples. Default: none";
     echo "  -n  Number of parallel jobs. Default: 1";
     echo "  -c  Use ccache. Default: 0 - do not use ccache";
     echo "  -i  Install the build. Default 0 - just build, do not install";
     echo "  -s  Use sudo to install. Default: 0 - do not use sudo";
     echo "  -a  C compiler path. Default: /usr/bin/gcc";
     echo "  -b  C++ compiler path. Default: /usr/bin/g++";
-    echo "  -e  List of the LLVM sub-projects to build. Default: clang;openmp";
+    echo "  -e  List of additional LLVM sub-projects to build. Default: none";
     echo "  -x  Extra CMake options. Default: ''";
     echo "  -v  Enable verbose output";
 }
 
-while getopts "t:d:p:n:cisa:b:e:x:v?" opt; do
+while getopts "t:d:p:X:n:cisa:b:e:x:v?" opt; do
     case "$opt" in
         t) TARGET=$OPTARG;;
         d) BUILD_TYPE=$OPTARG;;
         p) INSTALL_PREFIX=$OPTARG;;
+        X) CROSS_TARGETS=$OPTARG;;
         n) NPROC=$OPTARG;;
         c) USE_CCACHE="1";;
         i) DO_INSTALL="1";;
         s) USE_SUDO="1";;
         a) C_COMPILER_PATH=$OPTARG;;
         b) CXX_COMPILER_PATH=$OPTARG;;
-        e) LLVM_ENABLE_PROJECTS=$OPTARG;;
+        e) LLVM_EXTRA_PROJECTS=$OPTARG;;
         x) EXTRA_CMAKE_OPTS="$OPTARG";;
         v) VERBOSE="1";;
         ?) print_usage; exit 0;;
     esac
 done
 
 CMAKE_OPTIONS="-DCMAKE_INSTALL_PREFIX=$INSTALL_PREFIX \
-    -DCMAKE_BUILD_TYPE=$BUILD_TYPE \
-    -DCMAKE_C_COMPILER=$C_COMPILER_PATH \
-    -DCMAKE_CXX_COMPILER=$CXX_COMPILER_PATH \
-    -DLLVM_TARGETS_TO_BUILD=$TARGET \
-    -DLLVM_ENABLE_CLASSIC_FLANG=ON \
-    -DFLANG_BUILD_NEW_DRIVER=OFF"
-# Warning: the -DLLVM_ENABLE_PROJECTS option is specified with cmake
-# to avoid issues with nested quotation marks
+    -DCMAKE_BUILD_TYPE=$BUILD_TYPE"
 
 if [ $USE_CCACHE == "1" ]; then
   echo "Build using ccache"
@@ -77,16 +72,19 @@ if [ $USE_CCACHE == "1" ]; then
       -DCMAKE_CXX_COMPILER_LAUNCHER=ccache"
 fi
 
-if [ -n "$EXTRA_CMAKE_OPTS" ]; then
-  CMAKE_OPTIONS="$CMAKE_OPTIONS $EXTRA_CMAKE_OPTS"
-fi
-
-# Build and install
+# Build and install.
 mkdir -p build && cd build
 if [ -n "$VERBOSE" ]; then
   set -x
 fi
-cmake $CMAKE_OPTIONS -DLLVM_ENABLE_PROJECTS=$LLVM_ENABLE_PROJECTS ../llvm
+cmake $CMAKE_OPTIONS \
+    -DCMAKE_C_COMPILER=$C_COMPILER_PATH \
+    -DCMAKE_CXX_COMPILER=$CXX_COMPILER_PATH \
+    -DLLVM_ENABLE_CLASSIC_FLANG=ON \
+    -DLLVM_ENABLE_PROJECTS="clang;lld;openmp;$LLVM_EXTRA_PROJECTS" \
+    -DLLVM_TARGETS_TO_BUILD="$TARGET" \
+    $EXTRA_CMAKE_OPTS \
+    ../llvm
 set +x
 make -j$NPROC VERBOSE=$VERBOSE
 if [ $DO_INSTALL == "1" ]; then
@@ -100,3 +98,44 @@ if [ $DO_INSTALL == "1" ]; then
 fi
 cd ..
 
+# Cross-compile OpenMP libraries if requested.
+IFS=';' read -ra CROSS_TARGET_LIST <<< "$CROSS_TARGETS"
+for T in ${CROSS_TARGET_LIST[@]}; do
+  mkdir -p "build/openmp-$T"
+  pushd "build/openmp-$T"
+  CMAKE_OPTIONS="$CMAKE_OPTIONS \
+      -DCMAKE_AR=$INSTALL_PREFIX/bin/llvm-ar \
+      -DCMAKE_ASM_COMPILER=$INSTALL_PREFIX/bin/clang \
+      -DCMAKE_ASM_COMPILER_TARGET=$T \
+      -DCMAKE_C_COMPILER=$INSTALL_PREFIX/bin/clang \
+      -DCMAKE_C_COMPILER_TARGET=$T \
+      -DCMAKE_CXX_COMPILER=$INSTALL_PREFIX/bin/clang++ \
+      -DCMAKE_CXX_COMPILER_TARGET=$T \
+      -DCMAKE_RANLIB=$INSTALL_PREFIX/bin/llvm-ranlib \
+      -DCMAKE_SHARED_LINKER_FLAGS=-fuse-ld=lld"
+  if [ -n "$VERBOSE" ]; then
+    set -x
+  fi
+  cmake $CMAKE_OPTIONS \
+      -DLLVM_DEFAULT_TARGET_TRIPLE=$T \
+      -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON \
+      -DLLVM_ENABLE_RUNTIMES="openmp" \
+      -DLIBOMP_OMPT_SUPPORT=OFF \
+      -DOPENMP_ENABLE_LIBOMPTARGET=OFF \
+      -DOPENMP_ENABLE_OMPT_TOOLS=OFF \
+      -DOPENMP_LLVM_TOOLS_DIR=$PWD/../bin \
+      $EXTRA_CMAKE_OPTS \
+      ../../runtimes
+  set +x
+  make -j$NPROC VERBOSE=$VERBOSE
+  if [ $DO_INSTALL -eq 1 ]; then
+    if [ $USE_SUDO -eq 1 ]; then
+      echo "Install with sudo"
+      sudo make install
+    else
+      echo "Install without sudo"
+      make install
+    fi
+  fi
+  popd
+done

cmake/Modules/GetClangResourceDir.cmake

@@ -13,7 +13,11 @@ function(get_clang_resource_dir out_var)
     set(ret_dir bin/${CLANG_RESOURCE_DIR})
   else()
     if (NOT CLANG_VERSION_MAJOR)
-      string(REGEX MATCH "^[0-9]+" CLANG_VERSION_MAJOR ${PACKAGE_VERSION})
+      if (NOT PACKAGE_VERSION)
+        string(REGEX MATCH "^[0-9]+" CLANG_VERSION_MAJOR ${LLVM_VERSION_MAJOR})
+      else()
+        string(REGEX MATCH "^[0-9]+" CLANG_VERSION_MAJOR ${PACKAGE_VERSION})
+      endif()
     endif()
     set(ret_dir lib${LLVM_LIBDIR_SUFFIX}/clang/${CLANG_VERSION_MAJOR})
   endif()