llvm-orc-jit: add build-llvm.sh, enforce find_package success, and print used llvm/clang cmake config

4 files changed, 63 insertions, 2 deletions

diff --git a/content/2022-07-07-llvm-orc-jit/.gitignore b/content/2022-07-07-llvm-orc-jit/.gitignore
index 50f1b95..facd05e 100644
--- a/content/2022-07-07-llvm-orc-jit/.gitignore
+++ b/content/2022-07-07-llvm-orc-jit/.gitignore
@@ -1,3 +1,5 @@
 BUILD/
 compile_commands.json
 .cache
+install-llvm*
+src-llvm*
diff --git a/content/2022-07-07-llvm-orc-jit/CMakeLists.txt b/content/2022-07-07-llvm-orc-jit/CMakeLists.txt
index 04fe617..51989e9 100644
--- a/content/2022-07-07-llvm-orc-jit/CMakeLists.txt
+++ b/content/2022-07-07-llvm-orc-jit/CMakeLists.txt
@@ -8,7 +8,7 @@ target_compile_options(main PRIVATE -Wall -Wextra -Werror)
 
 # -- LLVM/CLANG ----------------------------------------------------------------
 
-find_package(Clang HINTS "${CLANG_INSTALL_PREFIX}/lib/cmake/clang")
+find_package(Clang REQUIRED CONFIG HINTS "${CLANG_INSTALL_PREFIX}/lib/cmake/clang")
 
 if (NOT ${CLANG_INSTALL_PREFIX} STREQUAL "/")
     # Treat custom LLVM/CLANG include path as system include path, such that
@@ -18,6 +18,11 @@ endif()
 
 target_link_libraries(main clang-cpp)
 
+message(STATUS "Using LLVMConfig.cmake: ${LLVM_CONFIG}")
+message(STATUS "LLVM version: ${LLVM_VERSION}")
+message(STATUS "Using ClangConfig.cmake: ${Clang_CONFIG}")
+message(STATUS "Clang version: ${Clang_VERSION}")
+
 # -- SANITIZER -----------------------------------------------------------------
 
 option(SANITIZER "Enable ASAN/LSAN/UBSAN" ON)
diff --git a/content/2022-07-07-llvm-orc-jit/build-llvm.sh b/content/2022-07-07-llvm-orc-jit/build-llvm.sh
new file mode 100644
index 0000000..df9d6b8
--- /dev/null
+++ b/content/2022-07-07-llvm-orc-jit/build-llvm.sh
@@ -0,0 +1,50 @@
+#!/bin/bash
+#
+# A small utility script to help me build specific llvm versions.
+#
+# ## General cmake build info
+#
+#    See [1] for an overview of the llvm cmake build and a discussion of the most
+#    frequently used cmake options.
+#
+# ## Building on low end machines
+#
+#    Builds with debug information can use a lot of RAM and disk space and is
+#    usually slower to run. You can improve RAM usage by using lld, see the
+#    LLVM_USE_LINKER option.
+#
+#    LLVM_PARALLEL_{COMPILE,LINK}_JOBS:STRING [2]
+#       Building the llvm toolchain can use a lot of resources, particularly
+#       linking. These options, when you use the Ninja generator, allow you to
+#       restrict the parallelism. For example, to avoid OOMs or going into swap,
+#       permit only one link job per 15GB of RAM available on a 32GB machine,
+#       specify -G Ninja -DLLVM_PARALLEL_LINK_JOBS=2.
+#
+# [1]: https://llvm.org/docs/CMake.html
+# [2]: https://llvm.org/docs/CMake.html#frequently-used-llvm-related-variables
+
+#TAG=llvmorg-14.0.6
+#TAG=llvmorg-15.0.0
+#TAG=llvmorg-15.0.7
+TAG=llvmorg-17.0.5
+
+SRCDIR=src-$TAG
+
+if [[ ! -d $SRCDIR ]]; then
+    git clone --depth 1 --branch $TAG https://github.com/llvm/llvm-project.git $SRCDIR
+fi
+
+cmake -S $SRCDIR/llvm -B $SRCDIR/BUILD -G Ninja \
+    -DCMAKE_C_COMPILER=clang \
+    -DCMAKE_CXX_COMPILER=clang++ \
+    -DCMAKE_INSTALL_PREFIX=$PWD/install-$TAG \
+    -DCMAKE_BUILD_TYPE=Debug \
+    -DLLVM_ENABLE_PROJECTS='clang' \
+    -DLLVM_BUILD_LLVM_DYLIB=1 \
+    -DLLVM_ENABLE_ASSERTIONS=ON \
+    -DLLVM_INCLUDE_TESTS=OFF \
+    -DLLVM_TARGETS_TO_BUILD='X86' \
+    -DLLVM_USE_LINKER=lld \
+    -DLLVM_PARALLEL_LINK_JOBS=1
+
+cmake --build $SRCDIR/BUILD --target install
diff --git a/content/2022-07-07-llvm-orc-jit/index.md b/content/2022-07-07-llvm-orc-jit/index.md
index e453f0c..0fc2f27 100644
--- a/content/2022-07-07-llvm-orc-jit/index.md
+++ b/content/2022-07-07-llvm-orc-jit/index.md
@@ -6,7 +6,7 @@ tags = ["llvm", "clang", "c++"]
 +++
 
 **EDIT**:
-- 2023-12-19: Migrate example to `llvm17`.
+- 2023-12-19: Migrate example to `LLVM-17`.
 
 Based on the in-memory compiler shared in the last post ([C to LLVM IR in
 memory using libclang](@/2022-06-18-libclang-c-to-llvm-ir/index.md)), this post
@@ -41,8 +41,12 @@ The sources are available under [llvm-orc-jit][post-src].
 The following [Makefile][post-makefile] provides a convenience wrapper to
 configure, build, and run the example with a single `make` invocation.
 
+Additionally, the [build-llvm.sh][post-build-llvm] script is provided to build
+specific LLVM versions.
+
 [post-src]: https://git.memzero.de/blog/tree/content/2022-07-07-llvm-orc-jit?h=main
 [post-makefile]: https://git.memzero.de/blog/tree/content/2022-07-07-llvm-orc-jit/Makefile?h=main
+[post-build-llvm]: https://git.memzero.de/blog/tree/content/2022-07-07-llvm-orc-jit/build-llvm.sh?h=main
 [src-clang]: https://github.com/llvm/llvm-project/tree/main/clang
 [blog-clang-in-memory]: https://blog.audio-tk.com/2018/09/18/compiling-c-code-in-memory-with-clang/
 [llvm-jit-tut]: https://www.llvm.org/docs/tutorial/BuildingAJIT1.html