NO_INSTALL_RPATH breaks in-tree builds with shared libs

[hvdijk]

The README states:

LLVM in-tree build

The translator can be built as a regular LLVM subproject. To do that you need to clone it into the llvm/projects or llvm/tools directory.

git clone https://github.com/llvm/llvm-project.git
cd llvm-project/llvm/projects
git clone https://github.com/KhronosGroup/SPIRV-LLVM-Translator.git

Run (or re-run) cmake as usual for LLVM. After that you should have llvm-spirv and check-llvm-spirv targets available.

Running CMake as usual for LLVM, for me, means including -DLLVM_BUILD_LLVM_DYLIB=ON -DLLVM_LINK_LLVM_DYLIB=ON.

Following these instructions, and installing LLVM, results in:

harald@noble:~/llvm-project/main/install/aarch64-linux$ bin/llvm-spirv --help
bin/llvm-spirv: error while loading shared libraries: libLLVM.so.20.0git: cannot open shared object file: No such file or directory

This is because of

SPIRV-LLVM-Translator/tools/llvm-spirv/CMakeLists.txt

Lines 19 to 20 in c1828a9

	# llvm_setup_rpath messes with the rpath making llvm-spirv not executable from the build directory
	NO_INSTALL_RPATH

setting NO_INSTALL_RPATH. But in this LLVM configuration, setting the rpath is required to make things work, and if I comment out the NO_INSTALL_RPATH, things do work.

Would it be possible to only set NO_INSTALL_RPATH in those cases where it is necessary (I do not know which cases), or if that is not possible, to provide an option so that users can choose whether or not to set the rpath depending on what is best for their situation?

[svenvh]

Would it be possible to only set NO_INSTALL_RPATH in those cases where it is necessary (I do not know which cases)

Looking at PR #3, I suspect NO_INSTALL_RPATH was added for supporting out-of-tree builds. Perhaps we should make this conditional on LLVM_SPIRV_BUILD_EXTERNAL then?

[hvdijk]

Looking at PR #3, I suspect NO_INSTALL_RPATH was added for supporting out-of-tree builds. Perhaps we should make this conditional on LLVM_SPIRV_BUILD_EXTERNAL then?

That would work for me, and it sounds like a trivial change to make. I will try to get a PR up for it, thanks.