Search code examples
cmakeclangtexas-instrumentscmake-modules

How to make CMake detect ar and nm if there is no dash after the toolchain prefix?

I'm working on a CMake toolchain file for the new LLVM/Clang based compiler from Texas Instruments (see ARM-CGT-CLANG-1).

CMake properly detects that it's a clang based compiler if I simply set CMAKE_C_COMPILER to the correct path of the tiarmclang binary. Unfortunately, I've noticed that it does not set CMAKE_AR, CMAKE_NM, CMAKE_READELF and CMAKE_STRIP correctly.

I've went through some of the modules included with CMake, including CMakeDetermineCCompiler and CMakeFindBinUtils. What I get from that, is that CMakeDetermineCCompiler determines the _CMAKE_TOOLCHAIN_PREFIX using a regular expression which expects a dash (-) in front of clang in the name of the compiler. This _CMAKE_TOOLCHAIN_PREFIX is later on used in CMakeFindBinUtils to prefix the names of the tools.

Unfortunately, TI decided to not include a dash in the name, which I think is the root cause of CMake not being able to detect the bin utils. I tried setting the _CMAKE_TOOLCHAIN_PREFIX from the toolchain file, but this does not work (it is overwritten in the CMakeDetermineCCompiler module).

Is there a way to have CMake find the tools automatically, despite the wonky prefix? Or is setting the variables for each binutil by hand from the toolchain file the only workaround (which I'm doing at the moment)?

Solution

  • After some further investigation, it turns out that setting the correct prefix in the cache will result in the bin utils to be discovered correctly (at least the ones that are included in the TI toolchain):

    set(_CMAKE_TOOLCHAIN_PREFIX "tiarm" CACHE INTERNAL "Toolchain prefix" FORCE)