[llvm-dev] Guidance on cross compiling LLVM with mingw-w64 and cmake

[Mike Edwards via llvm-dev]

Hi Tony,
I don't have experience with your specific circumstance, so sorry I can't
be much help there.  Thank you though for pointing out what appears to be a
typo.  CC'ing Chris Bieneman as he may be able to verify if this is correct.

Chris,
I have attached a patch which should fix the typo.  Would you mind having a
look and committing if you think it is all good?

Hope you both have a good day.

Thanks,
Mike Edwards

On Tue, Feb 9, 2016 at 8:21 PM, Tony Kelman via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> I need to build libLLVM (individual static libraries are fine at the
> moment) using mingw-w64 cross compilers, i686-w64-mingw32-gcc and
> (separately) x86_64-w64-mingw32-gcc. I'd like this to work from both
> Linux and Cygwin build environments. With autotools, this worked fine:
> ../configure --host=i686-w64-mingw32 and that's it (with mingw32-gcc-c++
> installed on Fedora 23, also works fine on Ubuntu, Cygwin, etc).
> I'm trying to recreate this with cmake so we don't get stuck on 3.8
> indefinitely. Here's what I've got so far:
>
> cmake .. -DCMAKE_C_COMPILER=/usr/bin/i686-w64-mingw32-gcc \
>   -DCMAKE_CXX_COMPILER=/usr/bin/i686-w64-mingw32-g++ \
>   -DCMAKE_SYSTEM_NAME=Windows \
>   -DCMAKE_RC_COMPILER=/usr/bin/i686-w64-mingw32-windres
> # (some older versions of cmake have issues if you don't
> # specify an absolute path to windres)
>
> When this gets to "Configuring NATIVE targets" it calls cmake again
> trying to use the same mingw compilers, but without CMAKE_SYSTEM_NAME
> set so it doesn't succeed in configuring. During the build I then get
> a "No rule to make target 'LLVMSupport'.  Stop." Full build log is at
> http://sprunge.us/bCUU
>
> I'd like to go with the default behavior of building a native version
> of TableGen, but the way that's currently set up in cmake isn't working
> here. I'm looking at cmake/modules/CrossCompile.cmake (and I think
> "toochain" on the first line is a typo?) and trying to figure out how
> to make its call to execute_process(COMMAND ${CMAKE_COMMAND} ...) not
> inherit the top-level settings for CMAKE_C_COMPILER etc from the cross
> build. Any ideas? I've tried moving my mingw settings from the command
> line to a toolchain file but that hasn't done anything different so far.
> I've also tried specifically creating a native toolchain file and
> tweaking the call to llvm_create_cross_target_internal at the end of
> CrossCompile.cmake to use it, but that hasn't worked either - keeps giving
> Could not find toolchain file: "/home/llvm/cmake/platforms/NATIVE.cmake"
>
> Is this a configuration anyone else has gotten working with cmake?
> Thanks,
> Tony
>
>
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diff --git a/cmake/modules/CrossCompile.cmake b/cmake/modules/CrossCompile.cmake
index c136dfa..9c598a6 100644
--- a/cmake/modules/CrossCompile.cmake
+++ b/cmake/modules/CrossCompile.cmake
@@ -1,4 +1,4 @@
-function(llvm_create_cross_target_internal target_name toochain buildtype)
+function(llvm_create_cross_target_internal target_name toolchain buildtype)
 
   if(NOT DEFINED LLVM_${target_name}_BUILD)
     set(LLVM_${target_name}_BUILD "${CMAKE_BINARY_DIR}/${target_name}")