llvm dev - Mar 2014 - [LLVMdev] Problems building host tools when cross compiling LLVM

Hi All,

I recently ran into an issue that was posted several years back on LLVMdev [1].
A brief recap of the problem is that when cross-compiling LLVM itself the
configure/make scripts get confused when creating the needed build host tools.
For example, building and configuring like:

  CC_FOR_BUILD='i686-pc-linux-gnu-gcc'
CXX_FOR_BUILD='i686-pc-linux-gnu-g++'
  CXX='i686-mingw32-g++' CC='i686-mingw32-gcc'
LD='i686-mingw32-ld' /scratch
  /meadori/llvm-trunk/src/trunk/configure --host=i686-mingw32

  CC_FOR_BUILD='i686-pc-linux-gnu-gcc'
CXX_FOR_BUILD='i686-pc-linux-gnu-g++'
  CXX='i686-mingw32-g++' CC='i686-mingw32-gcc'
LD='i686-mingw32-ld' make

causes the following build break:

  checking whether the C compiler works... configure: error: cannot run C
  compiled programs.
  If you meant to cross compile, use `--host'.
  See `config.log' for more details.

The 'config.log' shows that i686-mingw32-gcc is being used to create
executables for the build host:

  configure:2185: checking for C compiler default output file name
  configure:2212: i686-mingw32-gcc    conftest.c  >&5
  configure:2215: $? = 0
  configure:2261: result: a.exe
  configure:2266: checking whether the C compiler works
  configure:2276: ./a.exe
  run-detectors: unable to find an interpreter for ./a.exe
  configure:2279: $? = 2

The patch mentioned in [1] does fix the issue.

Is there any particular reason that patch was not applied or shouldn't be?

[1] http://lists.cs.uiuc.edu/pipermail/llvmdev/2010-November/036651.html

-- 
Meador Inge
CodeSourcery / Mentor Embedded

On Tue, Mar 18, 2014 at 9:55 AM, Meador Inge <meadori at codesourcery.com>
wrote:
> Hi All,
>
> I recently ran into an issue that was posted several years back on LLVMdev
[1].
> A brief recap of the problem is that when cross-compiling LLVM itself the
> configure/make scripts get confused when creating the needed build host
tools.
> For example, building and configuring like:
>
>   CC_FOR_BUILD='i686-pc-linux-gnu-gcc'
CXX_FOR_BUILD='i686-pc-linux-gnu-g++'
>   CXX='i686-mingw32-g++' CC='i686-mingw32-gcc'
LD='i686-mingw32-ld' /scratch
>   /meadori/llvm-trunk/src/trunk/configure --host=i686-mingw32
>
>   CC_FOR_BUILD='i686-pc-linux-gnu-gcc'
CXX_FOR_BUILD='i686-pc-linux-gnu-g++'
>   CXX='i686-mingw32-g++' CC='i686-mingw32-gcc'
LD='i686-mingw32-ld' make
>
> causes the following build break:
>
>   checking whether the C compiler works... configure: error: cannot run C
>   compiled programs.
>   If you meant to cross compile, use `--host'.
>   See `config.log' for more details.
>
> The 'config.log' shows that i686-mingw32-gcc is being used to
create
> executables for the build host:
>
>   configure:2185: checking for C compiler default output file name
>   configure:2212: i686-mingw32-gcc    conftest.c  >&5
>   configure:2215: $? = 0
>   configure:2261: result: a.exe
>   configure:2266: checking whether the C compiler works
>   configure:2276: ./a.exe
>   run-detectors: unable to find an interpreter for ./a.exe
>   configure:2279: $? = 2
>
> The patch mentioned in [1] does fix the issue.
>
> Is there any particular reason that patch was not applied or shouldn't
be?
>
I missed it coming across the first time (and that's a long time ago).
I haven't had a chance to look at it and the archives don't have the
actual patch. Can you send it?

-eric
> [1] http://lists.cs.uiuc.edu/pipermail/llvmdev/2010-November/036651.html
>
> --
> Meador Inge
> CodeSourcery / Mentor Embedded

On 03/18/2014 01:51 PM, Eric Christopher wrote:
> I missed it coming across the first time (and that's a long time ago).
> I haven't had a chance to look at it and the archives don't have
the
> actual patch. Can you send it?
Sure.  See attached.  This is the same as the patch provided by Ekaterina
Sanina in the thread I linked.

I can build fine with this applied for the scenario I described and the changes
seem reasonable, but I am not all that familiar with the Makefile bits and
might be missing something.

-- 
Meador Inge
CodeSourcery / Mentor Embedded
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