llvm dev - May 2014 - [LLVMdev] Compiler-RT on Buildbots

Folks,

I realised there's a "checkout_compiler_rt" option on
ClangBuilder,
which does checkout the sources, but couldn't build them on ARM. I
also don't build them during releases (yet) because the configure
script doesn't prepare the Makefiles for compiler-rt.

A while ago I got it running on ARM with CMake files, but since these
are buildbots, I'm not sure it'll be of any help. AFACT, all RT
builders do use CMake, but ClangBuilder only uses it on Windows.

Is it possible to build compiler-rt with autoconf? Do I need some
special configure flags?

If not, how hard would it be to add CMake support to ClangBuilder?
Would that be the best course of action?

cheers,
--renato

Renato Golin <renato.golin at linaro.org> writes:
> I realised there's a "checkout_compiler_rt" option on
ClangBuilder,
> which does checkout the sources, but couldn't build them on ARM. I
> also don't build them during releases (yet) because the configure
> script doesn't prepare the Makefiles for compiler-rt.
>
> A while ago I got it running on ARM with CMake files, but since these
> are buildbots, I'm not sure it'll be of any help. AFACT, all RT
> builders do use CMake, but ClangBuilder only uses it on Windows.
>
> Is it possible to build compiler-rt with autoconf? Do I need some
> special configure flags?
In the autoconf system, I'm pretty sure compiler-rt's build is triggered
by a Makefile in clang, tools/clang/runtime/compiler-rt/Makefile. This
Makefile comments "We currently only try to generate runtime libraries
on x86", so I guess that's the place to start if you want to get it to
build on ARM.
> If not, how hard would it be to add CMake support to ClangBuilder?
> Would that be the best course of action?
>
> cheers,
> --renato

On 28 May 2014 17:44, Justin Bogner <mail at justinbogner.com>
wrote:
> In the autoconf system, I'm pretty sure compiler-rt's build is
triggered
> by a Makefile in clang, tools/clang/runtime/compiler-rt/Makefile. This
> Makefile comments "We currently only try to generate runtime libraries
> on x86", so I guess that's the place to start if you want to get
it to
> build on ARM.
Ha! Thanks! I was looking on the LLVM side.

I'll give it a try, cheers!

--renato

On 28 May 2014 17:44, Justin Bogner <mail at justinbogner.com>
wrote:
> In the autoconf system, I'm pretty sure compiler-rt's build is
triggered
> by a Makefile in clang, tools/clang/runtime/compiler-rt/Makefile. This
> Makefile comments "We currently only try to generate runtime libraries
> on x86", so I guess that's the place to start if you want to get
it to
> build on ARM.
Hi Justin,

I'm having a go at autoconf-driven RT on ARM.

Without any change, autoconf doesn't even know compiler-rt is there.
Then, I added this:

ifeq ($(ARCH),ARM)
RuntimeLibrary.linux.Configs += builtins-ARM.a # rest to come once
this is working
endif

And I do get the build system to recognise, complain about ld not
supporting x86 on darwin:

warning: clang_darwin.mk: dropping arch 'i386' from lib '10.4'
(ld
does not support it)
warning: clang_darwin.mk: dropping arch 'x86_64' from lib '10.4'
(ld
does not support it)

and then the following error:

make[5]: Entering directory `/work/llvm/src/projects/compiler-rt'
make[5]: Nothing to be done for `clang_linux'.
make[5]: Leaving directory `/work/llvm/src/projects/compiler-rt'
llvm[4]: Copying runtime library linux/builtins-ARM to build dir
cp: cannot stat
‘/work/llvm/build/tools/clang/runtime/compiler-rt/clang_linux/builtins-ARM/libcompiler_rt.a’:
No such file or directory
make[4]: ***
[/work/llvm/build/Release+Asserts/lib/clang/3.5.0/lib/linux/libclang_rt.builtins-ARM.a]
Error 1
rm /work/llvm/build/Release+Asserts/lib/clang/3.5.0/lib/linux/.dir
make[4]: Leaving directory
`/work/llvm/build/tools/clang/runtime/compiler-rt'

I'm guessing the "nothing to be done" is the real culprit here,
and comes from:

BuildRuntimeLibraries:
        $(Verb) $(MAKE) -C $(COMPILERRT_SRC_ROOT) \
          ProjSrcRoot=$(COMPILERRT_SRC_ROOT) \
          ProjObjRoot=$(PROJ_OBJ_DIR) \
          CC="$(ToolDir)/clang" \
          LLVM_ANDROID_TOOLCHAIN_DIR="$(LLVM_ANDROID_TOOLCHAIN_DIR)" \
          $(COMPILERRT_MAKE_FLAGS) \
          $(RuntimeDirs:%=clang_%)

which executes the compiler-rt Makefile, which is where the
compiler-rt files are built.

This is what comes out:

make -C /work/llvm/src/projects/compiler-rt \
 ProjSrcRoot=/work/llvm/src/projects/compiler-rt \
 ProjObjRoot=/work/llvm/build/tools/clang/runtime/compiler-rt \
 CC="/work/llvm/build/Release+Asserts/bin/clang" \
 LLVM_ANDROID_TOOLCHAIN_DIR="" \
  \
 clang_linux

When I run "make info-platforms" in compiler-rt,
"clang_linux" is one
of them, so I added some ARM stuff to make/platform/clang_linux.mk to
no avail.

I'm also curious as to why the ld error mentioned above is on
clang_darwin.mk not clang_linux.mk, since this is clearly what it
should be running...

Any ideas? I'm not the most knowledgeable on autoconf/cmake stuff, as
you can see. :)

Thanks!
--renato