Tuesday, October 23, 2012

Building Cygwin GCC 4.5.3 with --enable-plugin

Many people have tried building GCC 4.5.3 on Cygwin with the configure flag of --enable-plugin only to find that make subsequently fails with the following errors.
checking for -rdynamic... objdump: conftest: not a dynamic object no
checking for library containing dlopen... none required
checking for -fPIC -shared... no
configure: error:
Building GCC with plugin support requires a host that supports
-fPIC, -shared, -ldl and -rdynamic.
make[1]: *** [configure-gcc] Error 1

It appears that GCC would not build with --enable-plugin on Cygwin as -rdynamic and -fPIC are not applicable for a Windows PE.

Why would it need -rdynamic and -fPIC? I honestly thought those requirements are purely artificial as it would be absolutely possible to create a DLL under Windows and there is no reason why GCC can't use it.

So I set about finding out how this could be done and eventually found two articles [1][2] that allowed me to get to a working solution. I've combined the two articles to create these procedures.

Note: Start the following steps from a directory where you will have all your GCC files location in it.

1) Download and extract helper files I've put together which you'll be using later.

# obtain Cygwin GCC Plugin helper files
wget http://www.zachsaw.com/downloads/cygwin_gcc_plugin/cygwin_gcc_plugin_files.tar.bz2
tar -jxvf cygwin_gcc_plugin_files.tar.bz2

2) Run the following commands

# obtain GCC 4.5.3 (see http://gcc.gnu.org/mirrors.html for alternate mirrors)
wget http://www.netgull.com/gcc/releases/gcc-4.5.3/gcc-4.5.3.tar.bz2
tar -jxvf gcc-4.5.3.tar.bz2

# apply patches
cd gcc-4.5.3
patch -p0 < ../cygwin_gcc_plugin/finish_decl.diff
patch -p0 < ../cygwin_gcc_plugin/cygwin_enable_plugin.diff
patch -p0 < ../cygwin_gcc_plugin/cygwin_enable_plugin_cc1.diff
patch -p0 < ../cygwin_gcc_plugin/cygwin_enable_plugin_cc1plus.diff

# build GCC
cd ..
mkdir gcc-objdir
mkdir gcc-dist

cd gcc-objdir

../gcc-4.5.3/configure --disable-bootstrap --enable-version-specific-runtime-libs --enable-static --enable-shared --enable-shared-libgcc --disable-__cxa_atexit --with-dwarf2 --disable-sjlj-exceptions --enable-languages=c,c++,lto --enable-lto --enable-libssp --enable-plugin --enable-threads=posix --prefix=$PWD/../gcc-dist

make install
cd ..

*** make took 2 hours on my machine!

3) Create symlink for g++-plugin and gcc-plugin in /usr/bin to point to the newly built g++ and gcc respectively.

4) Set environment vars for $GCC_PLUGIN_DIR and $builtgcc.

export GCC_PLUGIN_DIR=`g++-plugin -print-file-name=plugin`
export builtgcc=<path>/gcc-objdir

5) Generate import libraries.

mkdir $GCC_PLUGIN_DIR/lib
cygwin_gcc_plugin/lazyimp.pl $GCC_PLUGIN_DIR/lib/libcc1.a $builtgcc/gcc/cc1.def
cygwin_gcc_plugin/lazyimp.pl $GCC_PLUGIN_DIR/lib/libcc1plus.a $builtgcc/gcc/cc1plus.def  

This will take some time.

6) Compile dll.c and archive it into libcc1.a and libcc1plus.a

gcc-plugin -O3 -Wall cygwin_gcc_plugin/dll.c -c 
ar rcs $GCC_PLUGIN_DIR/lib/libcc1.a dll.o
ar rcs $GCC_PLUGIN_DIR/lib/libcc1plus.a dll.o 

7) You now have both libcc1.a (for C) and libcc1plus.a (for C++) that you can link to when you build your gcc plugin.

To build a plugin:
g++-plugin -c -I`g++-plugin -print-file-name=plugin`/include main.cpp
g++-plugin -fPIC -shared -Wl,-e,_lazymain@12 -L`g++-plugin -print-file-name=plugin`/lib -o plugin.dll main.o -lcc1plus

Or one step build and link:
g++-plugin -shared -Wl,-e,_lazymain@12 -I`g++-plugin -print-file-name=plugin`/include -L`g++-plugin -print-file-name=plugin`/lib -o plugin.dll main.cpp -lcc1plus

Test the plugin:
g++-plugin -S -fplugin=./plugin.dll test.cpp

1 comment:

Aykut K said...


Thanks for the post. Does this apply to later gcc versions? (ie 4.8.3 or 4.9.1)