binutils-gdb for AIX

What is this?

Its a work-in-progress fork of binutils to support AIX XCOFF to enable cross-compiling AIX C/C++ on Linux.

Why does it exist?

Developing on AIX is non-trivial and requires a dedicated power machine. Cross-compiling for development purposes allows a faster write-compile-test loop as only the testing portion requires an SSH connection to a real machine.

The goal is to be able to get binaries that work more often than not for dev and test. Production use of this is not on the cards.

Where has it got so far?

It creates object files that can be linked with both the AIX linker and the GNU linker. And fixes these bugs:

• 19153
• 21700

However... these results are often wrong:

• 32-bit

  • Compiles *.c and *.cpp files (gcc 6.4.0)
  • hello world in C (gcc 6.4.0)
  • simple exception catching in C++ from source (gcc 6.4.0)
  • function-level exception catching in C++ from source (gcc 6.4.0)
  • complex exception catching in C++ from source (gcc 6.4.0)

• 64-bit

  • Compiles *.c and *.cpp files (gcc 6.4.0)
  • hello world in C (gcc 6.4.0)
  • simple exception catching in C++ from source (gcc 6.4.0)
  • function-level exception catching in C++ from source (gcc 6.4.0)
  • complex exception catching in C++ from source (gcc 6.4.0)

All currently fail with bad relocation errors.

How do I build it?

Note: These instructions will build a toolchain in the current directory called aix6.1-toolchain. For just the binutils you don't need to fill the sysroot, for testing alongside gcc you need a sysroot from a working AIX box.

$ git clone https://github.com/JamesReynolds/binutils-gdb
$ mkdir build_binutils
$ cd build_binutils
$ ../binutils-gdb/configure --target=powerpc-ibm-aix6.1 \
               --prefix=$(pwd)/../aix6.1-toolchain \
               --with-sysroot=$(pwd)/../aix6.1-toolchain/sysroot
$ make
$ make install

How do I test it?

• Fill the sysroot directory by finding files on an AIX box that has gcc 6.3.0 installed:

AIX $ cd / ; find ./ -name *.o -o -name *.h -o -name *.exp -o -name *.a -name *.so | cpio -oLV > out.cpio
Linux $ cd $(pwd)/aix6.1-toolchain/sysroot ; cpio -imdV < out.cpio 

• Build gcc 6.4.0

This requires the following patch "gcc.patch" to fix a problem present in gcc 6.x but not 7.x:

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 67011707bfa..b08097550b9 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -33813,7 +33813,7 @@ rs6000_xcoff_declare_object_name (FILE *file, const char *name, tree decl)
   struct declare_alias_data data = {file, false};
   RS6000_OUTPUT_BASENAME (file, name);
   fputs (":\n", file);
-  symtab_node::get (decl)->call_for_symbol_and_aliases (rs6000_declare_alias, &data, true);
+  symtab_node::get_create (decl)->call_for_symbol_and_aliases (rs6000_declare_alias, &data, true);
 }
 
 /* Overide the default 'SYMBOL-.' syntax with AIX compatible 'SYMBOL-$'. */

The patched build runs as follows:

$ tar xf gcc-6.4.0.tar.gz
$ patch -p1 < gcc.patch
$ mkdir build_gcc
$ cd build_gcc
$ ../gcc-6.4.0/configure \
    --target=powerpc-ibm-aix6.1 \
    --prefix=$(pwd)/../aix6.1-toolchain \
    --with-sysroot=$(pwd)/../aix6.1-toolchain/sysroot \
    --with-gnu-as --with-gnu-ld \
    --enable-languages=c,c++ \
    --enable-version-specific-runtime-libs --disable-nls \
    --enable-decimal-float=dpd --with-cloog=no --with-ppl=no \
    --disable-libstdcxx-pch --enable-__cxa_atext
$ make
$ make install

The tests are run using an AIX box with an account linked via SSH ([email protected] in the Makefile):

$ cd test
$ ./binutils-gdb/test.sh ../aix6.1-toolchain

This will run all 32-bit tests (succeeding) and all 64-bit tests (failing).