[Caml-list] New ARM backend merged into trunk

[Benedikt Meurer <benedikt.meurer@googlemail.com>]

Dear list,

I just merged the latest patch for my new ARM backend into trunk (revision 12124). Compared to the old ARM backend, the new one does the following:

- Support for both software and hardware floating-point (VFPv3).
- Properly supports interworking with Thumb/Thumb-2 code for both OCaml and C code.
- Supports dynamic linking and large memory models (PR#5049).
- Optional support for position-independent code via a command line option -fPIC. This is disabled by default and not required for natdynlink.
- Can emit both ARM and Thumb-2 code, with avg. code size savings of 28% for Thumb-2 (quite close the optimal 30% advertised by ARM Ltd.).
- Supports both AAPCS (armel) as well as extended VFP calling conventions (armhf).
- Supports several special ARM instructions to reduce code size and latency.
- Uses standard ARM EABI runtime functions instead of relying on GCC internals.
- Supports exception backtraces.
- Supports profiling using gprof.

It'd be great to get some early feedback / testing (esp. with the upcoming Debian/Ubuntu armhf port). Note however that the object files generated by the new backend aren't compatible with old object files (and therefore also .cmxs and .a files).

Benedikt