[Bug target/63901] msp430 multilib must distinguish mhwmult

[pab at pabigot dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63901

--- Comment #5 from Peter A. Bigot <pab at pabigot dot com> ---
Yes, that could work.  msp430mcu in mspgcc days did a lot more than specs
fragments; if interested see the relevant material (BSD-3-Clause) is in the
msp430mcu repository at:
https://sourceforge.net/p/mspgcc/msp430mcu/ci/master/tree/

I still prefer the specs approach because it's nicer for the users.  But I'm
coming to accept the alternative you suggest.

So yes:  remove -mmcu interpretation from gcc and require people to provide all
the relevant specifications explicitly (defaulting to -mcpu=430 and
-mhwmult=none).  Implement a proper multilib demux based on both -mcpu and
-mhwmult, rather than making all libc users take on the overhead of software
multiply routines.  (Ick.)

Providing a tool that identifies the right -m* options for a specific MCU is
TI's responsibility.  They already do part of the job by providing the
device-specific headers and linker scripts (maybe someday as versioned
releases).  Adding an msp430-elf-mcu-options script should be less than a day's
effort for them.