Re: SPE configuration in GCC

[David Edelsohn <dje at watson dot ibm dot com>]

>>>>> Mark Mitchell writes:

Mark> So, it sounds like you would consider a patch which modified rs6000.h, 
Mark> so long as all the OS header files for which particular variants were 
Mark> inappropriate then zero'd the macros.  This certainly isn't a 4.0 
Mark> change, so I'll put in my possible-changes-to-implement-for-4.1 queue, 
Mark> if you're agreed with the idea in principle.

Mark> I'm working with a customer which is distributing cross compilers to 
Mark> GNU/Linux.  They are supporting both SPE/E500 and "traditional" PowerPC. 
Mark> They use different kernels and different GLIBC builds, for these 
Mark> environments.  However, they would like to use a single compiler.  I 
Mark> think this is a valid scenario where one wants a single compiler that 
Mark> can do both SPE/E500 GNU/Linux and traditional GNU/Linux.  So, if you 
Mark> don't think the change I'm suggesting is appropriate for GNU/Linux, then 
Mark> I'll just make a separate configuration header for this customer.

	As Aldy mentioned, there already is a powerpc-linuxspe
configuration that seems to do what your customer wants.
gcc/config/rs6000/linuxspe.h makes the options active and defaults to a
8540 scheduling model, but does not enable the SPE features by default.
This will generate a single compiler that targets PPC Linux with or
without e500 features.

	I am wliling to consider a patch to rs6000.h and the other
headers, but I am not sure what benefit it provides over the
configurations that Aldy already designed and implemented.

David