Changing register for passing return value from function call

[joel@OARcorp.com]

On Mon, 8 Feb 1999, Arjan Koers wrote:

> On Mon, 8 Feb 1999 07:13:48 -0600 (CST), joel@OARcorp.com wrote:
> 
> >On Thu, 4 Feb 1999, Arjan Koers wrote:
> >
> >> Some compiler directive to use %a0 that can be placed at the function
> >> delaration and at the function calls would be nice.
> >
> >IMO it would be much easier to write a small assembly function that moved
> >the value returned from a0 to d0 than to fiddle with gcc. 
> 
> Yes, that's the way I've implemented it at the moment. However,
> because I'm not the only one that's going to use GCC this way, I would
> prefer a method that's without assembly.

If this can be hidden in a run-time support library that is automatically
linked in, then it is still not a big deal to write it in assembly.  In
this case, you are tinkering with the specs file for your target which I
personally think is easier that changing the code generation.  

But if there are lots of system libraries that follow this convention (you
have only mentioned a few routines), then I guess you are stuck.

--joel
Joel Sherrill                    Director of Research & Development
joel@OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
   Support Available             (256) 722-9985


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