rfc: clobber all call-saved registers

[Richard Earnshaw]

> On Tue, 8 Jan 2002, Richard Henderson wrote:
> > I hate creating platform specific tests for potentially generic
> > problems, since the problem is bound to show up somewhere else
> > as well.  So what to do?  I can think of two options:
> >
> > (1) A header file somewhere in the testsuite that has a whole
> >     whale-load of ifdefs and chooses the correct asm statement,
> >
> > (2) A compiler builtin that generates the correct asm statement
> >     based on the contents of call_used[].
> >
> > Thoughts?
> 
> A trick question?  A built-in would solve the problem once and
> for all targets, new and old, it seems.  If you think a
> "self-serving" built-in looks bad, consider there are several
> EH-builtins with very limited use.  Right, the test-suite isn't
> a run-time library, but simplified test-cases are IMHO just as
> important.
> 
> I think there are different needs: call_used, non-call_used and
> all registers clobbered.  Perhaps others.

Rather than creating loads of builtins that do lots of randomly different 
things, how about a __builtin_diagnostic(type,...) that can be used for a 
whole slew of these.  Clearly these shouldn't be used anywhere outside 
testing the compiler, and we can even keep the public documentation down 
to a minimum.

R.