rfc: clobber all call-saved registers

[Gabriel Dos Reis]

Richard Earnshaw <rearnsha@arm.com> writes:

| > 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.

I do like the idea.  Any objection?

-- Gaby